The sensor histidine kinase belongs to two-component signal transduction systems. It catalyzes the ATP dependent autophosphorylation of a conserved histidine in its phosphoacceptor domain and the signal dependent phosphorylation of a conserved aspartic acid present in the response regulator receiver domain; Contains two transmembrane segments and an N-terminal PAS/PAC domain involved in many signalling proteins where they are used as a signal sensor domain; Localized in the cytoplasmic membrane; Family membership.

Nitrate/nitrite-specific MFS transporter protein; Putatively involved in the uptake of nitrate or extrusion of nitrite; The proteins contains 12 transmembrane segments; Localized in the cytoplasmic membrane; Function unclear.

Respiratory nitrate/nitrite reductase; Bifunctional enzyme involved in the denitrification processes (nitrate respiration). It contains in its N-terminal part a nitrate reductase module required for nitrate assimilation (reducing nitrate to nitrite) using molybdopterin and 1 4Fe-4S cluster as cofactors and in its C-terminal part a nitrite reductase module required for nitrite assimilation (reducing nitrite to ammonia) using FAD, 4Fe-4S cluster and siroheme as cofactors; Belongs to Belongs to the prokaryotic molybdopterin-containing oxidoreductase family and to the nitrite and sulfite r [...]

Nitrate-specific ABC transporter, ATPase component; This protein is the nucleotide-binding domain of the ABC transporters (ABC ATPase) encoded by a different gene of those that encode for the ABC transporter permease component (ABC membrane); Probably part of a high-affinity binding-protein-dependent transport system for nitrate. Probably responsible for energy coupling to the transport system; Family membership.

Nitrate-specific ABC transporter, ATPase component; This protein is the nucleotide-binding domain of the ABC transporters (ABC ATPase) encoded by a different gene of those that encode for the ABC transporter permease component (ABC membrane); Probably part of a high-affinity binding-protein-dependent transport system for nitrate. Probably responsible for energy coupling to the transport system; Family membership.

Nitrate-specific BPD transport, permease component; Probably part of a high-affinity binding-protein-dependent (BPD) transport system for nitrate; probably responsible for the translocation of the substrate across the membrane; Localized in the cytoplasmic membrane by six transmembrane segments; High confidence in function and specificity.

Response regulator proteins are involved in the two-component signal transduction systems to detect and respond to environmental changes. These proteins consist of two domains, an N-terminal response regulator receiver domain that is substrate for a histidine protein kinase sensor, and a variable C-terminal effector domain with DNA- binding activity (here a LuxR-type HTH domain) that acts as transcriptional regulator; Family membership.

Nitrite reductase, small subunit; Protein that consists of a Rieske domain; The rieske domain has a 2Fe-2S centre; Associates with NirB and is required for activity reductase of NirB; High confidence in function and specificity.

Essential component of the nitrate-transporting system. May be the substrate-binding protein; Lipoprotein putatively anchored in the outer membrane or in the cytoplasmic membrane (or in both membranes) by its N-terminal lipidic residue (peripheral membrane protein); High confidence in function and specificity.