1
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Parida PP, Saraswathi D, Mopidevi SM, Raran-Kurussi S. Advancing large-scale production of TEV protease through an innovative NT* tag-based fusion construct. Curr Res Struct Biol 2023; 6:100106. [PMID: 37822550 PMCID: PMC10563009 DOI: 10.1016/j.crstbi.2023.100106] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 09/29/2023] [Accepted: 09/29/2023] [Indexed: 10/13/2023] Open
Abstract
Tobacco etch virus Protease (TEVp), a cysteine protease, is renowned for its remarkable specific proteolysis, making it an invaluable tool for removing fusion tags from recombinant proteins. However, TEV protease's inherent insolubility limits its broad application. Fusion constructs like an N-terminal MBP fusion, known for its improved solubility, have been employed for TEVp production to address this issue. In this study, we fused the TEVp with the N-terminal domain of the spider silk protein, specifically utilizing a charge-reversed mutant (D40K/K65D) of the N-terminal domain of major ampullate spidroin-1 protein from Euprosthenops australis, referred to as NT*. This fusion construct contains a TEVp cleavage site, enabling intracellular self-processing and the release of a His7-tagged protease. The significant increase in soluble protein expression allowed us to purify approximately 90-100 mg of TEVp from a 1-L E. coli culture, surpassing previous findings by a considerable margin. The enzyme remained stable and catalytically active even after several months of storage in a deep freezer (-80 °C).
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Affiliation(s)
- Pragyan P. Parida
- Tata Institute of Fundamental Research Hyderabad, 36/P Gopanpally Village, Ranga Reddy District, Serilingampally, Hyderabad, 500046, Telangana, India
| | - Deepa Saraswathi
- Tata Institute of Fundamental Research Hyderabad, 36/P Gopanpally Village, Ranga Reddy District, Serilingampally, Hyderabad, 500046, Telangana, India
| | - Subbarao M.V. Mopidevi
- Tata Institute of Fundamental Research Hyderabad, 36/P Gopanpally Village, Ranga Reddy District, Serilingampally, Hyderabad, 500046, Telangana, India
| | - Sreejith Raran-Kurussi
- Tata Institute of Fundamental Research Hyderabad, 36/P Gopanpally Village, Ranga Reddy District, Serilingampally, Hyderabad, 500046, Telangana, India
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2
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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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3
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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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4
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Nayak TK, Mamidi P, Sahoo SS, Kumar PS, Mahish C, Chatterjee S, Subudhi BB, Chattopadhyay S, Chattopadhyay S. P38 and JNK Mitogen-Activated Protein Kinases Interact With Chikungunya Virus Non-structural Protein-2 and Regulate TNF Induction During Viral Infection in Macrophages. Front Immunol 2019; 10:786. [PMID: 31031770 PMCID: PMC6473476 DOI: 10.3389/fimmu.2019.00786] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 03/25/2019] [Indexed: 02/02/2023] Open
Abstract
Chikungunya virus (CHIKV), a mosquito-borne Alphavirus, is endemic in different parts of the globe. The host macrophages are identified as the major cellular reservoirs of CHIKV during infection and this virus triggers robust TNF production in the host macrophages, which might be a key mediator of virus induced inflammation. However, the molecular mechanism underneath TNF induction is not understood yet. Accordingly, the Raw264.7 cells, a mouse macrophage cell line, were infected with CHIKV to address the above-mentioned question. It was observed that CHIKV induces both p38 and JNK phosphorylation in macrophages in a time-dependent manner and p-p38 inhibitor, SB203580 is effective in reducing infection even at lower concentration as compared to the p-JNK inhibitor, SP600125. However, inhibition of p-p38 and p-JNK decreased CHIKV induced TNF production in the host macrophages. Moreover, CHIKV induced macrophage derived TNF was found to facilitate TCR driven T cell activation. Additionally, it was noticed that the expressions of key transcription factors involved mainly in antiviral responses (p-IRF3) and TNF production (p-c-jun) were induced significantly in the CHIKV infected macrophages as compared to the corresponding mock cells. Further, it was demonstrated that CHIKV mediated TNF production in the macrophages is dependent on p38 and JNK MAPK pathways linking p-c-jun transcription factor. Interestingly, it was found that CHIKV nsP2 interacts with both p-p38 and p-JNK MAPKs in the macrophages. This observation was supported by the in silico protein-protein docking analysis which illustrates the specific amino acids responsible for the nsP2-MAPKs interactions. A strong polar interaction was predicted between Thr-180 (within the phosphorylation lip) of p38 and Gln-273 of nsP2, whereas, no such polar interaction was predicted for the phosphorylation lip of JNK which indicates the differential roles of p-p38 and p-JNK during CHIKV infection in the host macrophages. In summary, for the first time it has been shown that CHIKV triggers robust TNF production in the host macrophages via both p-p38 and p-JNK/p-c-jun pathways and the interaction of viral protein, nsP2 with these MAPKs during infection. Hence, this information might shed light in rationale-based drug designing strategies toward a possible control measure of CHIKV infection in future.
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Affiliation(s)
- Tapas Kumar Nayak
- School of Biological Sciences, National Institute of Science Education and Research, HBNI, Bhubaneswar, India
| | - Prabhudutta Mamidi
- Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
| | - Subhransu Sekhar Sahoo
- School of Biological Sciences, National Institute of Science Education and Research, HBNI, Bhubaneswar, India
| | - P Sanjai Kumar
- School of Biological Sciences, National Institute of Science Education and Research, HBNI, Bhubaneswar, India
| | - Chandan Mahish
- School of Biological Sciences, National Institute of Science Education and Research, HBNI, Bhubaneswar, India
| | | | - Bharat Bhusan Subudhi
- School of Pharmaceutical Sciences, Siksha O Anusandhan University, Bhubaneswar, India
| | - Soma Chattopadhyay
- Infectious Disease Biology, Institute of Life Sciences, Bhubaneswar, India
| | - Subhasis Chattopadhyay
- School of Biological Sciences, National Institute of Science Education and Research, HBNI, Bhubaneswar, India
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5
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Morazzani EM, Compton JR, Leary DH, Berry AV, Hu X, Marugan JJ, Glass PJ, Legler PM. Proteolytic cleavage of host proteins by the Group IV viral proteases of Venezuelan equine encephalitis virus and Zika virus. Antiviral Res 2019; 164:106-122. [PMID: 30742841 DOI: 10.1016/j.antiviral.2019.02.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Revised: 01/13/2019] [Accepted: 02/01/2019] [Indexed: 12/12/2022]
Abstract
The alphaviral nonstructural protein 2 (nsP2) cysteine proteases (EC 3.4.22.-) are essential for the proteolytic processing of the nonstructural (ns) polyprotein and are validated drug targets. A common secondary role of these proteases is to antagonize the effects of interferon (IFN). After delineating the cleavage site motif of the Venezuelan equine encephalitis virus (VEEV) nsP2 cysteine protease, we searched the human genome to identify host protein substrates. Here we identify a new host substrate of the VEEV nsP2 protease, human TRIM14, a component of the mitochondrial antiviral-signaling protein (MAVS) signalosome. Short stretches of homologous host-pathogen protein sequences (SSHHPS) are present in the nonstructural polyprotein and TRIM14. A 25-residue cyan-yellow fluorescent protein TRIM14 substrate was cleaved in vitro by the VEEV nsP2 protease and the cleavage site was confirmed by tandem mass spectrometry. A TRIM14 cleavage product also was found in VEEV-infected cell lysates. At least ten other Group IV (+)ssRNA viral proteases have been shown to cleave host proteins involved in generating the innate immune responses against viruses, suggesting that the integration of these short host protein sequences into the viral protease cleavage sites may represent an embedded mechanism of IFN antagonism. This interference mechanism shows several parallels with those of CRISPR/Cas9 and RNAi/RISC, but with a protease recognizing a protein sequence common to both the host and pathogen. The short host sequences embedded within the viral genome appear to be analogous to the short phage sequences found in a host's CRISPR spacer sequences. To test this algorithm, we applied it to another Group IV virus, Zika virus (ZIKV), and identified cleavage sites within human SFRP1 (secreted frizzled related protein 1), a retinal Gs alpha subunit, NT5M, and Forkhead box protein G1 (FOXG1) in vitro. Proteolytic cleavage of these proteins suggests a possible link between the protease and the virus-induced phenotype of ZIKV. The algorithm may have value for selecting cell lines and animal models that recapitulate virus-induced phenotypes, predicting host-range and susceptibility, selecting oncolytic viruses, identifying biomarkers, and de-risking live virus vaccines. Inhibitors of the proteases that utilize this mechanism may both inhibit viral replication and alleviate suppression of the innate immune responses.
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Affiliation(s)
- Elaine M Morazzani
- United States Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702, USA
| | - Jaimee R Compton
- Center for Bio/molecular Science and Engineering, U.S. Naval Research Laboratory, Washington, DC 20375, USA
| | - Dagmar H Leary
- Center for Bio/molecular Science and Engineering, U.S. Naval Research Laboratory, Washington, DC 20375, USA
| | | | - Xin Hu
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, Rockville, MD 20850, USA
| | - Juan J Marugan
- NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, Rockville, MD 20850, USA
| | - Pamela J Glass
- United States Army Medical Research Institute of Infectious Diseases, Frederick, MD 21702, USA
| | - Patricia M Legler
- Center for Bio/molecular Science and Engineering, U.S. Naval Research Laboratory, Washington, DC 20375, USA.
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6
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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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7
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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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8
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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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9
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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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10
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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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Rupp JC, Sokoloski KJ, Gebhart NN, Hardy RW. Alphavirus RNA synthesis and non-structural protein functions. J Gen Virol 2015. [PMID: 26219641 DOI: 10.1099/jgv.0.000249] [Citation(s) in RCA: 162] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The members of the genus Alphavirus are positive-sense RNA viruses, which are predominantly transmitted to vertebrates by a mosquito vector. Alphavirus disease in humans can be severely debilitating, and depending on the particular viral species, infection may result in encephalitis and possibly death. In recent years, alphaviruses have received significant attention from public health authorities as a consequence of the dramatic emergence of chikungunya virus in the Indian Ocean islands and the Caribbean. Currently, no safe, approved or effective vaccine or antiviral intervention exists for human alphavirus infection. The molecular biology of alphavirus RNA synthesis has been well studied in a few species of the genus and represents a general target for antiviral drug development. This review describes what is currently understood about the regulation of alphavirus RNA synthesis, the roles of the viral non-structural proteins in this process and the functions of cis-acting RNA elements in replication, and points to open questions within the field.
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Affiliation(s)
- Jonathan C Rupp
- Department of Biology, Indiana University, 212 South Hawthorne Drive, Bloomington, IN 47405, USA
| | - Kevin J Sokoloski
- Department of Biology, Indiana University, 212 South Hawthorne Drive, Bloomington, IN 47405, USA
| | - Natasha N Gebhart
- Department of Biology, Indiana University, 212 South Hawthorne Drive, Bloomington, IN 47405, USA
| | - Richard W Hardy
- Department of Biology, Indiana University, 212 South Hawthorne Drive, Bloomington, IN 47405, USA
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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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Chung DH, Jonsson CB, Tower NA, Chu YK, Sahin E, Golden JE, Noah JW, Schroeder CE, Sotsky JB, Sosa MI, Cramer DE, McKellip SN, Rasmussen L, White EL, Schmaljohn CS, Julander JG, Smith JM, Filone CM, Connor JH, Sakurai Y, Davey RA. Discovery of a novel compound with anti-venezuelan equine encephalitis virus activity that targets the nonstructural protein 2. PLoS Pathog 2014; 10:e1004213. [PMID: 24967809 PMCID: PMC4072787 DOI: 10.1371/journal.ppat.1004213] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Accepted: 05/13/2014] [Indexed: 12/27/2022] Open
Abstract
Alphaviruses present serious health threats as emerging and re-emerging viruses. Venezuelan equine encephalitis virus (VEEV), a New World alphavirus, can cause encephalitis in humans and horses, but there are no therapeutics for treatment. To date, compounds reported as anti-VEEV or anti-alphavirus inhibitors have shown moderate activity. To discover new classes of anti-VEEV inhibitors with novel viral targets, we used a high-throughput screen based on the measurement of cell protection from live VEEV TC-83-induced cytopathic effect to screen a 340,000 compound library. Of those, we identified five novel anti-VEEV compounds and chose a quinazolinone compound, CID15997213 (IC50 = 0.84 µM), for further characterization. The antiviral effect of CID15997213 was alphavirus-specific, inhibiting VEEV and Western equine encephalitis virus, but not Eastern equine encephalitis virus. In vitro assays confirmed inhibition of viral RNA, protein, and progeny synthesis. No antiviral activity was detected against a select group of RNA viruses. We found mutations conferring the resistance to the compound in the N-terminal domain of nsP2 and confirmed the target residues using a reverse genetic approach. Time of addition studies showed that the compound inhibits the middle stage of replication when viral genome replication is most active. In mice, the compound showed complete protection from lethal VEEV disease at 50 mg/kg/day. Collectively, these results reveal a potent anti-VEEV compound that uniquely targets the viral nsP2 N-terminal domain. While the function of nsP2 has yet to be characterized, our studies suggest that the protein might play a critical role in viral replication, and further, may represent an innovative opportunity to develop therapeutic interventions for alphavirus infection. Alphaviruses occur worldwide, causing significant diseases such as encephalitis or arthritis in humans and animals. In addition, some alphaviruses, such as VEEV, pose a biothreat due to their high infectivity and lack of available treatments. To discover small molecule inhibitors with lead development potential, we used a cell-based assay to screen 348,140 compounds for inhibition of a VEEV-induced cytopathic effect. The screen revealed a scaffold with high inhibitory VEEV cellular potency and low cytotoxicity liability. While most previously reported anti-alphavirus compounds inhibit host proteins, evidence supported that this scaffold targeted the VEEV nsP2 protein, and that inhibition was associated with viral replication. Interestingly, compound resistance studies with VEEV mapped activity to the N-terminal domain of nsP2, to which no known function has been attributed. Ultimately, this discovery has delivered a small molecule-derived class of potent VEEV inhibitors whose activity is coupled to the nsP2 viral protein, a novel target with a previously unestablished biological role that is now implicated in viral replication.
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Affiliation(s)
- Dong-Hoon Chung
- Departments of Microbiology and Immunology, University of Louisville, Louisville, Kentucky, United States of America
- Center for Predictive Medicine for Biodefense and Emerging Infectious Diseases, University of Louisville, Louisville, Kentucky, United States of America
- * E-mail:
| | - Colleen B. Jonsson
- Departments of Microbiology and Immunology, University of Louisville, Louisville, Kentucky, United States of America
- Center for Predictive Medicine for Biodefense and Emerging Infectious Diseases, University of Louisville, Louisville, Kentucky, United States of America
- Department of Pharmacology and Toxicology, University of Louisville, Louisville, Kentucky, United States of America
| | - Nichole A. Tower
- Drug Discovery Department, Southern Research Institute, Birmingham, Alabama, United States of America
| | - Yong-Kyu Chu
- Center for Predictive Medicine for Biodefense and Emerging Infectious Diseases, University of Louisville, Louisville, Kentucky, United States of America
| | - Ergin Sahin
- Departments of Microbiology and Immunology, University of Louisville, Louisville, Kentucky, United States of America
- Center for Predictive Medicine for Biodefense and Emerging Infectious Diseases, University of Louisville, Louisville, Kentucky, United States of America
| | - Jennifer E. Golden
- University of Kansas Specialized Chemistry Center, Lawrence, Kansas, United States of America
| | - James W. Noah
- Drug Discovery Department, Southern Research Institute, Birmingham, Alabama, United States of America
| | - Chad E. Schroeder
- University of Kansas Specialized Chemistry Center, Lawrence, Kansas, United States of America
| | - Julie B. Sotsky
- Center for Predictive Medicine for Biodefense and Emerging Infectious Diseases, University of Louisville, Louisville, Kentucky, United States of America
| | - Melinda I. Sosa
- Drug Discovery Department, Southern Research Institute, Birmingham, Alabama, United States of America
| | - Daniel E. Cramer
- Center for Predictive Medicine for Biodefense and Emerging Infectious Diseases, University of Louisville, Louisville, Kentucky, United States of America
| | - Sara N. McKellip
- Drug Discovery Department, Southern Research Institute, Birmingham, Alabama, United States of America
| | - Lynn Rasmussen
- Drug Discovery Department, Southern Research Institute, Birmingham, Alabama, United States of America
| | - E. Lucile White
- Drug Discovery Department, Southern Research Institute, Birmingham, Alabama, United States of America
| | - Connie S. Schmaljohn
- The United States Army Medical Research Institute for Infectious Diseases, Ft. Detrick, Maryland, United States of America
| | - Justin G. Julander
- Institute for Antiviral Research, Utah State University, Logan, Utah, United States of America
| | - Jeffrey M. Smith
- The United States Army Medical Research Institute for Infectious Diseases, Ft. Detrick, Maryland, United States of America
| | | | - John H. Connor
- Boston University, Boston, Massachusetts, United States of America
| | - Yasuteru Sakurai
- Texas Biomedical Research Institute, San Antonio, Texas, United States of America
| | - Robert A. Davey
- Texas Biomedical Research Institute, San Antonio, Texas, United States of America
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Rana J, Rajasekharan S, Gulati S, Dudha N, Gupta A, Chaudhary VK, Gupta S. Network mapping among the functional domains of Chikungunya virus nonstructural proteins. Proteins 2014; 82:2403-11. [PMID: 24825751 DOI: 10.1002/prot.24602] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 04/27/2014] [Accepted: 04/29/2014] [Indexed: 11/11/2022]
Abstract
Formation of virus specific replicase complex is among the most important steps that determines the fate of viral transcription and replication during Chikungunya virus (CHIKV) infection. In the present study, the authors have computationally generated a 3D structure of CHIKV late replicase complex on the basis of the interactions identified among the domains of CHIKV nonstructural proteins (nsPs) which make up the late replicase complex. The interactions among the domains of CHIKV nsPs were identified using systems such as pull down, protein interaction ELISA, and yeast two-hybrid. The structures of nsPs were generated using I-TASSER and the biological assembly of the replicase complex was determined using ZRANK and RDOCK. A total of 36 interactions among the domains and full length proteins were tested and 12 novel interactions have been identified. These interactions included the homodimerization of nsP1 and nsP4 through their respective C-ter domains; the associations of nsP2 helicase domain and C-ter domain of nsP4 with methyltransferase and membrane binding domains of nsP1; the interaction of nsP2 protease domain with C-ter domain of nsP4; and the interaction of nsP3 macro and alphavirus unique domains with the C-ter domain of nsP1. The novel interactions identified in the current study form a network of organized associations that suggest the spatial arrangement of nsPs in the late replicase complex of CHIKV.
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Affiliation(s)
- Jyoti Rana
- Center for Emerging Diseases, Department of Biotechnology, Jaypee Institute of Information Technology, A-10, Noida, 201307, Uttar Pradesh, India
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Research applications of proteolytic enzymes in molecular biology. Biomolecules 2013; 3:923-42. [PMID: 24970197 PMCID: PMC4030975 DOI: 10.3390/biom3040923] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 11/04/2013] [Accepted: 11/06/2013] [Indexed: 01/04/2023] Open
Abstract
Proteolytic enzymes (also termed peptidases, proteases and proteinases) are capable of hydrolyzing peptide bonds in proteins. They can be found in all living organisms, from viruses to animals and humans. Proteolytic enzymes have great medical and pharmaceutical importance due to their key role in biological processes and in the life-cycle of many pathogens. Proteases are extensively applied enzymes in several sectors of industry and biotechnology, furthermore, numerous research applications require their use, including production of Klenow fragments, peptide synthesis, digestion of unwanted proteins during nucleic acid purification, cell culturing and tissue dissociation, preparation of recombinant antibody fragments for research, diagnostics and therapy, exploration of the structure-function relationships by structural studies, removal of affinity tags from fusion proteins in recombinant protein techniques, peptide sequencing and proteolytic digestion of proteins in proteomics. The aim of this paper is to review the molecular biological aspects of proteolytic enzymes and summarize their applications in the life sciences.
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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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Macromolecular assembly-driven processing of the 2/3 cleavage site in the alphavirus replicase polyprotein. J Virol 2011; 86:553-65. [PMID: 22031949 DOI: 10.1128/jvi.05195-11] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Semliki Forest virus (SFV) is a member of the Alphavirus genus, which produces its replicase proteins in the form of a nonstructural (ns) polyprotein precursor P1234. The maturation of the replicase occurs in a temporally controlled manner by protease activity of nsP2. The template preference and enzymatic capabilities of the alphaviral replication complex have a very important connection with its composition, which is irreversibly altered by proteolysis. The final cleavage of the 2/3 site in the ns polyprotein apparently leads to significant rearrangements within the replication complex and thus denotes the "point of no return" for viral replication progression. Numerous studies have devised rules for when and how ns protease acts, but how the alphaviral 2/3 site is recognized remained largely unexplained. In contrast to the other two cleavage sites within the ns polyprotein, the 2/3 site evidently lacks primary sequence elements in the vicinity of the scissile bond sufficient for specific protease recognition. In this study, we sought to investigate the molecular details of the regulation of the 2/3 site processing in the SFV ns polyprotein. We present evidence that correct macromolecular assembly, presumably strengthened by exosite interactions rather than the functionality of the individual nsP2 protease, is the driving force for specific substrate targeting. We conclude that structural elements within the macrodomain of nsP3 are used for precise positioning of a substrate recognition sequence at the catalytic center of the protease and that this process is coordinated by the exact N-terminal end of nsP2, thus representing a unique regulation mechanism used by alphaviruses.
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Singh KD, Kirubakaran P, Nagarajan S, Sakkiah S, Muthusamy K, Velmurgan D, Jeyakanthan J. Homology modeling, molecular dynamics, e-pharmacophore mapping and docking study of Chikungunya virus nsP2 protease. J Mol Model 2011; 18:39-51. [PMID: 21445710 DOI: 10.1007/s00894-011-1018-3] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 02/09/2011] [Indexed: 11/26/2022]
Abstract
To date, no suitable vaccine or specific antiviral drug is available to treat Chikungunya viral (CHIKV) fever. Hence, it is essential to identify drug candidates that could potentially impede CHIKV infection. Here, we present the development of a homology model of nsP2 protein based on the crystal structure of the nsP2 protein of Venezuelan equine encephalitis virus (VEEV). The protein modeled was optimized using molecular dynamics simulation; the junction peptides of a nonstructural protein complex were then docked in order to investigate the possible protein-protein interactions between nsP2 and the proteins cleaved by nsP2. The modeling studies conducted shed light on the binding modes, and the critical interactions with the peptides provide insight into the chemical features needed to inhibit the CHIK virus infection. Energy-optimized pharmacophore mapping was performed using the junction peptides. Based on the results, we propose the pharmacophore features that must be present in an inhibitor of nsP2 protease. The resulting pharmacophore model contained an aromatic ring, a hydrophobic and three hydrogen-bond donor sites. Using these pharmacophore features, we screened a large public library of compounds (Asinex, Maybridge, TOSLab, Binding Database) to find a potential ligand that could inhibit the nsP2 protein. The compounds that yielded a fitness score of more than 1.0 were further subjected to Glide HTVS and Glide XP. Here, we report the best four compounds based on their docking scores; these compounds have IDs of 27943, 21362, ASN 01107557 and ASN 01541696. We propose that these compounds could bind to the active site of nsP2 protease and inhibit this enzyme. Furthermore, the backbone structural scaffolds of these four lead compounds could serve as building blocks when designing drug-like molecules for the treatment of Chikungunya viral fever.
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Reichert E, Clase A, Bacetty A, Larsen J. Alphavirus antiviral drug development: scientific gap analysis and prospective research areas. Biosecur Bioterror 2010; 7:413-27. [PMID: 20028250 DOI: 10.1089/bsp.2009.0032] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The New World alphaviruses Venezuelan equine encephalitis virus (VEEV), eastern equine encephalitis virus (EEEV), and western equine encephalitis virus (WEEV) pose a significant threat to human health as the etiological agents of serious viral encephalitis through natural infection as well as through their potential use as a biological weapon. At present, there is no FDA-approved medical treatment for infection with these viruses. The Defense Threat Reduction Agency, Joint Science and Technology Office for Chemical and Biological Defense (DTRA/JSTO), is currently funding research aimed at developing antiviral drugs and vaccines against VEEV, EEEV, and WEEV. A review of antiviral drug discovery efforts for these viruses revealed significant gaps in the data, assays, and models required for successful drug development. This review provides a description of these gaps and highlights specific critical research areas for the development of a target-based drug discovery program for the VEEV, EEEV, and WEEV nonstructural proteins. These efforts will increase the probability of the successful development of a pharmaceutical intervention against these viral threat agents.
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Affiliation(s)
- Erin Reichert
- Biological Therapeutics, Defense Threat Reduction Agency, Fort Belvoir, Virginia 22060-6201, USA
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Gould EA, Coutard B, Malet H, Morin B, Jamal S, Weaver S, Gorbalenya A, Moureau G, Baronti C, Delogu I, Forrester N, Khasnatinov M, Gritsun T, de Lamballerie X, Canard B. Understanding the alphaviruses: recent research on important emerging pathogens and progress towards their control. Antiviral Res 2009; 87:111-24. [PMID: 19616028 PMCID: PMC7114216 DOI: 10.1016/j.antiviral.2009.07.007] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2009] [Revised: 07/07/2009] [Accepted: 07/11/2009] [Indexed: 11/28/2022]
Abstract
The alphaviruses were amongst the first arboviruses to be isolated, characterized and assigned a taxonomic status. They are globally very widespread, infecting a large variety of terrestrial animals, insects and even fish, and circulate both in the sylvatic and urban/peri-urban environment, causing considerable human morbidity and mortality. Nevertheless, despite their obvious importance as pathogens, there are currently no effective antiviral drugs with which to treat humans or animals infected by any of these viruses. The EU-supported project-VIZIER (Comparative Structural Genomics of Viral Enzymes Involved in Replication, FP6 PROJECT: 2004-511960) was instigated with an ultimate view of contributing to the development of antiviral therapies for RNA viruses, including the alphaviruses [Coutard, B., Gorbalenya, A.E., Snijder, E.J., Leontovich, A.M., Poupon, A., De Lamballerie, X., Charrel, R., Gould, E.A., Gunther, S., Norder, H., Klempa, B., Bourhy, H., Rohayemj, J., L'hermite, E., Nordlund, P., Stuart, D.I., Owens, R.J., Grimes, J.M., Tuckerm, P.A., Bolognesi, M., Mattevi, A., Coll, M., Jones, T.A., Aqvist, J., Unger, T., Hilgenfeld, R., Bricogne, G., Neyts, J., La Colla, P., Puerstinger, G., Gonzalez, J.P., Leroy, E., Cambillau, C., Romette, J.L., Canard, B., 2008. The VIZIER project: preparedness against pathogenic RNA viruses. Antiviral Res. 78, 37-46]. This review highlights some of the major features of alphaviruses that have been investigated during recent years. After describing their classification, epidemiology and evolutionary history and the expanding geographic distribution of Chikungunya virus, we review progress in understanding the structure and function of alphavirus replicative enzymes achieved under the VIZIER programme and the development of new disease control strategies.
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Affiliation(s)
- E A Gould
- Institut de Recherche pour le Développement UMR190/Unité des Virus Emergents, Université de la Méditerranée, Marseille, France.
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