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Gene Review

narK  -  nitrate/nitrite transporter

Escherichia coli str. K-12 substr. MG1655

Synonyms: ECK1217, JW1214
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Disease relevance of narK


High impact information on narK


Chemical compound and disease context of narK


Biological context of narK

  • The protein is considered to play a role as a transcriptional activator of the nitrate reductase operon, narCHJI, and the narK gene [1].
  • Loss of transport activity was recovered by transforming the mutant with a narK+ plasmid [6].
  • Based on the kinetics of nitrate reduction and of nitrite reduction and excretion in growing cultures and in washed cell suspensions, it is proposed that the narK gene encodes a nitrate/nitrite antiporter which facilitates anaerobic nitrate respiration by coupling the excretion of nitrite to nitrate uptake [5].

Associations of narK with chemical compounds

  • Disruption of fnr abolished both nitrate and fumarate utilization as electron acceptors and anaerobic induction of narK [2].
  • The failure of nitrate to suppress the reduction of trimethylamine N-oxide in narK mutants was not due to a change in the level of trimethylamine N-oxide reductase but apparently resulted from a relative decrease in the rate of anaerobic nitrate reduction caused by the loss of the antiporter system [5].

Regulatory relationships of narK

  • In chemostat competition experiments, a strain expressing only narU had a selective advantage relative to a strain expressing only narK during nutrient starvation or very slow growth, but NarK(+) bacteria had a much greater selective advantage during rapid growth [7].
  • By measuring nitrate and nitrite transport abilities of strains expressing only narK or expressing both narK and nirC, we hypothesized that NarK might function as a primary nitrate-nitrite antiporter [8].

Other interactions of narK

  • Homology between narU and narK on the one hand and narZYWV and narGHJI on the other hand is limited to the coding regions [9].


  1. The narX and narL genes encoding the nitrate-sensing regulators of Escherichia coli are homologous to a family of prokaryotic two-component regulatory genes. Nohno, T., Noji, S., Taniguchi, S., Saito, T. Nucleic Acids Res. (1989) [Pubmed]
  2. Anaerobic transcription activation in Bacillus subtilis: identification of distinct FNR-dependent and -independent regulatory mechanisms. Cruz Ramos, H., Boursier, L., Moszer, I., Kunst, F., Danchin, A., Glaser, P. EMBO J. (1995) [Pubmed]
  3. Bacillus subtilis Fnr senses oxygen via a [4Fe-4S] cluster coordinated by three cysteine residues without change in the oligomeric state. Reents, H., Gruner, I., Harmening, U., Böttger, L.H., Layer, G., Heathcote, P., Trautwein, A.X., Jahn, D., Härtig, E. Mol. Microbiol. (2006) [Pubmed]
  4. Regulation of narK gene expression in Escherichia coli in response to anaerobiosis, nitrate, iron, and molybdenum. Kolesnikow, T., Schröder, I., Gunsalus, R.P. J. Bacteriol. (1992) [Pubmed]
  5. NarK enhances nitrate uptake and nitrite excretion in Escherichia coli. DeMoss, J.A., Hsu, P.Y. J. Bacteriol. (1991) [Pubmed]
  6. The narK gene product participates in nitrate transport induced in Escherichia coli nitrate-respiring cells. Noji, S., Nohno, T., Saito, T., Taniguchi, S. FEBS Lett. (1989) [Pubmed]
  7. Role of the Escherichia coli nitrate transport protein, NarU, in survival during severe nutrient starvation and slow growth. Clegg, S.J., Jia, W., Cole, J.A. Microbiology (Reading, Engl.) (2006) [Pubmed]
  8. Nitrate and nitrite transport in Escherichia coli. Jia, W., Cole, J.A. Biochem. Soc. Trans. (2005) [Pubmed]
  9. Organization of the nar genes at the chlZ locus. Bonnefoy, V., Ratouchniak, J., Blasco, F., Chippaux, M. FEMS Microbiol. Lett. (1997) [Pubmed]
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