A delta 9 desaturase gene with a different substrate specificity is responsible for the cuticular diene hydrocarbon polymorphism in Drosophila melanogaster.
Journal - Proceedings of the National Academy of Sciences of the United States of America (UNITED STATES )
Drosophila melanogaster cuticular pheromones consist of unsaturated hydrocarbons with at least one double bond in position 7: 7 tricosene (T) in males and 7,11 heptacosadiene (HD) in females. However, in many African populations like the Tai strain, females possess low levels of 7,11 HD and high levels of its positional isomer 5,9 HD. We have previously isolated a desaturase gene, desat1, from the Canton-S strain (CS), a 7,11 HD-2-rich morph of D. melanogaster. This desaturase is located in 87C, a locus that has been involved in the difference between 7,11 HD and 5,9 HD morphs. Therefore, we have searched for different desaturase isoforms in both strains. We first cloned desat1 in the Tai strain and report here functional expression of desat1 in CS and Tai. In both strains, the Desat1 enzymes have the same Delta9 specificity and preferentially use palmitate as a substrate, leading to the synthesis of omega7 fatty acids. Also found was a desaturase sequence, named desat2, with a homologous catalytic domain and a markedly different N-terminal domain compared with desat1. In CS genome, it lies 3.8 kb upstream of desat1 and is not transcribed in either sex. In the Tai strain, it is expressed only in females and acts preferentially on myristate, leading to the synthesis of omega5 fatty acids. We suggest, therefore, that desat2 might play a control role in the biosynthesis of 5,9 HD hydrocarbons in Tai females and could explain the dienic hydrocarbon polymorphism in D. melanogaster.
|ISSN : ||0027-8424|
|Mesh Heading : ||Amino Acid Sequence Animals Cloning, Molecular Drosophila melanogaster Exons Fatty Acids Female Genes, Insect Genetic Complementation Test Hydrocarbons Introns Isoenzymes Male Molecular Sequence Data Recombinant Proteins Saccharomyces cerevisiae Sequence Alignment Stearoyl-CoA Desaturase Substrate Specificity classification genetics metabolism genetics analysis chemistry metabolism chemistry genetics chemistry genetics metabolism chemistry genetics metabolism genetics chemistry genetics|
|Mesh Heading Relevant : ||Sex Characteristics enzymology genetics metabolism metabolism|