Cell-free production of the silkworm sex pheromone bombykol

Cell-free production of bombykol was done by incubating a pheromone gland homogenate in the presence of NADPH, ATP, and CoA. Addition of n-hexane to the reaction mixture stimulated bombykol production, resulting in production of 238 ng of bombykol from the homogenate equivalent to 2 pheromone glands after 23 h. Removal of either NADPH, ATP, or CoA resulted in no stimulation of bombykol production, suggesting that the final step of the bombykol biosynthetic pathway is done by acyl CoA synthetase and reductase, sequentially. Incubation first with ATP or high concentrations of ATP suppressed the production of bombykol. Since incubation with ATP also inhibited conversion of [1-14C]palmitoyl CoA into 1-hexadecanol, the inhibitory action of ATP seemed attributable to inactivation of the acyl CoA reductase by phosphorylation, as mediated by a protein kinase in the homogenate. Our results suggest that the activity of acyl CoA reductase in bombykol biosynthesis is regulated by phosphorylation/dephosphorylation, and that the activation occurs by dephosphorylation as mediated by phosphoprotein phosphatase.