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Cited by 87Bacterial Genetics and BiotechnologyMetalloenzymes and iron-sulfur proteinsEnzyme Structure and Function

NapGH components of the periplasmic nitrate reductase of Escherichia coli K-12: location, topology and physiological roles in quinol oxidation and redox balancing

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BRONDIJK, T. Harma C., NILAVONGSE, Arjaree, FILENKO, Nina, RICHARDSON, David J., COLE, Jeffrey A.·2004·Biochemical Journal
DOI 10.1042/bj20031115PMC PMC1224043
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Abstract

Nap (periplasmic nitrate reductase) operons of many bacteria include four common, essential components, napD, napA, napB and napC (or a homologue of napC). In Escherichia coli there are three additional genes, napF, napG and napH, none of which are essential for Nap activity. We now show that deletion of either napG or napH almost abolished Nap-dependent nitrate reduction by strains defective in naphthoquinone synthesis. The residual rate of nitrate reduction (approx. 1% of that of napG+H+ strains) is sufficient to replace fumarate reduction in a redox-balancing role during growth by glucose fermentation. Western blotting combined with β-galactosidase and alkaline phosphatase fusion experiments established that NapH is an integral membrane protein with four transmembrane helices. Both the N- and C-termini as well as the two non-haem iron–sulphur centres are located in the cytoplasm. An N-terminal twin arginine motif was shown to be essential for NapG function, consistent with the expectation that NapG is secreted into the periplasm by the twin arginine translocation pathway. A bacterial two-hybrid system was used to show that NapH interacts, presumably on the cytoplasmic side of, or within, the membrane, with NapC. As expected for a periplasmic protein, no NapG interactions with NapC or NapH were detected in the cytoplasm. An in vitro quinol dehydrogenase assay was developed to show that both NapG and NapH are essential for rapid electron transfer from menadiol to the terminal NapAB complex. These new in vivo and in vitro results establish that NapG and NapH form a quinol dehydrogenase that couples electron transfer from the high midpoint redox potential ubiquinone–ubiquinol couple via NapC and NapB to NapA.

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  • The MQH2 couple has a lower midpoint redox potential than UQH2, −70 mV compared to +90 mV.

    “The MQH2 couple has a lower midpoint redox potential than UQH2, −70 mV compared to +90 mV,262”

    From Nitrate and periplasmic nitrate reductases (2014) · cites this paper as [262]

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Authors
BRONDIJK, T. H. C., NILAVONGSE, A., FILENKO, N., RICHARDSON, D. J., & COLE, J. A.
Affiliations
  • University of Birmingham (GB)
  • University of East Anglia (GB)
Corresponding author
  • NILAVONGSE, Arjaree
  • FILENKO, Nina
ORCID
Venue
Biochemical Journal
Publisher
Portland Press Ltd.
Published
2004-04-01
Volume
379
Issue
1
Pages
47-55
ISSN
  • 0264-6021 (ISSN-L)
  • 1470-8728
DOI
10.1042/bj20031115
PMC
PMC1224043
OpenAlex
W1974206082
Cited by
87
References
34
Citations by year
2026: 1 · 2025: 4 · 2023: 1 · 2021: 1 · 2020: 3 · 2019: 3 · 2018: 5 · 2017: 4 · 2016: 2 · 2015: 7 · 2014: 8 · 2013: 7 · 2012: 4
FWCI
3.03
Type
journal article
Language
en
Open access
Locations
  • Biochemical Journal (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
  • University of Birmingham Research Portal (University of Birmingham) (submittedVersion)
  • UEA Digital Repository (University of East Anglia) (submittedVersion)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Bacterial Genetics and Biotechnology
  • Physical Sciences › Energy › Renewable Energy, Sustainability and the Environment › Metalloenzymes and iron-sulfur proteins
  • Physical Sciences › Materials Science › Materials Chemistry › Enzyme Structure and Function
Keywords
periplasmic nitrate reductase, napA, Napf, electron transfer, redox balancing, fumarate reduction, twin-arginine translocation, naphthoquinone synthesis, glucose fermentation, Escherichia coli K-12
MeSH terms
Arginine, Base Sequence, Electron Transport, Escherichia coli, Genes, Bacterial, Molecular Sequence Data, Nitrate Reductases, Nitrites, Operon, Oxidation-Reduction, Oxidoreductases, Recombinant Fusion Proteins, Subcellular Fractions, Ubiquinone, Mutagenesis, Site-Directed, Protein Structure, Secondary, Two-Hybrid System Techniques, Escherichia coli Proteins, Periplasmic Proteins, Nitrate Reductase

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