title: The yexA gene product is required for phosphoribosylformylglycinamidine synthetase activity in Bacillus subtilis.
abstract: The yexA gene encodes an 84 amino acid reading frame; in Bacillus subtilis it is positioned between the purC and purQ genes of the purine biosynthetic operon. Disruption of yexA resulted in a purine-auxotrophic phenotype. When yexA was expressed in trans it was able to complement a yexA mutation. Growth experiments and enzyme analysis of yexA mutant strains revealed a defective phosphoribosylformylglycinamidine synthetase (FGAM synthetase). In the organisms in which FGAM synthetase has been studied a single polypeptide is responsible for activity. In some organisms two separate genes - in B. subtilis the purL and purQ genes - encode polypeptides with similarity to the N-terminal and the C-terminal region, respectively, of the single-polypeptide FGAM synthetase. Thus, active FGAM synthetase in B. subtilis requires the yexA gene product in addition to the purL and purQ gene products. Open reading frames with sequence similarity to yexA are found in other Gram-positive organisms, in a cyanobacterium and in methanogenic archaea. The designation purS is proposed for this novel function in purine biosynthesis in B. subtilis.
authors.affiliation: Department of Microbiology, Technical University of Denmark, Building 301, DK-2800 Lyngby, Denmark1.
authors.forename: Hans H
authors.initials: HH
authors.lastname: Saxild
authors.affiliation: Department of Biological Chemistry, Institute of Molecular Biology, University of Copenhagen, Sølvgade 83, DK-1307 Copenhagen, Denmark2.
authors.forename: Per
authors.initials: P
authors.lastname: Nygaard
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D019733:Carbon-Nitrogen Ligases with Glutamine as Amide-N-Donor / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D016366:Open Reading Frames / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D019733:Carbon-Nitrogen Ligases with Glutamine as Amide-N-Donor; C022385:phosphoribosylformylglycinamidine synthetase