Molecular cloning and characterization of biphenyl hydrolase-like (BPHL) protein gene from silkworm, Bombyx mori

Abstract

The cDNA of a biphenyl hydrolase-like (BPHL) protein from Bombyx mori was cloned via rapid amplification of cDNA ends and submitted to GenBank under accession number JN020647. The full-length BmBPHL cDNA was 1161bp, with four exons and three introns. It consisted of a 208bp 5′-terminal untranslated region (UTR) and a 191bp 3′-UTR with three polyadenylation signal sequences AATAAA and a poly(A) tail. The BmBPHL cDNA encodes a 253–amino acid polypeptide with a theoretical isoelectric point of 8.67 and a predicted molecular weight of 28.9kDa. The deduced amino acid sequence of BmBPHL contained an abhydrolase_6 domain and the Gly-X-Ser-X-Gly motif that is characteristic of serine hydrolases. Sequence comparison showed that BmBPHL is 51% identical to Tribolium castaneum BPHL and 50% identical to Nasonia vitripennis BPHL. Phylogenetic analysis revealed that BmBPHL is grouped with insect BPHL proteins, separating from vertebrate BPHLs. The BmBPHL mRNA transcripts were mainly detected in hemolymph and fat body using fluorescent quantitative real-time PCR. In addition, infection with B. mori cytoplasmic polyhedrosis virus (BmCPV) upregulated the relative BmBPHL expression in the hemolymph and midgut. Therefore, BmBPHL may have an important function in the response of silkworms to BmCPV infection.