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1.
ACS Infect Dis ; 8(8): 1533-1542, 2022 08 12.
Article in English | MEDLINE | ID: covidwho-1931304

ABSTRACT

SARS-CoV-2 non-structural protein 13 (nsp13) is a highly conserved helicase and RNA 5'-triphosphatase. It uses the energy derived from the hydrolysis of nucleoside triphosphates for directional movement along the nucleic acids and promotes the unwinding of double-stranded nucleic acids. Nsp13 is essential for replication and propagation of all human and non-human coronaviruses. Combined with its defined nucleotide binding site and druggability, nsp13 is one of the most promising candidates for the development of pan-coronavirus therapeutics. Here, we report the development and optimization of bioluminescence assays for kinetic characterization of nsp13 ATPase activity in the presence and absence of single-stranded DNA. Screening of a library of 5000 small molecules in the presence of single-stranded DNA resulted in the discovery of six nsp13 small-molecule inhibitors with IC50 values ranging from 6 ± 0.5 to 50 ± 6 µM. In addition to providing validated methods for high-throughput screening of nsp13 in drug discovery campaigns, the reproducible screening hits we present here could potentially be chemistry starting points toward the development of more potent and selective nsp13 inhibitors, enabling the discovery of antiviral therapeutics.


Subject(s)
Methyltransferases/metabolism , RNA Helicases/metabolism , SARS-CoV-2/chemistry , Viral Nonstructural Proteins/metabolism , Adenosine Triphosphatases , COVID-19/virology , DNA, Single-Stranded , Humans , Methyltransferases/antagonists & inhibitors , Nucleic Acids/metabolism , RNA Helicases/antagonists & inhibitors , SARS-CoV-2/physiology , Viral Nonstructural Proteins/antagonists & inhibitors
2.
Antiviral Res ; 204: 105364, 2022 08.
Article in English | MEDLINE | ID: covidwho-1894784

ABSTRACT

Viral exoribonucleases are uncommon in the world of RNA viruses. To date, they have only been identified in the Arenaviridae and the Coronaviridae families. The exoribonucleases of these viruses play a crucial role in the pathogenicity and interplay with host innate immune response. Moreover, coronaviruses exoribonuclease is also involved in a proofreading mechanism ensuring the genetic stability of the viral genome. Because of their key roles in virus life cycle, they constitute attractive target for drug design. Here we developed a sensitive, robust and reliable fluorescence polarization assay to measure the exoribonuclease activity and its inhibition in vitro. The effectiveness of the method was validated on three different viral exoribonucleases, including SARS-CoV-2, Lymphocytic Choriomeningitis and Machupo viruses. We performed a screening of a focused library consisting of 113 metal chelators. Hit compounds were recovered with an IC50 at micromolar level. We confirmed 3 hits in SARS-CoV-2 infected Vero-E6 cells.


Subject(s)
Antiviral Agents , Arenavirus , Exoribonucleases , SARS-CoV-2 , Animals , Antiviral Agents/pharmacology , Arenavirus/drug effects , Chlorocebus aethiops , Exoribonucleases/antagonists & inhibitors , Fluorescence Polarization , SARS-CoV-2/drug effects , Vero Cells , Viral Nonstructural Proteins/antagonists & inhibitors
3.
J Med Chem ; 65(8): 6231-6249, 2022 04 28.
Article in English | MEDLINE | ID: covidwho-1867997

ABSTRACT

Enzymes involved in RNA capping of SARS-CoV-2 are essential for the stability of viral RNA, translation of mRNAs, and virus evasion from innate immunity, making them attractive targets for antiviral agents. In this work, we focused on the design and synthesis of nucleoside-derived inhibitors against the SARS-CoV-2 nsp14 (N7-guanine)-methyltransferase (N7-MTase) that catalyzes the transfer of the methyl group from the S-adenosyl-l-methionine (SAM) cofactor to the N7-guanosine cap. Seven compounds out of 39 SAM analogues showed remarkable double-digit nanomolar inhibitory activity against the N7-MTase nsp14. Molecular docking supported the structure-activity relationships of these inhibitors and a bisubstrate-based mechanism of action. The three most potent inhibitors significantly stabilized nsp14 (ΔTm ≈ 11 °C), and the best inhibitor demonstrated high selectivity for nsp14 over human RNA N7-MTase.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/drug therapy , COVID-19/virology , Exoribonucleases/antagonists & inhibitors , Exoribonucleases/chemistry , Humans , Methyltransferases , Molecular Docking Simulation , RNA, Viral/genetics , S-Adenosylmethionine , SARS-CoV-2/drug effects , SARS-CoV-2/enzymology , Sulfonamides/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Viral Nonstructural Proteins/chemistry
4.
Sci Rep ; 12(1): 3860, 2022 03 09.
Article in English | MEDLINE | ID: covidwho-1799576

ABSTRACT

Non-structural protein 15 (Nsp15) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) forms a homo hexamer and functions as an endoribonuclease. Here, we propose that Nsp15 activity may be inhibited by preventing its hexamerization through drug binding. We first explored the stable conformation of the Nsp15 monomer as the global free energy minimum conformation in the free energy landscape using a combination of parallel cascade selection molecular dynamics (PaCS-MD) and the Markov state model (MSM), and found that the Nsp15 monomer forms a more open conformation with larger druggable pockets on the surface. Targeting the pockets with high druggability scores, we conducted ligand docking and identified compounds that tightly bind to the Nsp15 monomer. The top poses with Nsp15 were subjected to binding free energy calculations by dissociation PaCS-MD and MSM (dPaCS-MD/MSM), indicating the stability of the complexes. One of the identified pockets, which is distinctively bound by inosine analogues, may be an alternative binding site to stabilize viral RNA binding and/or an alternative catalytic site. We constructed a stable RNA structure model bound to both UTP and alternative binding sites, providing a reasonable proposed model of the Nsp15/RNA complex.


Subject(s)
Endoribonucleases/metabolism , RNA, Viral/chemistry , SARS-CoV-2/metabolism , Viral Nonstructural Proteins/metabolism , Antiviral Agents/chemistry , Antiviral Agents/metabolism , Binding Sites , COVID-19/pathology , COVID-19/virology , Endoribonucleases/antagonists & inhibitors , Humans , Markov Chains , Molecular Docking Simulation , Molecular Dynamics Simulation , Nucleic Acid Conformation , Protein Multimerization , SARS-CoV-2/genetics , SARS-CoV-2/isolation & purification , Static Electricity , Viral Nonstructural Proteins/antagonists & inhibitors
5.
Molecules ; 27(7)2022 Mar 31.
Article in English | MEDLINE | ID: covidwho-1792596

ABSTRACT

As a continuation of our earlier work against SARS-CoV-2, seven FDA-approved drugs were designated as the best SARS-CoV-2 nsp16-nsp10 2'-o-methyltransferase (2'OMTase) inhibitors through 3009 compounds. The in silico inhibitory potential of the examined compounds against SARS-CoV-2 nsp16-nsp10 2'-o-methyltransferase (PDB ID: (6W4H) was conducted through a multi-step screening approach. At the beginning, molecular fingerprints experiment with SAM (S-Adenosylmethionine), the co-crystallized ligand of the targeted enzyme, unveiled the resemblance of 147 drugs. Then, a structural similarity experiment recommended 26 compounds. Therefore, the 26 compounds were docked against 2'OMTase to reveal the potential inhibitory effect of seven promising compounds (Protirelin, (1187), Calcium folinate (1913), Raltegravir (1995), Regadenoson (2176), Ertapenem (2396), Methylergometrine (2532), and Thiamine pyrophosphate hydrochloride (2612)). Out of the docked ligands, Ertapenem (2396) showed an ideal binding mode like that of the co-crystallized ligand (SAM). It occupied all sub-pockets of the active site and bound the crucial amino acids. Accordingly, some MD simulation experiments (RMSD, RMSF, Rg, SASA, and H-bonding) have been conducted for the 2'OMTase-Ertapenem complex over 100 ns. The performed MD experiments verified the correct binding mode of Ertapenem against 2'OMTase exhibiting low energy and optimal dynamics. Finally, MM-PBSA studies indicated that Ertapenem bonded advantageously to the targeted protein with a free energy value of -43 KJ/mol. Furthermore, the binding free energy analysis revealed the essential amino acids of 2'OMTase that served positively to the binding. The achieved results bring hope to find a treatment for COVID-19 via in vitro and in vivo studies for the pointed compounds.


Subject(s)
Methyltransferases , SARS-CoV-2 , Viral Nonstructural Proteins , Viral Regulatory and Accessory Proteins , Ertapenem/pharmacology , Ligands , Methyltransferases/antagonists & inhibitors , Molecular Docking Simulation , Molecular Dynamics Simulation , S-Adenosylmethionine/chemistry , SARS-CoV-2/drug effects , Viral Nonstructural Proteins/antagonists & inhibitors , Viral Regulatory and Accessory Proteins/antagonists & inhibitors
6.
Eur J Med Chem ; 228: 114030, 2022 Jan 15.
Article in English | MEDLINE | ID: covidwho-1768048

ABSTRACT

The epidemic coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has now spread worldwide and efficacious therapeutics are urgently needed. 3-Chymotrypsin-like cysteine protease (3CLpro) is an indispensable protein in viral replication and represents an attractive drug target for fighting COVID-19. Herein, we report the discovery of 9,10-dihydrophenanthrene derivatives as non-peptidomimetic and non-covalent inhibitors of the SARS-CoV-2 3CLpro. The structure-activity relationships of 9,10-dihydrophenanthrenes as SARS-CoV-2 3CLpro inhibitors have carefully been investigated and discussed in this study. Among all tested 9,10-dihydrophenanthrene derivatives, C1 and C2 display the most potent SARS-CoV-2 3CLpro inhibition activity, with IC50 values of 1.55 ± 0.21 µM and 1.81 ± 0.17 µM, respectively. Further enzyme kinetics assays show that these two compounds dose-dependently inhibit SARS-CoV-2 3CLprovia a mixed-inhibition manner. Molecular docking simulations reveal the binding modes of C1 in the dimer interface and substrate-binding pocket of the target. In addition, C1 shows outstanding metabolic stability in the gastrointestinal tract, human plasma, and human liver microsome, suggesting that this agent has the potential to be developed as an orally administrated SARS-CoV-2 3CLpro inhibitor.


Subject(s)
Antiviral Agents/pharmacology , COVID-19/drug therapy , Coronavirus 3C Proteases/antagonists & inhibitors , Drug Discovery/methods , Antiviral Agents/chemistry , Antiviral Agents/therapeutic use , Dose-Response Relationship, Drug , Drug Evaluation, Preclinical , Gastrointestinal Tract/metabolism , Humans , Kinetics , Microsomes, Liver/metabolism , Molecular Docking Simulation , Protein Binding , Structure-Activity Relationship , Viral Nonstructural Proteins/antagonists & inhibitors
7.
Biomolecules ; 12(4)2022 03 22.
Article in English | MEDLINE | ID: covidwho-1753432

ABSTRACT

The merging of distinct computational approaches has become a powerful strategy for discovering new biologically active compounds. By using molecular modeling, significant efforts have recently resulted in the development of new molecules, demonstrating high efficiency in reducing the replication of severe acute respiratory coronavirus 2 (SARS-CoV-2), the agent responsible for the COVID-19 pandemic. We have focused our interest on non-structural protein Nsp13 (NTPase/helicase), as a crucial protein, embedded in the replication-transcription complex (RTC), that controls the virus life cycle. To assist in the identification of the most druggable surfaces of Nsps13, we applied a combination of four computational tools: FTMap, SiteMap, Fpocket and LigandScout. These software packages explored the binding sites for different three-dimensional structures of RTC complexes (PDB codes: 6XEZ, 7CXM, 7CXN), thus, detecting several hot spots, that were clustered to obtain ensemble consensus sites, through a combination of four different approaches. The comparison of data provided new insights about putative druggable sites that might be employed for further docking simulations on druggable surfaces of Nsps13, in a scenario of repurposing drugs.


Subject(s)
Antiviral Agents , RNA Helicases , SARS-CoV-2 , Viral Nonstructural Proteins , Antiviral Agents/chemistry , Binding Sites , COVID-19 , Humans , Pandemics , RNA Helicases/antagonists & inhibitors , SARS-CoV-2/drug effects , Viral Nonstructural Proteins/antagonists & inhibitors
8.
Commun Biol ; 5(1): 154, 2022 02 22.
Article in English | MEDLINE | ID: covidwho-1699831

ABSTRACT

SARS-CoV-2 has an exonuclease-based proofreader, which removes nucleotide inhibitors such as Remdesivir that are incorporated into the viral RNA during replication, reducing the efficacy of these drugs for treating COVID-19. Combinations of inhibitors of both the viral RNA-dependent RNA polymerase and the exonuclease could overcome this deficiency. Here we report the identification of hepatitis C virus NS5A inhibitors Pibrentasvir and Ombitasvir as SARS-CoV-2 exonuclease inhibitors. In the presence of Pibrentasvir, RNAs terminated with the active forms of the prodrugs Sofosbuvir, Remdesivir, Favipiravir, Molnupiravir and AT-527 were largely protected from excision by the exonuclease, while in the absence of Pibrentasvir, there was rapid excision. Due to its unique structure, Tenofovir-terminated RNA was highly resistant to exonuclease excision even in the absence of Pibrentasvir. Viral cell culture studies also demonstrate significant synergy using this combination strategy. This study supports the use of combination drugs that inhibit both the SARS-CoV-2 polymerase and exonuclease for effective COVID-19 treatment.


Subject(s)
Antiviral Agents/pharmacology , COVID-19/drug therapy , Exonucleases/antagonists & inhibitors , RNA-Dependent RNA Polymerase/antagonists & inhibitors , SARS-CoV-2/drug effects , Viral Nonstructural Proteins/antagonists & inhibitors , Amino Acid Sequence , Anilides/pharmacology , Animals , Base Sequence , Benzimidazoles/pharmacology , COVID-19/virology , Cell Line, Tumor , Chlorocebus aethiops , Drug Synergism , Exonucleases/genetics , Exonucleases/metabolism , Humans , Proline/pharmacology , Pyrrolidines/pharmacology , RNA, Viral/genetics , RNA, Viral/metabolism , RNA-Dependent RNA Polymerase/genetics , RNA-Dependent RNA Polymerase/metabolism , SARS-CoV-2/genetics , SARS-CoV-2/physiology , Valine/pharmacology , Vero Cells , Viral Nonstructural Proteins/genetics , Viral Nonstructural Proteins/metabolism , Virus Replication/drug effects , Virus Replication/genetics
9.
J Food Biochem ; 46(5): e14085, 2022 05.
Article in English | MEDLINE | ID: covidwho-1673175

ABSTRACT

SARS-CoV-2 wreaks havoc around the world, triggering the COVID-19 pandemic. It has been confirmed that the endoribonuclease NSP15 is crucial to the viral replication, and thus identified as a potential drug target against COVID-19. The NSP15 protein was used as the target to conduct high-throughput virtual screening on 30,926 natural products from the NPASS database to identify potential NSP15 inhibitors. And 100 ns molecular dynamics simulations were performed on the NSP15 and NSP15-NPC198199 system. In all, 10 natural products with high docking scores with NSP15 protein were obtained, among which compound NPC198199 scored the highest. The analysis of the binding mode between NPC198199 and NSP15 found that NPC198199 would form H-bond interactions with multiple key residues at the catalytic site. Subsequently, a series of post-dynamics simulation analyses (including RMSD, RMSF, PCA, DCCM, RIN, binding free energy, and H-bond occupancy) were performed to further explore inhibitory mechanism of compound NPC198199 on NSP15 protein at the molecular level. The research strongly indicates that the 10 natural compounds screened can be used as potential inhibitors of NSP15, and provides valuable information for the subsequent drug discovery of anti-SARS-CoV-2. PRACTICAL APPLICATIONS: Natural products play an important role in the treatment of many difficult diseases. In this study, high-throughput virtual screening technology was used to screen the natural product database to obtain potential inhibitors against endoribonuclease NSP15. The binding mechanism between natural products and NSP15 was investigated at the molecular level by molecular dynamics technology so that it is expected to become candidate drugs for the treatment of SARS-CoV-2. We hope that our research can provide new clue to combat COVID-19 and overcome the epidemic situation as soon as possible.


Subject(s)
Antiviral Agents , Biological Products , Endoribonucleases , SARS-CoV-2 , Viral Nonstructural Proteins , Antiviral Agents/chemistry , Antiviral Agents/pharmacology , Biological Products/pharmacology , COVID-19/drug therapy , Endoribonucleases/antagonists & inhibitors , Humans , Molecular Docking Simulation , Molecular Dynamics Simulation , SARS-CoV-2/drug effects , Viral Nonstructural Proteins/antagonists & inhibitors
10.
Nucleic Acids Res ; 50(3): 1484-1500, 2022 02 22.
Article in English | MEDLINE | ID: covidwho-1624985

ABSTRACT

The SARS-CoV-2 coronavirus is the causal agent of the current global pandemic. SARS-CoV-2 belongs to an order, Nidovirales, with very large RNA genomes. It is proposed that the fidelity of coronavirus (CoV) genome replication is aided by an RNA nuclease complex, comprising the non-structural proteins 14 and 10 (nsp14-nsp10), an attractive target for antiviral inhibition. Our results validate reports that the SARS-CoV-2 nsp14-nsp10 complex has RNase activity. Detailed functional characterization reveals nsp14-nsp10 is a versatile nuclease capable of digesting a wide variety of RNA structures, including those with a blocked 3'-terminus. Consistent with a role in maintaining viral genome integrity during replication, we find that nsp14-nsp10 activity is enhanced by the viral RNA-dependent RNA polymerase complex (RdRp) consisting of nsp12-nsp7-nsp8 (nsp12-7-8) and demonstrate that this stimulation is mediated by nsp8. We propose that the role of nsp14-nsp10 in maintaining replication fidelity goes beyond classical proofreading by purging the nascent replicating RNA strand of a range of potentially replication-terminating aberrations. Using our developed assays, we identify drug and drug-like molecules that inhibit nsp14-nsp10, including the known SARS-CoV-2 major protease (Mpro) inhibitor ebselen and the HIV integrase inhibitor raltegravir, revealing the potential for multifunctional inhibitors in COVID-19 treatment.


Subject(s)
Antiviral Agents/pharmacology , Drug Evaluation, Preclinical , Exoribonucleases/metabolism , Genome, Viral/genetics , Genomic Instability , SARS-CoV-2/enzymology , SARS-CoV-2/genetics , Viral Nonstructural Proteins/metabolism , Viral Regulatory and Accessory Proteins/metabolism , Coronavirus RNA-Dependent RNA Polymerase/metabolism , Exoribonucleases/antagonists & inhibitors , Genome, Viral/drug effects , Genomic Instability/drug effects , Genomic Instability/genetics , HIV Integrase Inhibitors/pharmacology , Isoindoles/pharmacology , Multienzyme Complexes/antagonists & inhibitors , Multienzyme Complexes/metabolism , Organoselenium Compounds/pharmacology , RNA, Viral/biosynthesis , RNA, Viral/genetics , Raltegravir Potassium/pharmacology , SARS-CoV-2/drug effects , Viral Nonstructural Proteins/antagonists & inhibitors , Viral Regulatory and Accessory Proteins/antagonists & inhibitors , Virus Replication/drug effects , Virus Replication/genetics
11.
Int J Mol Sci ; 22(19)2021 Oct 02.
Article in English | MEDLINE | ID: covidwho-1444233

ABSTRACT

Considering the current dramatic and fatal situation due to the high spreading of SARS-CoV-2 infection, there is an urgent unmet medical need to identify novel and effective approaches for prevention and treatment of Coronavirus disease (COVID 19) by re-evaluating and repurposing of known drugs. For this, tomatidine and patchouli alcohol have been selected as potential drugs for combating the virus. The hit compounds were subsequently docked into the active site and molecular docking analyses revealed that both drugs can bind the active site of SARS-CoV-2 3CLpro, PLpro, NSP15, COX-2 and PLA2 targets with a number of important binding interactions. To further validate the interactions of promising compound tomatidine, Molecular dynamics study of 100 ns was carried out towards 3CLpro, NSP15 and COX-2. This indicated that the protein-ligand complex was stable throughout the simulation period, and minimal backbone fluctuations have ensued in the system. Post dynamic MM-GBSA analysis of molecular dynamics data showed promising mean binding free energy 47.4633 ± 9.28, 51.8064 ± 8.91 and 54.8918 ± 7.55 kcal/mol, respectively. Likewise, in silico ADMET studies of the selected ligands showed excellent pharmacokinetic properties with good absorption, bioavailability and devoid of toxicity. Therefore, patchouli alcohol and especially, tomatidine may provide prospect treatment options against SARS-CoV-2 infection by potentially inhibiting virus duplication though more research is guaranteed and secured.


Subject(s)
Coronavirus 3C Proteases/antagonists & inhibitors , Coronavirus Papain-Like Proteases/antagonists & inhibitors , Endoribonucleases/antagonists & inhibitors , SARS-CoV-2/enzymology , Sesquiterpenes/pharmacology , Tomatine/analogs & derivatives , Viral Nonstructural Proteins/antagonists & inhibitors , Antiviral Agents/pharmacology , COVID-19/drug therapy , COVID-19/virology , Coronavirus 3C Proteases/metabolism , Coronavirus Papain-Like Proteases/metabolism , Endoribonucleases/metabolism , Enzyme Inhibitors/pharmacology , Humans , Molecular Docking Simulation , Molecular Dynamics Simulation , SARS-CoV-2/drug effects , Tomatine/pharmacology , Viral Nonstructural Proteins/metabolism
12.
Enzymes ; 49: 63-82, 2021.
Article in English | MEDLINE | ID: covidwho-1432697

ABSTRACT

The therapeutic targeting of the nonstructural protein 5B (NS5B) RNA-dependent RNA polymerase (RdRp) of the Hepatitis C Virus (HCV) with nucleotide analogs led to a deep understanding of this enzymes structure, function and substrate specificity. Unlike previously studied DNA polymerases including the reverse transcriptase of Human Immunodeficiency Virus, development of biochemical assays for HCV RdRp proved challenging due to low solubility of the full-length protein and inefficient acceptance of exogenous primer/templates. Despite the poor apparent specific activity, HCV RdRp was found to support rapid and processive transcription once elongation is initiated in vitro consistent with its high level of viral replication in the livers of patients. Understanding of the substrate specificity of HCV RdRp led to the discovery of the active triphosphate of sofosbuvir as a nonobligate chain-terminator of viral RNA transcripts. The ternary crystal structure of HCV RdRp, primer/template, and incoming nucleotide showed the interaction between the nucleotide analog and the 2'-hydroxyl binding pocket and how an unfit mutation of serine 282 to threonine results in resistance by interacting with the uracil base and modified 2'-position of the analog. Host polymerases mediate off-target toxicity of nucleotide analogs and the active metabolite of sofosbuvir was found to not be efficiently incorporated by host polymerases including the mitochondrial RNA polymerase (POLRMT). Knowledge from studying inhibitors of HCV RdRp serves to advance antiviral drug discovery for other emerging RNA viruses including the discovery of remdesivir as an inhibitor of severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), the virus that causes COVID-19.


Subject(s)
Hepacivirus , Sofosbuvir/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Hepacivirus/drug effects , Hepacivirus/enzymology , RNA, Viral , RNA-Dependent RNA Polymerase/genetics , SARS-CoV-2
13.
Future Med Chem ; 13(4): 363-378, 2021 02.
Article in English | MEDLINE | ID: covidwho-1389653

ABSTRACT

Background: The SARS-CoV-2 3CLpro is one of the primary targets for designing new and repurposing known drugs. Methodology: A virtual screening of molecules from the Natural Product Atlas was performed, followed by molecular dynamics simulations of the most potent inhibitor bound to two conformations of the protease and into two binding sites. Conclusion: Eight molecules with appropriate ADMET properties are suggested as potential inhibitors. The greatest benefit of this study is the demonstration that these ligands can bind in the catalytic site but also to the groove between domains II and III, where they interact with a series of residues which have an important role in the dimerization and the maturation process of the enzyme.


Subject(s)
Antiviral Agents/pharmacology , Biological Products/pharmacology , SARS-CoV-2/drug effects , Binding Sites , COVID-19/drug therapy , COVID-19/prevention & control , Computational Biology , Drug Design , Drug Repositioning , Humans , Ligands , Molecular Docking Simulation , Molecular Dynamics Simulation , Nucleosides/pharmacology , Peptide Hydrolases/chemistry , Protease Inhibitors/chemistry , Protein Binding , Protein Multimerization , Software , Viral Nonstructural Proteins/antagonists & inhibitors
14.
FEBS J ; 288(17): 5130-5147, 2021 09.
Article in English | MEDLINE | ID: covidwho-1388264

ABSTRACT

SARS-CoV-2 virus has triggered a global pandemic with devastating consequences. The understanding of fundamental aspects of this virus is of extreme importance. In this work, we studied the viral ribonuclease nsp14, one of the most interferon antagonists from SARS-CoV-2. Nsp14 is a multifunctional protein with two distinct activities, an N-terminal 3'-to-5' exoribonuclease (ExoN) and a C-terminal N7-methyltransferase (N7-MTase), both critical for coronaviruses life cycle, indicating nsp14 as a prominent target for the development of antiviral drugs. In coronaviruses, nsp14 ExoN activity is stimulated through the interaction with the nsp10 protein. We have performed a biochemical characterization of nsp14-nsp10 complex from SARS-CoV-2. We confirm the 3'-5' exoribonuclease and MTase activities of nsp14 and the critical role of nsp10 in upregulating the nsp14 ExoN activity. Furthermore, we demonstrate that SARS-CoV-2 nsp14 N7-MTase activity is functionally independent of the ExoN activity and nsp10. A model from SARS-CoV-2 nsp14-nsp10 complex allowed mapping key nsp10 residues involved in this interaction. Our results show that a stable interaction between nsp10 and nsp14 is required for the nsp14-mediated ExoN activity of SARS-CoV-2. We studied the role of conserved DEDD catalytic residues of SARS-CoV-2 nsp14 ExoN. Our results show that motif I of ExoN domain is essential for the nsp14 function, contrasting to the functionality of these residues in other coronaviruses, which can have important implications regarding the specific pathogenesis of SARS-CoV-2. This work unraveled a basis for discovering inhibitors targeting specific amino acids in order to disrupt the assembly of this complex and interfere with coronaviruses replication.


Subject(s)
COVID-19/genetics , Exoribonucleases/genetics , SARS-CoV-2/genetics , Viral Nonstructural Proteins/genetics , Viral Regulatory and Accessory Proteins/genetics , Antiviral Agents/chemistry , Antiviral Agents/therapeutic use , COVID-19/drug therapy , COVID-19/virology , Drug Design , Exoribonucleases/antagonists & inhibitors , Humans , Multiprotein Complexes/drug effects , Multiprotein Complexes/genetics , Protein Interaction Maps/genetics , SARS-CoV-2/drug effects , SARS-CoV-2/pathogenicity , Viral Nonstructural Proteins/antagonists & inhibitors , Viral Regulatory and Accessory Proteins/antagonists & inhibitors , Virus Replication/genetics
15.
Molecules ; 25(19)2020 Oct 06.
Article in English | MEDLINE | ID: covidwho-1389458

ABSTRACT

A novel series of some hydrazones bearing thiazole moiety were generated via solvent-drop grinding of thiazole carbohydrazide 2 with various carbonyl compounds. Also, dehydrative-cyclocondensation of 2 with active methylene compounds or anhydrides gave the respective pyarzole or pyrazine derivatives. The structures of the newly synthesized compounds were established based on spectroscopic evidences and their alternative syntheses. Additionally, the anti-viral activity of all the products was tested against SARS-CoV-2 main protease (Mpro) using molecular docking combined with molecular dynamics simulation (MDS). The average binding affinities of the compounds 3a, 3b, and 3c (-8.1 ± 0.33 kcal/mol, -8.0 ± 0.35 kcal/mol, and -8.2 ± 0.21 kcal/mol, respectively) are better than that of the positive control Nelfinavir (-6.9 ± 0.51 kcal/mol). This shows the possibility of these three compounds to effectively bind to SARS-CoV-2 Mpro and hence, contradict the virus lifecycle.


Subject(s)
Antiviral Agents/chemical synthesis , Betacoronavirus/enzymology , Hydrazones/chemical synthesis , Protease Inhibitors/chemical synthesis , Pyrazines/chemical synthesis , Pyrazoles/chemical synthesis , Viral Nonstructural Proteins/antagonists & inhibitors , Antiviral Agents/pharmacology , Betacoronavirus/chemistry , Betacoronavirus/drug effects , Binding Sites , COVID-19 , Coronavirus 3C Proteases , Coronavirus Infections/drug therapy , Cysteine Endopeptidases/chemistry , Cysteine Endopeptidases/metabolism , Drug Discovery , Humans , Hydrazones/pharmacology , Molecular Docking Simulation , Molecular Dynamics Simulation , Pandemics , Pneumonia, Viral/drug therapy , Protease Inhibitors/pharmacology , Protein Binding , Protein Conformation, alpha-Helical , Protein Conformation, beta-Strand , Protein Interaction Domains and Motifs , Pyrazines/pharmacology , Pyrazoles/pharmacology , SARS-CoV-2 , Thermodynamics , User-Computer Interface , Viral Nonstructural Proteins/chemistry , Viral Nonstructural Proteins/metabolism
16.
Biochemistry ; 59(39): 3741-3756, 2020 10 06.
Article in English | MEDLINE | ID: covidwho-1387098

ABSTRACT

The SARS-CoV-2 main protease (Mpro) is essential to viral replication and cleaves highly specific substrate sequences, making it an obvious target for inhibitor design. However, as for any virus, SARS-CoV-2 is subject to constant neutral drift and selection pressure, with new Mpro mutations arising over time. Identification and structural characterization of Mpro variants is thus critical for robust inhibitor design. Here we report sequence analysis, structure predictions, and molecular modeling for seventy-nine Mpro variants, constituting all clinically observed mutations in this protein as of April 29, 2020. Residue substitution is widely distributed, with some tendency toward larger and more hydrophobic residues. Modeling and protein structure network analysis suggest differences in cohesion and active site flexibility, revealing patterns in viral evolution that have relevance for drug discovery.


Subject(s)
Betacoronavirus/enzymology , Betacoronavirus/genetics , Models, Molecular , Mutation , Viral Nonstructural Proteins/genetics , Catalytic Domain , Drug Discovery , Evolution, Molecular , Humans , Molecular Structure , Phylogeny , Protease Inhibitors/chemistry , SARS-CoV-2 , Sequence Analysis, Protein , Viral Nonstructural Proteins/antagonists & inhibitors
17.
J Gen Virol ; 102(3)2021 03.
Article in English | MEDLINE | ID: covidwho-1369236

ABSTRACT

Coronavirus protease nsp5 (Mpro, 3CLpro) remains a primary target for coronavirus therapeutics due to its indispensable and conserved role in the proteolytic processing of the viral replicase polyproteins. In this review, we discuss the diversity of known coronaviruses, the role of nsp5 in coronavirus biology, and the structure and function of this protease across the diversity of known coronaviruses, and evaluate past and present efforts to develop inhibitors to the nsp5 protease with a particular emphasis on new and mostly unexplored potential targets of inhibition. With the recent emergence of pandemic SARS-CoV-2, this review provides novel and potentially innovative strategies and directions to develop effective therapeutics against the coronavirus protease nsp5.


Subject(s)
Antiviral Agents/therapeutic use , COVID-19/drug therapy , Coronavirus 3C Proteases/antagonists & inhibitors , Coronavirus 3C Proteases/chemistry , SARS-CoV-2/enzymology , Viral Nonstructural Proteins/antagonists & inhibitors , Viral Protease Inhibitors/therapeutic use , Amino Acid Sequence , COVID-19/virology , Coronavirus/enzymology , Coronavirus/metabolism , Coronavirus 3C Proteases/genetics , Coronavirus 3C Proteases/metabolism , Humans , Phylogeny , SARS-CoV-2/metabolism , Viral Nonstructural Proteins/metabolism
18.
Nat Commun ; 12(1): 4848, 2021 08 11.
Article in English | MEDLINE | ID: covidwho-1354102

ABSTRACT

There is currently a lack of effective drugs to treat people infected with SARS-CoV-2, the cause of the global COVID-19 pandemic. The SARS-CoV-2 Non-structural protein 13 (NSP13) has been identified as a target for anti-virals due to its high sequence conservation and essential role in viral replication. Structural analysis reveals two "druggable" pockets on NSP13 that are among the most conserved sites in the entire SARS-CoV-2 proteome. Here we present crystal structures of SARS-CoV-2 NSP13 solved in the APO form and in the presence of both phosphate and a non-hydrolysable ATP analog. Comparisons of these structures reveal details of conformational changes that provide insights into the helicase mechanism and possible modes of inhibition. To identify starting points for drug development we have performed a crystallographic fragment screen against NSP13. The screen reveals 65 fragment hits across 52 datasets opening the way to structure guided development of novel antiviral agents.


Subject(s)
Methyltransferases/chemistry , RNA Helicases/chemistry , SARS-CoV-2/chemistry , Viral Nonstructural Proteins/chemistry , Adenosine Triphosphate/chemistry , Adenosine Triphosphate/metabolism , Amino Acid Sequence , Apoenzymes/chemistry , Apoenzymes/metabolism , Binding Sites , Crystallography, X-Ray , Drug Design , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/metabolism , Methyltransferases/antagonists & inhibitors , Methyltransferases/metabolism , Models, Molecular , Phosphates/chemistry , Phosphates/metabolism , Protein Conformation , RNA Helicases/antagonists & inhibitors , RNA Helicases/metabolism , RNA, Viral/chemistry , RNA, Viral/metabolism , SARS-CoV-2/enzymology , Structure-Activity Relationship , Viral Nonstructural Proteins/antagonists & inhibitors , Viral Nonstructural Proteins/metabolism
19.
Antiviral Res ; 193: 105142, 2021 09.
Article in English | MEDLINE | ID: covidwho-1321985

ABSTRACT

SARS-CoV-2, the cause of the currently ongoing COVID-19 pandemic, encodes its own mRNA capping machinery. Insights into this capping system may provide new ideas for therapeutic interventions and drug discovery. In this work, we employ a previously developed Py-FLINT screening approach to study the inhibitory effects of compounds against the cap guanine N7-methyltransferase enzyme, which is involved in SARS-CoV-2 mRNA capping. We screened five commercially available libraries (7039 compounds in total) to identify 83 inhibitors with IC50 < 50 µM, which were further validated using RP HPLC and dot blot assays. Novel fluorescence anisotropy binding assays were developed to examine the targeted binding site. The inhibitor structures were analyzed for structure-activity relationships in order to define common structural patterns. Finally, the most potent inhibitors were tested for antiviral activity on SARS-CoV-2 in a cell based assay.


Subject(s)
Antiviral Agents/pharmacology , COVID-19/drug therapy , Methyltransferases/antagonists & inhibitors , Nucleotidyltransferases/antagonists & inhibitors , SARS-CoV-2/drug effects , Antiviral Agents/chemistry , COVID-19/virology , Cell Line , Exoribonucleases/antagonists & inhibitors , Exoribonucleases/metabolism , High-Throughput Screening Assays , Humans , Inhibitory Concentration 50 , Methyltransferases/metabolism , Nucleotidyltransferases/metabolism , RNA Caps , RNA, Viral/genetics , RNA, Viral/metabolism , SARS-CoV-2/genetics , SARS-CoV-2/metabolism , Viral Nonstructural Proteins/antagonists & inhibitors , Viral Nonstructural Proteins/metabolism , Virus Replication/drug effects
20.
PLoS One ; 16(7): e0253364, 2021.
Article in English | MEDLINE | ID: covidwho-1315884

ABSTRACT

Of the 16 non-structural proteins (Nsps) encoded by SARS CoV-2, Nsp3 is the largest and plays important roles in the viral life cycle. Being a large, multidomain, transmembrane protein, Nsp3 has been the most challenging Nsp to characterize. Encoded within Nsp3 is the papain-like protease domain (PLpro) that cleaves not only the viral polypeptide but also K48-linked polyubiquitin and the ubiquitin-like modifier, ISG15, from host cell proteins. We here compare the interactors of PLpro and Nsp3 and find a largely overlapping interactome. Intriguingly, we find that near full length Nsp3 is a more active protease compared to the minimal catalytic domain of PLpro. Using a MALDI-TOF based assay, we screen 1971 approved clinical compounds and identify five compounds that inhibit PLpro with IC50s in the low micromolar range but showed cross reactivity with other human deubiquitinases and had no significant antiviral activity in cellular SARS-CoV-2 infection assays. We therefore looked for alternative methods to block PLpro activity and engineered competitive nanobodies that bind to PLpro at the substrate binding site with nanomolar affinity thus inhibiting the enzyme. Our work highlights the importance of studying Nsp3 and provides tools and valuable insights to investigate Nsp3 biology during the viral infection cycle.


Subject(s)
Antiviral Agents/pharmacology , Protease Inhibitors/pharmacology , RNA-Dependent RNA Polymerase/antagonists & inhibitors , Single-Chain Antibodies/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , A549 Cells , Antigen-Antibody Complex , Humans , Inhibitory Concentration 50 , RNA-Dependent RNA Polymerase/immunology , RNA-Dependent RNA Polymerase/metabolism , Single-Chain Antibodies/immunology , Viral Nonstructural Proteins/immunology , Viral Nonstructural Proteins/metabolism
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