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1.
Proc Natl Acad Sci U S A ; 119(15): e2120913119, 2022 04 12.
Article in English | MEDLINE | ID: covidwho-1758464

ABSTRACT

SignificanceThe coronavirus main protease (Mpro) is required for viral replication. Here, we obtained the extended conformation of the native monomer of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Mpro by trapping it with nanobodies and found that the catalytic domain and the helix domain dissociate, revealing allosteric targets. Another monomeric state is termed compact conformation and is similar to one protomer of the dimeric form. We designed a Nanoluc Binary Techonology (NanoBiT)-based high-throughput allosteric inhibitor assay based on structural conformational change. Our results provide insight into the maturation, dimerization, and catalysis of the coronavirus Mpro and pave a way to develop an anticoronaviral drug through targeting the maturation process to inhibit the autocleavage of Mpro.


Subject(s)
Antiviral Agents , COVID-19 , Coronavirus 3C Proteases , Protease Inhibitors , SARS-CoV-2 , Allosteric Regulation/drug effects , Antiviral Agents/chemistry , Antiviral Agents/pharmacology , COVID-19/enzymology , Coronavirus 3C Proteases/antagonists & inhibitors , Coronavirus 3C Proteases/chemistry , Humans , Luciferases , Protease Inhibitors/chemistry , Protease Inhibitors/pharmacology , Protein Conformation , Protein Multimerization
2.
Int J Mol Sci ; 23(4)2022 Feb 16.
Article in English | MEDLINE | ID: covidwho-1700048

ABSTRACT

Structural and biochemical studies have recently revealed a range of rationally engineered nanobodies with efficient neutralizing capacity against the SARS-CoV-2 virus and resilience against mutational escape. In this study, we performed a comprehensive computational analysis of the SARS-CoV-2 spike trimer complexes with single nanobodies Nb6, VHH E, and complex with VHH E/VHH V nanobody combination. We combined coarse-grained and all-atom molecular simulations and collective dynamics analysis with binding free energy scanning, perturbation-response scanning, and network centrality analysis to examine mechanisms of nanobody-induced allosteric modulation and cooperativity in the SARS-CoV-2 spike trimer complexes with these nanobodies. By quantifying energetic and allosteric determinants of the SARS-CoV-2 spike protein binding with nanobodies, we also examined nanobody-induced modulation of escaping mutations and the effect of the Omicron variant on nanobody binding. The mutational scanning analysis supported the notion that E484A mutation can have a significant detrimental effect on nanobody binding and result in Omicron-induced escape from nanobody neutralization. Our findings showed that SARS-CoV-2 spike protein might exploit the plasticity of specific allosteric hotspots to generate escape mutants that alter response to binding without compromising activity. The network analysis supported these findings showing that VHH E/VHH V nanobody binding can induce long-range couplings between the cryptic binding epitope and ACE2-binding site through a broader ensemble of communication paths that is less dependent on specific mediating centers and therefore may be less sensitive to mutational perturbations of functional residues. The results suggest that binding affinity and long-range communications of the SARS-CoV-2 complexes with nanobodies can be determined by structurally stable regulatory centers and conformationally adaptable hotspots that are allosterically coupled and collectively control resilience to mutational escape.


Subject(s)
SARS-CoV-2/genetics , Single-Domain Antibodies/chemistry , Single-Domain Antibodies/metabolism , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/metabolism , Allosteric Regulation , Cryoelectron Microscopy , Molecular Conformation , Molecular Dynamics Simulation , Protein Stability , Spike Glycoprotein, Coronavirus/genetics
3.
Int J Mol Sci ; 23(3)2022 Jan 31.
Article in English | MEDLINE | ID: covidwho-1667196

ABSTRACT

Structural and functional studies of the SARS-CoV-2 spike proteins have recently determined distinct functional states of the B.1.1.7 and B.1.351 spike variants, providing a molecular framework for understanding the mechanisms that link the effect of mutations with the enhanced virus infectivity and transmissibility. A detailed dynamic and energetic analysis of these variants was undertaken in the present work to quantify the effects of different mutations on functional conformational changes and stability of the SARS-CoV-2 spike protein. We employed the efficient and accurate coarse-grained (CG) simulations of multiple functional states of the D614G mutant, B.1.1.7 and B.1.351 spike variants to characterize conformational dynamics of the SARS-CoV-2 spike proteins and identify dynamic signatures of the functional regions that regulate transitions between the closed and open forms. By combining molecular simulations with full atomistic reconstruction of the trajectories and the ensemble-based mutational frustration analysis, we characterized how the intrinsic flexibility of specific spike regions can control functional conformational changes required for binding with the host-cell receptor. Using the residue-based mutational scanning of protein stability, we determined protein stability hotspots and identified potential energetic drivers favoring the receptor-accessible open spike states for the B.1.1.7 and B.1.351 spike variants. The results suggested that modulation of the energetic frustration at the inter-protomer interfaces can serve as a mechanism for allosteric couplings between mutational sites and the inter-protomer hinges of functional motions. The proposed mechanism of mutation-induced energetic frustration may result in greater adaptability and the emergence of multiple conformational states in the open form. This study suggested that SARS-CoV-2 B.1.1.7 and B.1.351 variants may leverage the intrinsic plasticity of functional regions in the spike protein for mutation-induced modulation of protein dynamics and allosteric regulation to control binding with the host cell receptor.


Subject(s)
COVID-19/metabolism , SARS-CoV-2/ultrastructure , Spike Glycoprotein, Coronavirus/ultrastructure , Allosteric Regulation , Binding Sites , COVID-19/pathology , Humans , Molecular Conformation , Molecular Dynamics Simulation , Mutation , Protein Binding , Protein Stability , SARS-CoV-2/genetics , SARS-CoV-2/pathogenicity , Spike Glycoprotein, Coronavirus/genetics
4.
Proc Natl Acad Sci U S A ; 119(6)2022 02 08.
Article in English | MEDLINE | ID: covidwho-1650946

ABSTRACT

The development of small-molecules targeting different components of SARS-CoV-2 is a key strategy to complement antibody-based treatments and vaccination campaigns in managing the COVID-19 pandemic. Here, we show that two thiol-based chemical probes that act as reducing agents, P2119 and P2165, inhibit infection by human coronaviruses, including SARS-CoV-2, and decrease the binding of spike glycoprotein to its receptor, the angiotensin-converting enzyme 2 (ACE2). Proteomics and reactive cysteine profiling link the antiviral activity to the reduction of key disulfides, specifically by disruption of the Cys379-Cys432 and Cys391-Cys525 pairs distal to the receptor binding motif in the receptor binding domain (RBD) of the spike glycoprotein. Computational analyses provide insight into conformation changes that occur when these disulfides break or form, consistent with an allosteric role, and indicate that P2119/P2165 target a conserved hydrophobic binding pocket in the RBD with the benzyl thiol-reducing moiety pointed directly toward Cys432. These collective findings establish the vulnerability of human coronaviruses to thiol-based chemical probes and lay the groundwork for developing compounds of this class, as a strategy to inhibit the SARS-CoV-2 infection by shifting the spike glycoprotein redox scaffold.


Subject(s)
Amino Alcohols/pharmacology , Angiotensin-Converting Enzyme 2/chemistry , Antiviral Agents/pharmacology , Phenyl Ethers/pharmacology , Receptors, Virus/chemistry , SARS-CoV-2/drug effects , Spike Glycoprotein, Coronavirus/chemistry , Sulfhydryl Compounds/pharmacology , Allosteric Regulation , Amino Alcohols/chemistry , Angiotensin-Converting Enzyme 2/antagonists & inhibitors , Angiotensin-Converting Enzyme 2/genetics , Angiotensin-Converting Enzyme 2/metabolism , Antiviral Agents/chemistry , Binding Sites , COVID-19/drug therapy , COVID-19/virology , Cell Line , Disulfides/antagonists & inhibitors , Disulfides/chemistry , Disulfides/metabolism , Dose-Response Relationship, Drug , Humans , Molecular Docking Simulation , Nasal Mucosa/drug effects , Nasal Mucosa/metabolism , Nasal Mucosa/virology , Oxidation-Reduction , Phenyl Ethers/chemistry , Protein Binding , Protein Conformation, alpha-Helical , Protein Conformation, beta-Strand , Protein Interaction Domains and Motifs , Receptors, Virus/antagonists & inhibitors , Receptors, Virus/genetics , Receptors, Virus/metabolism , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , SARS-CoV-2/genetics , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/antagonists & inhibitors , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/metabolism , Sulfhydryl Compounds/chemistry
5.
Int J Biochem Cell Biol ; 143: 106138, 2022 02.
Article in English | MEDLINE | ID: covidwho-1588223

ABSTRACT

Nicotinic acetylcholine receptors mediate fast synaptic transmission in neuro-muscular junctions and autonomic ganglia and modulate survival, proliferation and neurotransmitter or cytokine release in the brain and non-excitable cells. The neuronal-type nicotinic acetylcholine receptors are expressed in the outer mitochondria membrane to regulate the release of pro-apoptotic substances like cytochrome c or reactive oxygen species. In the intracellular environment, nicotinic acetylcholine receptor signaling is ion-independent and triggers intramitochondrial kinases, similar to those activated by plasma membrane nicotinic acetylcholine receptors. The present review will describe the data obtained during the last five years including, in particular, post-translational glycosylation as a targeting signal to mitochondria, mechanisms of mitochondrial nicotinic acetylcholine receptor signaling studied with subtype-specific agonists, antagonists, positive allosteric modulators and knockout mice lacking certain nicotinic acetylcholine receptor subunits, interaction of mitochondrial nicotinic acetylcholine receptors with Bcl-2 family proteins and their involvement in important pathologies like neuroinflammation, liver damage and SARS-CoV-2 infection.


Subject(s)
COVID-19/genetics , Chemical and Drug Induced Liver Injury/genetics , Mitochondria/genetics , Proto-Oncogene Proteins c-bcl-2/genetics , Receptors, Nicotinic/genetics , Allosteric Regulation , Animals , COVID-19/metabolism , COVID-19/pathology , COVID-19/virology , Chemical and Drug Induced Liver Injury/metabolism , Chemical and Drug Induced Liver Injury/pathology , Disease Models, Animal , Humans , Mice , Mitochondria/metabolism , /pathology , Nicotinic Agonists/pharmacology , Nicotinic Antagonists/pharmacology , Protein Processing, Post-Translational , Proto-Oncogene Proteins c-bcl-2/metabolism , Receptors, Nicotinic/metabolism , SARS-CoV-2/pathogenicity , Signal Transduction , Voltage-Dependent Anion Channel 1/genetics , Voltage-Dependent Anion Channel 1/metabolism
6.
J Mol Biol ; 433(24): 167324, 2021 12 03.
Article in English | MEDLINE | ID: covidwho-1492300

ABSTRACT

The 3C-like protease (3CLpro) of SARS-CoV-2 is a potential therapeutic target for COVID-19. Importantly, it has an abundance of structural information solved as a complex with various drug candidate compounds. Collecting these crystal structures (83 Protein Data Bank (PDB) entries) together with those of the highly homologous 3CLpro of SARS-CoV (101 PDB entries), we constructed the crystal structure ensemble of 3CLpro to analyze the dynamic regulation of its catalytic function. The structural dynamics of the 3CLpro dimer observed in the ensemble were characterized by the motions of four separate loops (the C-loop, E-loop, H-loop, and Linker) and the C-terminal domain III on the rigid core of the chymotrypsin fold. Among the four moving loops, the C-loop (also known as the oxyanion binding loop) causes the order (active)-disorder (collapsed) transition, which is regulated cooperatively by five hydrogen bonds made with the surrounding residues. The C-loop, E-loop, and Linker constitute the major ligand binding sites, which consist of a limited variety of binding residues including the substrate binding subsites. Ligand binding causes a ligand size dependent conformational change to the E-loop and Linker, which further stabilize the C-loop via the hydrogen bond between the C-loop and E-loop. The T285A mutation from SARS-CoV 3CLpro to SARS-CoV-2 3CLpro significantly closes the interface of the domain III dimer and allosterically stabilizes the active conformation of the C-loop via hydrogen bonds with Ser1 and Gly2; thus, SARS-CoV-2 3CLpro seems to have increased activity relative to that of SARS-CoV 3CLpro.


Subject(s)
Coronavirus 3C Proteases/chemistry , Coronavirus 3C Proteases/metabolism , Mutation , SARS-CoV-2/enzymology , Viral Proteins/chemistry , Viral Proteins/metabolism , Allosteric Regulation , Binding Sites , Coronavirus 3C Proteases/genetics , Crystallography, X-Ray , Humans , Molecular Docking Simulation , Molecular Dynamics Simulation , Protein Conformation , Substrate Specificity , Viral Proteins/genetics
7.
J Phys Chem B ; 125(3): 850-873, 2021 01 28.
Article in English | MEDLINE | ID: covidwho-1387111

ABSTRACT

The rapidly growing body of structural and biochemical studies of the SARS-CoV-2 spike glycoprotein has revealed a variety of distinct functional states with radically different arrangements of the receptor-binding domain, highlighting a remarkable function-driven conformational plasticity and adaptability of the spike proteins. In this study, we examined molecular mechanisms underlying conformational and dynamic changes in the SARS-CoV-2 spike mutant trimers through the lens of dynamic analysis of allosteric interaction networks and atomistic modeling of signal transmission. Using an integrated approach that combined coarse-grained molecular simulations, protein stability analysis, and perturbation-based modeling of residue interaction networks, we examined how mutations in the regulatory regions of the SARS-CoV-2 spike protein can differentially affect dynamics and allosteric signaling in distinct functional states. The results of this study revealed key functional regions and regulatory centers that govern collective dynamics, allosteric interactions, and control signal transmission in the SARS-CoV-2 spike proteins. We found that the experimentally confirmed regulatory hotspots that dictate dynamic switching between conformational states of the SARS-CoV-2 spike protein correspond to the key hinge sites and global mediating centers of the allosteric interaction networks. The results of this study provide a novel insight into allosteric regulatory mechanisms of SARS-CoV-2 spike proteins showing that mutations at the key regulatory positions can differentially modulate distribution of states and determine topography of signal communication pathways operating through state-specific cascades of control switch points. This analysis provides a plausible strategy for allosteric probing of the conformational equilibrium and therapeutic intervention by targeting specific hotspots of allosteric interactions and communications in the SARS-CoV-2 spike proteins.


Subject(s)
Models, Biological , Mutation , SARS-CoV-2/chemistry , Spike Glycoprotein, Coronavirus/chemistry , Allosteric Regulation , Binding Sites , Cysteine/genetics , Molecular Dynamics Simulation , Protein Binding , Protein Conformation , Protein Stability , Protein Subunits , SARS-CoV-2/genetics , Signal Transduction/genetics , Spike Glycoprotein, Coronavirus/genetics
8.
J Med Chem ; 65(4): 2827-2835, 2022 02 24.
Article in English | MEDLINE | ID: covidwho-1366783

ABSTRACT

The receptor recognition of the novel coronavirus SARS-CoV-2 relies on the "down-to-up" conformational change in the receptor-binding domain (RBD) of the spike (S) protein. Therefore, understanding the process of this change at the molecular level facilitates the design of therapeutic agents. With the help of coarse-grained molecular dynamic simulations, we provide evidence showing that the conformational dynamics of the S protein are globally cooperative. Importantly, an allosteric path was discovered that correlates the motion of the RBD with the motion of the junction between the subdomain 1 (SD1) and the subdomain 2 (SD2) of the S protein. Building on this finding, we designed non-RBD binding modulators to inhibit SARS-CoV-2 by prohibiting the conformational change of the S protein. Their inhibition effect and function stages at inhibiting SARS-CoV-2 were evaluated experimentally. In summary, our studies establish a molecular basis for future therapeutic agent design through allosteric effects.


Subject(s)
Antiviral Agents/pharmacology , Molecular Dynamics Simulation , SARS-CoV-2/drug effects , Small Molecule Libraries/pharmacology , Spike Glycoprotein, Coronavirus/antagonists & inhibitors , Allosteric Regulation/drug effects , Animals , Antiviral Agents/chemical synthesis , Antiviral Agents/chemistry , Cells, Cultured , Chlorocebus aethiops , Drug Evaluation, Preclinical , Humans , Microbial Sensitivity Tests , Molecular Structure , SARS-CoV-2/metabolism , Small Molecule Libraries/chemical synthesis , Small Molecule Libraries/chemistry , Spike Glycoprotein, Coronavirus/metabolism , Vero Cells
9.
Biochem J ; 478(13): 2465-2479, 2021 07 16.
Article in English | MEDLINE | ID: covidwho-1290092

ABSTRACT

SARS-CoV-2 is responsible for COVID-19, a human disease that has caused over 2 million deaths, stretched health systems to near-breaking point and endangered economies of countries and families around the world. Antiviral treatments to combat COVID-19 are currently lacking. Remdesivir, the only antiviral drug approved for the treatment of COVID-19, can affect disease severity, but better treatments are needed. SARS-CoV-2 encodes 16 non-structural proteins (nsp) that possess different enzymatic activities with important roles in viral genome replication, transcription and host immune evasion. One key aspect of host immune evasion is performed by the uridine-directed endoribonuclease activity of nsp15. Here we describe the expression and purification of nsp15 recombinant protein. We have developed biochemical assays to follow its activity, and we have found evidence for allosteric behaviour. We screened a custom chemical library of over 5000 compounds to identify nsp15 endoribonuclease inhibitors, and we identified and validated NSC95397 as an inhibitor of nsp15 endoribonuclease in vitro. Although NSC95397 did not inhibit SARS-CoV-2 growth in VERO E6 cells, further studies will be required to determine the effect of nsp15 inhibition on host immune evasion.


Subject(s)
Antiviral Agents/chemistry , Antiviral Agents/pharmacology , Drug Evaluation, Preclinical , Endoribonucleases/antagonists & inhibitors , SARS-CoV-2/enzymology , Small Molecule Libraries/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Allosteric Regulation , Animals , Chlorocebus aethiops , Endoribonucleases/isolation & purification , Endoribonucleases/metabolism , Enzyme Assays , Fluorescence , High-Throughput Screening Assays , In Vitro Techniques , Kinetics , Naphthoquinones/pharmacology , Reproducibility of Results , SARS-CoV-2/drug effects , SARS-CoV-2/growth & development , Small Molecule Libraries/chemistry , Solutions , Vero Cells , Viral Nonstructural Proteins/isolation & purification , Viral Nonstructural Proteins/metabolism
10.
Molecules ; 26(9)2021 Apr 23.
Article in English | MEDLINE | ID: covidwho-1238919

ABSTRACT

The CB1 cannabinoid receptor (CB1R) contains one of the longest N termini among class A G protein-coupled receptors. Mutagenesis studies suggest that the allosteric binding site of cannabidiol (CBD) involves residues from the N terminal domain. In order to study the allosteric binding of CBD to CB1R we modeled the whole N-terminus of this receptor using the replica exchange molecular dynamics with solute tempering (REST2) approach. Then, the obtained structures of CB1R with the N terminus were used for ligand docking. A natural cannabinoid receptor agonist, Δ9-THC, was docked to the orthosteric site and a negative allosteric modulator, CBD, to the allosteric site positioned between extracellular ends of helices TM1 and TM2. The molecular dynamics simulations were then performed for CB1R with ligands: (i) CBD together with THC, and (ii) THC-only. Analyses of the differences in the residue-residue interaction patterns between those two cases allowed us to elucidate the allosteric network responsible for the modulation of the CB1R by CBD. In addition, we identified the changes in the orthosteric binding mode of Δ9-THC, as well as the changes in its binding energy, caused by the CBD allosteric binding. We have also found that the presence of a complete N-terminal domain is essential for a stable binding of CBD in the allosteric site of CB1R as well as for the allosteric-orthosteric coupling mechanism.


Subject(s)
Cannabidiol/metabolism , Receptor, Cannabinoid, CB1/metabolism , Allosteric Regulation/physiology , Allosteric Site , Animals , Humans , Magnetic Resonance Spectroscopy , Models, Molecular , Molecular Dynamics Simulation , Protein Binding , Protein Structure, Secondary , Receptor, Cannabinoid, CB1/chemistry
11.
Nat Commun ; 12(1): 2697, 2021 05 11.
Article in English | MEDLINE | ID: covidwho-1225508

ABSTRACT

Although human antibodies elicited by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid (N) protein are profoundly boosted upon infection, little is known about the function of N-reactive antibodies. Herein, we isolate and profile a panel of 32 N protein-specific monoclonal antibodies (mAbs) from a quick recovery coronavirus disease-19 (COVID-19) convalescent patient who has dominant antibody responses to the SARS-CoV-2 N protein rather than to the SARS-CoV-2 spike (S) protein. The complex structure of the N protein RNA binding domain with the highest binding affinity mAb (nCoV396) reveals changes in the epitopes and antigen's allosteric regulation. Functionally, a virus-free complement hyperactivation analysis demonstrates that nCoV396 specifically compromises the N protein-induced complement hyperactivation, which is a risk factor for the morbidity and mortality of COVID-19 patients, thus laying the foundation for the identification of functional anti-N protein mAbs.


Subject(s)
Antibodies, Viral/pharmacology , COVID-19/immunology , Complement Activation/drug effects , Coronavirus Nucleocapsid Proteins/immunology , SARS-CoV-2/immunology , Allosteric Regulation , Antibodies, Monoclonal/chemistry , Antibodies, Monoclonal/immunology , Antibodies, Viral/chemistry , Antibodies, Viral/immunology , Antibody Affinity , Antigen-Antibody Complex/chemistry , Convalescence , Coronavirus Nucleocapsid Proteins/chemistry , Crystallography, X-Ray , Epitopes , Humans , Phosphoproteins/chemistry , Phosphoproteins/immunology , Protein Conformation
12.
Biochemistry ; 60(19): 1459-1484, 2021 05 18.
Article in English | MEDLINE | ID: covidwho-1201221

ABSTRACT

In this study, we used an integrative computational approach to examine molecular mechanisms and determine functional signatures underlying the role of functional residues in the SARS-CoV-2 spike protein that are targeted by novel mutational variants and antibody-escaping mutations. Atomistic simulations and functional dynamics analysis are combined with alanine scanning and mutational sensitivity profiling of the SARS-CoV-2 spike protein complexes with the ACE2 host receptor and the REGN-COV2 antibody cocktail(REG10987+REG10933). Using alanine scanning and mutational sensitivity analysis, we have shown that K417, E484, and N501 residues correspond to key interacting centers with a significant degree of structural and energetic plasticity that allow mutants in these positions to afford the improved binding affinity with ACE2. Through perturbation-based network modeling and community analysis of the SARS-CoV-2 spike protein complexes with ACE2, we demonstrate that E406, N439, K417, and N501 residues serve as effector centers of allosteric interactions and anchor major intermolecular communities that mediate long-range communication in the complexes. The results provide support to a model according to which mutational variants and antibody-escaping mutations constrained by the requirements for host receptor binding and preservation of stability may preferentially select structurally plastic and energetically adaptable allosteric centers to differentially modulate collective motions and allosteric interactions in the complexes with the ACE2 enzyme and REGN-COV2 antibody combination. This study suggests that the SARS-CoV-2 spike protein may function as a versatile and functionally adaptable allosteric machine that exploits the plasticity of allosteric regulatory centers to fine-tune response to antibody binding without compromising the activity of the spike protein.


Subject(s)
Angiotensin-Converting Enzyme 2/chemistry , Antibodies, Neutralizing/chemistry , Antibodies, Viral/chemistry , Models, Molecular , SARS-CoV-2/chemistry , Spike Glycoprotein, Coronavirus/chemistry , Allosteric Regulation , Amino Acid Substitution , Angiotensin-Converting Enzyme 2/genetics , Antibodies, Neutralizing/genetics , Antibodies, Viral/genetics , Humans , Mutation, Missense , Protein Domains , Protein Structure, Quaternary , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics
13.
Proteins ; 89(9): 1134-1144, 2021 09.
Article in English | MEDLINE | ID: covidwho-1188037

ABSTRACT

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has caused substantially more infections, deaths, and economic disruptions than the 2002-2003 SARS-CoV. The key to understanding SARS-CoV-2's higher infectivity lies partly in its host receptor recognition mechanism. Experiments show that the human angiotensin converting enzyme 2 (ACE2) protein, which serves as the primary receptor for both CoVs, binds to the receptor binding domain (RBD) of CoV-2's spike protein stronger than SARS-CoV's spike RBD. The molecular basis for this difference in binding affinity, however, remains unexplained from X-ray structures. To go beyond insights gained from X-ray structures and investigate the role of thermal fluctuations in structure, we employ all-atom molecular dynamics simulations. Microseconds-long simulations reveal that while CoV and CoV-2 spike-ACE2 interfaces have similar conformational binding modes, CoV-2 spike interacts with ACE2 via a larger combinatorics of polar contacts, and on average, makes 45% more polar contacts. Correlation analysis and thermodynamic calculations indicate that these differences in the density and dynamics of polar contacts arise from differences in spatial arrangements of interfacial residues, and dynamical coupling between interfacial and non-interfacial residues. These results recommend that ongoing efforts to design spike-ACE2 peptide blockers will benefit from incorporating dynamical information as well as allosteric coupling effects.


Subject(s)
Angiotensin-Converting Enzyme 2/chemistry , Angiotensin-Converting Enzyme 2/metabolism , Molecular Dynamics Simulation , SARS-CoV-2/chemistry , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/metabolism , Allosteric Regulation , Humans , Mutation , Protein Binding , Receptors, Virus/chemistry , Receptors, Virus/metabolism , Thermodynamics
14.
J Phys Chem B ; 125(15): 3763-3780, 2021 04 22.
Article in English | MEDLINE | ID: covidwho-1180209

ABSTRACT

While the pervasiveness of allostery in proteins is commonly accepted, we further show the generic nature of allosteric mechanisms by analyzing here transmembrane ion-channel viroporin 3a and RNA-dependent RNA polymerase (RdRp) from SARS-CoV-2 along with metabolic enzymes isocitrate dehydrogenase 1 (IDH1) and fumarate hydratase (FH) implicated in cancers. Using the previously developed structure-based statistical mechanical model of allostery (SBSMMA), we share our experience in analyzing the allosteric signaling, predicting latent allosteric sites, inducing and tuning targeted allosteric response, and exploring the allosteric effects of mutations. This, yet incomplete list of phenomenology, forms a complex and unique allosteric territory of protein function, which should be thoroughly explored. We propose a generic computational framework, which not only allows one to obtain a comprehensive allosteric control over proteins but also provides an opportunity to approach the fragment-based design of allosteric effectors and drug candidates. The advantages of allosteric drugs over traditional orthosteric compounds, complemented by the emerging role of the allosteric effects of mutations in the expansion of the cancer mutational landscape and in the increased mutability of viral proteins, leave no choice besides further extensive studies of allosteric mechanisms and their biomedical implications.


Subject(s)
COVID-19 , Allosteric Regulation , Allosteric Site , Humans , Models, Molecular , SARS-CoV-2
15.
Curr Opin Struct Biol ; 65: 209-216, 2020 12.
Article in English | MEDLINE | ID: covidwho-1065572

ABSTRACT

Understanding allosteric regulation of proteins is fundamental to our study of protein structure and function. Moreover, allosteric binding pockets have become a major target of drug discovery efforts in recent years. However, even though the function of almost every protein can be influenced by allostery, it remains a challenge to discover, rationalise and validate putative allosteric binding pockets. This review examines how the discovery and analysis of putative allosteric binding sites have been influenced by the availability of centralised facilities for crystallographic fragment screening, along with newly developed computational methods for modelling low occupancy features. We discuss the experimental parameters required for success, and how new methods could influence the field in the future. Finally, we reflect on the general problem of how to translate these findings into actual ligand development programs.


Subject(s)
Proteins , Allosteric Regulation , Allosteric Site , Humans , Ligands , Protein Binding , Protein Conformation , Proteins/chemistry , Proteins/metabolism
16.
J Phys Chem B ; 125(3): 850-873, 2021 01 28.
Article in English | MEDLINE | ID: covidwho-1033630

ABSTRACT

The rapidly growing body of structural and biochemical studies of the SARS-CoV-2 spike glycoprotein has revealed a variety of distinct functional states with radically different arrangements of the receptor-binding domain, highlighting a remarkable function-driven conformational plasticity and adaptability of the spike proteins. In this study, we examined molecular mechanisms underlying conformational and dynamic changes in the SARS-CoV-2 spike mutant trimers through the lens of dynamic analysis of allosteric interaction networks and atomistic modeling of signal transmission. Using an integrated approach that combined coarse-grained molecular simulations, protein stability analysis, and perturbation-based modeling of residue interaction networks, we examined how mutations in the regulatory regions of the SARS-CoV-2 spike protein can differentially affect dynamics and allosteric signaling in distinct functional states. The results of this study revealed key functional regions and regulatory centers that govern collective dynamics, allosteric interactions, and control signal transmission in the SARS-CoV-2 spike proteins. We found that the experimentally confirmed regulatory hotspots that dictate dynamic switching between conformational states of the SARS-CoV-2 spike protein correspond to the key hinge sites and global mediating centers of the allosteric interaction networks. The results of this study provide a novel insight into allosteric regulatory mechanisms of SARS-CoV-2 spike proteins showing that mutations at the key regulatory positions can differentially modulate distribution of states and determine topography of signal communication pathways operating through state-specific cascades of control switch points. This analysis provides a plausible strategy for allosteric probing of the conformational equilibrium and therapeutic intervention by targeting specific hotspots of allosteric interactions and communications in the SARS-CoV-2 spike proteins.


Subject(s)
Models, Biological , Mutation , SARS-CoV-2/chemistry , Spike Glycoprotein, Coronavirus/chemistry , Allosteric Regulation , Binding Sites , Cysteine/genetics , Molecular Dynamics Simulation , Protein Binding , Protein Conformation , Protein Stability , Protein Subunits , SARS-CoV-2/genetics , Signal Transduction/genetics , Spike Glycoprotein, Coronavirus/genetics
17.
Sci Rep ; 10(1): 17699, 2020 10 19.
Article in English | MEDLINE | ID: covidwho-880703

ABSTRACT

Angiotensin converting enzyme 2 (ACE2) (EC:3.4.17.23) is a transmembrane protein which is considered as a receptor for spike protein binding of novel coronavirus (SARS-CoV2). Since no specific medication is available to treat COVID-19, designing of new drug is important and essential. In this regard, in silico method plays an important role, as it is rapid and cost effective compared to the trial and error methods using experimental studies. Natural products are safe and easily available to treat coronavirus affected patients, in the present alarming situation. In this paper five phytochemicals, which belong to flavonoid and anthraquinone subclass, have been selected as small molecules in molecular docking study of spike protein of SARS-CoV2 with its human receptor ACE2 molecule. Their molecular binding sites on spike protein bound structure with its receptor have been analyzed. From this analysis, hesperidin, emodin and chrysin are selected as competent natural products from both Indian and Chinese medicinal plants, to treat COVID-19. Among them, the phytochemical hesperidin can bind with ACE2 protein and bound structure of ACE2 protein and spike protein of SARS-CoV2 noncompetitively. The binding sites of ACE2 protein for spike protein and hesperidin, are located in different parts of ACE2 protein. Ligand spike protein causes conformational change in three-dimensional structure of protein ACE2, which is confirmed by molecular docking and molecular dynamics studies. This compound modulates the binding energy of bound structure of ACE2 and spike protein. This result indicates that due to presence of hesperidin, the bound structure of ACE2 and spike protein fragment becomes unstable. As a result, this natural product can impart antiviral activity in SARS CoV2 infection. The antiviral activity of these five natural compounds are further experimentally validated with QSAR study.


Subject(s)
Betacoronavirus/metabolism , Peptidyl-Dipeptidase A/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Allosteric Regulation , Amino Acid Sequence , Angiotensin-Converting Enzyme 2 , Anthraquinones/chemistry , Anthraquinones/metabolism , Betacoronavirus/isolation & purification , Binding Sites , COVID-19 , Coronavirus Infections/pathology , Coronavirus Infections/virology , Emodin/chemistry , Emodin/metabolism , Humans , Molecular Docking Simulation , Pandemics , Peptidyl-Dipeptidase A/chemistry , Pneumonia, Viral/pathology , Pneumonia, Viral/virology , Protein Binding , Protein Structure, Secondary , Protein Structure, Tertiary , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/chemistry
18.
J Proteome Res ; 19(11): 4587-4608, 2020 11 06.
Article in English | MEDLINE | ID: covidwho-811635

ABSTRACT

The development of computational strategies for the quantitative characterization of the functional mechanisms of SARS-CoV-2 spike proteins is of paramount importance in efforts to accelerate the discovery of novel therapeutic agents and vaccines combating the COVID-19 pandemic. Structural and biophysical studies have recently characterized the conformational landscapes of the SARS-CoV-2 spike glycoproteins in the prefusion form, revealing a spectrum of stable and more dynamic states. By employing molecular simulations and network modeling approaches, this study systematically examined functional dynamics and identified the regulatory centers of allosteric interactions for distinct functional states of the wild-type and mutant variants of the SARS-CoV-2 prefusion spike trimer. This study presents evidence that the SARS-CoV-2 spike protein can function as an allosteric regulatory engine that fluctuates between dynamically distinct functional states. Perturbation-based modeling of the interaction networks revealed a key role of the cross-talk between the effector hotspots in the receptor binding domain and the fusion peptide proximal region of the SARS-CoV-2 spike protein. The results have shown that the allosteric hotspots of the interaction networks in the SARS-CoV-2 spike protein can control the dynamic switching between functional conformational states that are associated with virus entry to the host receptor. This study offers a useful and novel perspective on the underlying mechanisms of the SARS-CoV-2 spike protein through the lens of allosteric signaling as a regulatory apparatus of virus transmission that could open up opportunities for targeted allosteric drug discovery against SARS-CoV-2 proteins and contribute to the rapid response to the current and potential future pandemic scenarios.


Subject(s)
Allosteric Regulation/physiology , Betacoronavirus , Coronavirus Infections/virology , Molecular Dynamics Simulation , Pneumonia, Viral/virology , Spike Glycoprotein, Coronavirus , Allosteric Regulation/genetics , Betacoronavirus/chemistry , Betacoronavirus/genetics , Betacoronavirus/metabolism , COVID-19 , Humans , Pandemics , Protein Binding , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/metabolism
19.
Angew Chem Int Ed Engl ; 59(52): 23544-23548, 2020 12 21.
Article in English | MEDLINE | ID: covidwho-728060

ABSTRACT

The SARS-CoV-2 main protease (Mpro ) cleaves along the two viral polypeptides to release non-structural proteins required for viral replication. MPro is an attractive target for antiviral therapies to combat the coronavirus-2019 disease. Here, we used native mass spectrometry to characterize the functional unit of Mpro . Analysis of the monomer/dimer equilibria reveals a dissociation constant of Kd =0.14±0.03 µM, indicating MPro has a strong preference to dimerize in solution. We characterized substrate turnover rates by following temporal changes in the enzyme-substrate complexes, and screened small molecules, that bind distant from the active site, for their ability to modulate activity. These compounds, including one proposed to disrupt the dimer, slow the rate of substrate processing by ≈35 %. This information, together with analysis of the x-ray crystal structures, provides a starting point for the development of more potent molecules that allosterically regulate MPro activity.


Subject(s)
Coronavirus 3C Proteases/chemistry , Coronavirus Protease Inhibitors/chemistry , Models, Molecular , SARS-CoV-2/enzymology , Small Molecule Libraries/chemistry , Allosteric Regulation , Binding Sites , Biological Assay , Coronavirus 3C Proteases/antagonists & inhibitors , Coronavirus Protease Inhibitors/pharmacology , Crystallography, X-Ray , Mass Spectrometry , Protein Binding , Protein Conformation , Protein Multimerization , SARS-CoV-2/physiology , Small Molecule Libraries/pharmacology , Substrate Specificity , Virus Replication
20.
ChemMedChem ; 15(18): 1682-1690, 2020 09 16.
Article in English | MEDLINE | ID: covidwho-641524

ABSTRACT

Angiotensin converting enzyme 2 (ACE2) is the human receptor that interacts with the spike protein of coronaviruses, including the one that produced the 2020 coronavirus pandemic (COVID-19). Thus, ACE2 is a potential target for drugs that disrupt the interaction of human cells with SARS-CoV-2 to abolish infection. There is also interest in drugs that inhibit or activate ACE2, that is, for cardiovascular disorders or colitis. Compounds binding at alternative sites could allosterically affect the interaction with the spike protein. Herein, we review biochemical, chemical biology, and structural information on ACE2, including the recent cryoEM structures of full-length ACE2. We conclude that ACE2 is very dynamic and that allosteric drugs could be developed to target ACE2. At the time of the 2020 pandemic, we suggest that available ACE2 inhibitors or activators in advanced development should be tested for their ability to allosterically displace the interaction between ACE2 and the spike protein.


Subject(s)
Angiotensin-Converting Enzyme Inhibitors/metabolism , Betacoronavirus/chemistry , Peptidyl-Dipeptidase A/metabolism , Receptors, Virus/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Allosteric Regulation , Angiotensin-Converting Enzyme 2 , Angiotensin-Converting Enzyme Inhibitors/chemistry , Catalytic Domain , Humans , Peptidyl-Dipeptidase A/chemistry , Protein Binding , Protein Domains , Receptors, Virus/antagonists & inhibitors , Receptors, Virus/chemistry , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/chemistry
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