In Klebsiella pneumoniae, the flavoprotein, NifL regulates NifA mediated transcriptional activation of the N2-fixation (nif) genes in response tomolecular O2and investigated the influence of membrane-bound oxidoreduc-tases on nif-regulation by biochemical analysis of purified NifLandbymonitoringNifA-mediated expressionofnifH¢-¢lacZ reporter fusions in different mutant backgrounds. NifL-bound FAD-cofactor was reduced by NADH only in the presence of a redox-mediator or inside-out vesicles derived from anaerobically grown ,.
