title: Unusual mechanism of hydrocarbon formation in the housefly: cytochrome P450 converts aldehyde to the sex pheromone component (Z)-9-tricosene and CO2.
abstract: An unusual mechanism for hydrocarbon biosynthesis is proposed from work examining the formation of (Z)-9-tricosene (Z9-23:Hy), the major sex pheromone component of the female housefly, Musca domestica. Incubation of (Z)-15-[1-14C]- and (Z)-15-[15,16-3H2]tetracosenoic acid (24:1 fatty acid) with microsomes from houseflies gave equal amounts of [3H]Z9-23:Hy and 14CO2. The formation of CO2 and not CO, as reported for hydrocarbon formation in plants, animals, and microorganisms [Dennis, M. & Kolattukudy, P. E. (1992) Proc. Natl. Acad. Sci. USA 89, 5306-5310], was verified by trapping agents and by radio-GLC analysis. Incubation of (Z)-15-[15,16-3H2]tetracosenoyl-CoA with microsomal preparations in the presence of NADPH and O2 gave almost equal amounts of (Z)-15-3H2]tetrasosenal (24:1 aldehyde) and Z9-23:Hy. Addition of increasing amounts of hydroxylamine (aldehyde trapping agent) caused a decrease in hydrocarbon formation with a concomitant increase in oxime (aldehyde derivative) formation. The 24:1 aldehyde was efficiently converted to (Z)-9-tricosene only in the presence of both NADPH and O2. Bubbling carbon monoxide (20:80 CO/O2) or including an antibody against housefly cytochrome P450 reductase inhibited the formation Z9-23:Hy from 24:1 aldehyde. These data demonstrate an unusual mechanism for hydrocarbon formation in insects in which the acyl-CoA is reduced to the corresponding aldehyde and then carbon-1 is removed as CO2. The requirement for NADPH and O2 and the inhibition by CO and the antibody to cytochrome P450 reductase strongly implicate the participation of a cytochrome P450 in this reaction.
authors.affiliation: Department of Biochemistry, University of Nevada, Reno 89557-0014.
authors.forename: J R
authors.initials: JR
authors.lastname: Reed
authors.forename: D
authors.initials: D
authors.lastname: Vanderwel
authors.forename: S
authors.initials: S
authors.lastname: Choi
authors.forename: J G
authors.initials: JG
authors.lastname: Pomonis
authors.forename: R C
authors.initials: RC
authors.lastname: Reitz
authors.forename: G J
authors.initials: GJ
authors.lastname: Blomquist
mesh_terms: D000447:Aldehydes / Q000378:metabolism; D000475:Alkenes / Q000378:metabolism*; D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D002250:Carbon Radioisotopes; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D005229:Fatty Acids, Monounsaturated / Q000378:metabolism*; D005260:Female; D006793:Houseflies / Q000201:enzymology*; D006838:Hydrocarbons / Q000378:metabolism; D007700:Kinetics; D008861:Microsomes / Q000201:enzymology*; D010675:Pheromones / Q000096:biosynthesis*; D011865:Radioisotope Dilution Technique; D014316:Tritium
chemical_list: D000447:Aldehydes; D000475:Alkenes; D002250:Carbon Radioisotopes; D005229:Fatty Acids, Monounsaturated; D006838:Hydrocarbons; D010675:Pheromones; D014316:Tritium; D002245:Carbon Dioxide; C064583:tetracosenoic acid; C003646:muscalure; D003577:Cytochrome P-450 Enzyme System