p260/270 expressed in embryonic abdominal leg cells of Bombyx mori can transfer palmitate to peptides

Abstract

During the study on the mechanisms of abdominal leg development in the silkworm Bombyx mori, we found that a high molecular mass protein (p260/270) was expressed specifically in abdominal leg cells during early embryonic stages and disappeared by a late embryonic stage. p260/270 consists of two polypeptides with molecular masses of 260 and 270 kDa. We have established a purification procedure for p260/270 and have raised an antibody against p260/270. Immunoblot analysis of the E(Cα)/E(Cα) (additional crescent) and E(N)/E(N) (new additional crescent) mutants, which lack the Bombyx abdominal- A gene and therefore do not express abdominal legs, demonstrated that the two mutants lacked p260/270. Therefore, we speculate that the expression of p260/270 may be regulated by the Bombyx abdominal-A gene. cDNA cloning and sequencing demonstrated that p260 and p270 have structures similar to that of rat fatty-acid synthase, which synthesizes palmitate. Most of the enzymatic domains for palmitate synthesis were well conserved in the amino acid sequences of p260 and p270, while the thioesterase domains of p260 and p270 were less homologous to that of rat fatty-acid synthase. Purified p260/270 can transfer palmitate to cysteine residues of synthetic peptides in vitro. We propose that p260/270 may be involved in protein palmitoylation and may function in abdominal leg development.