Identification and characterization of a fatty acyl reductase from a Spodoptera littoralis female gland involved in pheromone biosynthesis

Abstract Fatty acyl‐ C o A reductases ( FAR s), the enzymes that catalyse reduction of a fatty acyl‐ C o A to the corresponding alcohol in insect pheromone biosynthesis, are postulated to play an important role in determining the proportion of each component in the pheromone blend. For the first time, we have isolated and characterized from the E gyptian cotton leaf worm S podoptera littoralis ( L epidoptera: N octuidae) a FAR c DNA ( S lit‐ FAR1 ), which appeared to be expressed only in the pheromone gland and was undetectable in other female tissues, such as fat body, ovaries, wings, legs or thorax. The encoded protein has been successfully expressed in a recombinant system, and the recombinant enzyme is able to produce the intermediate fatty acid alcohols of the pheromone biosynthesis of S . littoralis from the corresponding acyl‐ C o A precursors. The kinetic variables K m and V max, which have been calculated for each acyl‐ C o A pheromone precursor, suggest that in S . littoralis pheromone biosynthesis other biosynthetic enzymes (e.g. desaturases, acetyl transferase) should also contribute to the final ratio of components of the pheromone blend. In a phylogenetic analysis, S lit‐ FAR1 appeared grouped in a cluster of other FAR s involved in the pheromone biosynthesis of other insects, with little or non‐specificity for the natural pheromone precursors.