Globin domain of Escherichia coli flavohemoglobin (Hmp) and related proteins
Flavohemoglobins (flavoHbs) function primarily as nitric oxide dioxygenases (NODs, EC 1.14.12.17), converting NO and O2 to inert NO3- (nitrate). They have an N-terminal globin domain and a C-terminal ferredoxin reductase-like NAD- and FAD-binding domain, and use the reducing power of cellular NAD(P)H to drive regeneration of the ferrous heme. They protect from nitrosative stress (the broad range of cellular toxicities caused by NO), and modulate NO signaling pathways. This subfamily includes Vibrio fischeri Hmp and E.coli Hmp. NO scavenging by flavoHb affects the swarming behavior of Escherichia coli, and protects against NO during initiation of the squid-Vibrio symbiosis. E.coli Hmp can catalyze the reduction of several alkylhydroperoxide substrates into their corresponding alcohols using NADH as an electron donor, and it has been suggested that it participates in the repair of the lipid membrane oxidative damage generated during oxidative/nitrosative stress.
Jiyao W et al.(2023). "The conserved domain database in 2023.",