Functional fat body proteomics and gene targeting reveal in vivo functions of Drosophila melanogaster α-Esterase-7

Carboxylesterases constitute a large enzyme family in insects, which is involved in diverse functions such as xenobiotic detoxification, lipid metabolism and reproduction. Phylogenetically, many insect carboxylesterases are represented by multienzyme clades, which are encoded by evolutionarily ancient gene clusters such as the alpha-Esterase cluster. Much in contrast to the vital importance attributed to carboxylesterases in general, the in vivo function of individual alpha-Esterase genes is largely unknown. This study employs a functional proteomics approach to identify esterolytic enzymes of the vinegar fly Drosophila melanogaster fat body. One of the fat body carboxylesterases, alpha-Esterase-7, was selected for mutational analysis by gene targeting to generate a deletion mutant fly. Phenotypic characterization of alpha-Esterase-7 null mutants and transgenic flies, which overexpress a chimeric alpha-Esterase-7:EGFP gene, reveals important functions of alpha-Esterase-7 in insecticide tolerance, lipid metabolism and lifespan control. The presented first deletion mutant of any alpha-Esterase in the model insect D. melanogaster generated by gene targeting not only provides experimental evidence for the endogenous functions of this gene family. It also offers an entry point for in vivo structure-function analyses of alpha-Esterase-7, which is of central importance for naturally occurring insecticide resistance in wild populations of various dipteran insect species. (C) 2011 Elsevier Ltd. All rights reserved.