title: Comparative study of two single CRD C-type lectins, CgCLec-4 and CgCLec-5, from pacific oyster Crassostrea gigas.
abstract: C-type lectins (CTLs), a superfamily of Ca2+-dependent carbohydrate-recognition proteins, are involved in nonself-recognition and pathogen elimination, and play crucial roles in the innate immunity. In the present study, two single CRD C-type lectins, CgCLec-4 and CgCLec-5, were identified from oyster Crassostrea gigas. The open reading frame (ORF) of CgCLec-4 and CgCLec-5 encoded polypeptides of 152 and 150 amino acids, respectively. Both CgCLec-4 and CgCLec-5 contained one CRD with six conserved cysteines to form three disulfide bridges. The motif in Ca2+-binding site 2 of CgCLec-4 was QPE, while it was QYE, a non-a typical motif in CgCLec-5. CgCLec-4 was a secreted lectin with a signal peptide which was highly expressed in hepatopancreas, mantle and hemocytes. CgCLec-5 was an intracellular lectin which was mostly expressed in hemocytes. The lipopolysaccharide stimulation could induce the expressions of CgCLec-4 and CgCLec-5. The recombinant proteins of CgCLec-4 and CgCLec-5 (rCgCLec-4 and rCgCLec-5) could bind to various PAMPs including LPS, PGN, GLU and mannan, while the binding affinity of rCgCLec-5 was stronger than that of rCgCLec-4. Meanwhile, rCgCLec-4 and rCgCLec-5 could bind to different kinds of microorganisms, including Staphylococcus aureus, Escherichia coli and Vibro anguillarum and Yarrowia lipolytica, and the microbial agglutinating ability of rCgCLec-4 was stronger than that of CgCLec-5. Moreover, rCgCLec-4 exhibited anti-microbial activity against bacteria and fungi, but anti-microbial activity of CgCLec-5 was not obvious. All these results suggested that CgCLec-4 and CgCLec-5 could function as an important PRR involved in immune defense against invading pathogen in oyster, and the diversity and complexity of motifs in Ca2+binding site 2 in CRDs determined their comprehensive recognition spectrum and multiple immune functions.
authors.affiliation: Key laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, No. 7 Nanhai Rd., Qingdao 266071, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Zhihao
authors.initials: Z
authors.lastname: Jia
authors.affiliation: Key laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, No. 7 Nanhai Rd., Qingdao 266071, China.
authors.forename: Huan
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Key laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, No. 7 Nanhai Rd., Qingdao 266071, China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Jiang
authors.affiliation: Key laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, No. 7 Nanhai Rd., Qingdao 266071, China.
authors.forename: Mengqiang
authors.initials: M
authors.lastname: Wang
authors.affiliation: Key Laboratory of Mariculture & Stock Enhancement in North China's Sea, Ministry of Agriculture, Dalian Ocean University, Dalian 116023, China.
authors.forename: Lingling
authors.initials: L
authors.lastname: Wang
authors.affiliation: Key Laboratory of Mariculture & Stock Enhancement in North China's Sea, Ministry of Agriculture, Dalian Ocean University, Dalian 116023, China. Electronic address: lshsong@ms.qdio.ac.cn.
authors.forename: Linsheng
authors.initials: L
authors.lastname: Song
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D049896:Crassostrea / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D006090:Gram-Negative Bacteria / Q000502:physiology; D006094:Gram-Positive Bacteria / Q000502:physiology; D006434:Hemocytes / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D007113:Immunity, Innate; D037181:Lectins, C-Type / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D009928:Organ Specificity; D000069452:Pathogen-Associated Molecular Pattern Molecules / Q000494:pharmacology*; D011487:Protein Conformation; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D059467:Transcriptome
chemical_list: D018076:DNA, Complementary; D037181:Lectins, C-Type; D000069452:Pathogen-Associated Molecular Pattern Molecules; D012333:RNA, Messenger
keywords: Antimicrobial activity; Crassostrea gigas; Innate immunity; Lectin; Recognition