A novel peptidoglycan recognition protein containing a goose-type lysozyme domain from the Pacific oyster, Crassostrea gigas
A novel peptidoglycan recognition protein containing a goose-type lysozyme domain from the Pacific oyster, Crassostrea gigas
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DOI：
10.1016/j.molimm.2009.01.022
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发表时间：
2009-05-01
影响因子：
3.6
通讯作者：
Takahashi, Keisuke G.
中科院分区：
文献类型：
--
作者：
Itoh, Naoki;Takahashi, Keisuke G.
肽聚糖识别蛋白（PGRP）被认为是无脊椎动物有效免疫的重要分子，它能够检测和澄清入侵细菌。双壳类软体动物也具有用于自卫的PGRP系统，但其在双壳类动物中的功能尚不清楚。本研究利用EST-based RACE PCR技术，从太平洋牡蛎（Crassostrea gigas）中鉴定出一种新的PGRP cDNA。该新型PGRP与短PGRP同源，并预测存在信号肽。虽然PGRP的分子量估计为54 kDa，接近于长PGRP基团，但PGRP被归类为短PGRP基团。保守结构域搜索在该PGRP结构中检测到amidase-2/PGRP和鹅型（g型）溶菌酶结构域。因此，该新型PGRP被命名为CgPGRP-L。PGRP和g型溶菌酶的催化残基保守性较好，提示CgPGRP-L可能对细菌具有结合和裂解功能。逆转录PCR （RT-PCR）检测循环血细胞中CgPGRP-L mRNA的表达，实时定量RT-PCR显示，在嗜盐马里纳球菌和结核弧菌暴露后，CgPGRP-L mRNA的表达增加。这些结果表明，CgPGRP-L可能通过细菌入侵在血细胞中表达，进而发挥短链PGRP和细菌溶菌酶的作用。2009爱思唯尔有限公司版权所有。
Peptidoglycan recognition protein (PGRP) is considered an essential molecule for effective immunity in invertebrates by its detection and clarification of invading bacteria. Bivalve mollusks also possess PGRP systems for self-defense, however, their functions in bivalves remain to be understood. In the present study, cDNA of a novel PGRP was identified from the Pacific oyster, Crassostrea gigas, using EST-based RACE PCR. This novel PGRP is homologous to short PGRPs and the presence of a signal peptide was predicted. The PGRP is classified into the short PGRP group, although its molecular weight was estimated as 54 kDa, close to that of long PGRP groups. A conserved domain search detected amidase-2/PGRP and goose-type (g-type) lysozyme domains in this PGRP structure. and thus this novel PGRP was designated as CgPGRP-L. Catalytic residues for PGRP and g-type lysozyme are well conserved, suggesting that CgPGRP-L may have both binding and lytic functions against bacteria. Reverser transcription PCR (RT-PCR) detected CgPGRP-L mRNA expression in circulatory hemocytes, and quantitative real-time RT-PCR revealed that its expression increased after Marinococcus halophilus and Vibrio tubiashii exposure. These results indicate that CgPGRP-L is expressed in hemocytes by bacterial invasion, and then may play roles of a short PGRP and bacterio-lytic lysozyme. (C) 2009 Elsevier Ltd. All rights reserved.