Regulation of Azospirillum brasilense nifA gene expression by ammonium and oxygen.
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.
Fadel-Picheth
C M
CM
Department of Medical Pathology, UFPR, C. Postal 19046, CEP 81531-990, Curitiba, Brazil.
Souza
E M
EM
Rigo
L U
LU
Funayama
S
S
Yates
M G
MG
Pedrosa
F O
FO
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
D001426:Bacterial Proteins; C061338:NifA protein, Bacteria; D000644:Quaternary Ammonium Compounds; D014157:Transcription Factors; D010100:Oxygen