Cloning and characterization of a new theta-class glutathione-S-transferase (GST) gene, gst-3, from Drosophila melanogaster

We report here on the cloning and characterization of a new theta-class glu tathione-S-transferase (GST) gene, gst-3, from Drosophila melanogaster. Its sequence is distinct from previously characterized Drosophila GST genes, a nd Southern blotting shows no other closely related genes in the genome. In -situ hybridization localizes the gene to chromosome 2 (55D), near gst-2 (5 3F), and clearly separate from the gst-D cluster at 87B. The gene is intron less and appears to possess conventional 5' TATA, Cap and 3' polyadenylatio n signals. A single transcript, approximately 1 kb in size, appears to be e xpressed at high levels in all developmental stages examined. When this gen e is overexpressed using various upstream GAL4 driver systems, no striking phenotypes are observed; however, we detect bristle morphology defects in s ome progeny. The gst-3 gene does not appear to be essential, based upon our observation that mutant flies homozygous for an EP element insertion 5' to the TATA box produce little or no detectable gst-3 mRNA; these flies are v iable and fertile at 25 and 29 degrees C. Nevertheless, the gst-3 gene appe ars to be evolutionarily conserved in other Drosophila species, suggesting that it may be functionally important. (C) 2000 Elsevier Science B.V. All r ights reserved.