title: Characterization and expression analysis of serpinB3, the first clade B serine protease inhibitor in Pacific white shrimp, Litopenaeus vannamei.
abstract: Currently, about nine serpin clades (A-I) were preferentially observed in higher animals and clustered on the basis of function. Of these, eight clades contain extracellular proteins, while clade B contains predominantly intracellular proteins. In the present study, the first clade B serpin (named LvserpinB3) was identified from the Pacific white shrimp Litopenaeus vannamei. LvserpinB3 encoded a 412-amino acid protein with a 19-amino acid signal peptide and a serpin domain. Moreover, a transmembrane helix (TMHs) was predicted to be located on the N-terminal of LvserpinB3. Alignment with the cDNA sequence indicated that the genomic LvserpinB3 gene contains 2 exons and 1 intron. The P1-P1' scissile bond of the core feature reactive center loop (RCL) represented for Arginine-Isoleucine (RI), which was in accordance with PmserpinB3, Msserpin-4, -5 and -7. The highest mRNA expression level of LvserpinB3 was detected in hepatopancreas. A significant decrease of LvserpinB3 was detected in hepatopancreas at 6 h post Vibrio anguillarum injection, and later on, the expression of LvserpinB3 was remarkably elevated at 24 h post bacterial challenge. Suppression of LvserpinB3 in vivo by double-stranded RNA (dsRNA) mediated RNA interference (RNAi) led to a significant increase in the transcripts of LvSP1 (Serine protease 1), LvPPAE2 (Prophenoloxidase-activating Enzyme 2) and cumulative mortality. Furthermore, rLvserpinB3 protein was expressed and purified in vitro for the prophenoloxidase inhibition assay. The rLvserpinB3 protein can strongly impede the extent of proPO cascade. All above imply that LvserpinB3 might be an inhibitor for prophenoloxidase-activating system.
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Shaanxi Yangling 712100, China.
authors.forename: Yongjie
authors.initials: Y
authors.lastname: Liu
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Shaanxi Yangling 712100, China.
authors.forename: Fujun
authors.initials: F
authors.lastname: Hou
authors.affiliation: College of Animal Science and Technology, Northwest A&F University, Shaanxi Yangling 712100, China. Electronic address: liuxiaolin@nwsuaf.edu.cn.
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Liu
mesh_terms: D000818:Animals; D000951:Antigens, Neoplasm / Q000235:genetics; D060829:Arthropod Proteins / Q000235:genetics / Q000378:metabolism*; D004156:Catechol Oxidase / Q000378:metabolism; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004792:Enzyme Precursors / Q000378:metabolism; D043143:Hepatopancreas / Q000276:immunology*; D006801:Humans; D007113:Immunity, Innate; D033561:Penaeidae / Q000276:immunology*; D034741:RNA, Small Interfering / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000378:metabolism; D057057:Serine Proteases / Q000378:metabolism; D015843:Serpins / Q000235:genetics; D015854:Up-Regulation; D014733:Vibrio / Q000276:immunology*; D014735:Vibrio Infections / Q000276:immunology*
chemical_list: D000951:Antigens, Neoplasm; D060829:Arthropod Proteins; D004792:Enzyme Precursors; D034741:RNA, Small Interfering; D015843:Serpins; C051072:squamous cell carcinoma-related antigen; C038451:pro-phenoloxidase; D004156:Catechol Oxidase; D057057:Serine Proteases; D012697:Serine Endopeptidases; C022435:prephenoloxidase-activating enzyme
keywords: Litopenaeus vannamei; Prophenoloxidase; RNAi; SerpinB3