A promoter region binding protein and DNA gyrase regulate anaerobic transcription of nifLA in Enterobacter cloacae

Our work provides evidence that a sequence characteristic of FNR binding si tes, when interacted with by a trans-acting factor, activates anaerobic tra nscription of the nifLA operon in Enterobacter cloacae. DNA gyrase activity has been found to be important for the anaerobic transcription of the nifL A promoter. Our results suggest that anaerobic regulation of the nifLA oper on is mediated through the control of the promoter region-binding trans-act ing factor at the transcriptional level, while DNA supercoiling functions i n providing a topological requirement for the activation of transcription.