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Tong Jia Ming S, Tan Yi Jun K, Carissimo G. Pathogenicity and virulence of O'nyong-nyong virus: A less studied Togaviridae with pandemic potential. Virulence 2024; 15:2355201. [PMID: 38797948 PMCID: PMC11135837 DOI: 10.1080/21505594.2024.2355201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 05/10/2024] [Indexed: 05/29/2024] Open
Abstract
O'nyong-nyong virus (ONNV) is a neglected mosquito-borne alphavirus belonging to the Togaviridae family. ONNV is known to be responsible for sporadic outbreaks of acute febrile disease and polyarthralgia in Africa. As climate change increases the geographical range of known and potential new vectors, recent data indicate a possibility for ONNV to spread outside of the African continent and grow into a greater public health concern. In this review, we summarise the current knowledge on ONNV epidemiology, host-pathogen interactions, vector-virus responses, and insights into possible avenues to control risk of further epidemics. In this review, the limited ONNV literature is compared and correlated to other findings on mainly Old World alphaviruses. We highlight and discuss studies that investigate viral and host factors that determine viral-vector specificity, along with important mechanisms that determine severity and disease outcome of ONNV infection.
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Affiliation(s)
- Samuel Tong Jia Ming
- A*STAR Infectious Diseases Labs (A*STAR ID Labs), Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Katrina Tan Yi Jun
- A*STAR Infectious Diseases Labs (A*STAR ID Labs), Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Guillaume Carissimo
- A*STAR Infectious Diseases Labs (A*STAR ID Labs), Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
- Infectious Diseases Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- Lee Kong Chian School of Medicine, Nanyang Technical University, Singapore, Singapore
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2
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Metibemu DS, Adeyinka OS, Falode J, Crown O, Ogungbe IV. Inhibitors of the Structural and Nonstructural Proteins of Alphaviruses. ACS Infect Dis 2024. [PMID: 38992989 DOI: 10.1021/acsinfecdis.4c00254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2024]
Abstract
The Alphavirus genus includes viruses that cause encephalitis due to neuroinvasion and viruses that cause arthritis due to acute and chronic inflammation. There is no approved therapeutic for alphavirus infections, but significant efforts are ongoing, more so in recent years, to develop vaccines and therapeutics for alphavirus infections. This review article highlights some of the major advances made so far to identify small molecules that can selectively target the structural and the nonstructural proteins in alphaviruses with the expectation that persistent investigation of an increasingly expanding chemical space through a variety of structure-based design and high-throughput screening strategies will yield candidate drugs for clinical studies. While most of the works discussed are still in the early discovery to lead optimization stages, promising avenues remain for drug development against this family of viruses.
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Affiliation(s)
- Damilohun Samuel Metibemu
- Chemistry and Biotechnology Science and Engineering Programs, The University of Alabama in Huntsville, 301 Sparkman Drive, Huntsville, Alabama 35899, United States
| | - Olawale Samuel Adeyinka
- Chemistry and Biotechnology Science and Engineering Programs, The University of Alabama in Huntsville, 301 Sparkman Drive, Huntsville, Alabama 35899, United States
| | - John Falode
- Chemistry and Biotechnology Science and Engineering Programs, The University of Alabama in Huntsville, 301 Sparkman Drive, Huntsville, Alabama 35899, United States
| | - Olamide Crown
- Chemistry and Biotechnology Science and Engineering Programs, The University of Alabama in Huntsville, 301 Sparkman Drive, Huntsville, Alabama 35899, United States
| | - Ifedayo Victor Ogungbe
- Chemistry and Biotechnology Science and Engineering Programs, The University of Alabama in Huntsville, 301 Sparkman Drive, Huntsville, Alabama 35899, United States
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3
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Merten EM, Sears JD, Leisner TM, Hardy PB, Ghoshal A, Hossain MA, Asressu KH, Brown PJ, Stashko MA, Herring L, Mordant AL, Webb TS, Mills CA, Barker NK, Streblow ZJ, Perveen S, Arrowsmith C, Arnold JJ, Cameron CE, Streblow DN, Moorman NJ, Heise M, Willson TM, Popov K, Pearce KH. Discovery of a cell-active chikungunya virus nsP2 protease inhibitor using a covalent fragment-based screening approach. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.22.586341. [PMID: 38562906 PMCID: PMC10983941 DOI: 10.1101/2024.03.22.586341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that has been responsible for numerous large-scale outbreaks in the last twenty years. Currently, there are no FDA-approved therapeutics for any alphavirus infection. CHIKV non-structural protein 2 (nsP2), which contains a cysteine protease domain, is essential for viral replication, making it an attractive target for a drug discovery campaign. Here, we optimized a CHIKV nsP2 protease (nsP2pro) biochemical assay for the screening of a 6,120-compound cysteine-directed covalent fragment library. Using a 50% inhibition threshold, we identified 153 hits (2.5% hit rate). In dose-response follow up, RA-0002034, a covalent fragment that contains a vinyl sulfone warhead, inhibited CHIKV nsP2pro with an IC 50 of 58 ± 17 nM, and further analysis with time-dependent inhibition studies yielded a k inact /K I of 6.4 x 10 3 M -1 s -1 . LC-MS/MS analysis determined that RA-0002034 covalently modified the catalytic cysteine in a site-specific manner. Additionally, RA-0002034 showed no significant off-target reactivity against a panel of cysteine proteases. In addition to the potent biochemical inhibition of CHIKV nsP2pro activity and exceptional selectivity, RA-0002034 was tested in cellular models of alphavirus infection and effectively inhibited viral replication of both CHIKV and related alphaviruses. This study highlights the discovery and characterization of the chemical probe RA-0002034 as a promising hit compound from covalent fragment-based screening for development toward a CHIKV or pan-alphavirus therapeutic. Significance Statement Chikungunya virus is one of the most prominent and widespread alphaviruses and has caused explosive outbreaks of arthritic disease. Currently, there are no FDA-approved drugs to treat disease caused by chikungunya virus or any other alphavirus-caused infection. Here, we report the discovery of a covalent small molecule inhibitor of chikungunya virus nsP2 protease activity and viral replication of four diverse alphaviruses. This finding highlights the utility of covalent fragment screening for inhibitor discovery and represents a starting point towards the development of alphavirus therapeutics targeting nsP2 protease.
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4
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Lima JCB, Barbosa JARG. Interaction models between peptide substrate and Alphavirus Protease nsP2 of Chikungunya and Mayaro and implications to the mechanism of action. J Biomol Struct Dyn 2023; 41:10851-10858. [PMID: 36562200 DOI: 10.1080/07391102.2022.2158941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 12/10/2022] [Indexed: 12/24/2022]
Abstract
The Arbovirus (Arthropod-borne virus) is a group which comprises viruses whose transmission is carried out by arthropod vectors infecting vertebrates. Some arboviruses related to human diseases have been given considerable relevance as Chikungunya and Mayaro of the family Togaviridae, genus Alphavirus. The lack of proper specific treatment has prompted the requirement for deeper structural studies that could unveil leads to new drugs. Among possible targets, viral proteases are recognized as proteins with big potential. These proteins, termed nsP2 in Alphavirus, have the function of cleaving certain regions of the viral polyprotein, being vital to the viral cycle. In this research, we used docking and molecular dynamics to analyze the contact between the protease nsP2 of Alphavirus Chikungunya and Mayaro and substrates formed by peptides with ten amino acid residues. A model of the Mayaro nsP2 was constructed based on homologous proteases. Our study suggests that the glycine specificity motif, a region where a highly conserved glycine residue in position P2 of the protease substrate is positioned, facilitates the nucleophilic attack by assisting in placing the P1 carbonyl group carbon. Stabilization of different substrate regions maybe explained by relevant contacts with the enzyme. Besides that, the phi and psi angles in the outlier region of the Ramachandran plot found for the P2 glycine of the Chikungunya substrate seems to indicate the necessity of this residue that can accommodate angles not allowed to other residues.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Jônatas Cunha Barbosa Lima
- Laboratório de Biofísica Molecular, Departamento de Biologia Celular, Instituto de Ciências Biológicas, Universidade de Brasília, Brasilia, DF, Brazil
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5
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Hoffka G, Lountos GT, Needle D, Wlodawer A, Waugh DS, Tőzsér J, Mótyán JA. Self-inhibited State of Venezuelan Equine Encephalitis Virus (VEEV) nsP2 Cysteine Protease: A Crystallographic and Molecular Dynamics Analysis. J Mol Biol 2023; 435:168012. [PMID: 36792007 PMCID: PMC10758287 DOI: 10.1016/j.jmb.2023.168012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 02/06/2023] [Accepted: 02/07/2023] [Indexed: 02/15/2023]
Abstract
The Venezuelan equine encephalitis virus (VEEV) belongs to the Togaviridae family and is pathogenic to both humans and equines. The VEEV non-structural protein 2 (nsP2) is a cysteine protease (nsP2pro) that processes the polyprotein and thus it is a drug target for inhibitor discovery. The atomic structure of the VEEV nsP2 catalytic domain was previously characterized by both X-ray crystallography and computational studies. A modified nsP2pro harboring a N475A mutation in the N terminus was observed to exhibit an unexpected conformation: the N-terminal residues bind to the active site, mimicking binding of a substrate. The large conformational change of the N terminus was assumed to be induced by the N475A mutation, as N475 has an important role in stabilization of the N terminus and the active site. This conformation was first observed in the N475A mutant, but we also found it while determining a crystal structure of the catalytically active nsP2pro containing the wild-type N475 active site residue and K741A/K767A surface entropy reduction mutations. This suggests that the N475A mutation is not a prerequisite for self-inhibition. Here, we describe a high resolution (1.46 Å) crystal structure of a truncated nsP2pro (residues 463-785, K741A/K767A) and analyze the structure further by molecular dynamics to study the active and self-inhibited conformations of nsP2pro and its N475A mutant. A comparison of the different conformations of the N-terminal residues sheds a light on the interactions that play an important role in the stabilization of the enzyme.
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Affiliation(s)
- Gyula Hoffka
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Hungary; Doctoral School of Molecular Cell and Immune Biology, University of Debrecen, Debrecen, Hungary
| | - George T Lountos
- Basic Science Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Danielle Needle
- Center for Structural Biology, National Cancer Institute, Frederick, MD 21702, USA
| | - Alexander Wlodawer
- Center for Structural Biology, National Cancer Institute, Frederick, MD 21702, USA
| | - David S Waugh
- Center for Structural Biology, National Cancer Institute, Frederick, MD 21702, USA
| | - József Tőzsér
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Hungary
| | - János András Mótyán
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, Hungary.
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6
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Rabelo VWH, de Palmer Paixão ICN, Abreu PA. Structural insights into the inhibition of the nsP2 protease from Chikungunya virus by molecular modeling approaches. J Mol Model 2022; 28:311. [PMID: 36097090 DOI: 10.1007/s00894-022-05316-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Accepted: 09/05/2022] [Indexed: 11/24/2022]
Abstract
Chikungunya virus (CHIKV) is the etiological agent of the Chikungunya fever which has spread worldwide. Clinically, this disease may lead to prolonged incapacitating joint pain that can compromise remarkably the patients' quality of life. However, there are no licensed vaccines or specific drugs to fight this infection yet, making the search for novel therapies an imperative need. In this scenario, the CHIKV nsP2 protease emerged as an attractive therapeutic target once this protein plays a pivotal role in viral replication and pathogenesis. Hence, we investigated the structural basis for the inhibition of this enzyme by using molecular docking and dynamics simulations. Compounds with inhibitory activities against CHIKV nsP2 protease determined experimentally were selected from the literature. Docking studies with a set of stereoisomers showed that trans isomers, but not cis ones, bound close to the catalytic dyad which may explain isomerism requirements to the enzyme's inhibition. Further, binding mode analyses of other known inhibitors revealed highly conserved contacts between inhibitors and enzyme residues like N1011, C1013, A1046, Y1079, N1082, W1084, L1205, and M1242. Molecular dynamics simulations reinforced the importance of some of these interactions and pointed to nonpolar interactions as the main forces for inhibitors' binding. Finally, we observed that true inhibitors exhibited lower structural fluctuation, higher ligand efficiency and did not induce significant changes in protein correlated motions. Collectively, our findings might allow discerning true inhibitors from false ones and can guide drug development efforts targeting the nsP2 protease to fight CHIKV infections in the future.
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Affiliation(s)
- Vitor Won-Held Rabelo
- Instituto de Biologia, Programa de Pós-Graduação em Ciências e Biotecnologia, Universidade Federal Fluminense, Niterói, RJ, 24210-201, Brazil
| | - Izabel Christina Nunes de Palmer Paixão
- Instituto de Biologia, Programa de Pós-Graduação em Ciências e Biotecnologia, Universidade Federal Fluminense, Niterói, RJ, 24210-201, Brazil.,Departamento de Biologia Celular e Molecular, Instituto de Biologia, Universidade Federal Fluminense, Niterói, RJ, 24210-201, Brazil
| | - Paula Alvarez Abreu
- Instituto de Biodiversidade e Sustentabilidade (NUPEM), Universidade Federal do Rio de Janeiro, Macaé, RJ, 27965-045, Brazil.
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Muniz LS, da Rocha Pita SS. In silico studies revealed interaction mechanisms of benzylidene–acrylohydrazide derivatives and nsP2 CHIKV. NEW J CHEM 2022. [DOI: 10.1039/d1nj05593c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Here we studied benzylidene–acrylohydrazide derivatives via ADMET properties and docking analysis in the hope that they will be useful chemical moieties against the Chikungunya virus.
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Affiliation(s)
- Larissa Silva Muniz
- Laboratory of Bioinformatics and Molecular Modeling (LaBiMM), Pharmacy College, Federal University of Bahia (UFBA), Rua Barão de Jeremoabo, 147, Salvador, 40170-115, Bahia, Brazil
| | - Samuel Silva da Rocha Pita
- Laboratory of Bioinformatics and Molecular Modeling (LaBiMM), Pharmacy College, Federal University of Bahia (UFBA), Rua Barão de Jeremoabo, 147, Salvador, 40170-115, Bahia, Brazil
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8
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Abstract
Alphaviruses are positive-strand RNA viruses, typically transmitted by mosquitoes between vertebrate hosts. They encode four essential replication proteins, the non-structural proteins nsP1-4, which possess the enzymatic activities of RNA capping, RNA helicase, site-specific protease, ADP-ribosyl removal and RNA polymerase. Alphaviruses have been key models in the study of membrane-associated RNA replication, which is a conserved feature among the positive-strand RNA viruses of animals and plants. We review new structural and functional information on the nsPs and their interaction with host proteins and membranes, as well as with viral RNA sequences. The dodecameric ring structure of nsP1 is likely to be one of the evolutionary innovations that facilitated the success of the progenitors of current positive-strand RNA viruses.
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Affiliation(s)
- Tero Ahola
- Department of Microbiology, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki, Finland
| | - Gerald McInerney
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Andres Merits
- Institute of Technology, University of Tartu, Tartu, Estonia.
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9
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Ivanova L, Rausalu K, Žusinaite E, Tammiku-Taul J, Merits A, Karelson M. 1,3-Thiazolbenzamide Derivatives as Chikungunya Virus nsP2 Protease Inhibitors. ACS OMEGA 2021; 6:5786-5794. [PMID: 33681617 PMCID: PMC7931429 DOI: 10.1021/acsomega.0c06191] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 02/03/2021] [Indexed: 05/17/2023]
Abstract
Chikungunya fever results from an infection with Chikungunya virus (CHIKV, genus Alphavirus) that is prevalent in tropical regions and is spreading fast to temperate climates with documented outbreaks in Europe and the Americas. Currently, there are no available vaccines or antiviral drugs for prevention or treatment of Chikungunya fever. The nonstructural proteins (nsPs) of CHIKV responsible for virus replication are promising targets for the development of new antivirals. This study was attempted to find out new potential inhibitors of CHIKV nsP2 protease using the ligand-based drug design. Two compounds 10 and 10c, identified by molecular docking, showed antiviral activity against CHIKV with IC50 of 13.1 and 8.3 μM, respectively. Both compounds demonstrated the ability to inhibit the activity of nsP2 in a cell-free assay, and the impact of compound 10 on virus replication was confirmed by western blot. The molecular dynamics study of the interactions of compounds 10 and 10c with CHIKV nsP2 showed that a possible mechanism of action of these compounds is the blocking of the active site and the catalytic dyad of nsP2.
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Affiliation(s)
- Larisa Ivanova
- Institute
of Chemistry, University of Tartu, Ravila 14A, 50411 Tartu, Estonia
| | - Kai Rausalu
- Institute
of Technology, University of Tartu, Nooruse 1, 50411 Tartu, Estonia
| | - Eva Žusinaite
- Institute
of Technology, University of Tartu, Nooruse 1, 50411 Tartu, Estonia
| | - Jaana Tammiku-Taul
- Institute
of Chemistry, University of Tartu, Ravila 14A, 50411 Tartu, Estonia
| | - Andres Merits
- Institute
of Technology, University of Tartu, Nooruse 1, 50411 Tartu, Estonia
| | - Mati Karelson
- Institute
of Chemistry, University of Tartu, Ravila 14A, 50411 Tartu, Estonia
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10
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Bozóki B, Mótyán JA, Hoffka G, Waugh DS, Tőzsér J. Specificity Studies of the Venezuelan Equine Encephalitis Virus Non-Structural Protein 2 Protease Using Recombinant Fluorescent Substrates. Int J Mol Sci 2020; 21:E7686. [PMID: 33081394 PMCID: PMC7593941 DOI: 10.3390/ijms21207686] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 10/13/2020] [Accepted: 10/14/2020] [Indexed: 11/16/2022] Open
Abstract
The non-structural protein 2 (nsP2) of alphavirus Venezuelan equine encephalitis virus (VEEV) is a cysteine protease that is responsible for processing of the viral non-structural polyprotein and is an important drug target owing to the clinical relevance of VEEV. In this study we designed two recombinant VEEV nsP2 constructs to study the effects of an N-terminal extension on the protease activity and to investigate the specificity of the elongated enzyme in vitro. The N-terminal extension was found to have no substantial effect on the protease activity. The amino acid preferences of the VEEV nsP2 protease were investigated on substrates representing wild-type and P5, P4, P2, P1, P1', and P2' variants of Semliki forest virus nsP1/nsP2 cleavage site, using a His6-MBP-mEYFP recombinant substrate-based protease assay which has been adapted for a 96-well plate-based format. The structural basis of enzyme specificity was also investigated in silico by analyzing a modeled structure of VEEV nsP2 complexed with oligopeptide substrate. To our knowledge, in vitro screening of P1' amino acid preferences of VEEV nsP2 protease remains undetermined to date, thus, our results may provide valuable information for studies and inhibitor design of different alphaviruses or other Group IV viruses.
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Affiliation(s)
- Beáta Bozóki
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (B.B.); (G.H.)
- Doctoral School of Molecular Cell and Immune Biology, University of Debrecen, 4032 Debrecen, Hungary
| | - János András Mótyán
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (B.B.); (G.H.)
| | - Gyula Hoffka
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (B.B.); (G.H.)
- Doctoral School of Molecular Cell and Immune Biology, University of Debrecen, 4032 Debrecen, Hungary
- MTA-DE Laboratory of Protein Dynamics, Department of Biochemistry and Molecular Biology, University of Debrecen, 4032 Debrecen, Hungary
| | - David S. Waugh
- Macromolecular Crystallography Laboratory, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702, USA;
| | - József Tőzsér
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (B.B.); (G.H.)
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Computer-Aided Design, Synthesis, and Antiviral Evaluation of Novel Acrylamides as Potential Inhibitors of E3-E2-E1 Glycoproteins Complex from Chikungunya Virus. Pharmaceuticals (Basel) 2020; 13:ph13070141. [PMID: 32629969 PMCID: PMC7407227 DOI: 10.3390/ph13070141] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 06/23/2020] [Accepted: 06/25/2020] [Indexed: 02/07/2023] Open
Abstract
Chikungunya virus (CHIKV) causes an infectious disease characterized by inflammation and pain of the musculoskeletal tissues accompanied by swelling in the joints and cartilage damage. Currently, there are no licensed vaccines or chemotherapeutic agents to prevent or treat CHIKV infections. In this context, our research aimed to explore the potential in vitro anti-CHIKV activity of acrylamide derivatives. In silico methods were applied to 132 Michael’s acceptors toward the six most important biological targets from CHIKV. Subsequently, the ten most promising acrylamides were selected and synthesized. From the cytotoxicity MTT assay, we verified that LQM330, 334, and 336 demonstrate high cell viability at 40 µM. Moreover, these derivatives exhibited anti-CHIKV activities, highlighting the compound LQM334 which exhibited an inhibition value of 81%. Thus, docking simulations were performed to suggest a potential CHIKV-target for LQM334. It was observed that the LQM334 has a high affinity towards the E3-E2-E1 glycoproteins complex. Moreover, LQM334 reduced the percentage of CHIKV-positive cells from 74.07 to 0.88%, 48h post-treatment on intracellular flow cytometry staining. In conclusion, all virtual simulations corroborated with experimental results, and LQM334 could be used as a promising anti-CHIKV scaffold for designing new drugs in the future.
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12
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Lulla V, Karo-Astover L, Rausalu K, Saul S, Merits A, Lulla A. Timeliness of Proteolytic Events Is Prerequisite for Efficient Functioning of the Alphaviral Replicase. J Virol 2018; 92:e00151-18. [PMID: 29695431 PMCID: PMC6026757 DOI: 10.1128/jvi.00151-18] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 04/16/2018] [Indexed: 11/20/2022] Open
Abstract
Polyprotein processing has an important regulatory role in the life cycle of positive-strand RNA viruses. In the case of alphaviruses, sequential cleavage of the nonstructural polyprotein (ns-polyprotein) at three sites eventually yields four mature nonstructural proteins (nsPs) that continue working in complex to replicate viral genomic RNA and transcribe subgenomic RNA. Recognition of cleavage sites by viral nsP2 protease is guided by short sequences upstream of the scissile bond and, more importantly, by the spatial organization of the replication complex. In this study, we analyzed the consequences of the artificially accelerated processing of the Semliki Forest virus ns-polyprotein. It was found that in mammalian cells, not only the order but also the correct timing of the cleavage events is essential for the success of viral replication. Analysis of the effects of compensatory mutations in rescued viruses as well as in vitro translation and trans-replicase assays corroborated our findings and revealed the importance of the V515 residue in nsP2 for recognizing the P4 position in the nsP1/nsP2 cleavage site. We also extended our conclusions to Sindbis virus by analyzing the properties of the hyperprocessive variant carrying the N614D mutation in nsP2. We conclude that the sequence of the nsP1/nsP2 site in alphaviruses is under selective pressure to avoid the presence of sequences that are recognized too efficiently and would otherwise lead to premature cleavage at this site before completion of essential tasks of RNA synthesis or virus-induced replication complex formation. Even subtle changes in the ns-polyprotein processing pattern appear to lead to virus attenuation.IMPORTANCE The polyprotein expression strategy is a cornerstone of alphavirus replication. Three sites within the ns-polyprotein are recognized by the viral nsP2 protease and cleaved in a defined order. Specific substrate targeting is achieved by the recognition of the short sequence upstream of the scissile bond and a correct macromolecular assembly of ns-polyprotein. Here, we highlighted the importance of the timeliness of proteolytic events, as an additional layer of regulation of efficient virus replication. We conclude that, somewhat counterintuitively, the cleavage site sequences at the nsP1/nsP2 and nsP2/nsP3 junctions are evolutionarily selected to be recognized by protease inefficiently, to avoid premature cleavages that would be detrimental for the assembly and functionality of the replication complex. Understanding the causes and consequences of viral polyprotein processing events is important for predicting the properties of mutant viruses and should be helpful for the development of better vaccine candidates and understanding potential mechanisms of resistance to protease inhibitors.
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Affiliation(s)
- Valeria Lulla
- Institute of Technology, University of Tartu, Tartu, Estonia
| | | | - Kai Rausalu
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Sirle Saul
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Andres Merits
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Aleksei Lulla
- Institute of Technology, University of Tartu, Tartu, Estonia
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13
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Chikungunya virus inhibition by peptidomimetic inhibitors targeting virus-specific cysteine protease. Biochimie 2018; 149:51-61. [DOI: 10.1016/j.biochi.2018.04.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 04/03/2018] [Indexed: 11/19/2022]
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14
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Narwal M, Singh H, Pratap S, Malik A, Kuhn RJ, Kumar P, Tomar S. Crystal structure of chikungunya virus nsP2 cysteine protease reveals a putative flexible loop blocking its active site. Int J Biol Macromol 2018; 116:451-462. [PMID: 29730006 DOI: 10.1016/j.ijbiomac.2018.05.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Revised: 05/01/2018] [Accepted: 05/02/2018] [Indexed: 12/30/2022]
Abstract
Chikungunya virus (CHIKV), a mosquito-borne pathogenic alphavirus is a growing public health threat. No vaccines or antiviral drug is currently available in the market for chikungunya treatment. nsP2pro, the viral cysteine protease, carries out an essential function of nonstructural polyprotein processing and forms four nonstructural proteins (nsPs) that makes the replication complex, hence constitute a promising drug target. In this study, crystal structure of nsP2pro has been determined at 2.59 Å, which reveals that the protein consists of two subdomains: an N-terminal protease subdomain and a C-terminal methyltransferase subdomain. Structural comparison of CHIKV nsP2pro with structures of other alphavirus nsP2 advances that the substrate binding cleft is present at the interface of two subdomains. Additionally, structure insights revealed that access to the active site and substrate binding cleft is blocked by a flexible interdomain loop in CHIKV nsP2pro. This loop contains His548, the catalytic residue, and Trp549 and Asn547, the residues predicted to bind substrate. Interestingly, mutation of Asn547 leads to three-fold increase in Km confirming that Asn547 plays important role in substrate binding and recognition. This study presents the detailed molecular analysis and signifies the substrate specificity residues of CHIKV nsP2pro, which will be beneficial for structure-based drug design and optimization of CHIKV protease inhibitors.
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Affiliation(s)
- Manju Narwal
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India
| | - Harvijay Singh
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India
| | - Shivendra Pratap
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India
| | - Anjali Malik
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India
| | - Richard J Kuhn
- Markey Center for Structural Biology and Purdue Institute for Inflammation, Immunology and Infectious Disease, Purdue University, West Lafayette, IN 47907, USA
| | - Pravindra Kumar
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India
| | - Shailly Tomar
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, Uttarakhand, India.
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15
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Compton JR, Mickey MJ, Hu X, Marugan JJ, Legler PM. Mutation of Asn-475 in the Venezuelan Equine Encephalitis Virus nsP2 Cysteine Protease Leads to a Self-Inhibited State. Biochemistry 2017; 56:6221-6230. [PMID: 29064679 DOI: 10.1021/acs.biochem.7b00746] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The alphaviral nsP2 cysteine protease of the Venezuelan equine encephalitis virus (VEEV) is a validated antiviral drug target. Clan CN proteases contain a cysteine protease domain that is intimately packed with an S-adenosyl-l-methionine-dependent RNA methyltransferase (SAM MTase) domain. Within a cleft formed at the interface of these two domains, the peptide substrate is thought to bind. The nucleophilic cysteine can be found within a conserved motif, 475NVCWAK480, which differs from that of papain (22CGSCWAFS29). Mutation of the motif residue, N475, to alanine unexpectedly produced a self-inhibited state in which the N-terminal residues flipped into the substrate-binding cleft. Notably, the N-terminal segment was not hydrolyzed-consistent with a catalytically incompetent state. The N475A mutation resulted in a 70-fold decrease in kcat/Km. A side chain-substrate interaction was predicted by the structure; the S701A mutation led to a 17-fold increase in Km. An Asn at the n-2 position relative to the Cys was also found in the coronaviral papain-like proteases/deubiquitinases (PLpro) of the SARS and MERS viruses, and in several papain-like human ubiquitin specific proteases (USP). The large conformational change in the N475A variant suggests that Asn-475 plays an important role in stabilizing the N-terminal residues and in orienting the carbonyl during nucleophilic attack but does not directly hydrogen bond the oxyanion. The state trapped in crystallo is an unusual result of site-directed mutagenesis but reveals the role of this highly conserved Asn and identifies key substrate-binding contacts that may be exploited by peptide-like inhibitors.
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Affiliation(s)
- Jaimee R Compton
- U.S. Naval Research Laboratory , 4555 Overlook Avenue, Washington, D.C. 20375, United States
| | | | - Xin Hu
- National Center for Advancing Translational Sciences, National Institutes of Health , Rockville, Maryland 20850, United States
| | - Juan J Marugan
- National Center for Advancing Translational Sciences, National Institutes of Health , Rockville, Maryland 20850, United States
| | - Patricia M Legler
- U.S. Naval Research Laboratory , 4555 Overlook Avenue, Washington, D.C. 20375, United States
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16
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da Silva-Júnior EF, Leoncini GO, Rodrigues ÉES, Aquino TM, Araújo-Júnior JX. The medicinal chemistry of Chikungunya virus. Bioorg Med Chem 2017; 25:4219-4244. [PMID: 28689975 PMCID: PMC7126832 DOI: 10.1016/j.bmc.2017.06.049] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Accepted: 06/28/2017] [Indexed: 02/06/2023]
Abstract
Arthropod-borne viruses (arboviruses) are an important threat to human and animal health globally. Among these, zoonotic diseases account for billions of cases of human illness and millions of deaths every year, representing an increasing public health problem. Chikungunya virus belongs to the genus Alphavirus of the family Togariridae, and is transmitted mainly by the bite of female mosquitoes of the Aedes aegypti and/or A. albopictus species. The focus of this review will be on the medicinal chemistry of Chikungunya virus, including synthetic and natural products, as well as rationally designed compounds.
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Affiliation(s)
- Edeildo F da Silva-Júnior
- Laboratory of Medicinal Chemistry, Nursing and Pharmacy School, Federal University of Alagoas, Lourival Melo Motta Avenue, Tabuleiro dos Martins, 57072-900 Maceió, Brazil; Chemistry and Biotechnology Institute, Federal University of Alagoas, Lourival Melo Motta Avenue, Tabuleiro dos Martins, 57072-900 Maceió, Brazil.
| | - Giovanni O Leoncini
- Laboratory of Medicinal Chemistry, Nursing and Pharmacy School, Federal University of Alagoas, Lourival Melo Motta Avenue, Tabuleiro dos Martins, 57072-900 Maceió, Brazil; Chemistry and Biotechnology Institute, Federal University of Alagoas, Lourival Melo Motta Avenue, Tabuleiro dos Martins, 57072-900 Maceió, Brazil
| | - Érica E S Rodrigues
- Laboratory of Medicinal Chemistry, Nursing and Pharmacy School, Federal University of Alagoas, Lourival Melo Motta Avenue, Tabuleiro dos Martins, 57072-900 Maceió, Brazil
| | - Thiago M Aquino
- Chemistry and Biotechnology Institute, Federal University of Alagoas, Lourival Melo Motta Avenue, Tabuleiro dos Martins, 57072-900 Maceió, Brazil
| | - João X Araújo-Júnior
- Laboratory of Medicinal Chemistry, Nursing and Pharmacy School, Federal University of Alagoas, Lourival Melo Motta Avenue, Tabuleiro dos Martins, 57072-900 Maceió, Brazil; Chemistry and Biotechnology Institute, Federal University of Alagoas, Lourival Melo Motta Avenue, Tabuleiro dos Martins, 57072-900 Maceió, Brazil.
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17
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Dhindwal S, Kesari P, Singh H, Kumar P, Tomar S. Conformer and pharmacophore based identification of peptidomimetic inhibitors of chikungunya virus nsP2 protease. J Biomol Struct Dyn 2016; 35:3522-3539. [DOI: 10.1080/07391102.2016.1261046] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Sonali Dhindwal
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, India
| | - Pooja Kesari
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, India
| | - Harvijay Singh
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, India
| | - Pravindra Kumar
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, India
| | - Shailly Tomar
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, India
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18
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Chikungunya virus infectivity, RNA replication and non-structural polyprotein processing depend on the nsP2 protease's active site cysteine residue. Sci Rep 2016; 6:37124. [PMID: 27845418 PMCID: PMC5109220 DOI: 10.1038/srep37124] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 10/24/2016] [Indexed: 11/23/2022] Open
Abstract
Chikungunya virus (CHIKV), genus Alphavirus, family Togaviridae, has a positive-stand RNA genome approximately 12 kb in length. In infected cells, the genome is translated into non-structural polyprotein P1234, an inactive precursor of the viral replicase, which is activated by cleavages carried out by the non-structural protease, nsP2. We have characterized CHIKV nsP2 using both cell-free and cell-based assays. First, we show that Cys478 residue in the active site of CHIKV nsP2 is indispensable for P1234 processing. Second, the substrate requirements of CHIKV nsP2 are quite similar to those of nsP2 of related Semliki Forest virus (SFV). Third, substitution of Ser482 residue, recently reported to contribute to the protease activity of nsP2, with Ala has almost no negative effect on the protease activity of CHIKV nsP2. Fourth, Cys478 to Ala as well as Trp479 to Ala mutations in nsP2 completely abolished RNA replication in CHIKV and SFV trans-replication systems. In contrast, trans-replicases with Ser482 to Ala mutation were similar to wild type counterparts. Fifth, Cys478 to Ala as well as Trp479 to Ala mutations in nsP2 abolished the rescue of infectious virus from CHIKV RNA transcripts while Ser482 to Ala mutation had no effect. Thus, CHIKV nsP2 is a cysteine protease.
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19
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Byler KG, Collins JT, Ogungbe IV, Setzer WN. Alphavirus protease inhibitors from natural sources: A homology modeling and molecular docking investigation. Comput Biol Chem 2016; 64:163-184. [DOI: 10.1016/j.compbiolchem.2016.06.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 05/08/2016] [Accepted: 06/20/2016] [Indexed: 12/11/2022]
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20
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Campos-Gomez J, Ahmad F, Rodriguez E, Saeed MF. A novel cell-based assay to measure activity of Venezuelan equine encephalitis virus nsP2 protease. Virology 2016; 496:77-89. [PMID: 27261892 DOI: 10.1016/j.virol.2016.05.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 04/06/2016] [Accepted: 05/16/2016] [Indexed: 11/26/2022]
Abstract
The encephalitic alphaviruses encode nsP2 protease (nsP2pro), which because of its vital role in virus replication, represents an attractive target for therapeutic intervention. To facilitate the discovery of nsP2 inhibitors we have developed a novel assay for quantitative measurement of nsP2pro activity in a cell-based format. The assay is based on a substrate fusion protein consisting of eGFP and Gaussia luciferase (Gluc) linked together by a small peptide containing a VEEV nsp2pro cleavage sequence. The expression of the substrate protein in cells along with recombinant nsP2pro results in cleavage of the substrate protein resulting in extracellular release of free Gluc. The Gluc activity in supernatants corresponds to intracellular nsP2pro-mediated substrate cleavage; thus, providing a simple and convenient way to quantify nsP2pro activity. Here, we demonstrate potential utility of the assay in identification of nsP2pro inhibitors, as well as in investigations related to molecular characterization of nsP2pro.
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Affiliation(s)
- Javier Campos-Gomez
- Department of Infectious Diseases, Drug Discovery Division, Southern Research, Birmingham, AL 35205, United States
| | - Fahim Ahmad
- Department of Infectious Diseases, Drug Discovery Division, Southern Research, Birmingham, AL 35205, United States
| | - Efrain Rodriguez
- Department of Infectious Diseases, Drug Discovery Division, Southern Research, Birmingham, AL 35205, United States
| | - Mohammad F Saeed
- Department of Infectious Diseases, Drug Discovery Division, Southern Research, Birmingham, AL 35205, United States.
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21
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Hu X, Compton JR, Leary DH, Olson MA, Lee MS, Cheung J, Ye W, Ferrer M, Southall N, Jadhav A, Morazzani EM, Glass PJ, Marugan J, Legler PM. Kinetic, Mutational, and Structural Studies of the Venezuelan Equine Encephalitis Virus Nonstructural Protein 2 Cysteine Protease. Biochemistry 2016; 55:3007-19. [PMID: 27030368 DOI: 10.1021/acs.biochem.5b00992] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Venezuelan equine encephalitis virus (VEEV) nonstructural protein 2 (nsP2) cysteine protease (EC 3.4.22.-) is essential for viral replication and is involved in the cytopathic effects (CPE) of the virus. The VEEV nsP2 protease is a member of MEROPS Clan CN and characteristically contains a papain-like protease linked to an S-adenosyl-l-methionine-dependent RNA methyltransferase (SAM MTase) domain. The protease contains an alternative active site motif, (475)NVCWAK(480), which differs from papain's (CGS(25)CWAFS), and the enzyme lacks a transition state-stabilizing residue homologous to Gln-19 in papain. To understand the roles of conserved residues in catalysis, we determined the structure of the free enzyme and the first structure of an inhibitor-bound alphaviral protease. The peptide-like E64d inhibitor was found to bind beneath a β-hairpin at the interface of the SAM MTase and protease domains. His-546 adopted a conformation that differed from that found in the free enzyme; one or both of the conformers may assist in leaving group departure of either the amine or Cys thiolate during the catalytic cycle. Interestingly, E64c (200 μM), the carboxylic acid form of the E64d ester, did not inhibit the nsP2 protease. To identify key residues involved in substrate binding, a number of mutants were analyzed. Mutation of the motif residue, N475A, led to a 24-fold reduction in kcat/Km, and the conformation of this residue did not change after inhibition. N475 forms a hydrogen bond with R662 in the SAM MTase domain, and the R662A and R662K mutations both led to 16-fold decreases in kcat/Km. N475 forms the base of the P1 binding site and likely orients the substrate for nucleophilic attack or plays a role in product release. An Asn homologous to N475 is similarly found in coronaviral papain-like proteases (PLpro) of the Severe Acute Respiratory Syndrome (SARS) virus and Middle East Respiratory Syndrome (MERS) virus. Mutation of another motif residue, K480A, led to a 9-fold decrease in kcat and kcat/Km. K480 likely enhances the nucleophilicity of the Cys. Consistent with our substrate-bound models, the SAM MTase domain K706A mutation increased Km 4.5-fold to 500 μM. Within the β-hairpin, the N545A mutation slightly but not significantly increased kcat and Km. The structures and identified active site residues may facilitate the discovery of protease inhibitors with antiviral activity.
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Affiliation(s)
- Xin Hu
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences , Rockville, Maryland 20850, United States
| | | | - Dagmar H Leary
- Center for Bio/molecular Science and Engineering, U.S. Naval Research Laboratory , Washington, D.C. 20375, United States
| | - Mark A Olson
- United States Army Medical Research Institute of Infectious Diseases , Frederick, Maryland 21702, United States
| | - Michael S Lee
- United States Army Medical Research Institute of Infectious Diseases , Frederick, Maryland 21702, United States
| | - Jonah Cheung
- New York Structural Biology Center , New York, New York 10027, United States
| | - Wenjuan Ye
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences , Rockville, Maryland 20850, United States
| | - Mark Ferrer
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences , Rockville, Maryland 20850, United States
| | - Noel Southall
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences , Rockville, Maryland 20850, United States
| | - Ajit Jadhav
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences , Rockville, Maryland 20850, United States
| | - Elaine M Morazzani
- United States Army Medical Research Institute of Infectious Diseases , Frederick, Maryland 21702, United States
| | - Pamela J Glass
- United States Army Medical Research Institute of Infectious Diseases , Frederick, Maryland 21702, United States
| | - Juan Marugan
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences , Rockville, Maryland 20850, United States
| | - Patricia M Legler
- Center for Bio/molecular Science and Engineering, U.S. Naval Research Laboratory , Washington, D.C. 20375, United States
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22
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Chikungunya nsP2 protease is not a papain-like cysteine protease and the catalytic dyad cysteine is interchangeable with a proximal serine. Sci Rep 2015; 5:17125. [PMID: 26597768 PMCID: PMC4657084 DOI: 10.1038/srep17125] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 10/26/2015] [Indexed: 12/20/2022] Open
Abstract
Chikungunya virus is the pathogenic alphavirus that causes chikungunya fever in humans. In the last decade millions of cases have been reported around the world from Africa to Asia to the Americas. The alphavirus nsP2 protein is multifunctional and is considered to be pivotal to viral replication, as the nsP2 protease activity is critical for proteolytic processing of the viral polyprotein during replication. Classically the alphavirus nsP2 protease is thought to be papain-like with the enzyme reaction proceeding through a cysteine/histidine catalytic dyad. We performed structure-function studies on the chikungunya nsP2 protease and show that the enzyme is not papain-like. Characterization of the catalytic dyad cysteine residue enabled us to identify a nearby serine that is catalytically interchangeable with the dyad cysteine residue. The enzyme retains activity upon alanine replacement of either residue but a replacement of both cysteine and serine residues results in no detectable activity. Protein dynamics appears to allow the use of either the cysteine or the serine residue in catalysis. This switchable dyad residue has not been previously reported for alphavirus nsP2 proteases and would have a major impact on the nsP2 protease as an anti-viral target.
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El-labbad EM, Ismail MAH, Abou Ei Ella DA, Ahmed M, Wang F, Barakat KH, Abouzid KAM. Discovery of Novel Peptidomimetics as Irreversible CHIKV NsP2 Protease Inhibitors Using Quantum Mechanical-Based Ligand Descriptors. Chem Biol Drug Des 2015. [DOI: 10.1111/cbdd.12621] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Eman M. El-labbad
- Department of Pharmaceutical Chemistry; Faculty of Pharmacy; Ain Shams University; Abbassia Cairo 11566 Egypt
| | - Mohammed A. H. Ismail
- Department of Pharmaceutical Chemistry; Faculty of Pharmacy; Ain Shams University; Abbassia Cairo 11566 Egypt
| | - Dalal A. Abou Ei Ella
- Department of Pharmaceutical Chemistry; Faculty of Pharmacy; Ain Shams University; Abbassia Cairo 11566 Egypt
| | - Marawan Ahmed
- Faculty of Pharmacy and Pharmaceutical Sciences; University of Alberta; Edmonton AB Canada
| | - Feng Wang
- Molecular Model Discovery Laboratory; Department of Chemistry and Biotechnology; Faculty of Science, Engineering and Technology; Swinburne University of Technology; Melbourne Vic. 3122 Australia
| | - Khaled H. Barakat
- Faculty of Pharmacy and Pharmaceutical Sciences; University of Alberta; Edmonton AB Canada
- LiKaShing Institute of Virology; University of Alberta; Edmonton AB Canada
- LiKaShing Applied Virology Institute; University of Alberta; Edmonton AB Canada
| | - Khaled A. M. Abouzid
- Department of Pharmaceutical Chemistry; Faculty of Pharmacy; Ain Shams University; Abbassia Cairo 11566 Egypt
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Viral Polymerase-Helicase Complexes Regulate Replication Fidelity To Overcome Intracellular Nucleotide Depletion. J Virol 2015; 89:11233-44. [PMID: 26311883 PMCID: PMC4645662 DOI: 10.1128/jvi.01553-15] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 08/20/2015] [Indexed: 12/21/2022] Open
Abstract
UNLABELLED To date, the majority of work on RNA virus replication fidelity has focused on the viral RNA polymerase, while the potential role of other viral replicase proteins in this process is poorly understood. Previous studies used resistance to broad-spectrum RNA mutagens, such as ribavirin, to identify polymerases with increased fidelity that avoid misincorporation of such base analogues. We identified a novel variant in the alphavirus viral helicase/protease, nonstructural protein 2 (nsP2) that operates in concert with the viral polymerase nsP4 to further alter replication complex fidelity, a functional linkage that was conserved among the alphavirus genus. Purified chikungunya virus nsP2 presented delayed helicase activity of the high-fidelity enzyme, and yet purified replication complexes manifested stronger RNA polymerization kinetics. Because mutagenic nucleoside analogs such as ribavirin also affect intracellular nucleotide pools, we addressed the link between nucleotide depletion and replication fidelity by using purine and pyrimidine biosynthesis inhibitors. High-fidelity viruses were more resistant to these conditions, and viral growth could be rescued by the addition of exogenous nucleosides, suggesting that mutagenesis by base analogues requires nucleotide pool depletion. This study describes a novel function for nsP2, highlighting the role of other components of the replication complex in regulating viral replication fidelity, and suggests that viruses can alter their replication complex fidelity to overcome intracellular nucleotide-depleting conditions. IMPORTANCE Previous studies using the RNA mutagen ribavirin to select for drug-resistant variants have highlighted the essential role of the viral RNA-dependent RNA polymerase in regulating replication fidelity. However, the role of other viral replicase components in replication fidelity has not been studied in detail. We identified here an RNA mutagen-resistant variant of the nsP2 helicase/protease that conferred increased fidelity and yet could not operate in the same manner as high-fidelity polymerases. We show that the alphavirus helicase is a key component of the fidelity-regulating machinery. Our data show that the RNA mutagenic activity of compounds such as ribavirin is coupled to and potentiated by nucleotide depletion and that RNA viruses can fine-tune their replication fidelity when faced with an intracellular environment depleted of nucleotides.
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25
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Differences in Processing Determinants of Nonstructural Polyprotein and in the Sequence of Nonstructural Protein 3 Affect Neurovirulence of Semliki Forest Virus. J Virol 2015; 89:11030-45. [PMID: 26311875 DOI: 10.1128/jvi.01186-15] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 08/19/2015] [Indexed: 01/04/2023] Open
Abstract
UNLABELLED The A7(74) strain of Semliki Forest virus (SFV; genus Alphavirus) is avirulent in adult mice, while the L10 strain is virulent in mice of all ages. It has been previously demonstrated that this phenotypic difference is associated with nonstructural protein 3 (nsP3). Consensus clones of L10 (designated SFV6) and A7(74) (designated A774wt) were used to construct a panel of recombinant viruses. The insertion of nsP3 from A774wt into the SFV6 backbone had a minor effect on the virulence of the resulting recombinant virus. Conversely, insertion of nsP3 from SFV6 into the A774wt backbone or replacement of A774wt nsP3 with two copies of nsP3 from SFV6 resulted in virulent viruses. Unexpectedly, duplication of nsP3-encoding sequences also resulted in elevated levels of nsP4, revealing that nsP3 is involved in the stabilization of nsP4. Interestingly, replacement of nsP3 of SFV6 with that of A774wt resulted in a virulent virus; the virulence of this recombinant was strongly reduced by functionally coupled substitutions for amino acid residues 534 (P4 position of the cleavage site between nsP1 and nsP2) and 1052 (S4 subsite residue of nsP2 protease) in the nonstructural polyprotein. Pulse-chase experiments revealed that A774wt and avirulent recombinant virus were characterized by increased processing speed of the cleavage site between nsP1 and nsP2. A His534-to-Arg substitution specifically activated this cleavage, while a Val1052-to-Glu substitution compensated for this effect by reducing the basal protease activity of nsP2. These findings provide a link between nonstructural polyprotein processing and the virulence of SFV. IMPORTANCE SFV infection of mice provides a well-characterized model to study viral encephalitis. SFV also serves as a model for studies of alphavirus molecular biology and host-pathogen interactions. Thus far, the genetic basis of different properties of SFV strains has been studied using molecular clones, which often contain mistakes originating from standard cDNA synthesis and cloning procedures. Here, for the first time, consensus clones of SFV strains were used to map virulence determinants. Existing data on the importance of nsP3 for virulent phenotypes were confirmed, another determinant of neurovirulence and its molecular basis was characterized, and a novel function of nsP3 was identified. These findings provide links between the molecular biology of SFV and its biological properties and significantly increase our understanding of the basis of alphavirus-induced pathology. In addition, the usefulness of consensus clones as tools for studies of alphaviruses was demonstrated.
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Full length and protease domain activity of chikungunya virus nsP2 differ from other alphavirus nsP2 proteases in recognition of small peptide substrates. Biosci Rep 2015; 35:BSR20150086. [PMID: 26182358 PMCID: PMC4445351 DOI: 10.1042/bsr20150086] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 04/13/2015] [Indexed: 02/06/2023] Open
Abstract
Alphavirus nsP2 proteins are multifunctional and essential for viral replication. The protease role of nsP2 is critical for virus replication as only the virus protease activity is used for processing of the viral non-structural polypeptide. Chikungunya virus is an emerging disease problem that is becoming a world-wide health issue. We have generated purified recombinant chikungunya virus nsP2 proteins, both full length and a truncated protease domain from the C-terminus of the nsP2 protein. Enzyme characterization shows that the protease domain alone has different properties compared with the full length nsP2 protease. We also show chikungunya nsP2 protease possesses different substrate specificity to the canonical alphavirus nsP2 polyprotein cleavage specificity. Moreover, the chikungunya nsP2 also appears to differ from other alphavirus nsP2 in its distinctive ability to recognize small peptide substrates. The protease role of alphavirus nsP2 is critical for virus replication as only the virus protease processes the viral non-structural polypeptide. We show chikungunya nsP2 protease possesses different substrate specificity to the canonical alphavirus nsP2 polyprotein cleavage specificity.
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27
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Das PK, Merits A, Lulla A. Functional cross-talk between distant domains of chikungunya virus non-structural protein 2 is decisive for its RNA-modulating activity. J Biol Chem 2014; 289:5635-53. [PMID: 24407286 DOI: 10.1074/jbc.m113.503433] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Chikungunya virus (CHIKV) non-structural protein 2 (nsP2) is a multifunctional protein that is considered a master regulator of the viral life cycle and a main viral factor responsible for cytopathic effects and subversion of antiviral defense. The C-terminal part of nsP2 possesses protease activity, whereas the N-terminal part exhibits NTPase and RNA triphosphatase activity and is proposed to have helicase activity. Bioinformatics analysis classified CHIKV nsP2 into helicase superfamily 1. However, the biochemical significance of a coexistence of two functionally unrelated modules in this single protein remains unknown. In this study, recombinant nsP2 demonstrated unwinding of double-stranded RNA in a 5'-3' directionally biased manner and RNA strand annealing activity. Comparative analysis of NTPase and helicase activities of wild type nsP2 with enzymatic capabilities of different truncated or N-terminally extended variants of nsP2 revealed that the C-terminal part of the protein is indispensable for helicase functionality and presumably provides a platform for RNA binding, whereas the N-terminal-most region is apparently involved in obtaining a conformation of nsP2 that allows for its maximal enzymatic activities. The establishment of the protocols for the production of biochemically active CHIKV nsP2 and optimization of the parameters for helicase and NTPase assays are expected to provide the starting point for a further search of possibilities for therapeutic interventions to suppress alphaviral infections.
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Affiliation(s)
- Pratyush Kumar Das
- From the Institute of Technology, University of Tartu, Nooruse 1, 50411 Tartu, Estonia
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28
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Rashad AA, Mahalingam S, Keller PA. Chikungunya virus: emerging targets and new opportunities for medicinal chemistry. J Med Chem 2013; 57:1147-66. [PMID: 24079775 DOI: 10.1021/jm400460d] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Chikungunya virus is an emerging arbovirus that is widespread in tropical regions and is spreading quickly to temperate climates with recent epidemics in Africa and Asia and documented outbreaks in Europe and the Americas. It is having an increasingly major impact on humankind, with potentially life-threatening and debilitating arthritis. There is no treatment available, and only in the past 24 months have lead compounds for development as potential therapeutics been reported. This Perspective discusses the chikungunya virus as a significant, new emerging topic for medicinal chemistry, highlighting the key viral target proteins and their molecular functions that can be used in drug design, as well as the most important ongoing developments for anti-chikungunya virus research. It represents a complete picture of the current medicinal chemistry of chikungunya, supporting the development of chemotherapeutics through drug discovery and design targeting this virus.
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Affiliation(s)
- Adel A Rashad
- Centre for Medicinal Chemistry, School of Chemistry, University of Wollongong , Wollongong, 2522, Australia
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29
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Presentation overrides specificity: probing the plasticity of alphaviral proteolytic activity through mutational analysis. J Virol 2013; 87:10207-20. [PMID: 23864614 DOI: 10.1128/jvi.01485-13] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Semliki Forest virus (genus Alphavirus) is an important model for studying regulated nonstructural (ns) polyprotein processing. In this study, we evaluated the strictness of the previously outlined cleavage rules, accounting for the timing and outcome of each of three cleavages within the ns polyprotein P1234, and assessed the significance of residues P6 to P4 within the cleavage sites using an alanine scanning approach. The processing of the 1/2 and 3/4 sites was most strongly affected following changes in residues P5 and P4, respectively. However, none of the mutations had a detectable effect on the processing of the 2/3 site. An analysis of recombinant viruses bearing combinations of mutations in cleavage sites revealed tolerance toward the cooccurrence of native and mutated cleavage sites within the same polyprotein, suggesting a remarkable plasticity of the protease recognition pocket. Even in a virus in which all of the cleavage sequences were replaced with alanines in the P6, P5, and P4 positions, the processing pattern was largely preserved, without leading to reversion of cleavage site mutations. Instead, the emergence of second-site mutations was identified, among which Q706R/L in nsP2 was confirmed to be associated with the recognition of the P4 position within the modified cleavage sites. Our results imply that the spatial arrangement of the viral replication complex inherently contributes to scissile-site presentation for the protease, alleviating stringent sequence recognition requirements yet ensuring the precision and the correct order of processing events. Obtaining a proper understanding of the consequences of cleavage site manipulations may provide new tools for taming alphaviruses.
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Hypervariable domain of nonstructural protein nsP3 of Venezuelan equine encephalitis virus determines cell-specific mode of virus replication. J Virol 2013; 87:7569-84. [PMID: 23637407 DOI: 10.1128/jvi.00720-13] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Venezuelan equine encephalitis virus (VEEV) is one of the most pathogenic members of the Alphavirus genus in the Togaviridae family. This genus is divided into the Old World and New World alphaviruses, which demonstrate profound differences in pathogenesis, replication, and virus-host interactions. VEEV is a representative member of the New World alphaviruses. The biology of this virus is still insufficiently understood, particularly the function of its nonstructural proteins in RNA replication and modification of the intracellular environment. One of these nonstructural proteins, nsP3, contains a hypervariable domain (HVD), which demonstrates very low overall similarity between different alphaviruses, suggesting the possibility of its function in virus adaptation to different hosts and vectors. The results of our study demonstrate the following. (i) Phosphorylation of the VEEV nsP3-specific HVD does not play a critical role in virus replication in cells of vertebrate origin but is important for virus replication in mosquito cells. (ii) The VEEV HVD is not required for viral RNA replication in the highly permissive BHK-21 cell line. In fact, it can be either completely deleted or replaced by a heterologous protein sequence. These variants require only one or two additional adaptive mutations in nsP3 and/or nsP2 proteins to achieve an efficiently replicating phenotype. (iii) However, the carboxy-terminal repeat in the VEEV HVD is indispensable for VEEV replication in the cell lines other than BHK-21 and plays a critical role in formation of VEEV-specific cytoplasmic protein complexes. Natural VEEV variants retain at least one of the repeated elements in their nsP3 HVDs.
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Computer-aided identification, design and synthesis of a novel series of compounds with selective antiviral activity against chikungunya virus. Antiviral Res 2013; 98:12-8. [PMID: 23380636 DOI: 10.1016/j.antiviral.2013.01.002] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 01/02/2013] [Accepted: 01/12/2013] [Indexed: 11/21/2022]
Abstract
Chikungunya virus (CHIKV) is an Arbovirus that is transmitted to humans primarily by the mosquito species Aedes aegypti. Infection with this pathogen is often associated with fever, rash and arthralgia. Neither a vaccine nor an antiviral drug is available for the prevention or treatment of this disease. Albeit considered a tropical pathogen, adaptation of the virus to the mosquito species Aedes albopictus, which is also very common in temperate zones, has resulted in recent outbreaks in Europe and the US. In the present study, we report on the discovery of a novel series of compounds that inhibit CHIKV replication in the low μM range. In particular, we initially performed a virtual screening simulation of ∼5 million compounds on the CHIKV nsP2, the viral protease, after which we investigated and explored the Structure-Activity Relationships of the hit identified in silico. Overall, a series of 26 compounds, including the original hit, was evaluated in a virus-cell-based CPE reduction assay. The study of such selective inhibitors will contribute to a better understanding of the CHIKV replication cycle and may represents a first step towards the development of a clinical candidate drug for the treatment of this disease.
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Structural and functional insights into alphavirus polyprotein processing and pathogenesis. Proc Natl Acad Sci U S A 2012; 109:16534-9. [PMID: 23010928 DOI: 10.1073/pnas.1210418109] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Alphaviruses, a group of positive-sense RNA viruses, are globally distributed arboviruses capable of causing rash, arthritis, encephalitis, and death in humans. The viral replication machinery consists of four nonstructural proteins (nsP1-4) produced as a single polyprotein. Processing of the polyprotein occurs in a highly regulated manner, with cleavage at the P2/3 junction influencing RNA template use during genome replication. Here, we report the structure of P23 in a precleavage form. The proteins form an extensive interface and nsP3 creates a ring structure that encircles nsP2. The P2/3 cleavage site is located at the base of a narrow cleft and is not readily accessible, suggesting a highly regulated cleavage. The nsP2 protease active site is over 40 Å away from the P2/3 cleavage site, supporting a trans cleavage mechanism. nsP3 contains a previously uncharacterized protein fold with a zinc-coordination site. Known mutations in nsP2 that result in formation of noncytopathic viruses or a temperature sensitive phenotype cluster at the nsP2/nsP3 interface. Structure-based mutations in nsP3 opposite the location of the nsP2 noncytopathic mutations prevent efficient cleavage of P23, affect RNA infectivity, and alter viral RNA production levels, highlighting the importance of the nsP2/nsP3 interaction in pathogenesis. A potential RNA-binding surface, spanning both nsP2 and nsP3, is proposed based on the location of ion-binding sites and adaptive mutations. These results offer unexpected insights into viral protein processing and pathogenesis that may be applicable to other polyprotein-encoding viruses such as HIV, hepatitis C virus (HCV), and Dengue virus.
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