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

Gates, Andrew J. ORCID: https://orcid.org/0000-0002-4594-5038, Luque‑Almagro, Victor M., Goddard, Alan D., Ferguson, Stuart J., Roldán, M. Dolores and Richardson, David J. ORCID: https://orcid.org/0000-0002-6847-1832 (2011) A composite biochemical system for bacterial nitrate and nitrite assimilation as exemplified by Paracoccus denitrificans. Biochemical Journal, 435 (3). pp. 743-753. ISSN 0264-6021

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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.

Item Type:	Article
Additional Information:	Funding information: This work was supported by the Biotechnology and Biological Sciences Research Council [grant numbers BBE0219991 and BBD5230191]. D.J.R. is a Royal Society and Wolfson Foundation for Merit Award Fellow. M.D.R. thanks the Ministerio de Ciencia y Tecnología for supporting this work [grant numbers BIO2005-07741-C02-01 and BIO2008-04542-C02-01] and the Junta de Andalucía [grant number CVI1728]. V.M.L.-A. was the recipient of a postdoctoral fellowship from the Ministerio de Ciencia y Tecnología, Spain. The authors are also grateful to the U.S. Department of Energy for providing the funds to sequence the genome of Paracoccus denitrificans PD1222.
Faculty \ School:	Faculty of Science > School of Biological Sciences
UEA Research Groups:	Faculty of Science > Research Groups > Molecular Microbiology Faculty of Science > Research Centres > Centre for Molecular and Structural Biochemistry Faculty of Science > Research Groups > Organisms and the Environment
Related URLs:	http://dx.doi.org/10.1042/BJ20101920
Depositing User:	Users 2731 not found.
Date Deposited:	15 Jun 2011 10:37
Last Modified:	24 Sep 2024 09:00
URI:	https://ueaeprints.uea.ac.uk/id/eprint/32581
DOI:	10.1042/BJ20101920

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