绿尾唇鱼bace2基因的克隆、序列分析、表达与亚细胞定位

Cheilinus chlorourus is an important economic fish species in South China Sea. As a carnivorous fish species lacking stomach, C. chlorourus does not express the pepsinogen gene. In this study, to investigate whether the β-site amyloid precursor protein cleaving enzyme 2(BACE2) functions in hydrolyzing food proteins in C. chlorourus, we employed several analytical techniques. We utilized sequence feature analysis to characterize the gene structure, bioinformatic analysis to predict protein function, and in situ hybridization to assess gene expression patterns of the BACE2 gene in C. chlorourus. The results showed that bace2 has an open reading frame(ORF) of 1 530 bp, encodes 509 amino acids. The BACE2 is highly conserved in Perciformes. It was highly similar with BACE2 from C. undulatus and Siniperca chuatsi. The predicted molecular weight of the protein was 55.27 kDa, and its isoelectric point was 5.10. It was a stable, hydrophilic protein with a signal peptide and two transmembrane domains. It also had three possible N-glycosylation sites and six possible O-glycosylation sites. Its secondary structure was mainly random coils. QRT-PCR analysis showed that bace2 exhibited the highest relative expression level in intestine. In situ hybridization showed that bace2 widely expressed in villi and intestinal crypt. Subcellular localization revealed that BACE2 primarily localized in cell membrane. These results suggested that BACE2 may be secreted by intestinal villus, contributing to the hydrolysis of extracellular proteins. Our findings provided useful information for studying the digestion of C. chlorourus and developing better artificial feeds.