ABSTRACT
New variants of the severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) emerged and spread rapidly all over the world, which strongly supports the need for pharmacological options to complement vaccine strategies. Main protease (Mpro or 3CLpro) is a critical enzyme in the life cycle of SARS-CoV-2 and appears to be highly conserved among different genera of coronaviruses, making it an ideal target for the development of drugs with broad-spectrum property. PF-07304814 developed by Pfizer is an intravenously administered inhibitor targeting SARS-CoV-2 Mpro. Here we showed that PF-07304814 displays broad-spectrum inhibitory activity against Mpros from multiple coronaviruses. Crystal structures of Mpros of SARS-CoV-2, SARS-CoV, MERS-CoV, and HCoV-NL63 bound to the inhibitor PF-07304814 revealed a conserved ligand-binding site, providing new insights into the mechanism of inhibition of viral replication. A detailed analysis of these crystal structures complemented by comprehensive comparison defined the key structural determinants essential for inhibition and illustrated the binding mode of action of Mpros from different coronaviruses. In view of the importance of Mpro for the medications of SARS-CoV-2 infection, insights derived from the present study should accelerate the design of pan-coronaviral main protease inhibitors that are safer and more effective.
Subject(s)
Coronavirus 3C Proteases , Coronavirus Protease Inhibitors , Indoles , Leucine , Pyrrolidinones , SARS-CoV-2 , Coronavirus 3C Proteases/antagonists & inhibitors , Coronavirus 3C Proteases/chemistry , Coronavirus Protease Inhibitors/chemistry , Coronavirus Protease Inhibitors/pharmacology , Drug Design , Humans , Indoles/chemistry , Indoles/pharmacology , Leucine/chemistry , Leucine/pharmacology , Ligands , Protein Binding , Pyrrolidinones/chemistry , Pyrrolidinones/pharmacology , SARS-CoV-2/drug effects , SARS-CoV-2/enzymologyABSTRACT
The high mutation rate of COVID-19 and the prevalence of multiple variants strongly support the need for pharmacological options to complement vaccine strategies. One region that appears highly conserved among different genera of coronaviruses is the substrate-binding site of the main protease (Mpro or 3CLpro), making it an attractive target for the development of broad-spectrum drugs for multiple coronaviruses. PF-07321332, developed by Pfizer, is the first orally administered inhibitor targeting the main protease of SARS-CoV-2, which also has shown potency against other coronaviruses. Here, we report three crystal structures of the main protease of SARS-CoV-2, SARS-CoV, and Middle East respiratory syndrome (MERS)-CoV bound to the inhibitor PF-07321332. The structures reveal a ligand-binding site that is conserved among SARS-CoV-2, SARS-CoV, and MERS-CoV, providing insights into the mechanism of inhibition of viral replication. The long and narrow cavity in the cleft between domains I and II of the main protease harbors multiple inhibitor-binding sites, where PF-07321332 occupies subsites S1, S2, and S4 and appears more restricted than other inhibitors. A detailed analysis of these structures illuminated key structural determinants essential for inhibition and elucidated the binding mode of action of the main proteases from different coronaviruses. Given the importance of the main protease for the treatment of SARS-CoV-2 infection, insights derived from this study should accelerate the design of safer and more effective antivirals. IMPORTANCE The current pandemic of multiple variants has created an urgent need for effective inhibitors of SARS-CoV-2 to complement vaccine strategies. PF-07321332, developed by Pfizer, is the first orally administered coronavirus-specific main protease inhibitor approved by the FDA. We solved the crystal structures of the main protease of SARS-CoV-2, SARS-CoV, and MERS-CoV that bound to the PF-07321332, suggesting PF-07321332 is a broad-spectrum inhibitor for coronaviruses. Structures of the main protease inhibitor complexes present an opportunity to discover safer and more effective inhibitors for COVID-19.
Subject(s)
Lactams , Leucine , Nitriles , Peptide Hydrolases , Proline , Antiviral Agents/chemistry , Antiviral Agents/metabolism , Humans , Lactams/chemistry , Lactams/metabolism , Leucine/chemistry , Leucine/metabolism , Middle East Respiratory Syndrome Coronavirus/chemistry , Middle East Respiratory Syndrome Coronavirus/enzymology , Nitriles/chemistry , Nitriles/metabolism , Peptide Hydrolases/chemistry , Peptide Hydrolases/metabolism , Proline/chemistry , Proline/metabolism , Protease Inhibitors/chemistry , Protease Inhibitors/metabolism , Severe acute respiratory syndrome-related coronavirus/chemistry , Severe acute respiratory syndrome-related coronavirus/enzymology , SARS-CoV-2/chemistry , SARS-CoV-2/enzymology , COVID-19 Drug TreatmentSubject(s)
COVID-19/enzymology , Coronavirus 3C Proteases , Cyclopropanes/chemistry , Cysteine Proteinase Inhibitors/chemistry , Leucine/analogs & derivatives , Proline/analogs & derivatives , SARS-CoV-2/enzymology , Sulfones/chemistry , Urea/chemistry , Coronavirus 3C Proteases/antagonists & inhibitors , Coronavirus 3C Proteases/chemistry , Cyclopropanes/pharmacology , Cysteine Proteinase Inhibitors/pharmacology , Hepacivirus/enzymology , Humans , Leucine/chemistry , Leucine/pharmacology , Proline/chemistry , Proline/pharmacology , Sulfones/pharmacology , Urea/pharmacology , COVID-19 Drug TreatmentABSTRACT
Angiotensin converting enzyme 2 (ACE2) plays a key role in renin-angiotensin system regulation and amino acid homeostasis. Human ACE2 acts as the receptor for severe acute respiratory syndrome coronaviruses SARS-CoV and SARS-CoV-2. ACE2 is also widely expressed in epithelial cells of the lungs, heart, kidney, and pancreas. It is considered an important drug target for treating SARS-CoV-2 as well as pulmonary diseases, heart failure, hypertension, renal diseases, and diabetes. Despite the critical importance, the mechanism of ligand binding to the human ACE2 receptor remains unknown. Here, we have addressed this challenge through all-atom simulations using a novel ligand Gaussian accelerated molecular dynamics (LiGaMD) method. Microsecond time scale LiGaMD simulations have unprecedentedly captured multiple times of spontaneous binding and unbinding of a potent inhibitor MLN-4760 in the ACE2 receptor. With ligand far away in the unbound state, the ACE2 receptor samples distinct Open, Partially Open, Closed, and Fully Closed conformations. Upon ligand binding to the active site, conformational ensemble of the ACE2 receptor is biased toward the Closed state as observed in the X-ray experimental structure. The LiGaMD simulations thus suggest a conformational selection mechanism for ligand recognition by the highly flexible ACE2 receptor, which is expected to facilitate rational drug design targeting human ACE2 against coronaviruses and other related human diseases.
Subject(s)
Angiotensin-Converting Enzyme 2/antagonists & inhibitors , Antiviral Agents/chemistry , COVID-19 Drug Treatment , Imidazoles/chemistry , Leucine/analogs & derivatives , Protease Inhibitors/chemistry , SARS-CoV-2/drug effects , Antiviral Agents/pharmacology , COVID-19/metabolism , Catalytic Domain , Drug Design , Humans , Imidazoles/pharmacology , Leucine/chemistry , Leucine/pharmacology , Ligands , Molecular Dynamics Simulation , Protease Inhibitors/pharmacology , Protein Binding , Protein Conformation , SARS-CoV-2/metabolismABSTRACT
We present a detailed computational analysis of the binding mode and reactivity of the novel oral inhibitor PF-07321332 developed against the SARS-CoV-2 3CL protease. Alchemical free energy calculations suggest that positions P3 and P4 could be susceptible to improvement in order to get a larger binding strength. QM/MM simulations unveil the reaction mechanism for covalent inhibition, showing that the nitrile warhead facilitates the recruitment of a water molecule for the proton transfer step.
Subject(s)
Coronavirus 3C Proteases/antagonists & inhibitors , Molecular Dynamics Simulation , Nitriles/chemistry , Protease Inhibitors/chemistry , SARS-CoV-2/enzymology , Binding Sites , COVID-19/pathology , COVID-19/virology , Catalytic Domain , Coronavirus 3C Proteases/metabolism , Humans , Lactams/chemistry , Lactams/metabolism , Leucine/chemistry , Leucine/metabolism , Nitriles/metabolism , Proline/chemistry , Proline/metabolism , Protease Inhibitors/metabolism , Quantum Theory , SARS-CoV-2/isolation & purification , ThermodynamicsABSTRACT
Specific anti-coronaviral drugs complementing available vaccines are urgently needed to fight the COVID-19 pandemic. Given its high conservation across the betacoronavirus genus and dissimilarity to human proteases, the SARS-CoV-2 main protease (Mpro) is an attractive drug target. SARS-CoV-2 Mpro inhibitors have been developed at unprecedented speed, most of them being substrate-derived peptidomimetics with cysteine-modifying warheads. In this study, Mpro has proven resistant towards the identification of high-affinity short substrate-derived peptides and peptidomimetics without warheads. 20 cyclic and linear substrate analogues bearing natural and unnatural residues, which were predicted by computational modelling to bind with high affinity and designed to establish structure-activity relationships, displayed no inhibitory activity at concentrations as high as 100 µM. Only a long linear peptide covering residues P6 to P5' displayed moderate inhibition (Ki = 57 µM). Our detailed findings will inform current and future drug discovery campaigns targeting Mpro.
Subject(s)
COVID-19/pathology , Coronavirus 3C Proteases/antagonists & inhibitors , Protease Inhibitors/chemistry , SARS-CoV-2/enzymology , COVID-19/virology , Coronavirus 3C Proteases/metabolism , Cysteine/chemistry , Cysteine/metabolism , Humans , Lactams/chemistry , Lactams/metabolism , Leucine/chemistry , Leucine/metabolism , Nitriles/chemistry , Nitriles/metabolism , Peptides/chemistry , Peptides/metabolism , Peptidomimetics/chemistry , Peptidomimetics/metabolism , Proline/chemistry , Proline/metabolism , Protease Inhibitors/metabolism , SARS-CoV-2/isolation & purification , Structure-Activity Relationship , Substrate SpecificityABSTRACT
Chloroquine (CQ) and hydroxychloroquine (HCQ) have shown the ability to inhibit in vitro viral replications of coronaviridae viruses such as SARS-CoV and SARS-CoV-2. However, clinical trial outcomes have been disparate, suggesting that CQ and HCQ antiviral mechanisms are not fully understood. Based on three-dimensional structural similarities between HCQ and the known ACE2 specific inhibitor MLN-4760, we compared their modulation on ACE2 activity. Here we describe, for the first time, in a cell-free in vitro system that HCQ directly and dose-dependently inhibits the activity of recombinant human ACE2, with a potency similar to the MLN-4760. Further analysis suggests that HCQ binds to a noncompetitive site other than the one occupied by MLN-4760. We also determined that the viral spike glycoprotein segment that comprises the RBD segment has no effect on ACE2 activity but unexpectedly was able to partially reverse the inhibition induced by HCQ but not that by MLN-4760. In summary, here we demonstrate the direct inhibitory action of HCQ over the activity of the enzyme ACE2. Then, by determining the activity of ACE2, we reveal that the interaction with the spike protein of SARS-CoV-2 leads to structural changes that at least partially displace the interaction of the said enzyme with HCQ. These results may help to explain why the effectiveness of HCQ in clinical trials has been so variable. Additionally, this knowledge could be used for to develop techniques for the detection of SARS-CoV-2.
Subject(s)
Angiotensin-Converting Enzyme 2 , Antiviral Agents , COVID-19 Drug Treatment , Hydroxychloroquine , Angiotensin-Converting Enzyme 2/antagonists & inhibitors , Angiotensin-Converting Enzyme 2/chemistry , Angiotensin-Converting Enzyme 2/metabolism , Antiviral Agents/chemistry , Antiviral Agents/metabolism , Antiviral Agents/pharmacology , Humans , Hydroxychloroquine/chemistry , Hydroxychloroquine/metabolism , Hydroxychloroquine/pharmacology , Imidazoles/chemistry , Imidazoles/metabolism , Imidazoles/pharmacology , Leucine/analogs & derivatives , Leucine/chemistry , Leucine/metabolism , Leucine/pharmacology , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/metabolismABSTRACT
The chemical structure of PF-07321332, the first orally available Covid-19 clinical candidate, has recently been revealed by Pfizer. No information has been provided about the interaction pattern between PF-07321332 and its biomolecular counterpart, the SARS-CoV-2 main protease (Mpro). In the present work, we exploited Supervised Molecular Dynamics (SuMD) simulations to elucidate the key features that characterise the interaction between this drug candidate and the protease, emphasising similarities and differences with other structurally related inhibitors such as Boceprevir and PF-07304814. The structural insights provided by SuMD will hopefully be able to inspire the rational discovery of other potent and selective protease inhibitors.
Subject(s)
Antiviral Agents/chemistry , Lactams/chemistry , Leucine/chemistry , Molecular Dynamics Simulation , Nitriles/chemistry , Proline/chemistry , Protease Inhibitors/chemistry , Antiviral Agents/pharmacology , Humans , Lactams/pharmacology , Leucine/pharmacology , Ligands , Nitriles/pharmacology , Peptide Hydrolases/metabolism , Proline/pharmacology , Protease Inhibitors/pharmacology , SARS-CoV-2/drug effects , SARS-CoV-2/enzymology , SoftwareABSTRACT
The COVID-19 outbreak continues to spread worldwide at a rapid rate. Currently, the absence of any effective antiviral treatment is the major concern for the global population. The reports of the occurrence of various point mutations within the important therapeutic target protein of SARS-CoV-2 has elevated the problem. The SARS-CoV-2 main protease (Mpro) is a major therapeutic target for new antiviral designs. In this study, the efficacy of PF-00835231 was investigated (a Mpro inhibitor under clinical trials) against the Mpro and their reported mutants. Various in silico approaches were used to investigate and compare the efficacy of PF-00835231 and five drugs previously documented to inhibit the Mpro. Our study shows that PF-00835231 is not only effective against the wild type but demonstrates a high affinity against the studied mutants as well.
Subject(s)
Antiviral Agents/chemistry , Antiviral Agents/pharmacology , Coronavirus 3C Proteases/antagonists & inhibitors , Indoles/chemistry , Indoles/pharmacology , Leucine/chemistry , Leucine/pharmacology , Protease Inhibitors/chemistry , Protease Inhibitors/pharmacology , Pyrrolidinones/chemistry , Pyrrolidinones/pharmacology , Binding Sites , Computer Simulation , Coronavirus 3C Proteases/chemistry , Coronavirus 3C Proteases/genetics , Databases, Protein , Diarylquinolines/chemistry , Diarylquinolines/pharmacology , Dihydropyridines/chemistry , Dihydropyridines/pharmacology , Humans , Ligands , Molecular Docking Simulation , Molecular Dynamics Simulation , Nitrobenzenes/chemistry , Nitrobenzenes/pharmacology , Nitrophenols/chemistry , Nitrophenols/pharmacology , Organophosphorus Compounds/chemistry , Organophosphorus Compounds/pharmacology , Piperazines/chemistry , Piperazines/pharmacology , Proline/analogs & derivatives , Proline/chemistry , Proline/pharmacology , SARS-CoV-2/drug effects , SARS-CoV-2/genetics , COVID-19 Drug TreatmentABSTRACT
BACKGROUND/AIM: Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). One drug that has attracted interest is the antiparasitic compound ivermectin, a macrocyclic lactone derived from the bacterium Streptomyces avermitilis. We carried out a docking study to determine if ivermectin might be able to attach to the SARS-CoV-2 spike receptor-binding domain bound with ACE2. MATERIALS AND METHODS: We used the program AutoDock Vina Extended to perform the docking study. RESULTS: Ivermectin docked in the region of leucine 91 of the spike and histidine 378 of the ACE2 receptor. The binding energy of ivermectin to the spike-ACE2 complex was -18 kcal/mol and binding constant was 5.8 e-08. CONCLUSION: The ivermectin docking we identified may interfere with the attachment of the spike to the human cell membrane. Clinical trials now underway should determine whether ivermectin is an effective treatment for SARS-Cov2 infection.