title: Porcine Deltacoronavirus nsp5 Antagonizes Type I Interferon Signaling by Cleaving STAT2.
abstract: Porcine deltacoronavirus (PDCoV) is an emerging swine enteropathogenic coronavirus. The first outbreak of PDCoV was announced from the United States in 2014, followed by reports in Asia. The nonstructural protein nsp5 is a 3C-like protease of coronavirus, and our previous study showed that PDCoV nsp5 inhibits type I interferon (IFN) production. In this study, we found that PDCoV nsp5 significantly inhibited IFN-stimulated response element (ISRE) promoter activity and transcription of IFN-stimulated genes (ISGs), suggesting that PDCoV nsp5 also suppresses IFN signaling. Detailed analysis showed that nsp5 cleaved signal transducer and activator of transcription 2 (STAT2) but not Janus kinase 1 (JAK1), tyrosine kinase 2 (TYK2), STAT1, and interferon regulatory factor 9 (IRF9), key molecules of the JAK-STAT pathway. STAT2 cleavage was dependent on the protease activity of nsp5. Interestingly, nsp5 cleaved STAT2 at two sites, glutamine 685 (Q685) and Q758, and similar cleavage was observed in PDCoV-infected cells. As expected, cleaved STAT2 impaired the ability to induce ISGs, demonstrating that STAT2 cleavage is an important mechanism utilized by PDCoV nsp5 to antagonize IFN signaling. We also discussed the substrate selection and binding mode of PDCoV nsp5 by homologous modeling of PDCoV nsp5 with the two cleaved peptide substrates. The results of our study demonstrate that PDCoV nsp5 antagonizes type I IFN signaling by cleaving STAT2 and provides structural insights for comprehending the cleavage mechanism of PDCoV nsp5, revealing a potential new function for PDCoV nsp5 in type I IFN signaling.IMPORTANCEThe 3C-like protease encoded by nsp5 is a major protease of coronaviruses; thus, it is an attractive target for development of anticoronavirus drugs. Previous studies have revealed that the 3C-like protease of coronaviruses, including PDCoV and porcine epidemic diarrhea virus (PEDV), antagonizes type I IFN production by targeting the NF-κB essential modulator (NEMO). Here, for the first time, we demonstrate that overexpression of PDCoV nsp5 also antagonizes IFN signaling by cleaving STAT2, an essential component of transcription factor complex ISGF3, and that PDCoV infection reduces the levels of STAT2, which may affect the innate immune response.
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.|The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China.
authors.forename: Xinyu
authors.initials: X
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.|The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China.
authors.forename: Dang
authors.initials: D
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.|The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China.
authors.forename: Junwei
authors.initials: J
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.|The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Pan
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.|The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China.
authors.forename: Jiyao
authors.initials: J
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.|The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China.
authors.forename: Yuting
authors.initials: Y
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.|The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China.
authors.forename: Mengting
authors.initials: M
authors.lastname: Lv
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.|The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Ye
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.|The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China.
authors.forename: Guiqing
authors.initials: G
authors.lastname: Peng
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China fanglr@mail.hzau.edu.cn vet@mail.hzau.edu.cn.|The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China.
authors.forename: Liurong
authors.initials: L
authors.lastname: Fang
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China fanglr@mail.hzau.edu.cn vet@mail.hzau.edu.cn.|The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China.
authors.forename: Shaobo
authors.initials: S
authors.lastname: Xiao
mesh_terms: D000818:Animals; D017934:Coronavirus / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D018352:Coronavirus Infections; D057809:HEK293 Cells; D054884:Host-Pathogen Interactions; D006801:Humans; D007113:Immunity, Innate; D007370:Interferon Type I / Q000378:metabolism*; D053485:Porcine epidemic diarrhea virus / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D050795:STAT2 Transcription Factor / Q000378:metabolism*; D016415:Sequence Alignment; D015398:Signal Transduction; D013552:Swine; D014764:Viral Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D007370:Interferon Type I; D050795:STAT2 Transcription Factor; D014764:Viral Proteins
keywords: STAT2; immune suppression; interferon signaling; nonstructural protein 5 (nsp5); porcine deltacoronavirus