Species-specific
sex pheromones released by female moths to attract conspecific male moths are synthesized de novo in the
pheromone gland (PG) via
fatty acid synthesis (FAS). Biosynthesis of moth
sex pheromones is usually regulated by a
neurohormone termed
pheromone biosynthesis activating
neuropeptide (PBAN), a 33-aa
peptide that originates in the subesophageal
ganglion. In the silkmoth, Bombyx mori, cytoplasmic lipid droplets (LDs), which store the
sex pheromone (
bombykol) precursor
fatty acid, accumulate in PG cells prior to eclosion. PBAN activation of the PBAN receptor stimulates lipolysis of the stored LD
triacylglycerols (TAGs) resulting in release of the
bombykol precursor for final modification. While we have previously characterized a number of molecules involved in
bombykol biosynthesis, little is known about the mechanisms of PBAN signaling that regulate the TAG lipolysis in PG cells. In the current study, we sought to further identify genes involved in
bombykol biosynthesis as well as PBAN signaling, by using a subset of 312 expressed-sequence tag (EST) clones that are in either our B. mori PG cDNA library or the public B. mori EST databases, SilkBase and CYBERGATE, and which are preferentially expressed in the PG. Using RT-PCR expression analysis and an RNAi screening approach, we have identified another eight EST clones involved in
bombykol biosynthesis. Furthermore, we have determined the functional role of a clone designated BmACP that encodes B. mori
acyl carrier protein (ACP). Our results indicate that BmACP plays an essential role in the biosynthesis of the
bombykol precursor
fatty acid via the canonical FAS pathway during pheromonogenesis.