Does not seem to have nitrate reductase activity. Binds 1 [4Fe-4S] cluster per subunit. Binds 1 molybdenum-bis(molybdopterin guanine dinucleotide) (Mo-bis-MGD) cofactor per subunit. Binds 2 heme b groups per subunit. Heme 1 is located at the cytoplasmic interface, heme 2 is located at the extracellular interface. Electrons are transferred from the extracellular to the cytoplasmic heme. A member of the dormancy regulon. Induced in response to reduced oxygen tension (hypoxia), low levels of nitric oxide (NO) and carbon monoxide (CO). It is hoped that this regulon will give insight into the latent, or dormant phase of infection. Induction by hypoxia is independent of nitrate and nitrate levels. No visible phenotype. This protein serves as an immunogenic antigen, inducing gamma-interferon responses in whole-blood cultures from M.tuberculosis-exposed adults in Uganda and South Africa, indicating this might be a good vaccine candidate. In the N-terminal section; belongs to the nitrate reductase alpha subunit family. In the central section; belongs to the NarJ/NarW family. In the C-terminal section; belongs to the nitrate reductase gamma subunit family.