In Silico Guided Drug Repurposing to Combat SARS-CoV-2 by Targeting Mpro, the Key Virus Specific Protease

27 February 2023, Version 2
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

The reemergence of SARS-CoV named, as SARS-CoV-2 has been highly infectious and able to infect a large population around the globe. The World Health Organization (WHO) has declared this SARS-CoV-2 associated Coronavirus Disease 2019 (COVID-19) as pandemic. SARS-CoV-2 genome is translated into polyproteins and has been processed by its protease enzymes. 3CLprotease is named as main protease (Mpro) enzyme which cleaves nsp4-nsp16. This crucial role of Mpro makes this enzyme a prime and promising antiviral target. The drug repurposing is a fast alternative method than the discovery of novel antiviral molecules. We have used high-throughput virtual screening approach to examine FDA approved LOPAC1280 library against Mpro. Primary screening have identified few potential drug molecule for the target among which 10 molecules were studied further. Molecular docking of selected molecules was done to detailed study about their binding energy and binding modes. Positively, Etoposide, BMS_195614, KT185, Idarubicin and WIN_62577 were found interacting with substrate binding pocket of Mpro with higher binding energy. These molecules are being advanced by our group for in vitro and in vivo testing to study the efficacy of identified drugs. As per our understanding, these molecules have the potential to efficiently interrupt the viral life cycle and may reduce or eliminate the expeditious outspreading of SARS-CoV-2.

Keywords

SARS-CoV-2
COVID-19
Mpro
3CLprotease
Structure based drug repurposing

Supplementary materials

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Fig. 1
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Fig. 1 – Schematic representation of SARS CoV-2 non-structural genes with boxes depicting their approximate protein size. Triangles show protease cleavage sites of PLpro (black) and Mpro (white).
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Fig. 2
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Fig. 2 – MSA of the binding pocket of Mpro of different SARS-CoV-2 and SARS-CoV strains, showing consensus amino acids in red color and available crystal structure of Mpro of SARS-CoV-2 (PDB ID:6LU7) was taken as a reference for secondary structure comparison. Figure created using Clustal Omega (Sievers et al., 2011) and Espript 3.0 webserver (Gouet et al., 1999). T= β turn, = β sheets, = α helix
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Fig. 3
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Fig. 3 - MSA of cleavage site between different non-structural proteins. (a) Pep1: between nsp4 - nsP5 (AVLQ—SGFR), (b) Pep2: between nsP5 - nsP6 (VTFQ—SAVK), (c) Pep3: between nsP6- nsP7 (ATVQ— SKMS), (d) Pep4: between nsP7 - nsP8 (ATLQ—AIAS), (e) Pep5: between nsP8 - nsP9 (VKLQ—NNEL), (f) Pep6: between nsp9 - nsp10 (VRLQ—AGNA), (g) Pep7: between nsp10 - nsp12 (PMLQ—SADA), (h) Pep8: between nsp12 - nsp13 (TVLQ—AVGA), (i) Pep9: between nsp13 - nsp14 (ATLQ—AENV), (j) Pep10: between nsp14 - nsp15 (TRLQ—SLEN) and (k) Pep11: between nsp15 - nsp16 (PKLQ—SSQA).
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Fig. 4
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Fig. 4 - Molecular docking interactions and orientations of top 10 screened ligands (top 5 compounds shown in green and remaining are in red) from LOPAC library and peptide (Pep1) displayed in black color with binding pocket of Mpro (a) Ribbon diagram and (b) Surface structure. Yellow color sticks represent interacting residues of Mpro.
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Fig. 5
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Fig. 5 – Molecular docking interactions and orientations of top-hit screened ligands from LOPAC library with binding pocket of Mpro. (a) Etoposide, (b) BMS-195614, (c) KT185, (d) Idarubicin and (e) WIN-62577. Cyan ribbons correspond to residues of Mpro, straightforward presentation of ligand (red-green) with 60% transparency, yellow stick model represents hydrogen bonds, and light blue stick model corresponds to hydrophobic interactions.
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Fig. 6
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Fig. 6 – In-silico molecular docking surface structure of top-hit screened ligands from LOPAC library with binding pocket of Mpro. (a) Etoposide, (b) BMS-195614, (c) KT185, (d) Idarubicin and (e) WIN-62577. Mpro residues are shown in marine with 20% transparency, hydrophobic residues are shown in green, hydrogen bonds are in red, and ligand residues are shown in orange with 20% transparency.
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Fig. 7
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Fig. 7 – In-silico molecular docking surface structure of top-hit screened ligands from LOPAC library with binding pocket of Mpro. (a) Etoposide, (b) BMS-195614, (c) KT185, (d) Idarubicin and (e) WIN-62577. Mpro residues are shown in marine with 20% transparency, hydrophobic residues are shown in green, hydrogen bonds are in red, and ligand residues are shown in orange with 20% transparency.
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Fig. 8
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Fig. 8– Schematic representation of interactions made by screened drug molecules with binding pocket of Mpro of SARS-CoV-2 upon analysis using LIGPLOT+. (a) Etoposide, (b) BMS-195614, (c) KT185, (d) Idarubicin and (e) WIN-62577. Ligands are colored and represented in purple color; hydrogen bonds are displayed in green dotted lines, red stellations illustrate hydrophobic interactions, and residues of proteins are shown in brown color.
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