Has nitric oxide reductase activity in combination with FprA; probably involved in nitrosative stress protection. Acts as an NADH:FprA oxidoreductase. Binds 2 iron ions per homodimer. Binds 2 FMN per homodimer. The occupancy is 1.3-1.9. Homodimer. Constitutively expressed. In the N-terminal section; belongs to the flavodoxin reductase family.