Molecular cloning and characterization of peptidoglycan recognition proteins from the rockfish, Sebastes schlegeli

Peptidoglycan recognition proteins (PGRPs) are innate immune molecules that are structurally conserved through evolution in both invertebrate and vertebrate animals. Here we report the identification and characterization of two long forms of PGRP (SsPGRP-L1 and SsPGRP-L2) from the rockfish, Sebastes schlegeli. The deduced amino acid sequences of SsPGRP-L1 and SsPGRP-L2, 466 and 482 residues respectively, contain the conserved PGRP domain and the four Zn2+-binding amino acid residues required for amidase activity. In addition to peptidoglycan-lytic amidase activity, recombinant SsPGRPs have broad-spectrum antimicrobial activity like zebrafish PGRPs. RT-PCR analysis of total RNA shows that the expression patterns of SsPGRP-L1 and SsPGRP-L2 genes are different, though they are widely expressed in the tissues that come in contact with bacteria. Overall, these data suggest that rockfish PGRPs are involved in the innate host defense of S. schlegeli against bacterial infections.