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Wydorski PM, Osipiuk J, Lanham BT, Tesar C, Endres M, Engle E, Jedrzejczak R, Mullapudi V, Michalska K, Fidelis K, Fushman D, Joachimiak A, Joachimiak LA. Dual domain recognition determines SARS-CoV-2 PLpro selectivity for human ISG15 and K48-linked di-ubiquitin. Nat Commun 2023; 14:2366. [PMID: 37185902 PMCID: PMC10126577 DOI: 10.1038/s41467-023-38031-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 04/11/2023] [Indexed: 05/17/2023] Open
Abstract
The Papain-like protease (PLpro) is a domain of a multi-functional, non-structural protein 3 of coronaviruses. PLpro cleaves viral polyproteins and posttranslational conjugates with poly-ubiquitin and protective ISG15, composed of two ubiquitin-like (UBL) domains. Across coronaviruses, PLpro showed divergent selectivity for recognition and cleavage of posttranslational conjugates despite sequence conservation. We show that SARS-CoV-2 PLpro binds human ISG15 and K48-linked di-ubiquitin (K48-Ub2) with nanomolar affinity and detect alternate weaker-binding modes. Crystal structures of untethered PLpro complexes with ISG15 and K48-Ub2 combined with solution NMR and cross-linking mass spectrometry revealed how the two domains of ISG15 or K48-Ub2 are differently utilized in interactions with PLpro. Analysis of protein interface energetics predicted differential binding stabilities of the two UBL/Ub domains that were validated experimentally. We emphasize how substrate recognition can be tuned to cleave specifically ISG15 or K48-Ub2 modifications while retaining capacity to cleave mono-Ub conjugates. These results highlight alternative druggable surfaces that would inhibit PLpro function.
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Affiliation(s)
- Pawel M Wydorski
- Molecular Biophysics Graduate Program, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Center for Alzheimer's and Neurodegenerative Diseases, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Jerzy Osipiuk
- Center for Structural Biology of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, IL, 60667, USA
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Benjamin T Lanham
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, MD, 20742, USA
| | - Christine Tesar
- Center for Structural Biology of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, IL, 60667, USA
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Michael Endres
- Center for Structural Biology of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, IL, 60667, USA
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Elizabeth Engle
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, MD, 20742, USA
| | - Robert Jedrzejczak
- Center for Structural Biology of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, IL, 60667, USA
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Vishruth Mullapudi
- Center for Alzheimer's and Neurodegenerative Diseases, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Karolina Michalska
- Center for Structural Biology of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, IL, 60667, USA
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA
| | - Krzysztof Fidelis
- Protein Structure Prediction Center, Genome and Biomedical Sciences Facilities, University of California, Davis, CA, 95616, USA
| | - David Fushman
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, MD, 20742, USA.
| | - Andrzej Joachimiak
- Center for Structural Biology of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, IL, 60667, USA.
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, IL, 60439, USA.
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60367, USA.
| | - Lukasz A Joachimiak
- Center for Alzheimer's and Neurodegenerative Diseases, Peter O'Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
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2
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Wydorski PM, Osipiuk J, Lanham BT, Tesar C, Endres M, Engle E, Jedrzejczak R, Mullapudi V, Michalska K, Fidelis K, Fushman D, Joachimiak A, Joachimiak LA. Dual domain recognition determines SARS-CoV-2 PLpro selectivity for human ISG15 and K48-linked di-ubiquitin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2021.09.15.460543. [PMID: 35547846 PMCID: PMC9094096 DOI: 10.1101/2021.09.15.460543] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The Papain-like protease (PLpro) is a domain of a multi-functional, non-structural protein 3 of coronaviruses. PLpro cleaves viral polyproteins and posttranslational conjugates with poly-ubiquitin and protective ISG15, composed of two ubiquitin-like (UBL) domains. Across coronaviruses, PLpro showed divergent selectivity for recognition and cleavage of posttranslational conjugates despite sequence conservation. We show that SARS-CoV-2 PLpro binds human ISG15 and K48-linked di-ubiquitin (K48-Ub 2 ) with nanomolar affinity and detect alternate weaker-binding modes. Crystal structures of untethered PLpro complexes with ISG15 and K48-Ub 2 combined with solution NMR and cross-linking mass spectrometry revealed how the two domains of ISG15 or K48-Ub 2 are differently utilized in interactions with PLpro. Analysis of protein interface energetics predicted differential binding stabilities of the two UBL/Ub domains that were validated experimentally. We emphasize how substrate recognition can be tuned to cleave specifically ISG15 or K48-Ub 2 modifications while retaining capacity to cleave mono-Ub conjugates. These results highlight alternative druggable surfaces that would inhibit PLpro function.
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Affiliation(s)
- Pawel M. Wydorski
- Molecular Biophysics Graduate Program, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
- Center for Alzheimer’s and Neurodegenerative Diseases, Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Jerzy Osipiuk
- Center for Structural Biology of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, IL, 60667 USA
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, IL, 60439 USA
| | - Benjamin T. Lanham
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, MD 20742 USA
| | - Christine Tesar
- Center for Structural Biology of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, IL, 60667 USA
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, IL, 60439 USA
| | - Michael Endres
- Center for Structural Biology of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, IL, 60667 USA
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, IL, 60439 USA
| | - Elizabeth Engle
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, MD 20742 USA
| | - Robert Jedrzejczak
- Center for Structural Biology of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, IL, 60667 USA
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, IL, 60439 USA
| | - Vishruth Mullapudi
- Center for Alzheimer’s and Neurodegenerative Diseases, Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Karolina Michalska
- Center for Structural Biology of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, IL, 60667 USA
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, IL, 60439 USA
| | - Krzysztof Fidelis
- Protein Structure Prediction Center, Genome and Biomedical Sciences Facilities, University of California, Davis, CA, 95616 USA
| | - David Fushman
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Organization, University of Maryland, College Park, MD 20742 USA
| | - Andrzej Joachimiak
- Center for Structural Biology of Infectious Diseases, Consortium for Advanced Science and Engineering, University of Chicago, Chicago, IL, 60667 USA
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, IL, 60439 USA
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60367 USA
| | - Lukasz A. Joachimiak
- Center for Alzheimer’s and Neurodegenerative Diseases, Peter O’Donnell Jr. Brain Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
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3
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Zang Y, Su M, Wang Q, Cheng X, Zhang W, Zhao Y, Chen T, Jiang Y, Shen Q, Du J, Tan Q, Wang P, Gao L, Jin Z, Zhang M, Li C, Zhu Y, Feng B, Tang B, Xie H, Wang MW, Zheng M, Pan X, Yang H, Xu Y, Wu B, Zhang L, Rao Z, Yang X, Jiang H, Xiao G, Zhao Q, Li J. High-throughput screening of SARS-CoV-2 main and papain-like protease inhibitors. Protein Cell 2022; 14:17-27. [PMID: 36726755 PMCID: PMC9871955 DOI: 10.1093/procel/pwac016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 04/07/2022] [Indexed: 02/04/2023] Open
Abstract
The global COVID-19 coronavirus pandemic has infected over 109 million people, leading to over 2 million deaths up to date and still lacking of effective drugs for patient treatment. Here, we screened about 1.8 million small molecules against the main protease (Mpro) and papain like protease (PLpro), two major proteases in severe acute respiratory syndrome-coronavirus 2 genome, and identified 1851Mpro inhibitors and 205 PLpro inhibitors with low nmol/l activity of the best hits. Among these inhibitors, eight small molecules showed dual inhibition effects on both Mpro and PLpro, exhibiting potential as better candidates for COVID-19 treatment. The best inhibitors of each protease were tested in antiviral assay, with over 40% of Mpro inhibitors and over 20% of PLpro inhibitors showing high potency in viral inhibition with low cytotoxicity. The X-ray crystal structure of SARS-CoV-2 Mpro in complex with its potent inhibitor 4a was determined at 1.8 Å resolution. Together with docking assays, our results provide a comprehensive resource for future research on anti-SARS-CoV-2 drug development.
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Affiliation(s)
| | | | | | | | | | | | - Tong Chen
- State Key Laboratory of Drug Research and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yingyan Jiang
- The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Qiang Shen
- The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Juan Du
- School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China
| | - Qiuxiang Tan
- State Key Laboratory of Drug Research and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Peipei Wang
- The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China,State Key Laboratory of Drug Research and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Lixin Gao
- The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China,State Key Laboratory of Drug Research and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Zhenming Jin
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Mengmeng Zhang
- The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China,State Key Laboratory of Drug Research and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Cong Li
- The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China,State Key Laboratory of Drug Research and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Ya Zhu
- State Key Laboratory of Drug Research and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Bo Feng
- The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China,State Key Laboratory of Drug Research and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Bixi Tang
- The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China,State Key Laboratory of Drug Research and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Han Xie
- State Key Laboratory of Drug Research and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Ming-Wei Wang
- The National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China,State Key Laboratory of Drug Research and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Mingyue Zheng
- State Key Laboratory of Drug Research and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China,School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoyan Pan
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430071, China
| | - Haitao Yang
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yechun Xu
- State Key Laboratory of Drug Research and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China,School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Beili Wu
- State Key Laboratory of Drug Research and CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China,School of Pharmaceutical Science and Technology, Hangzhou Institute for Advanced Study, UCAS, Hangzhou 310024, China,University of Chinese Academy of Sciences, Beijing 100049, China,CAS Center for Excellence in Biomacromolecules, Chinese Academy of Sciences, Beijing 100101, China
| | - Leike Zhang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan 430071, China
| | - Zihe Rao
- Shanghai Institute for Advanced Immunochemical Studies and School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
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Mirza MU, Ahmad S, Abdullah I, Froeyen M. Identification of novel human USP2 inhibitor and its putative role in treatment of COVID-19 by inhibiting SARS-CoV-2 papain-like (PLpro) protease. Comput Biol Chem 2020; 89:107376. [PMID: 32979815 PMCID: PMC7487165 DOI: 10.1016/j.compbiolchem.2020.107376] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 09/07/2020] [Accepted: 09/10/2020] [Indexed: 02/07/2023]
Abstract
Human ubiquitin carboxyl-terminal hydrolase-2 (USP2) inhibitors, such as thiopurine analogs, have been reported to inhibit SARS-CoV papain-like proteases (PLpro). The PLpro have significant functional implications in the innate immune response during SARS-CoV-2 infection and considered an important antiviral target. Both proteases share strikingly similar USP fold with right-handed thumb-palm-fingers structural scaffold and conserved catalytic triad Cys-His-Asp/Asn. In this urgency situation of COVID-19 outbreak, there is a lack of in-vitro facilities readily available to test SARS-CoV-2 inhibitors in whole-cell assays. Therefore, we adopted an alternate route to identify potential USP2 inhibitor through integrated in-silico efforts. After an extensive virtual screening protocol, the best compounds were selected and tested. The compound Z93 showed significant IC50 value against Jurkat (9.67 μM) and MOTL-4 cells (11.8 μM). The binding mode of Z93 was extensively analyzed through molecular docking, followed by MD simulations, and molecular interactions were compared with SARS-CoV-2. The relative binding poses of Z93 fitted well in the binding site of both proteases and showed consensus π-π stacking and H-bond interactions with histidine and aspartate/asparagine residues of the catalytic triad. These results led us to speculate that compound Z93 might be the first potential chemical lead against SARS-CoV-2 PLpro, which warrants in-vitro evaluations.
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Affiliation(s)
- Muhammad Usman Mirza
- Department of Pharmaceutical and Pharmacological Sciences, Rega Institute for Medical Research, Medicinal Chemistry, University of Leuven, B-3000, Leuven, Belgium
| | - Sarfraz Ahmad
- Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur, 50603, Malaysia
| | - Iskandar Abdullah
- Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur, 50603, Malaysia
| | - Matheus Froeyen
- Department of Pharmaceutical and Pharmacological Sciences, Rega Institute for Medical Research, Medicinal Chemistry, University of Leuven, B-3000, Leuven, Belgium.
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5
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Steinberger J, Skern T. The leader proteinase of foot-and-mouth disease virus: structure-function relationships in a proteolytic virulence factor. Biol Chem 2015; 395:1179-85. [PMID: 24670358 DOI: 10.1515/hsz-2014-0156] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 03/24/2014] [Indexed: 12/15/2022]
Abstract
The leader proteinase (Lpro) of the foot-and-mouth disease virus inhibits the host innate immune response by at least three different mechanisms. The most well-characterised of these is the prevention of the synthesis of cytokines such as interferons immediately after infection, brought about by specific proteolytic cleavage of the eukaryotic initiation factor 4G. This prevents the recruitment of capped cellular mRNA; however, the viral RNA can be translated under these conditions. The two other mechanisms are the induction of NF-κB cleavage and the deubiquitination of immune signalling molecules. This review focuses on the structure-function relationships in Lpro responsible for these widely divergent activities.
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6
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Dissection of amino-terminal functional domains of murine coronavirus nonstructural protein 3. J Virol 2015; 89:6033-47. [PMID: 25810552 DOI: 10.1128/jvi.00197-15] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 03/19/2015] [Indexed: 01/08/2023] Open
Abstract
UNLABELLED Coronaviruses, the largest RNA viruses, have a complex program of RNA synthesis that entails genome replication and transcription of subgenomic mRNAs. RNA synthesis by the prototype coronavirus mouse hepatitis virus (MHV) is carried out by a replicase-transcriptase composed of 16 nonstructural protein (nsp) subunits. Among these, nsp3 is the largest and the first to be inserted into the endoplasmic reticulum. nsp3 comprises multiple structural domains, including two papain-like proteases (PLPs) and a highly conserved ADP-ribose-1″-phosphatase (ADRP) macrodomain. We have previously shown that the ubiquitin-like domain at the amino terminus of nsp3 is essential and participates in a critical interaction with the viral nucleocapsid protein early in infection. In the current study, we exploited atypical expression schemes to uncouple PLP1 from the processing of nsp1 and nsp2 in order to investigate the requirements of nsp3 domains for viral RNA synthesis. In the first strategy, a mutant was created in which replicase polyprotein translation initiated with nsp3, thereby establishing that complete elimination of nsp1 and nsp2 does not abolish MHV viability. In the second strategy, a picornavirus autoprocessing element was used to separate a truncated nsp1 from nsp3. This provided a platform for further dissection of amino-terminal domains of nsp3. From this, we found that catalytic mutation of PLP1 or complete deletion of PLP1 and the adjacent ADRP domain was tolerated by the virus. These results showed that neither the PLP1 domain nor the ADRP domain of nsp3 provides integral activities essential for coronavirus genomic or subgenomic RNA synthesis. IMPORTANCE The largest component of the coronavirus replicase-transcriptase complex, nsp3, contains multiple modules, many of which do not have clearly defined functions in genome replication or transcription. These domains may play direct roles in RNA synthesis, or they may have evolved for other purposes, such as to combat host innate immunity. We initiated a dissection of MHV nsp3 aimed at identifying those activities or structures in this huge molecule that are essential to replicase activity. We found that both PLP1 and ADRP could be entirely deleted, provided that the requirement for proteolytic processing by PLP1 was offset by an alternative mechanism. This demonstrated that neither PLP1 nor ADRP plays an essential role in coronavirus RNA synthesis.
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7
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Edwards MC, Weiland JJ. Coat protein expression strategy of oat blue dwarf virus. Virology 2014; 450-451:290-6. [PMID: 24503092 PMCID: PMC7173039 DOI: 10.1016/j.virol.2013.12.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 10/19/2013] [Accepted: 12/15/2013] [Indexed: 02/03/2023]
Abstract
Oat blue dwarf virus (OBDV) is a member of the genus Marafivirus whose genome encodes a 227 kDa polyprotein (p227) ostensibly processed post-translationally into its functional components. Encoded near the 3' terminus and coterminal with the p227 ORF are ORFs specifying major and minor capsid proteins (CP). Since the CP expression strategy of marafiviruses has not been thoroughly investigated, we produced a series of point mutants in the OBDV CP encoding gene and examined expression in protoplasts. Results support a model in which the 21 kDa major CP is the product of direct translation of a sgRNA, while the 24 kDa minor CP is a cleavage product derived from both the polyprotein and a larger ~26 kDa precursor translated directly from the sgRNA. Cleavage occurs at an LXG[G/A] motif conserved in many viruses that use papain-like proteases for polyprotein processing and protection against degradation via the ubiquitin-proteasome system.
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Affiliation(s)
- Michael C Edwards
- USDA-Agricultural Research Service, Cereal Crops Research Unit, Northern Crop Science Laboratory, 1605 Albrecht Blvd. N., Fargo, ND 58102-2765, USA.
| | - John J Weiland
- USDA-Agricultural Research Service, Cereal Crops Research Unit, Northern Crop Science Laboratory, 1605 Albrecht Blvd. N., Fargo, ND 58102-2765, USA
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8
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Yang X, Chen X, Bian G, Tu J, Xing Y, Wang Y, Chen Z. Proteolytic processing, deubiquitinase and interferon antagonist activities of Middle East respiratory syndrome coronavirus papain-like protease. J Gen Virol 2013; 95:614-626. [PMID: 24362959 DOI: 10.1099/vir.0.059014-0] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The emerging Middle East respiratory syndrome coronavirus (MERS-CoV) causes severe pulmonary disease in humans and represents the second example of a highly pathogenic coronavirus (CoV) following severe acute respiratory syndrome coronavirus (SARS-CoV). Genomic studies revealed that two viral proteases, papain-like protease (PLpro) and 3C-like protease (3CLpro), process the polyproteins encoded by the MERS-CoV genomic RNA. We previously reported that SARS-CoV PLpro acts as both deubiquitinase (DUB) and IFN antagonist, but the function of the MERS-CoV PLpro was poorly understood. In this study, we characterized MERS-CoV PLpro, which is a protease and can recognize and process the cleavage sites (CS) of nsp1-2, nsp2-3 and nsp3-4. The LXGG consensus cleavage sites in the N terminus of pp1a/1ab, which is generally essential for CoV PLpro-mediated processing, were also characterized in MERS-CoV. MERS-CoV PLpro, like human SARS-CoV PLpro and NL63-CoV PLP2, is a viral deubiquitinating enzyme. It acts on both K48- and K63-linked ubiquitination and ISG15-linked ISGylation. We confirmed that MERS-CoV PLpro acts as an IFN antagonist through blocking the phosphorylation and nuclear translocation of IFN regulatory factor 3 (IRF3). These findings indicate that MERS-CoV PLpro acts as a viral DUB and suppresses production of IFN-β by an interfering IRF3-mediated signalling pathway, in addition to recognizing and processing the CS at the N terminus of replicase polyprotein to release the non-structural proteins. The characterization of proteolytic processing, DUB and IFN antagonist activities of MERS-CoV PLpro would reveal the interactions between MERS-CoV and its host, and be applicable to develop strategies targeting PLpro for the effective control of MERS-CoV infection.
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Affiliation(s)
- Xingxing Yang
- Anhui Medical University, Hefei, Anhui Province 230032, PR China.,Division of Infection and Immunity, Department of Electromagnetic and Laser Biology, Beijing Institute of Radiation Medicine, Beijing 100850, PR China
| | - Xiaojuan Chen
- Division of Infection and Immunity, Department of Electromagnetic and Laser Biology, Beijing Institute of Radiation Medicine, Beijing 100850, PR China
| | - Guangxing Bian
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 100850, PR China
| | - Jian Tu
- Australian School of Advanced Medicine, Macquarie University, Sydney, NSW 2109, Australia
| | - Yaling Xing
- Division of Infection and Immunity, Department of Electromagnetic and Laser Biology, Beijing Institute of Radiation Medicine, Beijing 100850, PR China
| | - Yayun Wang
- Division of Infection and Immunity, Department of Electromagnetic and Laser Biology, Beijing Institute of Radiation Medicine, Beijing 100850, PR China
| | - Zhongbin Chen
- Anhui Medical University, Hefei, Anhui Province 230032, PR China.,Division of Infection and Immunity, Department of Electromagnetic and Laser Biology, Beijing Institute of Radiation Medicine, Beijing 100850, PR China
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9
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Chaudhuri R, Tang S, Zhao G, Lu H, Case DA, Johnson ME. Comparison of SARS and NL63 papain-like protease binding sites and binding site dynamics: inhibitor design implications. J Mol Biol 2011; 414:272-88. [PMID: 22004941 PMCID: PMC3397151 DOI: 10.1016/j.jmb.2011.09.030] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Revised: 09/09/2011] [Accepted: 09/15/2011] [Indexed: 11/24/2022]
Abstract
The human severe acute respiratory syndrome coronavirus (SARS-CoV) and the NL63 coronaviruses are human respiratory pathogens for which no effective antiviral treatment exists. The papain-like cysteine proteases encoded by the coronavirus (SARS-CoV: PLpro; NL63: PLP1 and PLP2) represent potential targets for antiviral drug development. Three recent inhibitor-bound PLpro structures highlight the role of an extremely flexible six-residue loop in inhibitor binding. The high binding site plasticity is a major challenge in computational drug discovery/design efforts. From conventional molecular dynamics and accelerated molecular dynamics (aMD) simulations, we find that with conventional molecular dynamics simulation, PLpro translationally samples the open and closed conformation of BL2 loop on a picosecond–nanosecond timescale but does not reproduce the peptide bond inversion between loop residues Tyr269 and Gln270 that is observed on inhibitor GRL0617 binding. Only aMD simulation, starting from the closed loop conformation, reproduced the 180° ϕ–ψ dihedral rotation back to the open loop state. The Tyr–Gln peptide bond inversion appears to involve a progressive conformational change of the full loop, starting at one side, and progressing to the other. We used the SARS-CoV apo X-ray structure to develop a model of the NL63-PLP2 catalytic site. Superimposition of the PLP2 model on the PLpro X-ray structure identifies binding site residues in PLP2 that contribute to the distinct substrate cleavage site specificities between the two proteases. The topological and electrostatic differences between the two protease binding sites also help explain the selectivity of non-covalent PLpro inhibitors.
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Affiliation(s)
- Rima Chaudhuri
- Center for Pharmaceutical Biotechnology, University of Illinois at Chicago, Chicago, IL 60607, USA
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Papain-like protease 1 from transmissible gastroenteritis virus: crystal structure and enzymatic activity toward viral and cellular substrates. J Virol 2010; 84:10063-73. [PMID: 20668092 DOI: 10.1128/jvi.00898-10] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Coronaviruses encode two classes of cysteine proteases, which have narrow substrate specificities and either a chymotrypsin- or papain-like fold. These enzymes mediate the processing of the two precursor polyproteins of the viral replicase and are also thought to modulate host cell functions to facilitate infection. The papain-like protease 1 (PL1(pro)) domain is present in nonstructural protein 3 (nsp3) of alphacoronaviruses and subgroup 2a betacoronaviruses. It participates in the proteolytic processing of the N-terminal region of the replicase polyproteins in a manner that varies among different coronaviruses and remains poorly understood. Here we report the first structural and biochemical characterization of a purified coronavirus PL1(pro) domain, that of transmissible gastroenteritis virus (TGEV). Its tertiary structure is compared with that of severe acute respiratory syndrome (SARS) coronavirus PL2(pro), a downstream paralog that is conserved in the nsp3's of all coronaviruses. We identify both conserved and unique structural features likely controlling the interaction of PL1(pro) with cofactors and substrates, including the tentative mapping of substrate pocket residues. The purified recombinant TGEV PL1(pro) was shown to cleave a peptide mimicking the cognate nsp2|nsp3 cleavage site. Like its PL2(pro) paralogs from several coronaviruses, TGEV PL1(pro) was also found to have deubiquitinating activity in an in vitro cleavage assay, implicating it in counteracting ubiquitin-regulated host cell pathways, likely including innate immune responses. In combination with the prior characterization of PL2(pro) from other alphacoronaviruses, e.g., human coronaviruses 229E and NL63, our results unequivocally establish that these viruses employ two PL(pro)s with overlapping specificities toward both viral and cellular substrates.
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Exchange of the coronavirus replicase polyprotein cleavage sites alters protease specificity and processing. J Virol 2010; 84:6894-8. [PMID: 20427532 DOI: 10.1128/jvi.00752-10] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Coronavirus nonstructural proteins 1 to 3 are processed by one or two papain-like proteases (PLP1 and PLP2) at specific cleavage sites (CS1 to -3). Murine hepatitis virus (MHV) PLP2 and orthologs recognize and cleave at a position following a p4-Leu-X-Gly-Gly-p1 tetrapeptide, but it is unknown whether these residues are sufficient to result in processing by PLP2 at sites normally cleaved by PLP1. We demonstrate that exchange of CS1 and/or CS2 with the CS3 p4-p1 amino acids in engineered MHV mutants switches specificity from PLP1 to PLP2 at CS2, but not at CS1, and results in altered protein processing and virus replication. Thus, the p4-p1 residues are necessary for PLP2 processing but require a specific protein or cleavage site context for optimal PLP recognition and cleavage.
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12
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A noncovalent class of papain-like protease/deubiquitinase inhibitors blocks SARS virus replication. Proc Natl Acad Sci U S A 2008; 105:16119-24. [PMID: 18852458 DOI: 10.1073/pnas.0805240105] [Citation(s) in RCA: 351] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We report the discovery and optimization of a potent inhibitor against the papain-like protease (PLpro) from the coronavirus that causes severe acute respiratory syndrome (SARS-CoV). This unique protease is not only responsible for processing the viral polyprotein into its functional units but is also capable of cleaving ubiquitin and ISG15 conjugates and plays a significant role in helping SARS-CoV evade the human immune system. We screened a structurally diverse library of 50,080 compounds for inhibitors of PLpro and discovered a noncovalent lead inhibitor with an IC(50) value of 20 microM, which was improved to 600 nM via synthetic optimization. The resulting compound, GRL0617, inhibited SARS-CoV viral replication in Vero E6 cells with an EC(50) of 15 microM and had no associated cytotoxicity. The X-ray structure of PLpro in complex with GRL0617 indicates that the compound has a unique mode of inhibition whereby it binds within the S4-S3 subsites of the enzyme and induces a loop closure that shuts down catalysis at the active site. These findings provide proof-of-principle that PLpro is a viable target for development of antivirals directed against SARS-CoV, and that potent noncovalent cysteine protease inhibitors can be developed with specificity directed toward pathogenic deubiquitinating enzymes without inhibiting host DUBs.
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Ubiquitin and ubiquitin-like specific proteases targeted by infectious pathogens: Emerging patterns and molecular principles. Biochim Biophys Acta Mol Basis Dis 2008; 1782:809-16. [PMID: 18817868 PMCID: PMC7126189 DOI: 10.1016/j.bbadis.2008.08.010] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2008] [Revised: 08/26/2008] [Accepted: 08/27/2008] [Indexed: 01/08/2023]
Abstract
Attachment of ubiquitin (Ub) or ubiquitin-like (Ubl) modifiers is a reversible post-translational modification that regulates the fate and function of proteins. In particular, proteolytic enzymes with Ub/Ubl processing activity appear to be more widespread than originally anticipated. It is therefore not surprising that bacterial and viral pathogens have exploited many ways to interfere with Ub/Ubl conjugation, but also de-conjugation. On one hand, pathogens were shown to manipulate host encoded enzymes. On the other hand, pathogen derived sequences of proteases specific for Ub/Ubls are emerging as a common feature shared by many viruses, bacteria and protozoa, and we are at an early stage of understanding how these proteases contribute to the pathogenesis of infection. Whereas some of these proteases share a common origin with mammalian cell encoded hydrolases with specific properties towards Ub/Ubls, most of them have ancient intrinsic functions, such as processing pathogen protein components, and may have acquired the specificity for Ub/Ubls by interacting with mammalian hosts and their immune system throughout evolution. Since many of these proteases are clearly distinct from their mammalian counterparts, they represent attractive targets for drug design against infectious diseases.
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Abstract
Ubiquitin‐specific proteases (USPs) emerge as key regulators of numerous cellular processes and account for the bulk of human deubiquitinating enzymes (DUBs). Their modular structure, mostly annotated by sequence homology, is believed to determine substrate recognition and subcellular localization. Currently, a large proportion of known human USP sequences are not annotated either structurally or functionally, including regions both within and flanking their catalytic cores. To extend the current understanding of human USPs, we applied consensus fold recognition to the unannotated content of the human USP family. The most interesting discovery was the marked presence of reliably predicted ubiquitin‐like (UBL) domains in this family of enzymes. The UBL domain thus appears to be the most frequently occurring domain in the human USP family, after the characteristic catalytic domain. The presence of multiple UBL domains per USP protein, as well as of UBL domains embedded in the USP catalytic core, add to the structural complexity currently recognized for many DUBs. Possible functional roles of the newly uncovered UBL domains of human USPs, including proteasome binding, and substrate and protein target specificities, are discussed. Proteins 2007. © 2007 Wiley‐Liss, Inc.
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Affiliation(s)
- Xiao Zhu
- Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec H4P 2R2, Canada
- Department of Biochemistry, Université de Montréal, Montreal, Quebec H3C 3J7, Canada
| | - Robert Ménard
- Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec H4P 2R2, Canada
- Department of Biochemistry, Université de Montréal, Montreal, Quebec H3C 3J7, Canada
| | - Traian Sulea
- Biotechnology Research Institute, National Research Council of Canada, Montreal, Quebec H4P 2R2, Canada
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Lindner HA, Lytvyn V, Qi H, Lachance P, Ziomek E, Ménard R. Selectivity in ISG15 and ubiquitin recognition by the SARS coronavirus papain-like protease. Arch Biochem Biophys 2007; 466:8-14. [PMID: 17692280 PMCID: PMC7094341 DOI: 10.1016/j.abb.2007.07.006] [Citation(s) in RCA: 120] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Revised: 07/05/2007] [Accepted: 07/06/2007] [Indexed: 11/25/2022]
Abstract
The severe acute respiratory syndrome coronavirus papain-like protease (SARS-CoV PLpro) carries out N-terminal processing of the viral replicase polyprotein, and also exhibits Lys48-linked polyubiquitin chain debranching and ISG15 precursor processing activities in vitro. Here, we used SDS-PAGE and fluorescence-based assays to demonstrate that ISG15 derivatives are the preferred substrates for the deubiquitinating activity of the PLpro. With k(cat)/K(M) of 602,000 M(-1)s(-1), PLpro hydrolyzes ISG15-AMC 30- and 60-fold more efficiently than Ub-AMC and Nedd8-AMC, respectively. Data obtained with truncated ISG15 and hybrid Ub/ISG15 substrates indicate that both the N- and C-terminal Ub-like domains of ISG15 contribute to this preference. The enzyme also displays a preference for debranching Lys48- over Lys63-linked polyubiquitin chains. Our results demonstrate that SARS-CoV PLpro can differentiate between ubiquitin-like modifiers sharing a common C-terminal sequence, and that the debranching activity of the PLpro is linkage type selective. The potential structural basis for the demonstrated specificity of SARS-CoV PLpro is discussed.
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Affiliation(s)
- Holger A Lindner
- Biotechnology Research Institute, National Research Council of Canada, 6100 Royalmount Avenue, Montreal, Que., Canada H4P 2R2
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16
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Chen Z, Wang Y, Ratia K, Mesecar AD, Wilkinson KD, Baker SC. Proteolytic processing and deubiquitinating activity of papain-like proteases of human coronavirus NL63. J Virol 2007; 81:6007-18. [PMID: 17392370 PMCID: PMC1900296 DOI: 10.1128/jvi.02747-06] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human coronavirus NL63 (HCoV-NL63), a common human respiratory pathogen, is associated with both upper and lower respiratory tract disease in children and adults. Currently, no antiviral drugs are available to treat CoV infections; thus, potential drug targets need to be identified and characterized. Here, we identify HCoV-NL63 replicase gene products and characterize two viral papain-like proteases (PLPs), PLP1 and PLP2, which process the viral replicase polyprotein. We generated polyclonal antisera directed against two of the predicted replicase nonstructural proteins (nsp3 and nsp4) and detected replicase proteins from HCoV-NL63-infected LLC-MK2 cells by immunofluorescence, immunoprecipitation, and Western blot assays. We found that HCoV-NL63 replicase products can be detected at 24 h postinfection and that these proteins accumulate in perinuclear sites, consistent with membrane-associated replication complexes. To determine which viral proteases are responsible for processing these products, we generated constructs representing the amino-terminal end of the HCoV-NL63 replicase gene and established protease cis-cleavage assays. We found that PLP1 processes cleavage site 1 to release nsp1, whereas PLP2 is responsible for processing both cleavage sites 2 and 3 to release nsp2 and nsp3. We expressed and purified PLP2 and used a peptide-based assay to identify the cleavage sites recognized by this enzyme. Furthermore, by using K48-linked hexa-ubiquitin substrate and ubiquitin-vinylsulfone inhibitor specific for deubiquitinating enzymes (DUBs), we confirmed that, like severe acute respiratory syndrome (SARS) CoV PLpro, HCoV-NL63 PLP2 has DUB activity. The identification of the replicase products and characterization of HCoV-NL63 PLP DUB activity will facilitate comparative studies of CoV proteases and aid in the development of novel antiviral reagents directed against human pathogens such as HCoV-NL63 and SARS-CoV.
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Affiliation(s)
- Zhongbin Chen
- Department of Microbiology and Immunology, Loyola University Medical Center, 2160 South First Avenue, Bldg. 105, Rm. 3929, Maywood, IL 60153, USA
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Ziebuhr J, Schelle B, Karl N, Minskaia E, Bayer S, Siddell SG, Gorbalenya AE, Thiel V. Human coronavirus 229E papain-like proteases have overlapping specificities but distinct functions in viral replication. J Virol 2007; 81:3922-32. [PMID: 17251282 PMCID: PMC1866161 DOI: 10.1128/jvi.02091-06] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Expression of the exceptionally large RNA genomes of CoVs involves multiple regulatory mechanisms, including extensive proteolytic processing of the large replicase polyproteins, pp1a and pp1ab, by two types of cysteine proteases: the chymotrypsin-like main protease and papain-like accessory proteases (PLpros). Here, we characterized the proteolytic processing of the human coronavirus 229E (HCoV-229E) amino-proximal pp1a/pp1ab region by two paralogous PLpro activities. Reverse-genetics data revealed that replacement of the PL2pro active-site cysteine was lethal. By contrast, the PL1pro activity proved to be dispensable for HCoV-229E virus replication, although reversion of the PL1pro active-site substitution to the wild-type sequence after several passages in cell culture indicated that there was selection pressure to restore the PL1pro activity. Further experiments showed that both PL1pro and PL2pro were able to cleave the nsp1-nsp2 cleavage site, with PL2pro cleaving the site less efficiently. The PL1pro-negative mutant genotype could be stably maintained in cell culture when the nsp1-nsp2 site was replaced by a short autoproteolytic sequence, suggesting that the major driving force for the observed reversion of the PL1pro mutation was the requirement for efficient nsp1-nsp2 cleavage. The data suggest that the two HCoV-229E PLpro paralogs have overlapping substrate specificities but different functions in viral replication. Within the tightly controlled interplay of the two protease activities, PL2pro plays a universal and essential proteolytic role that appears to be assisted by the PL1pro paralog at specific sites. Functional and evolutionary implications of the differential amino-terminal polyprotein-processing pathways among the main CoV lineages are discussed.
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Affiliation(s)
- John Ziebuhr
- Centre for Cancer Research and Cell Biology, School of Biomedical Sciences, The Queen's University of Belfast, UK, and Kantonal Hospital St. Gallen, Research Department, 9007 St. Gallen, Switzerland
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Sulea T, Lindner HA, Ménard R. Structural aspects of recently discovered viral deubiquitinating activities. Biol Chem 2006; 387:853-62. [PMID: 16913834 DOI: 10.1515/bc.2006.108] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Protein ubiquitination has been identified as a regulatory mechanism in key cellular activities, and deubiquitination is recognized as an important step in processes governed by ubiquitin and ubiquitin-like modifiers. Viruses are known to target ubiquitin and ubiquitin-like modifier pathways using various strategies, including the recruitment of host deubiquitinating enzymes. Deubiquitinating activities have recently been described for proteins from three different virus families (adenovirus, coronavirus and herpesvirus), and predicted for others. This review centers on structural-functional aspects that characterize the confirmed viral deubiquitinating enzymes, and their relationships to established families of cellular deubiquitinating enzymes.
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Affiliation(s)
- Traian Sulea
- Biotechnology Research Institute, National Research Council of Canada, Montréal, Québec H4P 2R2, Canada.
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Graham RL, Denison MR. Replication of murine hepatitis virus is regulated by papain-like proteinase 1 processing of nonstructural proteins 1, 2, and 3. J Virol 2006; 80:11610-20. [PMID: 16971428 PMCID: PMC1642617 DOI: 10.1128/jvi.01428-06] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Coronaviruses are positive-strand RNA viruses that translate their genome RNA into polyproteins that are co- and posttranslationally processed into intermediate and mature replicase nonstructural proteins (nsps). In murine hepatitis virus (MHV), nsps 1, 2, and 3 are processed by two papain-like proteinase activities within nsp3 (PLP1 and PLP2) to yield nsp1, an nsp2-3 intermediate, and mature nsp2 and nsp3. To determine the role in replication of processing between nsp2 and nsp3 at cleavage site 2 (CS2) and PLP1 proteinase activity, mutations were engineered into the MHV genome at CS2, at CS1 and CS2, and at the PLP1 catalytic site, alone and in combination. Mutant viruses with abolished cleavage at CS2 were delayed in growth and RNA synthesis but grew to wild-type titers of >10(7) PFU/ml. Mutant viruses with deletion of both CS1 and CS2 exhibited both a delay in growth and a decrease in peak viral titer to approximately 10(4) PFU/ml. Inactivation of PLP1 catalytic residues resulted in a mutant virus that did not process at either CS1 or CS2 and was severely debilitated in growth, achieving only 10(2) PFU/ml. However, when both CS1 and CS2 were deleted in the presence of inactivated PLP1, the growth of the resulting mutant virus was partially compensated, comparable to that of the CS1 and CS2 deletion mutant. These results demonstrate that interactions of PLP1 with CS1 and CS2 are critical for protein processing and suggest that the interactions play specific roles in regulation of the functions of nsp1, 2, and 3 in viral RNA synthesis.
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Affiliation(s)
- Rachel L Graham
- Department of Pediatrics, Vanderbilt University Medical Center, D6217 MCN, 1161 21st Ave. S., Nashville, TN 37232-2581, USA
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