Peptidoglycan recognition proteins (PGRPs), which are discovered in invertebrates and vertebrates, play an important role in antibacterial immunity. However, the function of PGRPs is largely uninvestigated in reptiles. In the present study, a short-type PGRP gene, designed as C-turtle-PGRP-S, was identified in the Chinese soft-shelled turtle, Pelodiscus sinensis. The C-turtle-PGRP-S contains a highly conserved PGRP domain and has close relationship with PGRP-S orthologues in other species according to sequence and phylogenetic analyses. C-turtle-PGRP-S gene was constitutively expressed in all detected tissues and was induced by Edwardsiella tarda. Additionally, recombinant C-turtle-PGRP-S showed PGN binding activity and antibacterial function against E. tarda. Therefore, it is suggested that the function of PGRP-S is likely to be conserved in reptile vertebrates, as observed in other vertebrates, shedding light on the evolutionary conservation of PGRPs.

在无脊椎动物和脊椎动物中发现的肽聚糖识别蛋白 (PGRP) 在抗菌免疫中发挥着重要作用。然而，PGRP 的功能在爬行动物中很大程度上没有得到研究。在本研究中，在中华鳖Pelodiscus sinensis中鉴定出一个短型 PGRP 基因，设计为 C-turtle-PGRP-S 。根据序列和系统发育分析，C-turtle-PGRP-S 包含一个高度保守的 PGRP 结构域，并且与其他物种中的 PGRP-S 直系同源物具有密切的关系。C-turtle-PGRP-S 基因在所有检测到的组织中组成型表达，并由Edwardsiella tarda诱导。此外，重组 C-turtle-PGRP-S 显示出对E. tarda的 PGN 结合活性和抗菌功能. 因此，正如在其他脊椎动物中观察到的那样，PGRP-S 的功能可能在爬行动物脊椎动物中是保守的，这为 PGRPs 的进化保守性提供了启示。