FEMS Microbiology Letters · 1999 · 31 citations · 23 references
Life SciencesGeneticsMicrobiologyGene ExpressionMicrobial BiotechnologyMicrobial GeneticsBacterial Gene RegulationPlasmid BiologyPlasmid GeneticsPromoter ArchitecturePromoter RecognitionTranscriptional Regulation In ProkaryotesBacterial PromotersDeletion AnalysisGene Promoter BindingGene Promoter RegulationNif Gene RegulationSigma Factor FunctionSigma Factor RecognitionTranscription Start Site Mapping
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.
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