Structural and functional conservation and divergence among acyl-CoA desaturases of two noctuid species, the corn earworm, Helicoverpa zea, and the cabbage looper, Trichoplusia ni

In this report, we describe the structural and functional analyses of four acyl-CoA desaturase-encoding cDNAs that we isolated from RNA expressed in t he pheromone gland of the com earworm, Helicoverpa zea. We deduced the homo logy relationships of the encoded proteins, designated HzPGDs1, HzPGDs2, Hz PGDs3 and HzFBDs, to each other and to previously described desaturases of the cabbage looper moth, Trichoplusia ni, the fly, Drosophila melanogaster, and other more distantly related organisms. We also isolated genomic DNA f ragments of the four H. zea desaturase-encoding genes, determined the locat ions of introns present in them, and compared them to conserved intron posi tions in reported desaturase genes of other species. We measured the levels of the four desaturase mRNAs in H. zea pheromone glands and larval fat bod ies by RT-PCR. We established the functional identities of the deduced prot eins HzPGDs1 and HzPGDs2, encoded by the two desaturase mRNAs that are diff erentially and abundantly expressed in pheromone glands of sexually mature adult H. Zea females, by functional expression of their encoding cDNAs in a desaturase-deficient mutant, olel, of the yeast Saccharomyces cerevisiae. We compared the unique unsaturated fatty acid profiles of HzPGDs1- and HzPG Ds2-expressing transformants to those of strains expressing previously desc ribed Delta 11 and Delta9 desaturases of T ni. (C) 2001 Elsevier Science Lt d. All rights reserved.