The role of a novel cytochrome b-costaining nitrate reductase and quinone in the invitro reconstruction of formate-nitrate reductase activity of E. coli.

Enoch, Harry G.; Lester, Robert L.

doi:10.1016/s0006-291x(74)80416-x

Cited by 98 publications

(48 citation statements)

References 12 publications

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“…wt 150 000 and 66 000) are from nitrate reductase itself, and 3' (mol. wt 20 000) is the haem-bearing polypeptide of cytochrome b~ O 3 [ 1,6,13]. The extent to which these subunits are labelled from the periplasmic or the cytoplasmic surface of the cytoplasmic membrane is shown in fig.2 (A and B respectively).…”

Section: Resultsmentioning

confidence: 99%

“…Two components of this pathway which are induced by nitrate are, a b-type cytochrome (cyt: -vss6~-NO' 3) and nitrate reductase itself [1 ]. The transfer of one pair of reducing equivalents from UQH~, through ~yt h NO3 to nitrate reductase v556 and NO~ is accompanied by the outward translocation of two protons across the cytoplasmic membrane [23].…”

Section: Introductionmentioning

confidence: 99%

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A Transmembrane location for the proton‐translocating reduced ubiquinone→ nitrate reductase segment of the respiratory chain of Escherichia coli

Boxer

Clegg

1975

FEBS Letters

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Transmembrane location for the proton‐translocating reduced ubiquinone→ nitrate reductase segment of the respiratory chain of Escherichia coli

Boxer

Clegg

1975

FEBS Letters

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“…It couples the oxidation of physiological substrates, especially formate [3,4], to the reduction of nitrate and generation of a proton gradient [5]. The active site of the enzyme is within the α subunit, NarG, which faces the cytoplasm and co-ordinates a molybdopterin guanine dinucleotide cofactor [6][7][8]. Electrons are sequentially transferred to the α subunit from the quinone pool via the γ subunit, a b-type cytochrome that is thought to contain the quinol oxidation site, and the β subunit which is a non-haem iron-sulphur protein [9].…”

Section: Introductionmentioning

confidence: 99%

Essential roles for the products of the napABCD genes, but not napFGH, in periplasmic nitrate reduction by Escherichia coli K-12

Potter

Cole

1999

Biochemical Journal

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The seven nap genes at minute 47 on the Escherichia coli K-12 chromosome encode a functional nitrate reductase located in the periplasm. The molybdoprotein, NapA, is known to be essential for nitrate reduction. We now demonstrate that the two c-type cytochromes, the periplasmic NapB and the membrane-associated NapC, as well as a fourth polypeptide, NapD, are also essential for nitrate reduction in the periplasm by physiological substrates such as glycerol, formate and glucose. None of the three iron-sulphur proteins, NapF, NapG or NapH, are essential, irrespective of whether the bacteria are grown anaerobically in the presence of nitrate or fumarate as a terminal electron acceptor, or by glucose fermentation. Mutation of napD resulted in the total loss of Methyl Viologen-dependent nitrate reductase activity of the molybdoprotein, NapA, consistent with an earlier suggestion by others that NapD might be required for post-translational modification of NapA.

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“…Quinones or menaquinones donate electrons directly to the nitrate reductase complex in many of the gram-negative bacteria studied to date (13,20,37). The quinone is postulated to be involved in the proton pump mechanism for energy generation (36), while the cytochrome b transfers electrons to the iron-molybdenum centers of the nitrate reductase and thereby to nitrate.…”

mentioning

confidence: 99%

“…The use of nonionic detergents to solubilize NR from B. stearothermophilus provided greater stability (11). Unlike the respiratory NR solubilized from the membranes of gram-negative bacteria with nonionic detergents (10,12,20), enzyme extracted from bacilli with deoxycholate lacked cytochrome (44).…”

mentioning

confidence: 99%

Menaquinol-nitrate oxidoreductase of Bacillus halodenitrificans

et al. 1991

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When grown anaerobically on nitrate-containing medium, Bacillus halodenitrificans exhibited a membranebound nitrate reductase (NR) that was solubilized by 2% Triton X-100 but not by 1% cholate or deoxycholate. Purification on columns of DE-52, hydroxylapatite, and Sephacryl S-300 yielded reduced methyl viologen NR (MVH-NR) with specific activities of 20 to 35 U/mg of protein that was stable when stored in 40% sucrose at -20°C for 6 weeks. 3-[(3-cholamidopr6pyl)dimethylammonio]-2-hydroxypropone-l-sulfonate (CHAPSO) and dodecyl-o-D-maltoside stimulated enzyme activity three-to fourfold. Membrane extractions yielded purified NR that separated after electrophoresis into a 145-kDa a subunit, a 58-kDa I8 subunit, and a 23-kDa y subunit. The electronic spectrum of dithionite-reduced, purified NR displayed peaks at 424.6, 527, and 557 nm, indicative of the presence of a cytochrome b, an interpretation consistent with the pyridine hemochrome spectrum formed. Analyses revealed a molybdenum-heme-non-heme iron ratio of 1:1:8 for the NR and the presence of molybdopterin. Electron paramagnetic resonance (EPR) signals characteristic of iron-sulfur centers were detected at low temperature. EPR also revealed a minor signal centered in the g = 2 region of the spectra. Upon reduction with dithionite, the enzyme displayed signals at g = 2.064, 2.026, 1.906, and 1.888, indicative of the presence of low-potential iron-sulfur centers, which resolve most probably as two [4Fe-4S]+1 clusters. With menadiol as the substrate for nitrate reduction, the Km for nitrate was 50-fold less than that seen when MVH was the electron donor. The cytochrome b557-containing enzyme from B. halodenitrificans is characterized as a menaquinol-nitrate:oxidoreductase.

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The role of a novel cytochrome b-costaining nitrate reductase and quinone in the invitro reconstruction of formate-nitrate reductase activity of E. coli.

Cited by 98 publications

References 12 publications

A Transmembrane location for the proton‐translocating reduced ubiquinone→ nitrate reductase segment of the respiratory chain of Escherichia coli

A Transmembrane location for the proton‐translocating reduced ubiquinone→ nitrate reductase segment of the respiratory chain of Escherichia coli

Essential roles for the products of the napABCD genes, but not napFGH, in periplasmic nitrate reduction by Escherichia coli K-12

Menaquinol-nitrate oxidoreductase of Bacillus halodenitrificans

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