Abstract
Membrane attack complex/perforin (MACPF) domain containing proteins play crucial roles in the immune systems of various organisms, but their identification, classification and functions in oysters remain largely unknown. This study screened the MACPF domain containing proteins in the genome of oyster Crassostrea gigas, to identify and characterize MACPF containing proteins as well as explore their role in immune priming. In C. gigas, ten CgMACPFs with highly conserved MACPF domains were identified in the oyster genome, and their genes were distributed in four chromosomes. Among these, CgMACPF-1–7 contained only the MACPF domain and CgMACPF-8/9/10 all contained an additional ApeC domain. A search on MEME program identified 12 conserved motifs in CgMACPFs, with CgMACPF-1–5 contained more conserved motif compared with those in CgMACPF-6–10. Based on the phylogenetic analysis with MACPF proteins in other species and structure characteristics, CgMACPF1–5 were classified into MPEG1 subfamily and CgMACPF6–10 in Perforin-1 subfamily. By examining their expression patter during embryonic development and in response to immune stimulation, CgMACPFs in MPEG1 subfamily was found to functioning in embryonic development and were responsive for immune stimulation. And CgMACPFs in PRF1 subfamily (especially CgMACPF-7/8) were involved in immune priming response of oyster. This research characterized the two subfamilies of MACPF domain containing proteins in oyster, and also determined their responsiveness to immune stimulation and involvement in immune priming, which can expand our understanding of MACPF containing proteins in invertebrate immunology.