title: A C-type lectin (AiCTL-3) from bay scallop Argopecten irradians with mannose/galactose binding ability to bind various bacteria.
abstract: C-type lectins are a family of Ca(2+)-dependent carbohydrate-binding proteins playing crucial roles in innate immunity of vertebrates and invertebrates. In the present study, the cDNA of a C-type lectin with one carbohydrate-recognition domain (CRD) of 127 amino acids was cloned from bay scallop Argopecten irradians (designated AiCTL-3) by rapid amplification of cDNA end (RACE) techniques based on expressed sequence tag (EST) analysis. The mRNA transcripts of AiCTL-3 could be detected in all the tested tissues including hepatopancreas, gonad, adductor muscle, heart, hemocytes, mantle and gill, with the highest expression level in hepatopancreas. After the challenges with Vibrio anguillarum and Micrococcus luteus, the mRNA expression level of AiCTL-3 was obviously up-regulated and reached the maximum level at 9h (11.87fold, P<0.01, and 20.02-fold, P<0.05, respectively). The recombinant AiCTL-3 (designated as rAiCTL-3) could bind LPS, PGN, and glucan in vitro, but could not bind mannan. And it also bound Gram-positive bacteria Staphylococcus aureus as well as Gram-negative bacteria Escherichia coli and V. anguillarum. With a Ca(2+) binding site 2 EPN (Glu-Pro-Asn) motif, rAiCTL-3 could bind both mannose and galactose which was quite different from those in vertebrate. Meanwhile, it could significantly enhance the phagocytosis of scallop hemocytes in vitro. The results clearly suggested that AiCTL-3 could serve not only as a PRR participated in the immune response against various PAMPs and bacteria in non-self recognition via mannose/galactose binding specificity but an opsonin playing an important part in clearance of invaders.
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Mengmeng
authors.initials: M
authors.lastname: Huang
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Song
authors.forename: Jianmin
authors.initials: J
authors.lastname: Zhao
authors.forename: Changkao
authors.initials: C
authors.lastname: Mu
authors.forename: Lingling
authors.initials: L
authors.lastname: Wang
authors.forename: Huan
authors.initials: H
authors.lastname: Zhang
authors.forename: Zhi
authors.initials: Z
authors.lastname: Zhou
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Liu
authors.forename: Linsheng
authors.initials: L
authors.lastname: Song
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001419:Bacteria / Q000378:metabolism*; D001483:Base Sequence; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D005690:Galactose / Q000378:metabolism*; D006434:Hemocytes / Q000276:immunology / Q000378:metabolism; D037181:Lectins, C-Type / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008358:Mannose / Q000378:metabolism*; D008969:Molecular Sequence Data; D049897:Pectinidae / Q000235:genetics / Q000276:immunology* / Q000378:metabolism* / Q000382:microbiology; D010587:Phagocytosis / Q000276:immunology; D011485:Protein Binding; D011994:Recombinant Proteins
chemical_list: D018076:DNA, Complementary; D037181:Lectins, C-Type; D011994:Recombinant Proteins; D008358:Mannose; D005690:Galactose
keywords: Argopecten irradians; C-type lectin; CRD; CTL; EST; Innate immunity; LPS; Microbe binding ability; Non-self recognition; PAMP; PAMPs binding; PGN; PRR; Q-PCR; RACE; carbohydrate-recognition domains; expressed sequence tag; lipopolysaccharide; pathogen-associated molecular pattern; pattern recognition receptor; peptidoglycan; quantitative real-time PCR; rapid amplification of cDNA ends