Difference between revisions of "2024 DOCK tutorial 2 with PDBID 1NDV"

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== Introduction ==
 
== Introduction ==
−
DOCK is a powerful computational tool used in drug design. "Docking" refers to the identification of low energy binding conformations of a small molecule, or ligand, in an active site. There are three methods in which DOCK performs docking: rigid, fixed anchor, and flexible. DOCK also has the ability to perform a virtual screen, which is analogous to a high throughput screen often performed in wet labs. This method allows for thousands of molecules to be docked and ranked so that the highest scoring molecules can move to the next stage of testing. A virtual screen can save both time and money when compared to a traditional high throughput screen. This tutorial will guide you through the process of performing each method of docking, a virtual screen, and associated analysis using PDB 1NDV. Replace 1NDV with your target protein in this tutorial.
+
DOCK is a powerful computational tool used in drug design. "Docking" refers to the identification of low energy binding conformations of a small molecule, or ligand, in an active site. There are three methods in which DOCK performs docking: rigid, fixed anchor, and flexible. DOCK also has the ability to perform a virtual screen, which is analogous to a high throughput screen often performed in wet labs. This method allows for thousands of molecules to be docked and ranked so that the highest scoring molecules can move to the next stage of testing. A virtual screen can save both time and money when compared to a traditional high throughput screen. This tutorial will guide you through the process of performing each method of docking, a virtual screen, and associated analysis using PDB 1NDV on a HPC cluster (Seawulf). Replace 1NDV with your target protein in this tutorial.
 
=== Required Software and Skills ===
 
=== Required Software and Skills ===
 
In order to complete this tutorial [https://www.cgl.ucsf.edu/chimera/download.html UCSF Chimera] is required. Chimera is a powerful visualization tool that will aid in the preparation and analysis of the virtual screen. Please note that the newer version, Chimera X, can not be used for this tutorial as it lacks certain integrations with DOCK. While this tutorial will walk you through all steps necessary to use Chimera, it may be helpful to view this [https://ringo.ams.stonybrook.edu/index.php/Chimera tutorial] for a more in depth guide on the program.
 
In order to complete this tutorial [https://www.cgl.ucsf.edu/chimera/download.html UCSF Chimera] is required. Chimera is a powerful visualization tool that will aid in the preparation and analysis of the virtual screen. Please note that the newer version, Chimera X, can not be used for this tutorial as it lacks certain integrations with DOCK. While this tutorial will walk you through all steps necessary to use Chimera, it may be helpful to view this [https://ringo.ams.stonybrook.edu/index.php/Chimera tutorial] for a more in depth guide on the program.
  
 
It is also recommended that you have experience with Unix and vi. A Unix tutorial can be found on the site [https://ringo.ams.stonybrook.edu/index.php/Unix here] and a vi tutorial can be found [https://ringo.ams.stonybrook.edu/index.php/Vi here].
 
It is also recommended that you have experience with Unix and vi. A Unix tutorial can be found on the site [https://ringo.ams.stonybrook.edu/index.php/Unix here] and a vi tutorial can be found [https://ringo.ams.stonybrook.edu/index.php/Vi here].
 +
 
=== Set-up ===
 
=== Set-up ===
 
Before we begin, we need to set up our directories and download our file from the Protein Data Bank (PDB).
 
Before we begin, we need to set up our directories and download our file from the Protein Data Bank (PDB).
Line 11: Line 12:
 
Create a parent directory which will contain all subdirectors for each docking step. For this tutorial we will name the parent directory 1NDV_DOCK_VS. Now create the subdirectories using the following scheme.
 
Create a parent directory which will contain all subdirectors for each docking step. For this tutorial we will name the parent directory 1NDV_DOCK_VS. Now create the subdirectories using the following scheme.
  
−
[[File: |center|thumb]]
 
  
−
===== Downloading PDB 1NDV =====
+
[[File:1NDV_Chart.png|center|thumb]]
−
Visit the
+
 
 +
 
 +
===== Downloading PDB File =====
 +
Visit the RCSB Protein Data Bank (PDB) [https://www.rcsb.org website] and use the search bar to search for your target protein. As stated before, we will be using 1NDV for this tutorial.
 +
 
 +
 
 +
[[File:PDB_SearchBar.png|center|thumb|upright=4.25]]
 +
 
 +
 
 +
The page for the protein will look like this. Click the "Download Files" dropdown menu, and download the "PDB Format".
 +
 
 +
 
 +
[[File:1NDV-Download.png|thumb|center|upright=3]]
 +
 
 +
 
 +
With the PDB file saved, we are now ready to begin generating files for DOCK!
  
 
== Preparing Structure Files ==
 
== Preparing Structure Files ==
 +
To prepare structure files, the protein and ligand structures need to be prepped. It is important prepare your structure files using the following steps to ensure your files run properly and are considered correct chemical models of your system.
 +
 +
We will prep the protein and ligand structures using Chimera.
 +
 
=== Protein ===
 
=== Protein ===
 +
Required file: *Structure file from the RCSB Protein Data Bank (PDB).  *For this tutorial, is it 1ndv.pdb.
 
====Analyzing the Protein Structure:====
 
====Analyzing the Protein Structure:====
−
Open your protein.pdb in Chimera.
+
Open 1ndv.pdb in Chimera.
  
 
'''Assess the protein structure:'''
 
'''Assess the protein structure:'''
Line 25: Line 45:
 
1. Are there any missing loops?
 
1. Are there any missing loops?
  
−
2. Are there any metal coordination atoms forming key interactions with the protein?
+
2. Is there a metal coordination atom forming key interactions with the protein?
  
 
The .pdb for 1ndv from the RCSB Protein Data Bank is shown below.
 
The .pdb for 1ndv from the RCSB Protein Data Bank is shown below.
−
 
 
[[File:1ndv_raw_pdb.jpg|center|500px]]
 
[[File:1ndv_raw_pdb.jpg|center|500px]]
−
 
 
'''Assessment:'''
 
'''Assessment:'''
  
Line 37: Line 55:
 
2. Zinc coordination with the protein and a water molecule.  This zinc atom must be kept in the protein prep.
 
2. Zinc coordination with the protein and a water molecule.  This zinc atom must be kept in the protein prep.
  
 +
[[File:1ndv_coordination.jpg|center|500px]]
  
−
[[File:1ndv_coordination.jpg|center|500px]]
+
====Protein Prep====
 +
1. Select an atom on the protein
 +
 
 +
2. Select the entire protein by pressing the "up" arrow key.  You will want to keep the Zn in the complex so hold down the "shift" key and click the Zn atom to select it as well.
 +
 
 +
3. Go to the menu bar Select → Invert(all models). This will invert the selection and select waters, the ligand, and other compounds in the crystal structure that wasn't previously selected.
 +
 
 +
4. Go to the menu bar Actions → Atoms/Bonds → Delete.
 +
 
 +
5. Then save this structure with a a file name (i.e. 1ndv_protein_only.pdb). Go to the menu bar File → Save PBD. Your pdb file will now look similar to this:
 +
 
 +
[[File:1ndv_protein_only.png|center|500px]]
 +
 
 +
6. We also need to generate a .mol2 file. So go to File → Save Mol2 and give it a name 1ndv_protein_only.mol2.  The previous file as a .pdb extension and will not be overwritten as a mol2 file is separate from mol2 format.
 +
 
 +
====Adding Hydrogens and Charges====
 +
 
 +
We need to prepare the protein with hydrogens and charges. We must add hydrogens before adding charges.
 +
 
 +
7. Adding hydrogens.  To add hydrogen atoms click on: Tools → Structure Editing → AddH. This command will cause the following dialogue box to appear:
 +
 
 +
[[File:1ndv_protein_addH.png|center|300px]]
 +
 
 +
a. Click 'OK'. When the program is finished, the bottom left-hand side will say "Hydrogens added".  You may not see any changes in the structure. Here we can see hydrogens on residues surround the zinc atom. If so you can make sure by selecting a couple residues and clicking Actions → Atoms/Bonds → Show.  You can unselect these residues by clicking on the background.
 +
 
 +
[[File:1ndv protein hydrogens check.png|center|300px]]
 +
 
 +
b. Now once this check is done save your protein file with hydrogens as a .pdb (i.e 1ndv_protein_H.pdb) and .mol2 (i.e 1ndv_protein_H.mol2). It is useful to save changes in Chimera in steps as each change is not able to be undone.
 +
 
 +
8. Now we can add charges by Tools → Structure Editing → Add Charge and the following dialogue box will show up:
 +
 
 +
[[File:1ndv_protein_addcharge.png|center|300px]]
 +
 
 +
You can keep the defaults selected and click "OK".  If you have a metal coordination atom in your structure Chimera will ask you to specify the atom's charge.
 +
 
 +
[[File:1ndv protein addcharge Zn.png|center|500px]]
 +
 
 +
Once the program is finished in the bottom left hand corner will display what the total charge of the structure is.  This number should be an integer.
 +
 
 +
The protein structure is now completely prepared and ready for docking.
 +
 
 +
The final step is to save two files, a .pdb and a .mol2 file of this structure (i.e. 1ndv_protein_H_charges.pdb and 1ndv_protein_H_charges.mol2)
  
 
=== Ligand ===
 
=== Ligand ===
 +
We must first create a .pdb file with only the ligand. To do this we must select the ligand in Chimera. There are two ways to do this:
 +
 +
1.Select an atom on the ligand, and use the up arrow until the entire ligand is selected
 +
 +
-or-
 +
 +
2. Use the toolbar and click "Select" → "Structure" → "Ligand"
 +
 +
Once the ligand is selected use "Select" → "Invert" to select all other atoms present in the session.
 +
 +
Then use "Actions" → "Atoms/Bonds" → "Delete" to delete everything except the ligand.
 +
 +
It should look like this.
 +
 +
[[File:1ndv-ligand-only.png|thumb|center|upright=1.5]]
 +
 +
You can now save only the ligand in a separate .pbd file. We will name this file 1ndv_ligand_only.pdb.
 +
 +
We will also save the ligand in this state as a .mol2 file. We will name this file 1ndv_no_hydrogens_no_charges.mol2
 +
 +
We now need to add hydrogens and charges like we did previously for the protein. It is important to be careful and to cross reference the structure of the ligand in the PDB to ensure that hydrogens are being added in the right places, and that the overall charge of the ligand remains the same. After adding hydrogens, your structure should look similar to this:
 +
 +
[[File:1ndv-ligand-only-H.png|thumb|center|upright=1.5]]
 +
 +
We must now look at the structure in the PDB to ensure Chimera is adding the hydrogens in the proper place. To do this, scroll down on the PDB page of the protein until you see the table labeled "Small Molecules".
 +
 +
[[File:1ndv-small-mol.png|center|thumb|upright=1.5]]
 +
 +
Now click on the "2D Diagram" of the ligand to bring up a larger picture.
 +
 +
[[File:1ndv-small-mol-big.png|center|thumb|upright=1.5]]
 +
 +
It appears that Chimera has added an extra Hydrogen to N26. We need to remove that by simply selecting and deleting that hydrogen. The ligand should now look like this:
 +
 +
[[File:1ndv-ligand-with-H.png|thumb|center|upright=1.5]]
 +
 +
We can now add charges to the ligand. When the dialogue box appears, be sure to set the overall charge to 0 for this ligand. With this step complete we can now save a .pdb file and .mol2 with the name 1ndv_ligand_H_charge.
 +
 +
Upload all four of the .mol2 files created during the protein and ligand preparation process to Seawulf for use with DOCK.
 +
 
== Surface Spheres ==
 
== Surface Spheres ==
 +
This section will walk you through the steps necessary to identify the binding site of the protein using a function within DOCK to place surface spheres along the protein.
 
=== DMS file ===
 
=== DMS file ===
 +
In Chimera, open the 1ndv_protein_only.pdb file. Go to Actions → Surface → show. This will display the van der Waals surface of your protein. Your image should be similar to:
 +
 +
[[File:1ndv surface.png|center|500px]]
 +
 +
There may be a warning that could pop up about letting you know that a failure for disconnected additional components, such as the zinc atom, occurred.  Since we have our desired surface we can continue and close the warning box.
 +
 +
[[File:1ndv surface warning.png|center|300px]]
 +
 +
Next we need to write the .dms file.  To do this select Tools → Structure Editing → Write DMS.  You will need to give the file a name (i.e. 1ndv_surface.dms). To check if the .dms file represents the surface of the protein well we can overlay the .dms file with the protein_only file.
 +
 +
To do this, close your current session, open the 4s0v_protein_only.pdb and then open the 4s0v_surface.dms. If everything worked as it should you should see an image similar to:
 +
 +
[[File:1ndv surface dms.png|center|500px]]
 +
 +
The small dots (which is the .dms file) is perfectly aligned over the protein structure. Now that we have verified that everything looks good, we can continue.
 +
 +
The 1ndv_surface.dms can be deposited into the folder 002.surface_spheres.
 +
 
=== sphgen ===
 
=== sphgen ===
 +
Open your to your 002_surface_spheres directory and create a file to run sphgen:
 +
 +
vi INSP
 +
 +
Then hit the "Insert" key to start inserting text and type:
 +
 +
1ndv_surface.dms
 +
R
 +
X
 +
0.0
 +
4.0
 +
1.4
 +
1ndv.sph
 +
 +
Note: If you are running different filename will need to change the name of your files on the first and last line above.  Using a text editor like Sublime text or Notepad can make is easier to make these changes to your code and then you can paste into the vi editor when you are ready.
 +
 +
To save your file hit the colon/semi-colon key and type:
 +
 +
:wq!
 +
 +
to save your work.
 +
 +
Then using command line type the command below to run sphgen on your protein.
 +
 +
sphgen -i INSPH -o OUTSPH
 +
 +
Once this is completed you will see the 1ndv_binding_spheres.sph in your directory. To check the binding_sphere.sph file was generated correctly open it in Chimera with the original .pdb file.  The two structures should be aligned to each other. The image should be similar to:
 +
 +
[[File:1ndv binding spheres.png|center|500px]]
 +
 +
The binding_spheres.sph overlay well with the original protein pdb and are good to proceed to the next step.
 +
 
=== sphere selector ===
 
=== sphere selector ===
 +
This step runs a DOCK program called sphere_selector which is again run on the command line. Return to your 002.surface_spheres directory. Then type:
 +
 +
sphere_selector 1ndv_binding_spheres.sph ../001.structure/1ndv_ligand_H_charge.mol2 10.0
 +
 +
When this program has successfully completed you'll see a new file in your directory called selected_spheres.sph. This file generated spheres which should line up with the binding site of the protein. To verify this open both the selected_spheres.sph file and your original protein/ligand complex file (1ndv.pdb) in Chimera.  You should see the spheres located within the binding site of the protein similar to this picture below:
 +
 +
[[File:1ndv selected spheres.png|center|500px]]
 +
 +
To check the selected spheres are near the ligand you can either:
 +
a. Ctrl-click on a sphere and hit the "Up" arrow until all the spheres are selected. Then go to Actions → Atoms/Bonds → Hide. or
 +
b. On the Model Panel click on the Cluster 1 - selected_spheres.sph and selecte hide.
 +
 +
We can now see our ligand (green) and can confirm the selected_spheres are near our ligand.
 +
 +
[[File:1ndv selected spheres check.png|center|500px]]
 +
 
== Gridbox ==
 
== Gridbox ==
−
=== showbox ===
+
While it is possible to calculate interactions between the ligand and the entire protein surface, this is computationally expensive. In this tutorial we will define a box of interest in the active site of the protein, and DOCK will generate a grid to calculate interaction energies within this box.
−
=== grid ===
+
=== Generating the Box ===
−
== Energy Minimization for Ligand ==
+
To generate the box we use a DOCK program called showbox. This program is accessed through the command line. First navigate to your 003.gridbox directory and create a new file called showbox.in. Place the following commands into the new file:
 +
Y
 +
8.0
 +
../002.surface_spheres/selected_spheres.sph
 +
1
 +
1ndv.box.pdb
 +
 
 +
Remember to change "1ndv" to your protein name. This file may need to be modified for your system if you need a larger box. This file currently draws a box of 8.0 angstroms around the selected spheres. To change this, simply change the "8.0" in the input file.
 +
 
 +
To run this file type:
 +
showbox < showbox.in
 +
If showbox ran successfully you will now have a file named 1ndv.box.pdb in the directory.
 +
 
 +
=== Generating the Grid===
 +
Now that the box has been defined, we can generate the grid. We do this using a Dock program called grid. Make a new file called grid.in. Place the following commands into the new file:
 +
 
 +
allow_non_integral_charges                no
 +
  compute_grids                            yes
 +
  grid_spacing                              0.4
 +
  output_molecule                          no
 +
  contact_score                            no
 +
  energy_score                              yes
 +
  energy_cutoff_distance                    9999
 +
  atom_model                                a
 +
  attractive_exponent                      6
 +
  repulsive_exponent                        9
 +
  distance_dielectric                      yes
 +
  dielectric_factor                        4.
 +
  bump_filter                              yes
 +
  bump_overlap                              0.75
 +
  receptor_file                              ../001.structure/1ndv_protein_only_H_charge.mol2
 +
  box_file                                  1ndv.box.pdb
 +
  vdw_definition_file                      /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/vdw_AMBER_parm99.defn
 +
  score_grid_prefix                        grid
 +
 
 +
Be sure you are using the receptor_file and box_file for your protein.
 +
 
 +
Run the file with the following command:
 +
grid -i grid.in -o 1ndvGridInfo.out
 +
 
 +
This program will take a few minutes to run. If it ran succesfully you will see three new files in your direcotry:
 +
#grid.bmp
 +
#grid.nrg
 +
#1ndvGridInfo.out
 +
 
 +
After successfully generating the box and grid, we can begin energy minimization.
 +
 
 +
== Ligand Energy Minimization ==
 +
DOCK calculates interaction energies between the protein and the ligand. It is important that we first minimize the ligand to a low energy conformer before we dock it into the binding site of the protein to ensure accurate results.
 +
 
 +
First navigate to the 004.minization directory and create a new file called min.in. Place the follow lines in the new file.
 +
 
 +
conformer_search_type                                        rigid
 +
use_internal_energy                                          yes
 +
internal_energy_rep_exp                                      12
 +
internal_energy_cutoff                                      100.0
 +
ligand_atom_file                                          /gpfs/projects/AMS536/2024/students/group_2_1NDV/dock_screen/001.structure/1ndv_ligand_only_H_charge.mol2
 +
limit_max_ligands                                            no
 +
skip_molecule                                                no
 +
read_mol_solvation                                          no
 +
calculate_rmsd                                              yes
 +
use_rmsd_reference_mol                                      yes
 +
rmsd_reference_filename                                      /gpfs/projects/AMS536/2024/students/group_2_1NDV/dock_screen/001.structure/1ndv_ligand_only_H_charge.mol2
 +
use_database_filter                                          no
 +
orient_ligand                                                no
 +
bump_filter                                                  no
 +
score_molecules                                              yes
 +
contact_score_primary                                        no
 +
grid_score_primary                                          yes
 +
grid_score_rep_rad_scale                                    1
 +
grid_score_vdw_scale                                        1
 +
grid_score_es_scale                                          1
 +
grid_score_grid_prefix                                      /gpfs/projects/AMS536/2024/students/group_2_1NDV/dock_screen/003.gridbox/grid
 +
minimize_ligand                                              yes
 +
simplex_max_iterations                                      1000
 +
simplex_tors_premin_iterations                              0
 +
simplex_max_cycles                                          1
 +
simplex_score_converge                                      0.1
 +
simplex_cycle_converge                                      1.0
 +
simplex_trans_step                                          1.0
 +
simplex_rot_step                                            0.1
 +
simplex_tors_step                                            10.0
 +
simplex_random_seed                                          0
 +
simplex_restraint_min                                        yes
 +
simplex_coefficient_restraint                                10.0
 +
atom_model                                                  all
 +
vdw_defn_file                                                /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/vdw_AMBER_parm99.defn
 +
flex_defn_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex.defn
 +
flex_drive_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex_drive.tbl
 +
ligand_outfile_prefix                                        1ndv.lig.min
 +
write_orientations                                          no
 +
num_scored_conformers                                        1
 +
rank_ligands                                                no
 +
 
 +
Now run the file with the following command:
 +
dock6 -i min.in -o min.out
 +
 
 +
If the program ran successfully you will see a 1ndv.lig.min.mol2 file.
 +
 
 +
Save this file to your local computer and open it in Chimera with the original ligand file. You will see that DOCK has made very slight changes to the strucutre.
 +
 
 +
[[File:1ndv-min.png|thumb|center|upright=1.5]]
  
 
== Footprint Generation ==
 
== Footprint Generation ==
 +
Footprint analysis is a method where the intermolecular hydrogen bonds and energy (van der Waals and electrostatics) interactions can be computed between the ligand and each residue of the receptor.  It is used to compare how similar two poses or molecules are to each other.
 +
 +
Open your 005.footprint directory and create a footprint input file by the command below:
 +
 +
vi footprint.in
 +
 +
Next enter the following information for your protein.  *File names will need to be changed if you are running different files or from different parameter locations.
 +
 +
conformer_search_type                                        rigid
 +
use_internal_energy                                          no
 +
ligand_atom_file                                            .../004.energy_min/1ndv.lig.min_scored.mol2
 +
limit_max_ligands                                            no
 +
skip_molecule                                                no
 +
read_mol_solvation                                          no
 +
calculate_rmsd                                              no
 +
use_database_filter                                          no
 +
orient_ligand                                                no
 +
bump_filter                                                  no
 +
score_molecules                                              yes
 +
contact_score_primary                                        no
 +
grid_score_primary                                          no
 +
multigrid_score_primary                                      no
 +
dock3.5_score_primary                                        no
 +
continuous_score_primary                                    no
 +
footprint_similarity_score_primary                          yes
 +
fps_score_use_footprint_reference_mol2                      yes
 +
fps_score_footprint_reference_mol2_filename                  .../001.structure/1ndv_ligand_only_H_charge.mol2
 +
fps_score_foot_compare_type                                  Euclidean
 +
fps_score_normalize_foot                                    no
 +
fps_score_foot_comp_all_residue                              yes
 +
fps_score_receptor_filename                                  .../001.structure/1ndv_protein_only_H_charge.mol2
 +
fps_score_vdw_att_exp                                        6
 +
fps_score_vdw_rep_exp                                        9
 +
fps_score_vdw_rep_rad_scale                                  1
 +
fps_score_use_distance_dependent_dielectric                  yes
 +
fps_score_dielectric                                        4.0
 +
fps_score_vdw_fp_scale                                      1
 +
fps_score_es_fp_scale                                        1
 +
fps_score_hb_fp_scale                                        0
 +
minimize_ligand                                              no
 +
atom_model                                                  all
 +
vdw_defn_file                                                /gpfs/projects/AMS536/zzz.programs/dock6.9_release/parameters/vdw_AMBER_parm99.defn
 +
flex_defn_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.9_release/parameters/flex.defn
 +
flex_drive_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.9_release/parameters/flex_drive.tbl
 +
ligand_outfile_prefix                                        1ndv_footprint.out
 +
write_footprints                                            yes
 +
write_hbonds                                                yes
 +
write_orientations                                          no
 +
num_scored_conformers                                        1
 +
rank_ligands                                                no
 +
 +
Next use the command below to generate your footprint analysis:
 +
 +
dock6 -i footprint.in
 +
 +
If the program ran successfully the following three files will be now in your directory:
 +
 +
- 1ndv_footprint.out_footprint_scored.txt
 +
 +
- 1ndvv_footprint.out_hbond_scored.txt
 +
 +
- 1ndv_footprint.out_scored.mol2
 +
 +
There is a python script from the Rizzo group that can be used to generate a graph of the footprint analysis "plot_footprint_single_magnitude.py". This needs to copied into your 005.footprint directory and can be run using the following command:
 +
 +
module load python
 +
 +
python plot_footprint_single_magnitude.py 1ndv_footprint.out_footprint_scored.txt  50
 +
 +
This will generate a .pdf file of your ligand's footprint in your directory.  The 50 variable at the end of the code is adjustable to show the top specified number of residues.
 +
 +
[[File:1ndv footprint analysis.png|center|650px]]
  
 
== Rigid Docking ==
 
== Rigid Docking ==
 +
The first docking method we will be using is rigid docking. In this method, the ligand is treated as a rigid structure. DOCK attempts to fit the ligand into the binding site using the structure provided, and different ligand conformations are not sampled. For this step we will be working in the 0006.rigid_docking directory and will be using the minimized ligand structure.
 +
 +
Create a new file called rigid.in and place the following lines into it:
 +
 +
conformer_search_type                                        rigid
 +
use_internal_energy                                          yes
 +
internal_energy_rep_exp                                      12
 +
internal_energy_cutoff                                      100.0
 +
ligand_atom_file                                            ../004.energy_min/1ndv.lig.min_scored.mol2
 +
limit_max_ligands                                            no
 +
skip_molecule                                                no
 +
read_mol_solvation                                          no
 +
calculate_rmsd                                              yes
 +
use_rmsd_reference_mol                                      yes
 +
rmsd_reference_filename                                      ../004.energy_min/1ndv.lig.min_scored.mol2
 +
use_database_filter                                          no
 +
orient_ligand                                                yes
 +
automated_matching                                          yes
 +
receptor_site_file                                          ../002.surface_spheres/selected_spheres.sph
 +
max_orientations                                            1000
 +
critical_points                                              no
 +
chemical_matching                                            no
 +
use_ligand_spheres                                          no
 +
bump_filter                                                  no
 +
score_molecules                                              yes
 +
contact_score_primary                                        no
 +
grid_score_primary                                          yes
 +
grid_score_rep_rad_scale                                    1
 +
grid_score_vdw_scale                                        1
 +
grid_score_es_scale                                          1
 +
grid_score_grid_prefix                                      ../003.gridbox/grid
 +
minimize_ligand                                              yes
 +
simplex_max_iterations                                      1000
 +
simplex_tors_premin_iterations                              0
 +
simplex_max_cycles                                          1
 +
simplex_score_converge                                      0.1
 +
simplex_cycle_converge                                      1.0
 +
simplex_trans_step                                          1.0
 +
simplex_rot_step                                            0.1
 +
simplex_tors_step                                            10.0
 +
simplex_random_seed                                          0
 +
simplex_restraint_min                                        no
 +
atom_model                                                  all
 +
vdw_defn_file                                                /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/vdw_AMBER_parm99.defn
 +
flex_defn_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex.defn
 +
flex_drive_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex_drive.tbl
 +
ligand_outfile_prefix                                        rigid.out
 +
write_orientations                                          no
 +
num_scored_conformers                                        10
 +
write_conformations                                          yes
 +
cluster_conformations                                        yes
 +
cluster_rmsd_threshold                                      2.0
 +
rank_ligands                                                no
 +
 +
Remember to change paths so that they point to the files on your system. Now run the program using the following command:
 +
 +
dock6 -i rigid.in -o rigid.out
 +
 +
This step may take a few minutes. You will know it ran successfully when you see a file named rigid.out_scored.mol2. This file will contain your docked ligand in 10 orientations. Let's open this file with the minimized ligand file.
 +
 +
First, open the minimized ligand file in Chimera normally. We will use the View Dock tool in Chimera to view the different orientations of the rigid docking results. To do this click "Tools"→ "Surface/Binding Analysis" → "ViewDock". then select "Dock 4,5 or 6" as the file type. Now select "Column" → "Show" → "Grid Score" so we can see how DOCK scored these orientations. You can now view each orientation individually or a selection of them all at once. Here is our top scoring orientation and our minimized ligand.
 +
 +
[[File:1ndv-rigid.png|thumb|center|upright=2.5]]
 +
 
== Fixed Anchor Docking ==
 
== Fixed Anchor Docking ==
 +
Fixed anchor docking allows some heavy atoms to move via rotatable bonds while keeping the majority of the ligand's position fixed during docking.
 +
 +
To model fixed anchor docking, open your 007.fixed_anchor_docking directory and create an input file by the command below:
 +
 +
vi fixed.in
 +
 +
Then type the following lines:
 +
- File names will need to be changed if you are running different files or from different parameter locations.
 +
 +
conformer_search_type                                        flex
 +
write_fragment_libraries                                    no
 +
user_specified_anchor                                        no
 +
limit_max_anchors                                            no
 +
min_anchor_size                                              5
 +
pruning_use_clustering                                      yes
 +
pruning_max_orients                                          1000
 +
pruning_clustering_cutoff                                    100
 +
pruning_conformer_score_cutoff                              100.0
 +
pruning_conformer_score_scaling_factor                      1.0
 +
use_clash_overlap                                            no
 +
write_growth_tree                                            no
 +
use_internal_energy                                          yes
 +
internal_energy_rep_exp                                      12
 +
internal_energy_cutoff                                      100.0
 +
ligand_atom_file                                            ../004.energy_min/1ndv.lig.min_scored.mol2
 +
limit_max_ligands                                            no
 +
skip_molecule                                                no
 +
read_mol_solvation                                          no
 +
calculate_rmsd                                              yes
 +
use_rmsd_reference_mol                                      yes
 +
rmsd_reference_filename                                      ../004.energy_min/1ndv.lig.min_scored.mol2
 +
use_database_filter                                          no
 +
orient_ligand                                                no
 +
bump_filter                                                  no
 +
score_molecules                                              yes
 +
contact_score_primary                                        no
 +
grid_score_primary                                          yes
 +
grid_score_rep_rad_scale                                    1
 +
grid_score_vdw_scale                                        1
 +
grid_score_es_scale                                          1
 +
grid_score_grid_prefix                                      ../003.gridbox/grid
 +
minimize_ligand                                              yes
 +
minimize_anchor                                              yes
 +
minimize_flexible_growth                                    yes
 +
use_advanced_simplex_parameters                              no
 +
minimize_flexible_growth_ramp                                no
 +
simplex_max_cycles                                          1
 +
simplex_score_converge                                      0.1
 +
simplex_cycle_converge                                      1
 +
simplex_trans_step                                          1
 +
simplex_rot_step                                            0.1
 +
simplex_tors_step                                            10.0
 +
simplex_anchor_max_iterations                                500
 +
simplex_grow_max_iterations                                  500
 +
simplex_grow_tors_premin_iterations                          0
 +
simplex_random_seed                                          0
 +
simplex_restraint_min                                        no
 +
atom_model                                                  all
 +
vdw_defn_file                                                /gpfs/projects/AMS536/zzz.programs/dock6.9_release/parameters/vdw_AMBER_parm99.defn
 +
flex_defn_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.9_release/parameters/flex.defn
 +
flex_drive_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.9_release/parameters/flex_drive.tbl
 +
ligand_outfile_prefix                                        1ndv_fixed_output
 +
write_orientations                                          no
 +
num_scored_conformers                                        10
 +
write_conformations                                          yes
 +
cluster_conformations                                        yes
 +
cluster_rmsd_threshold                                      2.0
 +
rank_ligands                                                no
 +
 +
Also note the option below allows for 10 conformers to be generated:
 +
 +
num_scored_conformers                                        10
 +
 +
To your input file type:
 +
 +
dock6 -i fixed.in -o fixed.out
 +
 +
Once the job is complete, you will see three new files in your directory:
 +
 +
-fixed.out
 +
 +
-1ndv_fixed_output_scored.mol2
 +
 +
-1ndv_fixed_output_conformers.mol2
 +
 +
Next return to your Chimera session and load your original pdb (1ndv.pdb).
 +
 +
To open multiple conformers go to Surface/Binding Analysis → ViewDock and select Dock 6 option to open your multiple conformations in your file 1ndv_fixed_output_scored.mol2.  You will see a window like one shown below and can select through the various docking poses. To see Grid_Scores, go to Column →  Show → Grid_Score.
 +
 +
[[File:1ndv viewdock.png|center|500px]]
 +
 +
Our top pose is skewed due to hydrogens on the ligand looking for form coordination with the Zn atom, whereas our second best grid score pose recapitulates the crystal structure well.
 +
 +
[[File:1ndv fixed secondGS.png|center|750px]]
 +
 
== Flex Docking ==
 
== Flex Docking ==
 +
The last docking method will we try is called flexible docking. This method is the most computationally expensive, but also samples the most conformational space. In this method DOCK will sample conformations of all rotatable bonds and will attempt to minimize the energy of the ligand. Navigate to the 008.flex_docking directory and create a new file with the name flex.in. Add the following lines to the new file:
 +
conformer_search_type                                        flex
 +
write_fragment_libraries                                    no
 +
user_specified_anchor                                        no
 +
limit_max_anchors                                            no
 +
min_anchor_size                                              5
 +
pruning_use_clustering                                      yes
 +
pruning_max_orients                                          1000
 +
pruning_clustering_cutoff                                    100
 +
pruning_conformer_score_cutoff                              100.0
 +
pruning_conformer_score_scaling_factor                      1.0
 +
use_clash_overlap                                            no
 +
write_growth_tree                                            no
 +
use_internal_energy                                          yes
 +
internal_energy_rep_exp                                      12
 +
internal_energy_cutoff                                      100.0
 +
ligand_atom_file                                            ../004.energy_min/1ndv.lig.min_scored.mol2
 +
limit_max_ligands                                            no
 +
skip_molecule                                                no
 +
read_mol_solvation                                          no
 +
calculate_rmsd                                              yes
 +
use_rmsd_reference_mol                                      yes
 +
rmsd_reference_filename                                     
 +
../004.energy_min/1ndv.lig.min_scored.mol2
 +
use_database_filter                                          no
 +
orient_ligand                                                yes
 +
automated_matching                                          yes
 +
receptor_site_file                                         
 +
../002.surface_spheres/selected_spheres.sph
 +
max_orientations                                            1000
 +
critical_points                                              no
 +
chemical_matching                                            no
 +
use_ligand_spheres                                          no
 +
bump_filter                                                  no
 +
score_molecules                                              yes
 +
contact_score_primary                                        no
 +
grid_score_primary                                          yes
 +
grid_score_rep_rad_scale                                    1
 +
grid_score_vdw_scale                                        1
 +
grid_score_es_scale                                          1
 +
grid_score_grid_prefix                                      ../003.gridbox/grid
 +
minimize_ligand                                              yes
 +
minimize_anchor                                              yes
 +
minimize_flexible_growth                                    yes
 +
use_advanced_simplex_parameters                              no
 +
minimize_flexible_growth_ramp                                no
 +
simplex_max_cycles                                          1
 +
simplex_score_converge                                      0.1
 +
simplex_cycle_converge                                      1.0
 +
simplex_trans_step                                          1.0
 +
simplex_rot_step                                            0.1
 +
simplex_tors_step                                            10.0
 +
simplex_anchor_max_iterations                                500
 +
simplex_grow_max_iterations                                  500
 +
simplex_grow_tors_premin_iterations                          0
 +
simplex_random_seed                                          0
 +
simplex_restraint_min                                        no
 +
atom_model                                                  all
 +
vdw_defn_file                                                /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/vdw_AMBER_parm99.defn
 +
flex_defn_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex.defn
 +
flex_drive_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex_drive.tbl
 +
ligand_outfile_prefix                                        flex.out
 +
write_orientations                                          no
 +
num_scored_conformers                                        1
 +
rank_ligands                                                no
 +
 +
This file will only save 1 conformation. This can be changed by adjusting the "write_orientations" parameter. Use the following command to run the docking:
 +
 +
dock6 -i flex.in -o flex.out
 +
 +
You will know the program ran successfully when you se a flex.out_scored.mol2 file. Save this file on your local system and open it in Chimera along with the minimized ligand file. We can open both of these files normally as we only saved 1 conformation. This is what our docking result looks like in Chimera:
 +
 +
[[File:1ndv-ligand-flex.png|thumb|center|upright=1.5]]
 +
 
== Virtual Screening ==
 
== Virtual Screening ==
 +
Virtual Screening is a method that can dock several hundred to thousands of compounds into a receptor.
 +
 +
To set up your virtual screening script, open your 009.virtual_screening directory and create an input file by the following command below:
 +
 +
vi virtual.in
 +
 +
Then type the following lines:
 +
- File names will need to be changed if you are running different files or from different parameter locations.
 +
 +
conformer_search_type                                        flex
 +
write_fragment_libraries                                    no
 +
user_specified_anchor                                        no
 +
limit_max_anchors                                            no
 +
min_anchor_size                                              5
 +
pruning_use_clustering                                      yes
 +
pruning_max_orients                                          1000
 +
pruning_clustering_cutoff                                    100
 +
pruning_conformer_score_cutoff                              100.0
 +
pruning_conformer_score_scaling_factor                      1.0
 +
use_clash_overlap                                            no
 +
write_growth_tree                                            no
 +
use_internal_energy                                          yes
 +
internal_energy_rep_exp                                      12
 +
internal_energy_cutoff                                      100.0
 +
ligand_atom_file                                            /gpfs/projects/AMS536/zzz.programs/VS_libraries/VS_library_100.mol2
 +
limit_max_ligands                                            no
 +
skip_molecule                                                no
 +
read_mol_solvation                                          no
 +
calculate_rmsd                                              no
 +
use_database_filter                                          no
 +
orient_ligand                                                yes
 +
automated_matching                                          yes
 +
receptor_site_file                                          ../002.surface_spheres/selected_spheres.sph
 +
max_orientations                                            1000
 +
critical_points                                              no
 +
chemical_matching                                            no
 +
use_ligand_spheres                                          no
 +
bump_filter                                                  no
 +
score_molecules                                              yes
 +
contact_score_primary                                        no
 +
grid_score_primary                                          yes
 +
grid_score_rep_rad_scale                                    1
 +
grid_score_vdw_scale                                        1
 +
grid_score_es_scale                                          1
 +
grid_score_grid_prefix                                      ../003.gridbox/grid
 +
minimize_ligand                                              yes
 +
minimize_anchor                                              yes
 +
minimize_flexible_growth                                    yes
 +
use_advanced_simplex_parameters                              no
 +
minimize_flexible_growth_ramp                                yes
 +
simplex_max_cycles                                          1
 +
simplex_score_converge                                      0.1
 +
simplex_initial_score_coverge                                5
 +
simplex_cycle_converge                                      1.0
 +
simplex_trans_step                                          1.0
 +
simplex_rot_step                                            0.1
 +
simplex_tors_step                                            10.0
 +
simplex_anchor_max_iterations                                500
 +
simplex_grow_max_iterations                                  250
 +
simplex_grow_tors_premin_iterations                          0
 +
simplex_random_seed                                          0
 +
simplex_restraint_min                                        no
 +
atom_model                                                  all
 +
vdw_defn_file                                                /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/vdw_AMBER_parm99.defn
 +
flex_defn_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex.defn
 +
flex_drive_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex_drive.tbl
 +
ligand_outfile_prefix                                        virtual.out
 +
write_orientations                                          no
 +
num_scored_conformers                                        1
 +
rank_ligands                                                no
 +
 
=== Slurm ===
 
=== Slurm ===
 +
Slurm is a scheduler that allows jobs to be managed on a cluster without gumming up the flow or resources of the computing cluster.  It is important to use slurm scripts on jobs that will either take longer than a few minutes or need debugging.
 +
 +
To create our slurm script, you can vi your file name:
 +
 +
vi 1ndv_virtual.slurm
 +
 +
and then type the following below:
 +
- File names and queue details will need to be changed if you are running different files or from different parameter locations.
 +
 +
#!/bin/bash
 +
#
 +
#SBATCH --job-name=1ndv_vs_tutorial
 +
#SBATCH --output=vs_output.txt
 +
#SBATCH --ntasks=24
 +
#SBATCH --nodes=6
 +
#SBATCH --time=4:00:00
 +
#SBATCH -p short-28core
 +
 
 +
module load intel/mpi/64/2018/18.0.3
 +
 
 +
mpirun -np 144 dock6.mpi -i virtual.in -o virtual.out
 +
 +
To get this script to run, on the command line, type:
 +
 +
module load slurm
 +
sbatch 1ndv_virtual.slurm
 +
 +
If for any reason you need to cancel your job, you can use:
 +
scancel (followed by your jobid)
  
 
== Cartesian Minimization ==
 
== Cartesian Minimization ==
 +
In this step we will minimize all the molecules that were docked during the virtual screen. Navigate to the 010.cartesian_minimization directory and create a new file called min.in. Add the following lines to the new file:
 +
 +
conformer_search_type                                        rigid
 +
use_internal_energy                                          yes
 +
internal_energy_rep_exp                                      12
 +
internal_energy_cutoff                                      100.0
 +
ligand_atom_file                                            ../009.virtual_screening/virtual.out.mol2
 +
limit_max_ligands                                            no
 +
skip_molecule                                                no
 +
read_mol_solvation                                          no
 +
calculate_rmsd                                              no
 +
use_database_filter                                          no
 +
orient_ligand                                                no
 +
bump_filter                                                  no
 +
score_molecules                                              yes
 +
contact_score_primary                                        no
 +
grid_score_primary                                          no
 +
multigrid_score_primary                                      no
 +
dock3.5_score_primary                                        no
 +
continuous_score_primary                                    yes
 +
cont_score_rec_filename                                      ../001.structure/1ndv_protein_only_H_charge.mol2
 +
cont_score_att_exp                                          6
 +
cont_score_rep_exp                                          12
 +
cont_score_rep_rad_scale                                    1
 +
cont_score_use_dist_dep_dielectric                          yes
 +
cont_score_dielectric                                        4.0
 +
cont_score_vdw_scale                                        1
 +
cont_score_es_scale                                          1
 +
minimize_ligand                                              yes
 +
simplex_max_iterations                                      1000
 +
simplex_tors_premin_iterations                              0
 +
simplex_max_cycles                                          1
 +
simplex_score_converge                                      0.1
 +
simplex_cycle_converge                                      1.0
 +
simplex_trans_step                                          1.0
 +
simplex_rot_step                                            0.1
 +
simplex_tors_step                                            10.0
 +
simplex_random_seed                                          0
 +
simplex_restraint_min                                        no
 +
atom_model                                                  all
 +
vdw_defn_file                                                /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/vdw_AMBER_parm99.defn
 +
flex_defn_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex.defn
 +
flex_drive_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex_drive.tbl
 +
ligand_outfile_prefix                                        1ndv.virtual_screen.min
 +
write_orientations                                          no
 +
num_scored_conformers                                        1
 +
rank_ligands                                                no
 +
 +
Do NOT run this on the login node. Create a slurm script similar to this one which we tiltled run.min:
 +
 +
#!/bin/bash
 +
#
 +
#SBATCH --job-name=1ndv_minimization_tutorial
 +
#SBATCH --output=vs_output.txt
 +
#SBATCH --ntasks=28
 +
#SBATCH --nodes=6
 +
#SBATCH --time=48:00:00
 +
#SBATCH -p long-28core
 +
 +
dock6 -i min.in -o min.out
 +
 +
Once this is complete, we will rescore the molecules based on their minimized structures.
 +
 
== reScore ==
 
== reScore ==
 +
For reScoring the virtual screen to find molecule rankings, we can create an input file below:
 +
 +
vi rescore.in
 +
 +
conformer_search_type                                        rigid
 +
use_internal_energy                                          yes
 +
internal_energy_rep_exp                                      12
 +
internal_energy_cutoff                                      100.0
 +
ligand_atom_file                                            ../009.virtual_screening/virtual.out.mol2
 +
limit_max_ligands                                            no
 +
skip_molecule                                                no
 +
read_mol_solvation                                          no
 +
calculate_rmsd                                              no
 +
use_database_filter                                          no
 +
orient_ligand                                                no
 +
bump_filter                                                  no
 +
score_molecules                                              yes
 +
contact_score_primary                                        no
 +
grid_score_primary                                          no
 +
multigrid_score_primary                                      no
 +
dock3.5_score_primary                                        no
 +
continuous_score_primary                                    no
 +
footprint_similarity_score_primary                          no
 +
pharmacophore_score_primary                                  no
 +
hbond_score_primary                                          no
 +
internal_energy_score_primary                                no
 +
descriptor_score_primary                                    yes
 +
descriptor_use_grid_score                                    no
 +
descriptor_use_multigrid_score                              no
 +
descriptor_use_continuous_score                              no
 +
descriptor_use_footprint_similarity                          yes
 +
descriptor_use_pharmacophore_score                          yes
 +
descriptor_use_tanimoto                                      no
 +
descriptor_use_hungarian                                    yes
 +
descriptor_use_volume_overlap                                yes
 +
descriptor_fps_score_use_footprint_reference_mol2            yes
 +
descriptor_fps_score_footprint_reference_mol2_filename      ../004.energy_min/1ndv.lig.min_scored.mol2
 +
descriptor_fps_score_foot_compare_type                      Euclidean
 +
descriptor_fps_score_normalize_foot                          no
 +
descriptor_fps_score_foot_comp_all_residue                  yes
 +
descriptor_fps_score_receptor_filename                      ../001.structure/1ndv_protein_only_H_charge.mol2
 +
descriptor_fps_score_vdw_att_exp                            6
 +
descriptor_fps_score_vdw_rep_exp                            12
 +
descriptor_fps_score_vdw_rep_rad_scale                      1
 +
descriptor_fps_score_use_distance_dependent_dielectric      yes
 +
descriptor_fps_score_dielectric                              4.0
 +
descriptor_fps_score_vdw_fp_scale                            1
 +
descriptor_fps_score_es_fp_scale                            1
 +
descriptor_fps_score_hb_fp_scale                            0
 +
descriptor_fms_score_use_ref_mol2                            yes
 +
descriptor_fms_score_ref_mol2_filename                      ../004.energy_min/1ndv.lig.min_scored.mol2
 +
descriptor_fms_score_write_reference_pharmacophore_mol2      no
 +
descriptor_fms_score_write_reference_pharmacophore_txt      no
 +
descriptor_fms_score_write_candidate_pharmacophore          no
 +
descriptor_fms_score_write_matched_pharmacophore            no
 +
descriptor_fms_score_compare_type                            overlap
 +
descriptor_fms_score_full_match                              yes
 +
descriptor_fms_score_match_rate_weight                      5.0
 +
descriptor_fms_score_match_dist_cutoff                      1.0
 +
descriptor_fms_score_match_proj_cutoff                      0.7071
 +
descriptor_fms_score_max_score                              20
 +
descriptor_hms_score_ref_filename                            ../004.energy_min/1ndv.lig.min_scored.mol2
 +
descriptor_hms_score_matching_coeff                          -5
 +
descriptor_hms_score_rmsd_coeff                              1
 +
descriptor_volume_score_reference_mol2_filename              ../004.energy_min/1ndv.lig.min_scored.mol2
 +
descriptor_volume_score_overlap_compute_method              analytical
 +
descriptor_weight_fps_score                                  1
 +
descriptor_weight_pharmacophore_score                        1
 +
descriptor_weight_hms_score                                  1
 +
descriptor_weight_volume_overlap_score                      -1
 +
minimize_ligand                                              no
 +
atom_model                                                  all
 +
vdw_defn_file                                                /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/vdw_AMBER_parm99.defn
 +
flex_defn_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex.defn
 +
flex_drive_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex_drive.tbl
 +
chem_defn_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/chem.defn
 +
pharmacophore_defn_file                                      /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/ph4.defn
 +
ligand_outfile_prefix                                        1ndv.output
 +
write_footprints                                            yes
 +
write_hbonds                                                yes
 +
write_orientations                                          no
 +
num_scored_conformers                                        1
 +
rank_ligands                                                no
 +
 +
This file will need to be run using slurm.
 +
 +
vi 1ndv_rescore.slurm
 +
 +
#!/bin/bash
 +
#
 +
#SBATCH --job-name=1ndv_rescoring
 +
#SBATCH --output=rescoring.txt
 +
#SBATCH --ntasks-per-node=24
 +
#SBATCH --nodes=6
 +
#SBATCH --time=1:00:00
 +
#SBATCH -p debug-28core
 +
 +
module load intel/mpi/64/2018/18.0.3
 +
 
 +
mpirun -np 144  dock6.mpi -i rescore.in -o rescore.out
 +
 +
and can be run using the command
 +
 +
sbatch 1ndv_rescore.slurm
 +
 +
Once the job is completed 1ndv.output_scored.mol2 will appear in your directory.  Open this using the ViewDock analysis to compare molecules using various descriptors.

Latest revision as of 13:43, 6 May 2024

Introduction

DOCK is a powerful computational tool used in drug design. "Docking" refers to the identification of low energy binding conformations of a small molecule, or ligand, in an active site. There are three methods in which DOCK performs docking: rigid, fixed anchor, and flexible. DOCK also has the ability to perform a virtual screen, which is analogous to a high throughput screen often performed in wet labs. This method allows for thousands of molecules to be docked and ranked so that the highest scoring molecules can move to the next stage of testing. A virtual screen can save both time and money when compared to a traditional high throughput screen. This tutorial will guide you through the process of performing each method of docking, a virtual screen, and associated analysis using PDB 1NDV on a HPC cluster (Seawulf). Replace 1NDV with your target protein in this tutorial.

Required Software and Skills

In order to complete this tutorial UCSF Chimera is required. Chimera is a powerful visualization tool that will aid in the preparation and analysis of the virtual screen. Please note that the newer version, Chimera X, can not be used for this tutorial as it lacks certain integrations with DOCK. While this tutorial will walk you through all steps necessary to use Chimera, it may be helpful to view this tutorial for a more in depth guide on the program.

It is also recommended that you have experience with Unix and vi. A Unix tutorial can be found on the site here and a vi tutorial can be found here.

Set-up

Before we begin, we need to set up our directories and download our file from the Protein Data Bank (PDB).

Creating Directories

Create a parent directory which will contain all subdirectors for each docking step. For this tutorial we will name the parent directory 1NDV_DOCK_VS. Now create the subdirectories using the following scheme.


1NDV Chart.png


Downloading PDB File

Visit the RCSB Protein Data Bank (PDB) website and use the search bar to search for your target protein. As stated before, we will be using 1NDV for this tutorial.


PDB SearchBar.png


The page for the protein will look like this. Click the "Download Files" dropdown menu, and download the "PDB Format".


1NDV-Download.png


With the PDB file saved, we are now ready to begin generating files for DOCK!

Preparing Structure Files

To prepare structure files, the protein and ligand structures need to be prepped. It is important prepare your structure files using the following steps to ensure your files run properly and are considered correct chemical models of your system.

We will prep the protein and ligand structures using Chimera.

Protein

Required file: *Structure file from the RCSB Protein Data Bank (PDB). *For this tutorial, is it 1ndv.pdb.

Analyzing the Protein Structure:

Open 1ndv.pdb in Chimera.

Assess the protein structure:

1. Are there any missing loops?

2. Is there a metal coordination atom forming key interactions with the protein?

The .pdb for 1ndv from the RCSB Protein Data Bank is shown below.

1ndv raw pdb.jpg

Assessment:

1. No missing loops.

2. Zinc coordination with the protein and a water molecule. This zinc atom must be kept in the protein prep.

1ndv coordination.jpg

Protein Prep

1. Select an atom on the protein

2. Select the entire protein by pressing the "up" arrow key. You will want to keep the Zn in the complex so hold down the "shift" key and click the Zn atom to select it as well.

3. Go to the menu bar Select → Invert(all models). This will invert the selection and select waters, the ligand, and other compounds in the crystal structure that wasn't previously selected.

4. Go to the menu bar Actions → Atoms/Bonds → Delete.

5. Then save this structure with a a file name (i.e. 1ndv_protein_only.pdb). Go to the menu bar File → Save PBD. Your pdb file will now look similar to this:

1ndv protein only.png

6. We also need to generate a .mol2 file. So go to File → Save Mol2 and give it a name 1ndv_protein_only.mol2. The previous file as a .pdb extension and will not be overwritten as a mol2 file is separate from mol2 format.

Adding Hydrogens and Charges

We need to prepare the protein with hydrogens and charges. We must add hydrogens before adding charges.

7. Adding hydrogens. To add hydrogen atoms click on: Tools → Structure Editing → AddH. This command will cause the following dialogue box to appear:

1ndv protein addH.png

a. Click 'OK'. When the program is finished, the bottom left-hand side will say "Hydrogens added". You may not see any changes in the structure. Here we can see hydrogens on residues surround the zinc atom. If so you can make sure by selecting a couple residues and clicking Actions → Atoms/Bonds → Show. You can unselect these residues by clicking on the background.

1ndv protein hydrogens check.png

b. Now once this check is done save your protein file with hydrogens as a .pdb (i.e 1ndv_protein_H.pdb) and .mol2 (i.e 1ndv_protein_H.mol2). It is useful to save changes in Chimera in steps as each change is not able to be undone.

8. Now we can add charges by Tools → Structure Editing → Add Charge and the following dialogue box will show up:

1ndv protein addcharge.png

You can keep the defaults selected and click "OK". If you have a metal coordination atom in your structure Chimera will ask you to specify the atom's charge.

1ndv protein addcharge Zn.png

Once the program is finished in the bottom left hand corner will display what the total charge of the structure is. This number should be an integer.

The protein structure is now completely prepared and ready for docking.

The final step is to save two files, a .pdb and a .mol2 file of this structure (i.e. 1ndv_protein_H_charges.pdb and 1ndv_protein_H_charges.mol2)

Ligand

We must first create a .pdb file with only the ligand. To do this we must select the ligand in Chimera. There are two ways to do this:

1.Select an atom on the ligand, and use the up arrow until the entire ligand is selected

-or-

2. Use the toolbar and click "Select" → "Structure" → "Ligand"

Once the ligand is selected use "Select" → "Invert" to select all other atoms present in the session.

Then use "Actions" → "Atoms/Bonds" → "Delete" to delete everything except the ligand.

It should look like this.

1ndv-ligand-only.png

You can now save only the ligand in a separate .pbd file. We will name this file 1ndv_ligand_only.pdb.

We will also save the ligand in this state as a .mol2 file. We will name this file 1ndv_no_hydrogens_no_charges.mol2

We now need to add hydrogens and charges like we did previously for the protein. It is important to be careful and to cross reference the structure of the ligand in the PDB to ensure that hydrogens are being added in the right places, and that the overall charge of the ligand remains the same. After adding hydrogens, your structure should look similar to this:

1ndv-ligand-only-H.png

We must now look at the structure in the PDB to ensure Chimera is adding the hydrogens in the proper place. To do this, scroll down on the PDB page of the protein until you see the table labeled "Small Molecules".

1ndv-small-mol.png

Now click on the "2D Diagram" of the ligand to bring up a larger picture.

1ndv-small-mol-big.png

It appears that Chimera has added an extra Hydrogen to N26. We need to remove that by simply selecting and deleting that hydrogen. The ligand should now look like this:

1ndv-ligand-with-H.png

We can now add charges to the ligand. When the dialogue box appears, be sure to set the overall charge to 0 for this ligand. With this step complete we can now save a .pdb file and .mol2 with the name 1ndv_ligand_H_charge.

Upload all four of the .mol2 files created during the protein and ligand preparation process to Seawulf for use with DOCK.

Surface Spheres

This section will walk you through the steps necessary to identify the binding site of the protein using a function within DOCK to place surface spheres along the protein.

DMS file

In Chimera, open the 1ndv_protein_only.pdb file. Go to Actions → Surface → show. This will display the van der Waals surface of your protein. Your image should be similar to:

1ndv surface.png

There may be a warning that could pop up about letting you know that a failure for disconnected additional components, such as the zinc atom, occurred. Since we have our desired surface we can continue and close the warning box.

1ndv surface warning.png

Next we need to write the .dms file. To do this select Tools → Structure Editing → Write DMS. You will need to give the file a name (i.e. 1ndv_surface.dms). To check if the .dms file represents the surface of the protein well we can overlay the .dms file with the protein_only file.

To do this, close your current session, open the 4s0v_protein_only.pdb and then open the 4s0v_surface.dms. If everything worked as it should you should see an image similar to:

1ndv surface dms.png

The small dots (which is the .dms file) is perfectly aligned over the protein structure. Now that we have verified that everything looks good, we can continue.

The 1ndv_surface.dms can be deposited into the folder 002.surface_spheres.

sphgen

Open your to your 002_surface_spheres directory and create a file to run sphgen: 

vi INSP

Then hit the "Insert" key to start inserting text and type: 

1ndv_surface.dms
R
X
0.0
4.0
1.4
1ndv.sph

Note: If you are running different filename will need to change the name of your files on the first and last line above. Using a text editor like Sublime text or Notepad can make is easier to make these changes to your code and then you can paste into the vi editor when you are ready.

To save your file hit the colon/semi-colon key and type: 

:wq!

to save your work.

Then using command line type the command below to run sphgen on your protein. 

sphgen -i INSPH -o OUTSPH

Once this is completed you will see the 1ndv_binding_spheres.sph in your directory. To check the binding_sphere.sph file was generated correctly open it in Chimera with the original .pdb file. The two structures should be aligned to each other. The image should be similar to:

1ndv binding spheres.png

The binding_spheres.sph overlay well with the original protein pdb and are good to proceed to the next step.

sphere selector

This step runs a DOCK program called sphere_selector which is again run on the command line. Return to your 002.surface_spheres directory. Then type: 

sphere_selector 1ndv_binding_spheres.sph ../001.structure/1ndv_ligand_H_charge.mol2 10.0

When this program has successfully completed you'll see a new file in your directory called selected_spheres.sph. This file generated spheres which should line up with the binding site of the protein. To verify this open both the selected_spheres.sph file and your original protein/ligand complex file (1ndv.pdb) in Chimera. You should see the spheres located within the binding site of the protein similar to this picture below:

1ndv selected spheres.png

To check the selected spheres are near the ligand you can either: a. Ctrl-click on a sphere and hit the "Up" arrow until all the spheres are selected. Then go to Actions → Atoms/Bonds → Hide. or b. On the Model Panel click on the Cluster 1 - selected_spheres.sph and selecte hide.

We can now see our ligand (green) and can confirm the selected_spheres are near our ligand.

1ndv selected spheres check.png

Gridbox

While it is possible to calculate interactions between the ligand and the entire protein surface, this is computationally expensive. In this tutorial we will define a box of interest in the active site of the protein, and DOCK will generate a grid to calculate interaction energies within this box.

Generating the Box

To generate the box we use a DOCK program called showbox. This program is accessed through the command line. First navigate to your 003.gridbox directory and create a new file called showbox.in. Place the following commands into the new file: 

Y
8.0 
../002.surface_spheres/selected_spheres.sph
1 
1ndv.box.pdb

Remember to change "1ndv" to your protein name. This file may need to be modified for your system if you need a larger box. This file currently draws a box of 8.0 angstroms around the selected spheres. To change this, simply change the "8.0" in the input file.

To run this file type: 

showbox < showbox.in

If showbox ran successfully you will now have a file named 1ndv.box.pdb in the directory.

Generating the Grid

Now that the box has been defined, we can generate the grid. We do this using a Dock program called grid. Make a new file called grid.in. Place the following commands into the new file: 

allow_non_integral_charges                no
  compute_grids                             yes
  grid_spacing                              0.4
  output_molecule                           no
  contact_score                             no
  energy_score                              yes
  energy_cutoff_distance                    9999
  atom_model                                a
  attractive_exponent                       6
  repulsive_exponent                        9
  distance_dielectric                       yes
  dielectric_factor                         4.
  bump_filter                               yes
  bump_overlap                              0.75
  receptor_file                              ../001.structure/1ndv_protein_only_H_charge.mol2
  box_file                                  1ndv.box.pdb
  vdw_definition_file                       /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/vdw_AMBER_parm99.defn
  score_grid_prefix                         grid

Be sure you are using the receptor_file and box_file for your protein.

Run the file with the following command: 

grid -i grid.in -o 1ndvGridInfo.out

This program will take a few minutes to run. If it ran succesfully you will see three new files in your direcotry:

  1. grid.bmp
  2. grid.nrg
  3. 1ndvGridInfo.out

After successfully generating the box and grid, we can begin energy minimization.

Ligand Energy Minimization

DOCK calculates interaction energies between the protein and the ligand. It is important that we first minimize the ligand to a low energy conformer before we dock it into the binding site of the protein to ensure accurate results.

First navigate to the 004.minization directory and create a new file called min.in. Place the follow lines in the new file. 

conformer_search_type                                        rigid
use_internal_energy                                          yes
internal_energy_rep_exp                                      12
internal_energy_cutoff                                       100.0
ligand_atom_file                                          /gpfs/projects/AMS536/2024/students/group_2_1NDV/dock_screen/001.structure/1ndv_ligand_only_H_charge.mol2
limit_max_ligands                                            no
skip_molecule                                                no
read_mol_solvation                                           no
calculate_rmsd                                               yes
use_rmsd_reference_mol                                       yes
rmsd_reference_filename                                      /gpfs/projects/AMS536/2024/students/group_2_1NDV/dock_screen/001.structure/1ndv_ligand_only_H_charge.mol2
use_database_filter                                          no
orient_ligand                                                no
bump_filter                                                  no
score_molecules                                              yes
contact_score_primary                                        no
grid_score_primary                                           yes
grid_score_rep_rad_scale                                     1
grid_score_vdw_scale                                         1
grid_score_es_scale                                          1
grid_score_grid_prefix                                       /gpfs/projects/AMS536/2024/students/group_2_1NDV/dock_screen/003.gridbox/grid
minimize_ligand                                              yes
simplex_max_iterations                                       1000
simplex_tors_premin_iterations                               0
simplex_max_cycles                                           1
simplex_score_converge                                       0.1
simplex_cycle_converge                                       1.0
simplex_trans_step                                           1.0
simplex_rot_step                                             0.1
simplex_tors_step                                            10.0
simplex_random_seed                                          0
simplex_restraint_min                                        yes
simplex_coefficient_restraint                                10.0
atom_model                                                   all
vdw_defn_file                                                /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/vdw_AMBER_parm99.defn
flex_defn_file                                               /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex.defn
flex_drive_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex_drive.tbl
ligand_outfile_prefix                                        1ndv.lig.min
write_orientations                                           no
num_scored_conformers                                        1
rank_ligands                                                 no

Now run the file with the following command: 

dock6 -i min.in -o min.out

If the program ran successfully you will see a 1ndv.lig.min.mol2 file.

Save this file to your local computer and open it in Chimera with the original ligand file. You will see that DOCK has made very slight changes to the strucutre.

1ndv-min.png

Footprint Generation

Footprint analysis is a method where the intermolecular hydrogen bonds and energy (van der Waals and electrostatics) interactions can be computed between the ligand and each residue of the receptor. It is used to compare how similar two poses or molecules are to each other.

Open your 005.footprint directory and create a footprint input file by the command below: 

vi footprint.in

Next enter the following information for your protein. *File names will need to be changed if you are running different files or from different parameter locations. 

conformer_search_type                                        rigid
use_internal_energy                                          no
ligand_atom_file                                             .../004.energy_min/1ndv.lig.min_scored.mol2
limit_max_ligands                                            no
skip_molecule                                                no
read_mol_solvation                                           no
calculate_rmsd                                               no
use_database_filter                                          no
orient_ligand                                                no
bump_filter                                                  no
score_molecules                                              yes
contact_score_primary                                        no
grid_score_primary                                           no
multigrid_score_primary                                      no
dock3.5_score_primary                                        no
continuous_score_primary                                     no
footprint_similarity_score_primary                           yes
fps_score_use_footprint_reference_mol2                       yes
fps_score_footprint_reference_mol2_filename                  .../001.structure/1ndv_ligand_only_H_charge.mol2
fps_score_foot_compare_type                                  Euclidean
fps_score_normalize_foot                                     no
fps_score_foot_comp_all_residue                              yes
fps_score_receptor_filename                                  .../001.structure/1ndv_protein_only_H_charge.mol2
fps_score_vdw_att_exp                                        6
fps_score_vdw_rep_exp                                        9
fps_score_vdw_rep_rad_scale                                  1
fps_score_use_distance_dependent_dielectric                  yes
fps_score_dielectric                                         4.0
fps_score_vdw_fp_scale                                       1
fps_score_es_fp_scale                                        1
fps_score_hb_fp_scale                                        0
minimize_ligand                                              no
atom_model                                                   all
vdw_defn_file                                                /gpfs/projects/AMS536/zzz.programs/dock6.9_release/parameters/vdw_AMBER_parm99.defn
flex_defn_file                                               /gpfs/projects/AMS536/zzz.programs/dock6.9_release/parameters/flex.defn
flex_drive_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.9_release/parameters/flex_drive.tbl
ligand_outfile_prefix                                        1ndv_footprint.out
write_footprints                                             yes
write_hbonds                                                 yes
write_orientations                                           no
num_scored_conformers                                        1
rank_ligands                                                 no

Next use the command below to generate your footprint analysis: 

dock6 -i footprint.in

If the program ran successfully the following three files will be now in your directory:

- 1ndv_footprint.out_footprint_scored.txt

- 1ndvv_footprint.out_hbond_scored.txt

- 1ndv_footprint.out_scored.mol2

There is a python script from the Rizzo group that can be used to generate a graph of the footprint analysis "plot_footprint_single_magnitude.py". This needs to copied into your 005.footprint directory and can be run using the following command: 

module load python

python plot_footprint_single_magnitude.py 1ndv_footprint.out_footprint_scored.txt  50

This will generate a .pdf file of your ligand's footprint in your directory. The 50 variable at the end of the code is adjustable to show the top specified number of residues.

1ndv footprint analysis.png

Rigid Docking

The first docking method we will be using is rigid docking. In this method, the ligand is treated as a rigid structure. DOCK attempts to fit the ligand into the binding site using the structure provided, and different ligand conformations are not sampled. For this step we will be working in the 0006.rigid_docking directory and will be using the minimized ligand structure.

Create a new file called rigid.in and place the following lines into it: 

conformer_search_type                                        rigid
use_internal_energy                                          yes
internal_energy_rep_exp                                      12
internal_energy_cutoff                                       100.0
ligand_atom_file                                             ../004.energy_min/1ndv.lig.min_scored.mol2
limit_max_ligands                                            no
skip_molecule                                                no
read_mol_solvation                                           no
calculate_rmsd                                               yes
use_rmsd_reference_mol                                       yes
rmsd_reference_filename                                      ../004.energy_min/1ndv.lig.min_scored.mol2
use_database_filter                                          no
orient_ligand                                                yes
automated_matching                                           yes
receptor_site_file                                           ../002.surface_spheres/selected_spheres.sph
max_orientations                                             1000
critical_points                                              no
chemical_matching                                            no
use_ligand_spheres                                           no
bump_filter                                                  no
score_molecules                                              yes
contact_score_primary                                        no
grid_score_primary                                           yes
grid_score_rep_rad_scale                                     1
grid_score_vdw_scale                                         1
grid_score_es_scale                                          1
grid_score_grid_prefix                                       ../003.gridbox/grid
minimize_ligand                                              yes
simplex_max_iterations                                       1000
simplex_tors_premin_iterations                               0
simplex_max_cycles                                           1
simplex_score_converge                                       0.1
simplex_cycle_converge                                       1.0
simplex_trans_step                                           1.0
simplex_rot_step                                             0.1
simplex_tors_step                                            10.0
simplex_random_seed                                          0
simplex_restraint_min                                        no
atom_model                                                   all
vdw_defn_file                                                /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/vdw_AMBER_parm99.defn
flex_defn_file                                               /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex.defn
flex_drive_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex_drive.tbl
ligand_outfile_prefix                                        rigid.out
write_orientations                                           no
num_scored_conformers                                        10
write_conformations                                          yes
cluster_conformations                                        yes
cluster_rmsd_threshold                                       2.0
rank_ligands                                                 no

Remember to change paths so that they point to the files on your system. Now run the program using the following command: 

dock6 -i rigid.in -o rigid.out

This step may take a few minutes. You will know it ran successfully when you see a file named rigid.out_scored.mol2. This file will contain your docked ligand in 10 orientations. Let's open this file with the minimized ligand file.

First, open the minimized ligand file in Chimera normally. We will use the View Dock tool in Chimera to view the different orientations of the rigid docking results. To do this click "Tools"→ "Surface/Binding Analysis" → "ViewDock". then select "Dock 4,5 or 6" as the file type. Now select "Column" → "Show" → "Grid Score" so we can see how DOCK scored these orientations. You can now view each orientation individually or a selection of them all at once. Here is our top scoring orientation and our minimized ligand.

1ndv-rigid.png

Fixed Anchor Docking

Fixed anchor docking allows some heavy atoms to move via rotatable bonds while keeping the majority of the ligand's position fixed during docking.

To model fixed anchor docking, open your 007.fixed_anchor_docking directory and create an input file by the command below: 

vi fixed.in

Then type the following lines: - File names will need to be changed if you are running different files or from different parameter locations. 

conformer_search_type                                        flex
write_fragment_libraries                                     no
user_specified_anchor                                        no
limit_max_anchors                                            no
min_anchor_size                                              5
pruning_use_clustering                                       yes
pruning_max_orients                                          1000
pruning_clustering_cutoff                                    100
pruning_conformer_score_cutoff                               100.0
pruning_conformer_score_scaling_factor                       1.0
use_clash_overlap                                            no
write_growth_tree                                            no
use_internal_energy                                          yes
internal_energy_rep_exp                                      12
internal_energy_cutoff                                       100.0
ligand_atom_file                                             ../004.energy_min/1ndv.lig.min_scored.mol2
limit_max_ligands                                            no
skip_molecule                                                no
read_mol_solvation                                           no
calculate_rmsd                                               yes
use_rmsd_reference_mol                                       yes
rmsd_reference_filename                                      ../004.energy_min/1ndv.lig.min_scored.mol2
use_database_filter                                          no
orient_ligand                                                no
bump_filter                                                  no
score_molecules                                              yes
contact_score_primary                                        no
grid_score_primary                                           yes
grid_score_rep_rad_scale                                     1
grid_score_vdw_scale                                         1
grid_score_es_scale                                          1
grid_score_grid_prefix                                       ../003.gridbox/grid
minimize_ligand                                              yes
minimize_anchor                                              yes
minimize_flexible_growth                                     yes
use_advanced_simplex_parameters                              no
minimize_flexible_growth_ramp                                no
simplex_max_cycles                                           1
simplex_score_converge                                       0.1
simplex_cycle_converge                                       1
simplex_trans_step                                           1
simplex_rot_step                                             0.1
simplex_tors_step                                            10.0
simplex_anchor_max_iterations                                500
simplex_grow_max_iterations                                  500
simplex_grow_tors_premin_iterations                          0
simplex_random_seed                                          0
simplex_restraint_min                                        no
atom_model                                                   all
vdw_defn_file                                                /gpfs/projects/AMS536/zzz.programs/dock6.9_release/parameters/vdw_AMBER_parm99.defn
flex_defn_file                                               /gpfs/projects/AMS536/zzz.programs/dock6.9_release/parameters/flex.defn
flex_drive_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.9_release/parameters/flex_drive.tbl
ligand_outfile_prefix                                        1ndv_fixed_output
write_orientations                                           no
num_scored_conformers                                        10
write_conformations                                          yes
cluster_conformations                                        yes
cluster_rmsd_threshold                                       2.0
rank_ligands                                                 no

Also note the option below allows for 10 conformers to be generated: 

num_scored_conformers                                        10

To your input file type: 

dock6 -i fixed.in -o fixed.out

Once the job is complete, you will see three new files in your directory:

-fixed.out

-1ndv_fixed_output_scored.mol2

-1ndv_fixed_output_conformers.mol2

Next return to your Chimera session and load your original pdb (1ndv.pdb).

To open multiple conformers go to Surface/Binding Analysis → ViewDock and select Dock 6 option to open your multiple conformations in your file 1ndv_fixed_output_scored.mol2. You will see a window like one shown below and can select through the various docking poses. To see Grid_Scores, go to Column → Show → Grid_Score.

1ndv viewdock.png

Our top pose is skewed due to hydrogens on the ligand looking for form coordination with the Zn atom, whereas our second best grid score pose recapitulates the crystal structure well.

1ndv fixed secondGS.png

Flex Docking

The last docking method will we try is called flexible docking. This method is the most computationally expensive, but also samples the most conformational space. In this method DOCK will sample conformations of all rotatable bonds and will attempt to minimize the energy of the ligand. Navigate to the 008.flex_docking directory and create a new file with the name flex.in. Add the following lines to the new file: 

conformer_search_type                                        flex
write_fragment_libraries                                     no
user_specified_anchor                                        no
limit_max_anchors                                            no
min_anchor_size                                              5
pruning_use_clustering                                       yes
pruning_max_orients                                          1000
pruning_clustering_cutoff                                    100
pruning_conformer_score_cutoff                               100.0
pruning_conformer_score_scaling_factor                       1.0
use_clash_overlap                                            no
write_growth_tree                                            no
use_internal_energy                                          yes
internal_energy_rep_exp                                      12
internal_energy_cutoff                                       100.0
ligand_atom_file                                             ../004.energy_min/1ndv.lig.min_scored.mol2
limit_max_ligands                                            no
skip_molecule                                                no
read_mol_solvation                                           no
calculate_rmsd                                               yes
use_rmsd_reference_mol                                       yes
rmsd_reference_filename

../004.energy_min/1ndv.lig.min_scored.mol2 

use_database_filter                                          no
orient_ligand                                                yes
automated_matching                                           yes
receptor_site_file

../002.surface_spheres/selected_spheres.sph 

max_orientations                                             1000
critical_points                                              no
chemical_matching                                            no
use_ligand_spheres                                           no
bump_filter                                                  no
score_molecules                                              yes
contact_score_primary                                        no
grid_score_primary                                           yes
grid_score_rep_rad_scale                                     1
grid_score_vdw_scale                                         1
grid_score_es_scale                                          1
grid_score_grid_prefix                                       ../003.gridbox/grid
minimize_ligand                                              yes
minimize_anchor                                              yes
minimize_flexible_growth                                     yes
use_advanced_simplex_parameters                              no
minimize_flexible_growth_ramp                                no
simplex_max_cycles                                           1
simplex_score_converge                                       0.1
simplex_cycle_converge                                       1.0
simplex_trans_step                                           1.0
simplex_rot_step                                             0.1
simplex_tors_step                                            10.0
simplex_anchor_max_iterations                                500
simplex_grow_max_iterations                                  500
simplex_grow_tors_premin_iterations                          0
simplex_random_seed                                          0
simplex_restraint_min                                        no
atom_model                                                   all
vdw_defn_file                                                /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/vdw_AMBER_parm99.defn
flex_defn_file                                               /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex.defn
flex_drive_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex_drive.tbl
ligand_outfile_prefix                                        flex.out
write_orientations                                           no
num_scored_conformers                                        1
rank_ligands                                                 no

This file will only save 1 conformation. This can be changed by adjusting the "write_orientations" parameter. Use the following command to run the docking: 

dock6 -i flex.in -o flex.out

You will know the program ran successfully when you se a flex.out_scored.mol2 file. Save this file on your local system and open it in Chimera along with the minimized ligand file. We can open both of these files normally as we only saved 1 conformation. This is what our docking result looks like in Chimera:

1ndv-ligand-flex.png

Virtual Screening

Virtual Screening is a method that can dock several hundred to thousands of compounds into a receptor.

To set up your virtual screening script, open your 009.virtual_screening directory and create an input file by the following command below: 

vi virtual.in

Then type the following lines: - File names will need to be changed if you are running different files or from different parameter locations. 

conformer_search_type                                        flex
write_fragment_libraries                                     no
user_specified_anchor                                        no
limit_max_anchors                                            no
min_anchor_size                                              5
pruning_use_clustering                                       yes
pruning_max_orients                                          1000
pruning_clustering_cutoff                                    100
pruning_conformer_score_cutoff                               100.0
pruning_conformer_score_scaling_factor                       1.0
use_clash_overlap                                            no
write_growth_tree                                            no
use_internal_energy                                          yes
internal_energy_rep_exp                                      12
internal_energy_cutoff                                       100.0
ligand_atom_file                                             /gpfs/projects/AMS536/zzz.programs/VS_libraries/VS_library_100.mol2
limit_max_ligands                                            no
skip_molecule                                                no
read_mol_solvation                                           no
calculate_rmsd                                               no
use_database_filter                                          no
orient_ligand                                                yes
automated_matching                                           yes
receptor_site_file                                           ../002.surface_spheres/selected_spheres.sph 
max_orientations                                             1000
critical_points                                              no
chemical_matching                                            no
use_ligand_spheres                                           no
bump_filter                                                  no
score_molecules                                              yes
contact_score_primary                                        no
grid_score_primary                                           yes
grid_score_rep_rad_scale                                     1
grid_score_vdw_scale                                         1
grid_score_es_scale                                          1
grid_score_grid_prefix                                       ../003.gridbox/grid
minimize_ligand                                              yes
minimize_anchor                                              yes
minimize_flexible_growth                                     yes
use_advanced_simplex_parameters                              no
minimize_flexible_growth_ramp                                yes
simplex_max_cycles                                           1
simplex_score_converge                                       0.1
simplex_initial_score_coverge                                5
simplex_cycle_converge                                       1.0
simplex_trans_step                                           1.0
simplex_rot_step                                             0.1
simplex_tors_step                                            10.0
simplex_anchor_max_iterations                                500
simplex_grow_max_iterations                                  250
simplex_grow_tors_premin_iterations                          0
simplex_random_seed                                          0
simplex_restraint_min                                        no
atom_model                                                   all
vdw_defn_file                                                /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/vdw_AMBER_parm99.defn
flex_defn_file                                               /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex.defn
flex_drive_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex_drive.tbl
ligand_outfile_prefix                                        virtual.out
write_orientations                                           no
num_scored_conformers                                        1
rank_ligands                                                 no

Slurm

Slurm is a scheduler that allows jobs to be managed on a cluster without gumming up the flow or resources of the computing cluster. It is important to use slurm scripts on jobs that will either take longer than a few minutes or need debugging.

To create our slurm script, you can vi your file name: 

vi 1ndv_virtual.slurm

and then type the following below: - File names and queue details will need to be changed if you are running different files or from different parameter locations. 

#!/bin/bash
#
#SBATCH --job-name=1ndv_vs_tutorial
#SBATCH --output=vs_output.txt
#SBATCH --ntasks=24
#SBATCH --nodes=6
#SBATCH --time=4:00:00
#SBATCH -p short-28core
  
module load intel/mpi/64/2018/18.0.3
  
mpirun -np 144 dock6.mpi -i virtual.in -o virtual.out

To get this script to run, on the command line, type: 

module load slurm
sbatch 1ndv_virtual.slurm

If for any reason you need to cancel your job, you can use: 

scancel (followed by your jobid)

Cartesian Minimization

In this step we will minimize all the molecules that were docked during the virtual screen. Navigate to the 010.cartesian_minimization directory and create a new file called min.in. Add the following lines to the new file: 

conformer_search_type                                        rigid
use_internal_energy                                          yes
internal_energy_rep_exp                                      12
internal_energy_cutoff                                       100.0
ligand_atom_file                                             ../009.virtual_screening/virtual.out.mol2
limit_max_ligands                                            no
skip_molecule                                                no
read_mol_solvation                                           no
calculate_rmsd                                               no
use_database_filter                                          no
orient_ligand                                                no
bump_filter                                                  no
score_molecules                                              yes
contact_score_primary                                        no
grid_score_primary                                           no
multigrid_score_primary                                      no
dock3.5_score_primary                                        no
continuous_score_primary                                     yes
cont_score_rec_filename                                      ../001.structure/1ndv_protein_only_H_charge.mol2
cont_score_att_exp                                           6
cont_score_rep_exp                                           12
cont_score_rep_rad_scale                                     1
cont_score_use_dist_dep_dielectric                           yes
cont_score_dielectric                                        4.0
cont_score_vdw_scale                                         1
cont_score_es_scale                                          1
minimize_ligand                                              yes
simplex_max_iterations                                       1000
simplex_tors_premin_iterations                               0
simplex_max_cycles                                           1
simplex_score_converge                                       0.1
simplex_cycle_converge                                       1.0
simplex_trans_step                                           1.0
simplex_rot_step                                             0.1
simplex_tors_step                                            10.0
simplex_random_seed                                          0
simplex_restraint_min                                        no
atom_model                                                   all
vdw_defn_file                                                /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/vdw_AMBER_parm99.defn
flex_defn_file                                               /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex.defn
flex_drive_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex_drive.tbl
ligand_outfile_prefix                                        1ndv.virtual_screen.min
write_orientations                                           no
num_scored_conformers                                        1
rank_ligands                                                 no

Do NOT run this on the login node. Create a slurm script similar to this one which we tiltled run.min: 

#!/bin/bash
#
#SBATCH --job-name=1ndv_minimization_tutorial
#SBATCH --output=vs_output.txt
#SBATCH --ntasks=28
#SBATCH --nodes=6
#SBATCH --time=48:00:00
#SBATCH -p long-28core

dock6 -i min.in -o min.out

Once this is complete, we will rescore the molecules based on their minimized structures.

reScore

For reScoring the virtual screen to find molecule rankings, we can create an input file below: 

vi rescore.in

conformer_search_type                                        rigid
use_internal_energy                                          yes
internal_energy_rep_exp                                      12
internal_energy_cutoff                                       100.0
ligand_atom_file                                             ../009.virtual_screening/virtual.out.mol2
limit_max_ligands                                            no
skip_molecule                                                no
read_mol_solvation                                           no
calculate_rmsd                                               no
use_database_filter                                          no
orient_ligand                                                no
bump_filter                                                  no
score_molecules                                              yes
contact_score_primary                                        no
grid_score_primary                                           no
multigrid_score_primary                                      no
dock3.5_score_primary                                        no
continuous_score_primary                                     no
footprint_similarity_score_primary                           no
pharmacophore_score_primary                                  no
hbond_score_primary                                          no
internal_energy_score_primary                                no
descriptor_score_primary                                     yes
descriptor_use_grid_score                                    no
descriptor_use_multigrid_score                               no
descriptor_use_continuous_score                              no
descriptor_use_footprint_similarity                          yes
descriptor_use_pharmacophore_score                           yes
descriptor_use_tanimoto                                      no
descriptor_use_hungarian                                     yes
descriptor_use_volume_overlap                                yes
descriptor_fps_score_use_footprint_reference_mol2            yes
descriptor_fps_score_footprint_reference_mol2_filename       ../004.energy_min/1ndv.lig.min_scored.mol2
descriptor_fps_score_foot_compare_type                       Euclidean
descriptor_fps_score_normalize_foot                          no
descriptor_fps_score_foot_comp_all_residue                   yes
descriptor_fps_score_receptor_filename                       ../001.structure/1ndv_protein_only_H_charge.mol2
descriptor_fps_score_vdw_att_exp                             6
descriptor_fps_score_vdw_rep_exp                             12
descriptor_fps_score_vdw_rep_rad_scale                       1
descriptor_fps_score_use_distance_dependent_dielectric       yes
descriptor_fps_score_dielectric                              4.0
descriptor_fps_score_vdw_fp_scale                            1
descriptor_fps_score_es_fp_scale                             1
descriptor_fps_score_hb_fp_scale                             0
descriptor_fms_score_use_ref_mol2                            yes
descriptor_fms_score_ref_mol2_filename                       ../004.energy_min/1ndv.lig.min_scored.mol2
descriptor_fms_score_write_reference_pharmacophore_mol2      no
descriptor_fms_score_write_reference_pharmacophore_txt       no
descriptor_fms_score_write_candidate_pharmacophore           no
descriptor_fms_score_write_matched_pharmacophore             no
descriptor_fms_score_compare_type                            overlap
descriptor_fms_score_full_match                              yes
descriptor_fms_score_match_rate_weight                       5.0
descriptor_fms_score_match_dist_cutoff                       1.0
descriptor_fms_score_match_proj_cutoff                       0.7071
descriptor_fms_score_max_score                               20
descriptor_hms_score_ref_filename                            ../004.energy_min/1ndv.lig.min_scored.mol2
descriptor_hms_score_matching_coeff                          -5
descriptor_hms_score_rmsd_coeff                              1
descriptor_volume_score_reference_mol2_filename              ../004.energy_min/1ndv.lig.min_scored.mol2
descriptor_volume_score_overlap_compute_method               analytical
descriptor_weight_fps_score                                  1
descriptor_weight_pharmacophore_score                        1
descriptor_weight_hms_score                                  1
descriptor_weight_volume_overlap_score                       -1
minimize_ligand                                              no
atom_model                                                   all
vdw_defn_file                                                /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/vdw_AMBER_parm99.defn
flex_defn_file                                               /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex.defn
flex_drive_file                                              /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/flex_drive.tbl
chem_defn_file                                               /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/chem.defn
pharmacophore_defn_file                                      /gpfs/projects/AMS536/zzz.programs/dock6.10/parameters/ph4.defn
ligand_outfile_prefix                                        1ndv.output
write_footprints                                             yes
write_hbonds                                                 yes
write_orientations                                           no
num_scored_conformers                                        1
rank_ligands                                                 no

This file will need to be run using slurm. 

vi 1ndv_rescore.slurm

#!/bin/bash
#
#SBATCH --job-name=1ndv_rescoring
#SBATCH --output=rescoring.txt
#SBATCH --ntasks-per-node=24
#SBATCH --nodes=6
#SBATCH --time=1:00:00
#SBATCH -p debug-28core

module load intel/mpi/64/2018/18.0.3
 
mpirun -np 144  dock6.mpi -i rescore.in -o rescore.out

and can be run using the command 

sbatch 1ndv_rescore.slurm

Once the job is completed 1ndv.output_scored.mol2 will appear in your directory. Open this using the ViewDock analysis to compare molecules using various descriptors.

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