NO-H-NOX-Regulated Two-Component Signaling

Bacteria employ two-component signaling to detect and respond to environmental stimuli. In essence, two-component signaling relies on a protein called a response regulator that can elicit a change in gene expression or protein function in response to phosphoryl transfer from a histidine kinase. Phosphorylation of the associated histidine kinase is regulated by detection of an environmental signal, thus linking sensing to a cellular response. Recently, it has been suggested that H-NOX (heme-nitric oxide/oxygen binding) proteins may act as nitric oxide (NO) sensors in two-component signaling systems. Although this is still a relatively new area of research, herein we review the literature describing a biological function mediated by NO/H-NOX-regulated histidine kinase signaling.