title: Complement factor I from flatfish half-smooth tongue (Cynoglossus semilaevis) exhibited anti-microbial activities.
abstract: Complement factor I (Cfi) is a soluble serine protease which plays a crucial role in the modulation of complement cascades. In the presence of substrate modulating cofactors (such as complement factor H, C4bp, CR1, etc), Cfi cleaves and inactivates C3b and C4b, thereby controlling the complement-mediated processes. In this study, we sequenced and characterized Cfi gene from Cynoglossus Semilaevis (designated as CsCfi) for the first time. The full-length cDNA of CsCfi was 2230 bp in length, including a 98 bp 5'-untranslated region (UTR), a 164 bp 3'-UTR and a 1968 bp open reading frame (ORF). It encoded a polypeptide of 656 amino acids, with a molecular mass of 72.28 kDa and an isoelectric point of 7.71. A signal peptide was defined at N-terminus, resulting in a 626-residue mature protein. Multiple sequence alignment revealed that Cfi proteins were well conserved with the typical modular architecture and identical active sites throughout the vertebrates, which suggested the conserved function of Cfi. Phylogenetic analysis indicated that CsCfi and the homologous Cfi sequences from teleosts clustered into a clade, separating from another clade from the cartilaginous fish and other vertebrates. Tissue expression profile analysis by quantitative real-time PCR (qRT-PCR) showed that CsCfi mRNA constitutively expressed in all tested tissues, with the predominant expression in liver and the lowest in stomach. Temporal expression levels of CsCfi after challenging with Vibrio anguillarum showed different expression patterns in intestine, spleen, skin, blood, head kidney and liver. The recombinant CsCfi (rCsCfi) protein showed broad-spectrum antimicrobial activities against the Gram-positive bacteria Staphylococcus aureus and the Gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa and Shewanella putrefaciens. The research revealed that CsCfi plays an important role in C. Semilaevis immunity.
authors.affiliation: Key Laboratory for Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; Colleage of Fisheries and Life Science, Shanghai Ocean University, Shanghai 201306, China; Function Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266235, China.
authors.forename: Jinsong
authors.initials: J
authors.lastname: Xiang
authors.affiliation: Key Laboratory for Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; Function Laboratory for Marine Fisheries Science and Food Production Processes, National Lab for Ocean Science and Technology, Qingdao 266235, China.
authors.forename: Xihong
authors.initials: X
authors.lastname: Li
authors.affiliation: Key Laboratory for Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; Function Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266235, China.
authors.forename: Yadong
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Key Laboratory for Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; Function Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266235, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Key Laboratory for Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; Function Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266235, China; Colleage of Fisheries and Life Science, Dalian Ocean University, Dalian 116023, China.
authors.forename: Mengjun
authors.initials: M
authors.lastname: Yu
authors.affiliation: Key Laboratory for Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; Colleage of Fisheries and Life Science, Shanghai Ocean University, Shanghai 201306, China; Function Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266235, China.
authors.forename: Xuejie
authors.initials: X
authors.lastname: Chen
authors.affiliation: Key Laboratory for Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; Colleage of Fisheries and Life Science, Dalian Ocean University, Dalian 116023, China.
authors.forename: Wenting
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Key Laboratory for Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; Colleage of Fisheries and Life Science, Dalian Ocean University, Dalian 116023, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zeng
authors.affiliation: Key Laboratory for Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; Colleage of Fisheries and Life Science, Dalian Ocean University, Dalian 116023, China.
authors.forename: Luming
authors.initials: L
authors.lastname: Sun
authors.affiliation: Key Laboratory for Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; Function Laboratory for Marine Fisheries Science and Food Production Processes, National Lab for Ocean Science and Technology, Qingdao 266235, China.
authors.forename: Songlin
authors.initials: S
authors.lastname: Chen
authors.affiliation: Key Laboratory for Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao 266071, China; Function Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266235, China. Electronic address: shazx@ysfri.ac.cn.
authors.forename: Zhenxia
authors.initials: Z
authors.lastname: Sha
mesh_terms: D000818:Animals; D001483:Base Sequence; D017244:Complement Factor I / Q000235:genetics* / Q000276:immunology*; D017124:Conserved Sequence / Q000235:genetics; D004926:Escherichia coli / Q000276:immunology; D005393:Fish Diseases / Q000276:immunology* / Q000382:microbiology; D005412:Flatfishes / Q000235:genetics / Q000276:immunology*; D020869:Gene Expression Profiling; D008969:Molecular Sequence Data; D010802:Phylogeny; D011550:Pseudomonas aeruginosa / Q000276:immunology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D020614:Shewanella putrefaciens / Q000276:immunology; D013211:Staphylococcus aureus / Q000276:immunology; D014733:Vibrio / Q000276:immunology
chemical_list: D017244:Complement Factor I
keywords: Antimicrobial activity; Bacterial infection; Complement factor I; Cynoglossus semilaevis; Expression profile