Genome-Wide Identification of M14 Family Metal Carboxypeptidases in Antheraea pernyi (Lepidoptera: Saturniidae)

The M14 family metal carboxypeptidase genes play an important role in digestion and pathogenic infections in the gut of insects. However, the roles of these genes in Antheraea pernyi (Guérin-Méneville, 1855) remain to be analyzed. In the present study, we cloned a highly expressed M14 metal carboxypeptidase gene (ApMCP1) found in the gut and discovered that it contained a 1,194 bp open reading frame encoding a 397-amino acid protein with a predicted molecular weight of 45 kDa. Furthermore, 14 members of the M14 family metal carboxypeptidases (ApMCP1–ApMCP14) were identified in the A. pernyi genome, with typical Zn_pept domains and two Zn-anchoring motifs, and were further classified into M14A, M14B, and M14D subfamilies. Expression analysis indicated that ApMCP1 and ApMCP9 were mainly expressed in the gut. Additionally, we observed that ApMCP1 and ApMCP9 displayed opposite expression patterns after starvation, highlighting their functional divergence during digestion. Following natural infection with baculovirus NPV, their expression was significantly upregulated in the gut of A. pernyi. Our results suggest that the M14 family metal carboxypeptidase genes are conservatively digestive enzymes and evolutionarily involved in exogenous pathogenic infections.