State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei Province 430072, China.
Fish Shellfish Immunol. 2013 Aug;35(2):221-30. doi: 10.1016/j.fsi.2013.04.025. Epub 2013 May 6.
Peptidoglycan recognition proteins (PGRPs), which are evolutionarily conserved from insects to mammals, recognize bacterial peptidoglycan (PGN) and function in antibacterial innate immunity. In this study, a short-form PGRP, designated as gcPGRP5 was identified from grass carp Ctenopharyngodon idella. The deduced amino acid sequence of gcPGRP5 is composed of 180 residues with a conserved PGRP domain at the C-terminus. The gcPGRP5 gene consists of four exons and three introns, spacing approximately 2.3 kb in genomic sequence. Phylogenetic analysis demonstrated that the gcPGRP5 is clustered with other PGRP-S identified in teleost fish. The gcPGRP5 is constitutively expressed in all organs/tissues examined, and its expression was significantly induced in CIK cells treated with lipoteichoic acid (LTA), polyinosinic polycytidylic acid (Poly I:C) and PGN. Fluorescence analysis showed that gcPGRP5 is distributed in cytoplasm of CIK cells, and cell lysates from CIK cells transfected with pTurbo-gcPGRP5-GFP and ptGFP1-gcPGRP5 plasmids display the binding activity and peptidoglycan-lytic amidase activity toward Lys-PGN from Staphylococcus aureus and Dap-PGN from Bacillus subtilis. Furthermore, heat-shock protein70 (Hsp70), and MyD88, an adaptor molecule in Toll-like receptor pathway, had an increased expression in CIK cells overexpressed with gcPGRP5. It is thus indicated that gcPGRP5 exhibits amidase activity, and also possesses roles in anti-stress, and in Toll-like receptor signaling pathway.
肽聚糖识别蛋白（PGRPs）在从昆虫到哺乳动物的进化过程中是保守的，它们识别细菌肽聚糖（PGN），并在抗菌先天免疫中发挥作用。在这项研究中，从草鱼（Ctenopharyngodon idella）中鉴定出一种短形式的 PGRP，命名为 gcPGRP5。gcPGRP5 的推导氨基酸序列由 180 个残基组成，在 C 末端具有保守的 PGRP 结构域。gcPGRP5 基因由四个外显子和三个内含子组成，基因组序列约为 2.3 kb。系统发育分析表明，gcPGRP5 与其他在硬骨鱼中鉴定的 PGRP-S 聚类在一起。gcPGRP5 在所有检测的器官/组织中均呈组成型表达，并且在用脂磷壁酸（LTA）、多聚肌苷酸多胞嘧啶核苷酸（Poly I:C）和 PGN 处理的 CIK 细胞中其表达显著诱导。荧光分析表明 gcPGRP5 分布在 CIK 细胞的细胞质中，并且从用 pTurbo-gcPGRP5-GFP 和 ptGFP1-gcPGRP5 质粒转染的 CIK 细胞的细胞裂解物中显示出对金黄色葡萄球菌 Lys-PGN 和枯草芽孢杆菌 Dap-PGN 的结合活性和肽聚糖裂解酰胺酶活性。此外，在过表达 gcPGRP5 的 CIK 细胞中，热休克蛋白 70（Hsp70）和 Toll 样受体途径中的衔接子分子 MyD88 的表达增加。因此，表明 gcPGRP5 表现出酰胺酶活性，并且还在应激反应和 Toll 样受体信号通路中发挥作用。
