title: Two short peptidoglycan recognition proteins from Crassostrea gigas with similar structure exhibited different PAMP binding activity.
abstract: Peptidoglycan recognition protein (PGRP) is an essential molecule in innate immunity for both invertebrates and vertebrates, owing to its prominent ability in specifically recognizing bacterial peptidoglycan (PGN) and eliminating the invading bacteria. In the present study, the full length cDNA of two PGRP genes, CgPGRPS2 and CgPGRPS4, were cloned from oyster Crassostrea gigas. Their amino acid sequences both contained one signal peptide, one typical PGRP/amidase domain with conserved catalytic residues responsible for amidase activity (55H, 90Y, 164H, 172C in CgPGRPS2, and 98H, 133Y, 207H, 215C in CgPGRPS4), and specific PGN recognition (84R, 85W, 104R, 109V in CgPGRPS2, and 127G, 128W, 147R, 152V in CgPGRPS4), and they shared 55.9% sequence similarity. The mRNA transcripts of CgPGRPS2 and CgPGRPS4 were constitutively expressed in all the examined tissues, including haemocytes, hepatopancreas, mantle, gonad, heart, adductor muscle and gill, with the highest expression level in adductor muscle and hepatopancreas, respectively. Both CgPGRPS2 and CgPGRPS4 proteins were mainly localized in the cytoplasma. The recombinant protein of CgPGRPS2 (rCgPGRPS2) could bind lipopolysaccharide (LPS), PGN and mannan (Man), as well as various microorganisms including Gram-negative bacteria Escherichia coli, Vibrio anguillarum, Gram-positive bacteria Staphylococcus aureus and fungi Yarrowia lipolytica. The recombinant protein of CgPGRPS4 (rCgPGRPS4) exhibited higher binding affinity to PGN, lower binding affinity to LPS, while no binding activity to Man and Y. lipolytica. The results indicated that CgPGRPS2 and CgPGRPS4 could function as pattern recognition receptors (PRR) in the innate immune response of oyster, and they exhibited a certain degree of functional differentiation in recognition of Man.
authors.affiliation: Liaoning Key Laboratory of Marine Animal Immunology and Disease Control, Dalian Ocean University, Dalian 116023, China.
authors.forename: Chuanyan
authors.initials: C
authors.lastname: Yang
authors.affiliation: Liaoning Key Laboratory of Marine Animal Immunology and Disease Control, Dalian Ocean University, Dalian 116023, China; Functional Laboratory of Marine Fisheries Science and Food Production Process, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266200, China.
authors.forename: Lingling
authors.initials: L
authors.lastname: Wang
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
authors.forename: Zhihao
authors.initials: Z
authors.lastname: Jia
authors.affiliation: Liaoning Key Laboratory of Marine Animal Immunology and Disease Control, Dalian Ocean University, Dalian 116023, China.
authors.forename: Qilin
authors.initials: Q
authors.lastname: Yi
authors.affiliation: Liaoning Key Laboratory of Marine Animal Immunology and Disease Control, Dalian Ocean University, Dalian 116023, China.
authors.forename: Qingsong
authors.initials: Q
authors.lastname: Xu
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
authors.forename: Weilin
authors.initials: W
authors.lastname: Wang
authors.affiliation: Liaoning Key Laboratory of Marine Animal Immunology and Disease Control, Dalian Ocean University, Dalian 116023, China.
authors.forename: Changhao
authors.initials: C
authors.lastname: Gong
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
authors.forename: Conghui
authors.initials: C
authors.lastname: Liu
authors.affiliation: Liaoning Key Laboratory of Marine Animal Immunology and Disease Control, Dalian Ocean University, Dalian 116023, China; Functional Laboratory of Marine Fisheries Science and Food Production Process, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266200, China. Electronic address: lshsong@dlou.edu.cn.
authors.forename: Linsheng
authors.initials: L
authors.lastname: Song
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D049896:Crassostrea / Q000276:immunology*; D054884:Host-Pathogen Interactions; D007113:Immunity, Innate; D008070:Lipopolysaccharides / Q000276:immunology; D010457:Peptidoglycan / Q000276:immunology / Q000378:metabolism; D010802:Phylogeny; D011485:Protein Binding; D051192:Receptors, Pattern Recognition / Q000235:genetics / Q000378:metabolism*; D040681:Structural Homology, Protein; D059467:Transcriptome; D014735:Vibrio Infections / Q000276:immunology*
chemical_list: D057134:Antibodies, Neutralizing; D002352:Carrier Proteins; D008070:Lipopolysaccharides; D010457:Peptidoglycan; D051192:Receptors, Pattern Recognition; C118897:peptidoglycan recognition protein
keywords: Crassostrea gigas; Innate immunity; PAMP binding activity; PGRP; Pattern recognition receptor