Required for the expression of anaerobic nitric oxide (NO) reductase, acts as a transcriptional activator for at least the norVW operon. Activation also requires sigma-54. Not required for induction of the aerobic NO-detoxifying enzyme NO dioxygenase. Binds to the promoter region of norVW, to a consensus target sequence, GT-(N7)-AC, which is highly conserved among proteobacteria (By similarity). Nitrogen metabolism; nitric oxide reduction. By anaerobic conditions, however not induced by NO alone.