MOLECULAR CHARACTERIZATION OF THE DROSOPHILA-MELANOGASTER URATE OXIDASE GENE, AN ECDYSONE-REPRESSIBLE GENE EXPRESSED ONLY IN THE MALPIGHIAN TUBULES

The urate oxidase (UO) gene of Drosophila melanogaster is expressed during the third-instar larval and adult stages, exclusively within a subset of cells of the Malpighian tubules. The UO gene contains a 69-base-pair intron and encodes mature mRNAs of 1,224, 1,227 and 1,244 nucleotides, depending on the site of 3' endonucleolytic cleavage prior to polyadenylation. A direct repeat, 5'-AAGTGAGAGTGAT-3', is the proposed cis-regulatory element involved in 2-hydroxyecdysone repression of the UO gene. The deduced amino acid sequences of UO of D. melanogaster, rat, mouse and pig and uricase II of soybean show 32 to 38% identity, with 22% of amino acid residues identical in all six species. With use of P-element-mediated germ line transformation, 826 base pairs 5' and approximately 1,200 base pairs 3' of the D. melanogaster UO transcribed region contain all of the cis elements allowing for appropriate temporal regulation and Malpighian tubule-specific expression of the UO gene.