The nonstructural protein 11 of porcine reproductive and respiratory syndrome virus inhibits NF-κB signaling by means of its deubiquitinating activity.
Since its emergence in the late 1980s, porcine reproductive and respiratory syndrome (PRRS) has been devastating the swine industry worldwide. The causative agent is an Arterivirus, referred to as PRRS virus (PRRSV). The pathogenic mechanisms of PRRS are poorly understood, but are believed to correlate with the ability of PRRSV to inhibit immune responses of the host. However, precisely how the virus is capable of doing so remains obscure. In this study, we showed that PRRSV infection led to reduced ubiquitination of cellular proteins. Screening all of the 12 nonstructural proteins (Nsps) encoded by PRRSV revealed that, apart from the Nsp2 which contains the deubiqintinating (DUB) ovarian tumor (OTU) domain, Nsp11, which encodes a unique and conserved endoribonuclease (NendoU) throughout the Nidovirus order, also possesses DUB activity. In vivo assay demonstrated that Nsp11 specifically removed lysine 48 (K48)-linked polyubiquitin chains and the conserved sites C112, H144, D173, K180, and Y219 were critical for its DUB activity. Remarkably, DUB activity was responsible for the capacity of Nsp11 to inhibit nuclear factor κB (NF-κB) activation. Mutations abrogating the DUB activity of Nsp11 toward K48-linked polyubiquitin chains of IκBα nullified the suppressive effect on NF-κB. Our data add Nsp11 to the list of DUBs encoded by PRRSV and uncover a novel mechanism by which PRRSV cripples host innate immune responses.
State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China.
Dang
D
Wang
State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China.
Jinxiu
J
Fan
State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China.
Liurong
L
Fang
State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China.
Rui
R
Luo
State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China.
Haiping
H
Ouyang
State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China.
Chao
C
Ouyang
State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China.
Huan
H
Zhang
State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China.
Huanchun
H
Chen
Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA.
Kui
K
Li
State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China. Electronic address: vet@mail.hzau.edu.cn.
Shaobo
S
Xiao
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D004847:Epithelial Cells / Q000276:immunology* / Q000821:virology; D017930:Genes, Reporter; D057809:HEK293 Cells; D054884:Host-Pathogen Interactions; D006801:Humans; D020672:I-kappa B Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D008156:Luciferases / Q000235:genetics / Q000276:immunology; D008969:Molecular Sequence Data; D009154:Mutation; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D019316:Porcine respiratory and reproductive syndrome virus / Q000235:genetics / Q000276:immunology*; D011499:Protein Processing, Post-Translational; D016415:Sequence Alignment; D015398:Signal Transduction; D013329:Structure-Activity Relationship; D013552:Swine; D054875:Ubiquitination; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*
D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D017361:Viral Nonstructural Proteins; D000072000:NF-KappaB Inhibitor alpha; D008156:Luciferases
Deubiquitinating activity; NF-κB; Nonstructural protein 11; Porcine reproductive and respiratory syndrome virus