title: The second anti-lipopolysaccharide factor (EsALF-2) with antimicrobial activity from Eriocheir sinensis.
abstract: The anti-lipopolysaccharide factor (ALF) is a small basic protein that can bind and neutralize lipopolysaccharide (LPS), mediating degranulation and activation of an intracellular coagulation cascade. In the present study, cDNA of the second Eriocheir sinensis ALF (designated as EsALF-2) was cloned and the full-length cDNA of EsALF-2 was of 724bp, consisting of an open reading frame (ORF) of 363bp encoding a polypeptide of 120 amino acids. The deduced amino acid of EsALF-2 shared 82% similarity with EsALF-1 from E. sinensis and about 53-65% similarity with ALFs from other crustaceans. The potential tertiary structures of EsALF-1 and EsALF-2 contained two highly conserved-cysteine residues to define the LPS binding site, but the N-terminal of EsALF-1 formed a single additional alpha-helix compared to EsALF-2, implying that EsALF-1 and EsALF-2 might represent different biological functions in E. sinensis. The mRNA transcript of EsALF-2 was detected in all examined tissues of healthy crabs, including haemocytes, hepatopancreas, gill, muscle, heart and gonad, which suggested that EsALF-2 could be a multifunctional molecule for the host immune defense responses and thereby provided systemic protection against pathogens. The mRNA expression of EsALF-2 was up-regulated after Listonella anguillarum and Pichia pastoris challenge and the recombinant protein of EsALF-2 showed antimicrobial activity against L. anguillarum and P. pastoris, indicating that EsALF-2 was involved in the immune defense responses in Chinese mitten crab against L. anguillarum and P. pastoris. These results together indicated that there were abundant and diverse ALFs in E. sinensis with various biological functions and these ALFs would provide candidate promising therapeutic or prophylactic agents in health management and diseases control of crab aquaculture.
authors.affiliation: The Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Rd., Qingdao 266071, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
authors.forename: Lingling
authors.initials: L
authors.lastname: Wang
authors.forename: Leilei
authors.initials: L
authors.lastname: Wang
authors.forename: Jialong
authors.initials: J
authors.lastname: Yang
authors.forename: Yunchao
authors.initials: Y
authors.lastname: Gai
authors.forename: Limei
authors.initials: L
authors.lastname: Qiu
authors.forename: Linsheng
authors.initials: L
authors.lastname: Song
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000890:Anti-Infective Agents / Q000276:immunology / Q000378:metabolism; D001777:Blood Coagulation; D003386:Brachyura; D003001:Cloning, Molecular; D020869:Gene Expression Profiling; D016905:Gram-Negative Bacterial Infections / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D007113:Immunity, Innate / Q000235:genetics; D007447:Invertebrate Hormones / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors / Q000378:metabolism*; D053526:Listonella / Q000276:immunology* / Q000472:pathogenicity; D008969:Molecular Sequence Data; D009181:Mycoses / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D010843:Pichia / Q000276:immunology* / Q000472:pathogenicity; D017385:Sequence Homology; D012758:Shellfish
chemical_list: D000890:Anti-Infective Agents; D007447:Invertebrate Hormones; D008070:Lipopolysaccharides