title: Regulation of Azospirillum brasilense nifA gene expression by ammonium and oxygen.
abstract: The structure and activity of the nifA promoter of Azospirillum brasilense was studied using deletion analysis. An essential region for nifA promoter activity was identified between nucleotides -67 and -47 from the identified transcription start site. A sequence resembling a sigma(70) recognition site occurs in this region and may constitute the nifA gene promoter. The regulation of the nifA gene was studied in plasmid and chromosomal nifA::lacZ fusions. Full expression was obtained under low oxygen levels and in the absence of ammonium ions. Repression of nifA expression involves a synergistic effect between oxygen and ammonium.
authors.affiliation: Department of Medical Pathology, UFPR, C. Postal 19046, CEP 81531-990, Curitiba, Brazil.
authors.forename: C M
authors.initials: CM
authors.lastname: Fadel-Picheth
authors.forename: E M
authors.initials: EM
authors.lastname: Souza
authors.forename: L U
authors.initials: LU
authors.lastname: Rigo
authors.forename: S
authors.initials: S
authors.lastname: Funayama
authors.forename: M G
authors.initials: MG
authors.lastname: Yates
authors.forename: F O
authors.initials: FO
authors.lastname: Pedrosa
mesh_terms: D019677:Artificial Gene Fusion; D015806:Azospirillum brasilense / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D008969:Molecular Sequence Data; D010100:Oxygen / Q000494:pharmacology*; D010957:Plasmids; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology*; D014157:Transcription Factors / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C061338:NifA protein, Bacteria; D000644:Quaternary Ammonium Compounds; D014157:Transcription Factors; D010100:Oxygen