title: Proteolytic processing, deubiquitinase and interferon antagonist activities of Middle East respiratory syndrome coronavirus papain-like protease.
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.
authors.affiliation: 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.
authors.forename: Xingxing
authors.initials: X
authors.lastname: Yang
authors.affiliation: Division of Infection and Immunity, Department of Electromagnetic and Laser Biology, Beijing Institute of Radiation Medicine, Beijing 100850, PR China.
authors.forename: Xiaojuan
authors.initials: X
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 100850, PR China.
authors.forename: Guangxing
authors.initials: G
authors.lastname: Bian
authors.affiliation: Australian School of Advanced Medicine, Macquarie University, Sydney, NSW 2109, Australia.
authors.forename: Jian
authors.initials: J
authors.lastname: Tu
authors.affiliation: Division of Infection and Immunity, Department of Electromagnetic and Laser Biology, Beijing Institute of Radiation Medicine, Beijing 100850, PR China.
authors.forename: Yaling
authors.initials: Y
authors.lastname: Xing
authors.affiliation: Division of Infection and Immunity, Department of Electromagnetic and Laser Biology, Beijing Institute of Radiation Medicine, Beijing 100850, PR China.
authors.forename: Yayun
authors.initials: Y
authors.lastname: Wang
authors.affiliation: 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.
authors.forename: Zhongbin
authors.initials: Z
authors.lastname: Chen
mesh_terms: D000595:Amino Acid Sequence; D020134:Catalytic Domain; D003332:Coronaviridae / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D003333:Coronaviridae Infections / Q000378:metabolism* / Q000821:virology; D006801:Humans; D050838:Interferon Regulatory Factor-3 / Q000378:metabolism; D016899:Interferon-beta / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008969:Molecular Sequence Data; D010206:Papain / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D020815:Polyproteins / Q000235:genetics / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D059748:Proteolysis; D016415:Sequence Alignment; D025801:Ubiquitin; D064570:Ubiquitin-Specific Proteases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D050838:Interferon Regulatory Factor-3; D020815:Polyproteins; D025801:Ubiquitin; D014764:Viral Proteins; D016899:Interferon-beta; D064570:Ubiquitin-Specific Proteases; D010206:Papain