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Cloning and functional expression of a cDNA encoding a pheromone gland-specific acyl-CoA delta(11)-desaturase of the cabbage looper moth, Trichoplusia ni

Knipple, D.C., Rosenfield, C.L., Miller, S.J., Liu, W., Tang, J., Ma, P.W.K., Roelofs, W.L.
Proceedings of the National Academy of Sciences of the United States of America 1998 v.95 no.26 pp. 15287-15292
genetic transformation, gene transfer, messenger RNA, animal glands, Trichoplusia ni, complementary DNA, open reading frames, enzyme activity, unsaturated fatty acids, mutation, Saccharomyces cerevisiae, amino acid sequences, gene expression, genetic complementation, hydrophobicity, molecular weight, stearoyl-CoA desaturase
Desaturation of coenenzyme-A esters of saturated fatty acids is a common feature of sex pheromone biosynthetic pathways in the Lepidoptera. The enzymes that catalyze this step share several biochemical properties with the ubiquitous acyl-Co delta 9-desaturases of animals and fungi, suggesting a common ancestral origin. Unlike metabolic acyl-CoA delta 9-desaturases, pheromone desaturases have evolved unusual regio- and stereoselective activities that contribute to the remarkable diversity of chemical structures used as pheromones in this large taxonomic group. In this report, we describe the isolation of a cDNA encoding a pheromone gland desaturase from the cabbage looper moth, Trichoplusia ni, a species in which all unsaturated pheromone products are produced via a delta 11Z-desaturation mechanism. The largest ORF of the approximate 1,250-bp cDNA encodes a 349-aa apoprotein (PDesat-Tn delta 11Z) with a predicted molecular mass of 40,240 Da. Its hydrophobicity profile is similar overall to those of rat and yeast delta 9-desaturases, suggesting conserved transmembrane topology. A 182-aa core domain delimited by conserved histidine-rich motifs implicated in iron-binding and catalysis has 72 and 58% similarity (including conservative substitutions(to acyl-CoA delta 9Z-desaturases of rat and yeast, respectively. Northern blot analysis revealed an approximately equal to 1,250-nt PDesat-Tn delta 11Z mRNA that is consistent with the spatial and temporal distribution of delta 11-desaturase enzyme activity. Genetic transformation of a desaturase-deficient strain of the yeast Saccharomyces cerevisiae with an expression plasmid encoding PDesat-Tn delta 11Z resulted in complementation of the strain's fatty acid auxotrophy and the production of delta 11Z-unsaturated fatty acids.