The <i>narK</i> gene product participates in nitrate transport induced in <i>Escherichia coli</i> nitrate‐respiring cells

Noji, Sumihare; Nohno, Tsutomu; Saito, Taiichi; Taniguchi, Shigehiko

doi:10.1016/0014-5793(89)80906-8

Cited by 85 publications

(61 citation statements)

References 32 publications

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“…The results of the studies on solid cultures also indicate that nitrate uptake into the cytoplasm is not so strictly controlled by oxygen as appears to be the situation in M. tuberculosis, where, although Nar is synthesized constitutively, the synthesis of the nitrate transporter NarK2 is induced when the oxygen concentration is reduced (Sohaskey, 2005;Sohaskey & Modesti, 2009), or in E. coli, where nitrate uptake activity is inhibited by oxygen (Noji & Taniguchi, 1987).…”

Section: Discussionmentioning

confidence: 92%

The obligate aerobe Streptomyces coelicolor A3(2) synthesizes three active respiratory nitrate reductases

et al. 2010

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Streptomyces coelicolor A3(2) synthesizes three membrane-associated respiratory nitrate reductases (Nars). During aerobic growth in liquid medium the bacterium was able to reduce 50 mM nitrate stoichiometrically to nitrite. Construction and analysis of a mutant in which all three narGHJI operons were deleted showed that it failed to reduce nitrate. Deletion of the gene encoding MoaA, which catalyses the first step in molybdenum cofactor biosynthesis, also prevented nitrate reduction, consistent with the Nars being molybdoenzymes. In contrast to the triple narGHJI mutant, the moaA mutant was also unable to use nitrate as sole nitrogen source, which indicates that the assimilatory nitrate reductases in S. coelicolor are also molybdenumdependent. Analysis of S. coelicolor growth on solid medium demonstrated that Nar activity is present in both spores and mycelium (hypha). Development of a survival assay with the nitrate analogue chlorate revealed that wild-type S. coelicolor spores and mycelium were sensitive to chlorate after anaerobic incubation, independent of the presence of nitrate, while both the moaA and triple nar mutants were chlorate-resistant. Complementation of the triple nar mutant with the individual narGHJI operons delivered on cosmids revealed that each operon encoded an enzyme that was synthesized and active in nitrate or chlorate reduction. The data obtained from these studies allow a tentative assignment of Nar1 activity to spores, Nar2 to spores and mycelium, and Nar3 exclusively to mycelium.

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Section: Discussionmentioning

confidence: 92%

The obligate aerobe Streptomyces coelicolor A3(2) synthesizes three active respiratory nitrate reductases

et al. 2010

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“…Regulation of nitrate transport by oxygen has been documented in other bacteria (John, 1977;Noji & Taniguchi, 1987;Hernandez & Rowe, 1988). It is intriguing that M. tuberculosis, classified as an obligate aerobe, should have such intricate control of an anaerobic enzyme system.…”

Section: Discussionmentioning

confidence: 95%

Regulation of nitrate reductase activity in Mycobacterium tuberculosis by oxygen and nitric oxide

Sohaskey

2005

Microbiology

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Nitrate reduction by Mycobacterium tuberculosis is regulated by control of the transport of nitrate into the cell by NarK2. When oxygen was introduced into hypoxic cultures, nitrite production was quickly inhibited. The nitrate-reducing enzyme itself is relatively insensitive to oxygen, suggesting that the inhibition of nitrite production by oxygen was a result of interference with nitrate transport. This was not due to degradation of NarK2, as the inhibition was reversed by the removal of oxygen although chloramphenicol prevented new synthesis of NarK2. The oxidant potassium ferricyanide was added to anaerobic cultures to produce a positive redox potential in the absence of oxygen. Nitrite production decreased, signifying that oxidizing conditions, rather than oxygen itself, were responsible for the inhibition of nitrate transport. Nitric oxide added to cultures allowed NarK2 to be active even in the presence of oxygen. A similar result was obtained with hydroxylamine and ethanol, both of which interfere with oxygen utilization and the electron transport chain. It is proposed that NarK2 senses the redox state of the cell, possibly by monitoring the flow of electrons to cytochrome oxidase, and adjusts its activity so that nitrate is transported under reducing, but not under oxidizing, conditions.

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“…The amino acid identity of the NarK to Pseudomonas fluorescens NarK (Philippot et al, 2001) and E. coli NarK (Noji et al, 1989) was 41% and 37%, respectively. Different from S. ruminantium narK, narK in E. coli and P. fluorescens has been reported to be located upstream of narG (Noji et al, 1989;Philippot et al, 2001). Another narK gene was not found in the region upstream of narG in S. ruminantium.…”

Section: Presence and Arrangement Of Nar G H J And I Genesmentioning

confidence: 99%

Molecular characterization and transcriptional regulation of nitrate reductase in a ruminal bacterium, Selenomonas ruminantium

Asanuma

Iwamoto

Yoshii

et al. 2004

J. Gen. Appl. Microbiol.

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The narK gene product participates in nitrate transport induced in Escherichia coli nitrate‐respiring cells

Cited by 85 publications

References 32 publications

The obligate aerobe Streptomyces coelicolor A3(2) synthesizes three active respiratory nitrate reductases

The obligate aerobe Streptomyces coelicolor A3(2) synthesizes three active respiratory nitrate reductases

Regulation of nitrate reductase activity in Mycobacterium tuberculosis by oxygen and nitric oxide

Molecular characterization and transcriptional regulation of nitrate reductase in a ruminal bacterium, Selenomonas ruminantium

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