School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei Province 430074, China; School of Environment and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou, Henan Province 450011, China.
Mol Immunol. 2013 Dec;56(4):729-38. doi: 10.1016/j.molimm.2013.06.019. Epub 2013 Aug 7.
Peptidoglycan recognition proteins (PGRPs), which are evolutionarily conserved from invertebrates to vertebrates, function as pattern-recognition and effector molecules in innate immunity. In the present study, a short-form PGRP, designated as HcPGRPS1 was identified from freshwater mussel Hyriopsis cumingi. The deduced amino acid sequence of HcPGRPS1 is composed of 235 residues which contains a conserved PGRP domain at the C-terminus. Sequence analysis showed that HcPGRPS1 shared high identities with other known PGRPs. The mRNA of HcPGRPS1 is constitutively expressed in a wide range of all tested tissues, with highest expression level in hepatopancreas, and its expression in tissues (gonad, nephridium, gill and foot) was up-regulated significantly after LPS or PGN stimulation (P<0.05). The recombinant protein of HcPGRPS1 exhibited binding activity and peptidoglycan-lytic amidase activity toward Lys-PGN from Staphylococcus aureus and DAP-PGN from Bacillus subtilis. Furthermore, recombinant HcPGRPS1 displayed strong antibacterial activity to both Gram-negative bacteria Escherichia coli, Aeromonas hydrophila, Aeromonas sobria and Gram-positive bacteria S. aureus in the presence of Zn(2+). These results suggested that HcPGRPS1 plays a multifunctional role in the defense and protection mechanisms of mussel innate immunity against infections.
肽聚糖识别蛋白（PGRPs）在从无脊椎动物到脊椎动物的进化过程中是保守的，它们作为模式识别和效应分子在先天免疫中发挥作用。本研究从淡水贻贝 Hyriopsis cumingi 中鉴定出一种短形式的 PGRP，命名为 HcPGRPS1。HcPGRPS1 的推导氨基酸序列由 235 个残基组成，其 C 末端含有一个保守的 PGRP 结构域。序列分析表明，HcPGRPS1 与其他已知的 PGRPs 具有高度的同一性。HcPGRPS1 的 mRNA 在广泛的所有测试组织中持续表达，在肝胰腺中的表达水平最高，在 LPS 或 PGN 刺激后其在组织（性腺、肾、鳃和足）中的表达显著上调（P<0.05）。HcPGRPS1 的重组蛋白对来自金黄色葡萄球菌的 Lys-PGN 和来自枯草芽孢杆菌的 DAP-PGN 具有结合活性和肽聚糖裂解酰胺酶活性。此外，重组 HcPGRPS1 在存在 Zn(2+)的情况下对革兰氏阴性菌大肠杆菌、嗜水气单胞菌、温和气单胞菌和革兰氏阳性菌金黄色葡萄球菌均显示出强烈的抗菌活性。这些结果表明 HcPGRPS1 在贻贝先天免疫防御和保护机制中对感染具有多功能作用。
