PROSITE documentation PDOC50906

Nitrate and nitrite sensing (NIT) domain profile

The nitrate and nitrite sensing (NIT) domain is an about 250-residue sensor domain which has been detected in various receptor components of signal transduction pathways from different bacterial lineages. All proteins which contain a NIT domain belong to one of the four known classes of prokaryotic signal transduction proteins, namely:

• Intracellular transcription anti-termination regulators,
• Sensor histidine kinases,
• Methyl-accepting chemotaxis proteins,
• Diguanylate cyclases and phosphodiesterases.

NIT-containing receptors regulate cellular functions such as gene expression (transcription anti-terminators and histidine kinases), cell motility (chemotaxis receptors) and enzyme activity (diguanylate cyclases and phosphodiesterases), in response to changes in nitrate and/or nitrite concentrations. The NIT domain is found both as an extracellular and an intracellular sensor. It can be found in association with others signalling domains like ANTAR, HAMP (see <PDOC50885>), MCP, Hemerythrins (see <PDOC00476>), CHASE (see <PDOC50839>), GGDEF (see <PDOC50887>), PAS (see <PDOC50112>), EAL (see <PDOC50883>), HK (see <PDOC50109>), GAF, REC and HPt (see <PDOC50894>).

The NIT domain is predicted to be all α-helical. Several conserved charged residues form a signature for the NIT domain: the Glu-Arg couple in α-helix 1, Asp in α-helix 2, Arg in α-helix 3, and the charged residue (Glu or Arg) in α-helix 5. In addition a conserved aromatic residue is found in α-helix 10 [1].

The profile we developed covers the entire core of the NIT domain.