Useful scripts

Disclaimer: All these scripts were written by Emil Åberg
Imagine you have multiple folders with rec.pdbqt and rec.pdb files and have a folder with all the ligands with .pdbqt files. Imagine now you want to dock all the ligands with receptors present in all the folders. You can use a script something like the following
#3fli, 3fxv name of the folders which contain receptor pdb and pdbqt files
for i in 3fli 3fxv 3l1b 3okh 3olf 3omk 3omm 3oof 4qe6 4qe8; do

cd $i
../VS.bash

cd ..

done
the VS.bash file looks something like following
#!/bin/bash
#Ligands are situated at ../Ligands/Withoutcharges/ folder
for f in lig{1..36}_noch.pdbqt; do  b=`basename $f .pdbqt`; echo Processing ligand $b; mkdir -p data01; cp ../Ligands/Withoutcharges/$f . ; vina --config conf.txt --ligand $f --out data01/$f.pdbqt --log data01/$f.txt; done
#result analysis
cd data01
grep "   1 " *.txt | cut -c35-42,1-12 >>result
#sort
sort -rt" " +2 result >result2
cat result2
Now imagine in case of each receptor (for each folder) you want to list the binding affinity of all the 36 receptors in a text file you might like to use the following script
for a in 1osh_2 3fli 3fxv 3l1b 3okh 3olf 3omk 3omm 3oof 4qe6 4qe8 3dct 3dcu 3hc5 3hc6 3p88 3rut 3ruu_noanisou apo; do
cd $a/
echo -n >affinities_$a.txt
  
   cd data01/
     
    for i in {1..36}; do

               grep ' 1 ' lig${i}_noch.pdbqt.txt | awk '{print $2}' >>../affinities_$a.txt
    
        done


   cd ../../

    echo "Rec $a" 

done

 

Modelling of ZIKA proteases

Disclaimer: This blog is made public in order to inspire a new generation of enthusiastic people to start working on this neglected disease as soon as possible.

I was doing some side-project especially with flaviviruses and the drug discovery targeting flavivirus proteases. That’s why ZIKA break into the scene of my research as ZIKA is likely to be the next big target in the field of drug discovery and development.

Due its similarity with dengue and hepatitis C the drug hunters have some obvious target in their mind which are targeting NS2B-NS3 and NS5 non-structural proteases. Keeping that in mind I designed two protein structures using homology modeling by Swiss-Model server.

  1. Model of NS5: The sequence of ZIKA NS5 (RNA dependent RNA polymerase) was retrieved from NCBI curated database for ZIKA (Accession Id: YP_009227205.1 and link: http://www.ncbi.nlm.nih.gov/protein/985757036?report=fasta ) and submitted into the Swiss-Model server. The homology modeled structure for ZIKA NS5 was described in Figure 1. The homology model was generated using the crystal structure of Of the full-length Japanese Encephalitis Virus Ns5 (PDB: 4K6M)which has a 69.79% sequence identity and 98% query coverage in the blast run.zika_ns5

Figure 1. 3D homology modeled structure of ZIKA NS5 protease using the template of PDB: 4K6M. The nucleotide was introduced in the binding site to map the binding site residues.

The ligand interaction map (Figure 2) of ZIKA NS5 highlighted plausible binding site residues present in the active site of RNA dependent RNA polymerase.

zika_ns5_liginteraction

Figure 2. Ligand interaction map ZIKA NS5 active site residues with nucleoside.

The quality assessments for the NS5 structure is presented below (Figure 3)

torsion

qmeanns5

local_quality_estimate

Figure 3. Several quality assessment parameter for the homology modeled ZIKA NS5 structure.

The assessment of the structure resulted led me to believe that the modeled structure is well predicted.

2. Model of NS2B-NS3 protease: The model of ZIKA NS2B-NS3 pro was designed using the template of ligand bound structure of Dengue NS2B-NS3 (PDB: 3U1I). A 3D ribbon representation of ZIKA NS2B-NS3 pro is presented in Figure 4.

zika_ns3

Figure 4. The 3D ribbon representation of ZIKA NS2B-NS3 pro using the template structure of Dengue serine protease (PDB: 3 U1I).

Here is the sequence of ZIKA NS2B-NS3 pro:

VDMYIERAGDITWEKDAEVTGNSPRLDVALDESGDFSLVEDDGSGSGVKTGKRSGALWDVPAPKEVKKGETTDGVYRVMTRRLLGSTQV

GVGVMQEGVFHTMWHVTKGSALRSGEGRLDPYWGDVKQDLVSYCGPWKLDAAWDGHSEVQLLAVPPGERARNIQTLPGIFKTKDGDIGAVALDYPAGTSG

SPILDKCGRVIGLYGNGVVIKNGSYVSAITQGRREEET

I ran a 27ns NVT MD simulation to refine the structural model and then uploaded the structure in the MolProbity geometry analysis. The analysis report is mentioned with the attached PDF link prot27000_1-rama

These are just the very basic work but it gives an idea about the binding site which is clearly defined in case of both NS3 and NS5. I realized that there might be a bit more computational study necessary to refine the homology modeled structure but keeping in mind the defined active site, I believe it will be a great starting point for virtual screening and pharamacophore based drug design campaign.

Note: If you are using any of this material for your science or inspired by this short piece of work please cite it accordingly. Happy drug hunting!!

New review on “Flap Dynamics”

Our latest review deals with computational study on “Flap dynamics” across proteases has been accepted in Chemical Biology & Drug Design.

Drug re-purposing by targeting Dengue and CHIKV

One of our long standing dream to use drug re-purpose or repositioning strategy on neglected tropical diseases such as Dengue or CHIKV was finally successful with the publication of the latest article entitled “Reaching beyond HIV/HCV: nelfinavir as a potential starting point for broad-spectrum protease inhibitors against dengue and chikungunya virus” in RSC Advances (LINK). We are in process to further boost the selectivity index using computer aided drug design strategy.

MD study to understand the effect of T68A/N126Y mutations on CVB3 3C protease

graphical_abstract_coxsackie

One of the first paper which described the effect of T68A/N126Y double mutations got accepted recently in Molecular Biosystems. The paper entitled “Effect of T68A/N126Y mutations on conformational and ligand binding landscape of Coxsackievirus B3 3C protease” will hopefully provide some critical insights into molecular mechanism of mutations which affects drug design towards Coxsackievirus B3 3C protease.

New Review on Computational Perspective on Hsp90 is now available

bhakat

Our new review which just got published with Chemical Biology and Drug Design (Impact factor: 2.5) highlights an updated account of computational works on Hsp90 and future prospective.

New review on Chikungunya inhibitors from Natural Sources

graphical_abstract

One of our new review entitled “Chikungunya Virus (CHIKV) Inhibitors from Natural Sources: A Medicinal Chemistry Perspective accepted recently in Journal of Natural Medicines (Impact factor: 1.447). This review highlights all current efforts to identify novel CHIKV inhibitors from natural resources.