Molecular and functional identification of a short-type peptidoglycan recognition protein, PGRP-S, in the Chinese soft-shelled turtle Pelodiscus sinensis.

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.
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