title: Unusual organizational features of the Drosophila Gart locus are not conserved within Diptera.
abstract: The Drosophila Gart locus consists of two genes. One gene encodes three enzymes in the de novo purine nucleotide biosynthesis pathway [glycinamide ribonucleotide synthetase (GARS), aminoimidazole ribonucleotide synthetase (AIRS), and glycinamide ribonucleotide transformylase (GART)]. The second gene lies within an intron of the purine gene and encodes a cuticle protein. To investigate the evolution of the Gart locus, the Chironomus tentans homolog was cloned by screening a genomic DNA library with a polymerase chain reaction product. This study shows that the interesting structural features of this locus conserved in two distant Drosophila species are not found in the Chironomus homolog. These features include the cuticle protein gene nested within an intron and the existence of an alternative transcript to yield a monofunctional enzyme. In addition, the extremely rapid divergence of coding sequence seen for members of the tandemly duplicated AIRS domain in Drosophila is found to be much less rapid in Chironomus.
authors.affiliation: Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98104.
authors.forename: D V
authors.initials: DV
authors.lastname: Clark
authors.forename: S
authors.initials: S
authors.lastname: Henikoff
mesh_terms: D000217:Acyltransferases / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001419:Bacteria / Q000235:genetics; D001483:Base Sequence; D019731:Carbon-Nitrogen Ligases; D002683:Chironomidae / Q000235:genetics; D004175:Diptera / Q000235:genetics*; D004330:Drosophila / Q000235:genetics*; D005658:Fungi / Q000235:genetics; D005796:Genes; D005807:Genes, Overlapping; D019877:Hydroxymethyl and Formyl Transferases; D019476:Insect Proteins; D007438:Introns; D008025:Ligases / Q000235:genetics*; D008969:Molecular Sequence Data; D051026:Phosphoribosylglycinamide Formyltransferase; D010802:Phylogeny; D011506:Proteins / Q000235:genetics; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity
chemical_list: D019476:Insect Proteins; D011506:Proteins; D012333:RNA, Messenger; C047663:cuticle proteins, insects; D019877:Hydroxymethyl and Formyl Transferases; D051026:Phosphoribosylglycinamide Formyltransferase; D000217:Acyltransferases; D008025:Ligases; D019731:Carbon-Nitrogen Ligases; C022380:phosphoribosylaminoimidazole synthase; C022387:phosphoribosylamine-glycine ligase