title: Mutations in the Bacillus subtilis glnRA operon that cause nitrogen source-dependent defects in regulation of TnrA activity.
abstract: The Bacillus subtilis nitrogen transcriptional factor TnrA is inactive in cells grown with excess nitrogen, e.g., glutamine or glutamate plus ammonium, because feedback-inhibited glutamine synthetase (product of glnA) binds to TnrA and blocks its DNA-binding activity. Two conditional mutations that allow TnrA-dependent gene expression in cells grown with glutamate plus ammonium, but not in glutamine-grown cells, were characterized. One mutant contained a mutation in the glnA ribosome binding site, while the other mutant synthesized a truncated GlnR protein that constitutively repressed glnRA expression. The levels of glutamine synthetase were reduced in both mutants. As a result, when these mutants are grown with excess nitrogen in the absence of glutamine, there is insufficient production of the feedback inhibitors necessary to convert glutamine synthetase into its feedback-inhibited form and TnrA-activated genes are expressed at high levels.
authors.affiliation: Department of Microbiology, Boston University School of Medicine, Boston, Massachusetts 02118, USA. shfisher@bu.edu
authors.forename: Susan H
authors.initials: SH
authors.lastname: Fisher
authors.forename: Lewis V
authors.initials: LV
authors.lastname: Wray
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D001665:Binding Sites / Q000235:genetics; D004268:DNA-Binding Proteins; D015964:Gene Expression Regulation, Bacterial; D005974:Glutamate-Ammonia Ligase / Q000235:genetics / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism; D009154:Mutation / Q000502:physiology; D009584:Nitrogen / Q000378:metabolism*; D009876:Operon / Q000235:genetics; D010641:Phenotype; D012097:Repressor Proteins; D012270:Ribosomes / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C082451:GlnR protein, Streptomyces coelicolor; D012097:Repressor Proteins; C101458:ScgR protein, Bacillus subtilis; D015534:Trans-Activators; D014157:Transcription Factors; D005973:Glutamine; D018698:Glutamic Acid; C081173:glutamine synthetase I; D005974:Glutamate-Ammonia Ligase; D009584:Nitrogen