title: The oxpA5 mutation of Aspergillus nidulans is an allele of adB, the gene encoding adenylosuccinate synthetase.
abstract: The oxpA5 mutation in Aspergillus nidulans results in a pleiotropic phenotype, including resistance to oxypurinol and partial constitutivity of the enzymes of purine catabolism. Here we show that the oxpA5 mutation is an allele of adB, the gene encoding adenylosuccinate synthetase (ASS). Cloning, sequencing and characterisation of the adB gene are reported in this paper. In vivo complementation tests indicate that the oxpA5 mutation is a partial loss-of-function mutation, and altered kinetic parameters of the ASS could account for the pleiotropic phenotype of the oxpA5 mutant. The transcriptional regulation of adB presents some interesting features, including increased gene expression in the presence of ammonium and of AMP, the final product of purine biosynthesis. The adB gene is located adjacent to helA, a newly identified gene coding for a putative RNA helicase.
authors.affiliation: Institut de Génétique et Microbiologie, Université Paris XI, Orsay, France.
authors.forename: C
authors.initials: C
authors.lastname: Ribard
authors.forename: C
authors.initials: C
authors.lastname: Scazzocchio
authors.forename: N
authors.initials: N
authors.lastname: Oestreicher
mesh_terms: D000265:Adenylosuccinate Synthase / Q000235:genetics*; D000483:Alleles; D000595:Amino Acid Sequence; D001233:Aspergillus nidulans / Q000201:enzymology / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D025141:Drug Resistance, Fungal; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D010117:Oxypurinol / Q000494:pharmacology; D011687:Purines / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D011687:Purines; D000265:Adenylosuccinate Synthase; D010117:Oxypurinol