title: An LRR-only protein representing a new type of pattern recognition receptor in Chlamys farreri.
abstract: Accumulating evidence has demonstrated that leucine-rich repeat (LRR)-only proteins could mediate protein-ligand and protein-protein interactions and were involved in the immune response. In the present study, an LRR-only protein (designed as CfLRRop-1) was cloned from Zhikong scallop Chlamys farreri. The complete cDNA sequence of CfLRRop-1 contained an open reading frame (ORF) of 1377 bp, which encoded a protein of 458 amino acids. An LRRNT motif, an LRR_7 motif and seven LRR motifs were found in the deduced amino acid sequence of CfLRRop-1. And these seven LRR motifs contained a conserved signature sequence LxxLxLxxNxL. The mRNA transcripts of CfLRRop-1 were constitutively expressed in all the tested tissues, including haemocytes, muscle, mantle, gill, hepatopancreas and gonad, with the highest expression level in hepatopancreas. After the stimulation of lipopolysaccharide (LPS), peptidoglycan (PGN), glucan (GLU) and polyinosinic-polycytidylic acid (poly I:C), the mRNA transcripts of CfLRRop-1 in haemocytes all increased firstly within the first 6 h and secondly during 12-24 h post stimulation. The mRNA expression level of CfLRRop-1 was continuously up-regulated, after the expression of CfTLR (previously identified Toll-like receptor in C. farreri) was suppressed via RNA interference (RNAi). The recombinant CfLRRop-1 protein could directly bind LPS, PGN, GLU and poly I:C, and induce the release of TNF-α in mixed primary cultured scallop haemocytes. These results collectively indicated that CfLRRop-1 would function as a powerful pattern recognition receptor (PRR) and play a pivotal role in the immune response of scallops.
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Rd., Qingdao 266071, China.
authors.forename: Mengqiang
authors.initials: M
authors.lastname: Wang
authors.affiliation: Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Rd., Qingdao 266071, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China. Electronic address: wanglingling@ms.qdio.ac.cn.
authors.forename: Lingling
authors.initials: L
authors.lastname: Wang
authors.affiliation: 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: Guo
authors.affiliation: Key Laboratory of Mariculture & Stock Enhancement in North China's Sea, Ministry of Agriculture, Dalian Ocean University, Dalian 116023, China.
authors.forename: Qilin
authors.initials: Q
authors.lastname: Yi
authors.affiliation: Key Laboratory of Mariculture & Stock Enhancement in North China's Sea, Ministry of Agriculture, Dalian Ocean University, Dalian 116023, China.
authors.forename: Linsheng
authors.initials: L
authors.lastname: Song
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D007113:Immunity, Innate / Q000235:genetics / Q000276:immunology*; D049897:Pectinidae / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D051192:Receptors, Pattern Recognition / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D016415:Sequence Alignment
chemical_list: D051192:Receptors, Pattern Recognition
keywords: Chlamys farreri; Innate immunity; LRR-only protein; Leucine-rich repeat; Pattern recognition receptor