A composite biochemical system for bacterial nitrate and nitrite assimilation as exemplified by Paracoccus denitrificans

Andrew J. Gates, Victor M. Luque-Almagro, Alan D. Goddard, Stuart J. Ferguson, M. Dolores Roldán, David J. Richardson

Research output: Contribution to journalArticle

Abstract

The denitrifying bacterium Paracoccus denitrificans can grow aerobically or anaerobically using nitrate or nitrite as the sole nitrogen source. The biochemical pathway responsible is expressed from a gene cluster comprising a nitrate/nitrite transporter (NasA), nitrite transporter (NasH), nitrite reductase (NasB), ferredoxin (NasG) and nitrate reductase (NasC). NasB and NasG are essential for growth with nitrate or nitrite as the nitrogen source. NADH serves as the electron donor for nitrate and nitrite reduction, but only NasB has a NADH-oxidizing domain. Nitrate and nitrite reductase activities show the same Km for NADH and can be separated by anion-exchange chromatography, but only fractions containing NasB retain the ability to oxidize NADH. This implies that NasG mediates electron flux from the NADH-oxidizing site in NasB to the sites of nitrate and nitrite reduction in NasC and NasB respectively. Delivery of extracellular nitrate to NasBGC is mediated by NasA, but both NasA and NasH contribute to nitrite uptake. The roles of NasA and NasC can be substituted during anaerobic growth by the biochemically distinct membrane-bound respiratory nitrate reductase (Nar), demonstrating functional overlap. nasG is highly conserved in nitrate/nitrite assimilation gene clusters, which is consistent with a key role for the NasG ferredoxin, as part of a phylogenetically widespread composite nitrate and nitrite reductase system.

Original languageEnglish
Pages (from-to)743-753
Number of pages11
JournalBiochemical Journal
Volume435
Issue number3
DOIs
Publication statusPublished - 1 May 2011

Fingerprint

Paracoccus denitrificans
Nitrites
Nitrates
Composite materials
NAD
Nitrate Reductase
Nitrite Reductases
Multigene Family
Ferredoxin-Nitrite Reductase
Nitrogen
Genes
Ferredoxins
Electrons
Chromatography
Growth
Anions
Bacteria
Fluxes
Membranes

Keywords

  • Nitrate reductase
  • Nitrate transport
  • Nitrite reductase
  • Nitrogen assimilation
  • Paracoccus denitrificans

Cite this

Gates, Andrew J. ; Luque-Almagro, Victor M. ; Goddard, Alan D. ; Ferguson, Stuart J. ; Roldán, M. Dolores ; Richardson, David J. / A composite biochemical system for bacterial nitrate and nitrite assimilation as exemplified by Paracoccus denitrificans. In: Biochemical Journal. 2011 ; Vol. 435, No. 3. pp. 743-753.
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A composite biochemical system for bacterial nitrate and nitrite assimilation as exemplified by Paracoccus denitrificans. / Gates, Andrew J.; Luque-Almagro, Victor M.; Goddard, Alan D.; Ferguson, Stuart J.; Roldán, M. Dolores; Richardson, David J.

In: Biochemical Journal, Vol. 435, No. 3, 01.05.2011, p. 743-753.

Research output: Contribution to journalArticle

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AU - Gates, Andrew J.

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