title: A scallop C-type lectin from Argopecten irradians (AiCTL5) with activities of lipopolysaccharide binding and Gram-negative bacteria agglutination.
abstract: C-type lectins are a family of calcium-dependent carbohydrate-binding proteins. In the present study, a C-type lectin (designated as AiCTL5) was identified and characterized from Argopecten irradians. The full-length cDNA of AiCTL5 was of 673 bp, containing a 5' untranslated region (UTR) of 24 bp, a 3' UTR of 130 bp with a poly (A) tail, and an open reading frame (ORF) of 519 bp encoding a polypeptide of 172 amino acids with a putative signal peptide of 17 amino acids. A C-type lectin-like domain (CRD) containing 6 conserved cysteines and a putative glycosylation sites were identified in the deduced amino acid sequence of AiCTL5. AiCTL5 shared 11%-27.5% identity with the previous reported C-type lectin from A. irradians. The cDNA fragment encoding the mature peptide of AiCTL5 was recombined into pET-21a (+) with a C-terminal hexa-histidine tag fused in-frame, and expressed in Escherichia coli Origami (DE3). The recombinant AiCTL5 (rAiCTL5) agglutinated Gram-negative E. coli TOP10F' and Listonella anguillarum, but did not agglutinate Gram-positive bacteria Bacillus thuringiensis and Micrococcus luteus, and the agglutination could be inhibited by EDTA, indicating that AiCTL5 was a Ca(2+)-dependent lectin. rAiCTL5 exhibited a significantly strong activity to bind LPS from E. coli, which conformed to the agglutinating activity toward Gram-negative bacteria. Moreover, rAiCTL5 also agglutinated rabbit erythrocytes. These results indicated that AiCTL5 could function as a pattern recognition receptor to protect bay scallop from Gram-negative bacterial infection, and also provide evidence to understand the structural and functional diverse of lectin.
authors.affiliation: School of Marine Science of Ningbo University, Ningbo, China.
authors.forename: Changkao
authors.initials: C
authors.lastname: Mu
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Song
authors.forename: Jianmin
authors.initials: J
authors.lastname: Zhao
authors.forename: Lingling
authors.initials: L
authors.lastname: Wang
authors.forename: Limei
authors.initials: L
authors.lastname: Qiu
authors.forename: Huan
authors.initials: H
authors.lastname: Zhang
authors.forename: Zhi
authors.initials: Z
authors.lastname: Zhou
authors.forename: Mengqiang
authors.initials: M
authors.lastname: Wang
authors.forename: Linsheng
authors.initials: L
authors.lastname: Song
authors.forename: Chunlin
authors.initials: C
authors.lastname: Wang
mesh_terms: D000371:Agglutination; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004912:Erythrocytes / Q000276:immunology; D020869:Gene Expression Profiling / Q000662:veterinary; D006090:Gram-Negative Bacteria / Q000235:genetics / Q000276:immunology; D006094:Gram-Positive Bacteria / Q000235:genetics / Q000276:immunology; D007113:Immunity, Innate; D037181:Lectins, C-Type / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000378:metabolism / Q000494:pharmacology; D008969:Molecular Sequence Data; D049897:Pectinidae / Q000235:genetics* / Q000276:immunology* / Q000382:microbiology; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D011817:Rabbits; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology; D016415:Sequence Alignment / Q000662:veterinary
chemical_list: D018076:DNA, Complementary; D037181:Lectins, C-Type; D008070:Lipopolysaccharides; D011994:Recombinant Proteins