title: Characterization of a novel anti-lipopolysaccharide factor isoform (SpALF5) in mud crab, Scylla paramamosain.
abstract: Anti-lipopolysaccharide factors (ALFs), the potential antimicrobial peptides that bind and neutralize lipopolysaccharide (LPS), are common effectors of innate immunity in crustaceans. In this study, a novel isoform of ALFs (SpALF5) was isolated from the hemocytes of mud crab Scylla paramamosain. The full-length 975bp SpALF5 contains a 375bp open reading frame (ORF) encoding 125 amino acids. Although SpALF5 exhibits a low degree of nucleotide homology with other reported ALFs, it contains the conserved amino acid sequence with a signal peptide and a LPS-binding domain including two conservative cysteine residues. The genomic organization of SpALF5 consists of four exons and three introns, with each intron containing one or more tandem repeats. Unlike most of ALFs mainly distributed in crab hemocytes, SpALF5 transcript was predominantly observed in the brain, muscle and skin, while barely detected in the hemocytes in our study. In situ hybridization assay also showed that SpALF5 mRNA was localized in brain, muscle and skin tissues of mud crab. Further, SpALF5 transcript was significantly up-regulated after challenge with LPS, polyinosinic polycytidylic acid (PolyI:C) (with the except of that in brain), Vibrio parahemolyticus or white spot syndrome virus (WSSV). The recombinant SpALF5 protein showed a varying degree of binding activity towards bacteria and fungus. Moreover, in vitro, the recombinant SpALF5 revealed a strong antimicrobial activity against Gram-negative bacteria (V. parahemolyticus, Vibrio alginolyticus, Escherichia coli, Aeromonas hydrophila) and fungus (Sacchromyces cerevisiae), but could only inhibited the growth of some Gram-positive bacteria like Staphylococcus aureus. The results suggest that SpALF5 is a potent immune protector and plays an important role in immune defense against invading pathogens in S. paramamosain.
authors.affiliation: Guangdong Provincial Key Laboratory of Marine Biology, Shantou University, Shantou 515063, China; Marine Biology Institute, Shantou University, Shantou 515063, China.
authors.forename: Wanwei
authors.initials: W
authors.lastname: Sun
authors.affiliation: Guangdong Provincial Key Laboratory of Marine Biology, Shantou University, Shantou 515063, China; Marine Biology Institute, Shantou University, Shantou 515063, China.
authors.forename: Weisong
authors.initials: W
authors.lastname: Wan
authors.affiliation: Guangdong Provincial Key Laboratory of Marine Biology, Shantou University, Shantou 515063, China; Marine Biology Institute, Shantou University, Shantou 515063, China.
authors.forename: Shuo
authors.initials: S
authors.lastname: Zhu
authors.affiliation: Guangdong Provincial Key Laboratory of Marine Biology, Shantou University, Shantou 515063, China; Marine Biology Institute, Shantou University, Shantou 515063, China.
authors.forename: Shasha
authors.initials: S
authors.lastname: Wang
authors.affiliation: Guangdong Provincial Key Laboratory of Marine Biology, Shantou University, Shantou 515063, China; Marine Biology Institute, Shantou University, Shantou 515063, China.
authors.forename: Shuqi
authors.initials: S
authors.lastname: Wang
authors.affiliation: Guangdong Provincial Key Laboratory of Marine Biology, Shantou University, Shantou 515063, China.
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Wen
authors.affiliation: Guangdong Provincial Key Laboratory of Marine Biology, Shantou University, Shantou 515063, China; Marine Biology Institute, Shantou University, Shantou 515063, China.
authors.forename: Huaiping
authors.initials: H
authors.lastname: Zheng
authors.affiliation: Guangdong Provincial Key Laboratory of Marine Biology, Shantou University, Shantou 515063, China; Marine Biology Institute, Shantou University, Shantou 515063, China.
authors.forename: Yueling
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Guangdong Provincial Key Laboratory of Marine Biology, Shantou University, Shantou 515063, China; Marine Biology Institute, Shantou University, Shantou 515063, China. Electronic address: lisk@stu.edu.cn.
authors.forename: Shengkang
authors.initials: S
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000494:pharmacology; D003386:Brachyura / Q000187:drug effects / Q000235:genetics / Q000276:immunology*; D001921:Brain / Q000276:immunology; D017124:Conserved Sequence; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005091:Exons; D015870:Gene Expression; D006090:Gram-Negative Bacteria / Q000187:drug effects / Q000254:growth & development; D006434:Hemocytes / Q000276:immunology; D007113:Immunity, Innate; D007438:Introns; D008070:Lipopolysaccharides / Q000494:pharmacology; D008969:Molecular Sequence Data; D009132:Muscles / Q000276:immunology; D016366:Open Reading Frames; D011070:Poly I-C / Q000494:pharmacology; D021382:Protein Sorting Signals; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000494:pharmacology; D012867:Skin / Q000276:immunology; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development; D046848:White spot syndrome virus 1 / Q000187:drug effects / Q000254:growth & development
chemical_list: D023181:Antimicrobial Cationic Peptides; D008070:Lipopolysaccharides; D021382:Protein Sorting Signals; D011994:Recombinant Proteins; D011070:Poly I-C
keywords: Antimicrobial peptide; S. paramamosain; SpALF5