The periplasmic nitrate reductase of Thiosphaera pantotropha

The napEDABC locus coding for the periplasmic nitrate reductase of Thiosphaera pantotropha has been cloned and sequenced. The large and small subunits of the enzyme are coded by napA and napB. The sequence of NapA indicates that this protein binds the GMP-conjugated form of the molybdopterin cofactor. Cysteine-181 is proposed to ligate the molybdenum atom. It is inferred that the active site of the periplasmic nitrate reductase is structurally related to those of the molybdenum-dependent formate dehydrogenases and bacterial assimilatory nitrate reductases, but is distinct from that of the membrane-bound respiratory nitrate reductases. A four-cysteine motif at the N-terminus of NapA binds a [4Fe-4S] cluster. The DNA- and protein-derived primary sequence of NapB confirm that this protein is a dihaem c-type cytochrome and, together with spectroscopic data, indicate that both NapB haems have bis-histidine ligation. napC is predicted to code for a membrane-anchored tetrahaem c-type cytochrome that shows sequence similarity to the NirT cytochrome c family. NapC may be the direct electron donor to the NapAB complex. napD is predicted to encode a soluble cytoplasmic protein and napE a monotopic integral membrane protein, napDABC genes can be discerned at the aeg-46.5 locus of Escherichia coli K-12, suggesting that this operon encodes a periplasmic nitrate reductase system, while napD and napC are identified adjacent to the napAB genes of Alcaligenes eutrophus H16.

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Mo(V) Electron Paramagnetic Resonance Signals from the Periplasmic Nitrate Reductase of Thiosphaera Pantotropha

European Journal of Biochemistry ◽

10.1111/j.1432-1033.1994.00789.x ◽

1994 ◽

Vol 226 (3) ◽

pp. 789-798 ◽

Cited By ~ 28

Author(s):

Brian Bennett ◽

Ben C. Berks ◽

Stuart J. Ferguson ◽

Andrew J. Thomson ◽

David J. Richardson

Keyword(s):

Electron Paramagnetic Resonance ◽

Nitrate Reductase ◽

Paramagnetic Resonance ◽

Periplasmic Nitrate Reductase ◽

Thiosphaera Pantotropha ◽

Electron Paramagnetic

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Structural investigation of the molybdenum site of the periplasmic nitrate reductase from Thiosphaera pantotropha by X-ray absorption spectroscopy

Biochemical Journal ◽

10.1042/bj3170557 ◽

1996 ◽

Vol 317 (2) ◽

pp. 557-563 ◽

Cited By ~ 12

Author(s):

Brian BENNETT ◽

John M. CHARNOCK ◽

Heather J. SEARS ◽

Ben C. BERKS ◽

Andrew J. THOMSON ◽

...

Keyword(s):

Nitrate Reductase ◽

Absorption Spectroscopy ◽

X Ray ◽

Periplasmic Nitrate Reductase ◽

Thiosphaera Pantotropha ◽

Treated Sample ◽

Membrane Bound ◽

X Ray Absorption ◽

Best Fit ◽

Respiratory Nitrate Reductase

The molybdenum centre of the periplasmic respiratory nitrate reductase from the denitrifying bacterium Thiosphaera pantotropha has been probed using molybdenum K-edge X-ray absorption spectroscopy. The optimum fit of the Mo(VI) EXAFS suggests two =O, three –S– and either a fourth –S– or an –O–/–N– as molybdenum ligands in the ferricyanide-oxidized enzyme. Three of the –S– ligands are proposed to be the two sulphur atoms of the molybdopterin dithiolene group and Cys-181. Comparison of the EXAFS of the ferricyanide-oxidized enzyme with that of a nitrate-treated sample containing 30% Mo(V) suggests that the Mo(VI) → Mo(V) reduction is accompanied by conversion of one =O to –O–. The best fit to the Mo(IV) EXAFS of dithionite-reduced enzyme was obtained using one =O, one –O– and four –S–/–Cl ligands. The periplasmic nitrate reductase molybdenum co-ordination environment in both the Mo(VI) and Mo(IV) oxidation states is distinct from that found in the membrane-bound respiratory nitrate reductase.

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Faculty Opinions recommendation of Kinetic consequences of the endogenous ligand to molybdenum in the DMSO reductase family: a case study with periplasmic nitrate reductase.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.739398058.793587072 ◽

2021 ◽

Author(s):

Martin Kirk

Keyword(s):

Nitrate Reductase ◽

Endogenous Ligand ◽

Dmso Reductase ◽

Periplasmic Nitrate Reductase

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The periplasmic nitrate reductase of

Journal of Inorganic Biochemistry ◽

10.1016/0162-0134(93)85400-3 ◽

1993 ◽

Vol 51 (1-2) ◽

pp. 369

Author(s):

B.C. Berks ◽

D.J. Richardson ◽

S. Marritt ◽

A.J. Thomson ◽

S.J. Ferguson

Keyword(s):

Nitrate Reductase ◽

Periplasmic Nitrate Reductase

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Oxygen control of nitrogen oxide respiration, focusing on α-proteobacteria

Biochemical Society Transactions ◽

10.1042/bst0390179 ◽

2011 ◽

Vol 39 (1) ◽

pp. 179-183 ◽

Cited By ~ 19

Author(s):

James P. Shapleigh

Keyword(s):

Nitrate Reductase ◽

Nitrogen Oxide ◽

Physiological Function ◽

Physiological Role ◽

Present Review ◽

Oxygen Control ◽

Anoxic Conditions ◽

Periplasmic Nitrate Reductase

Denitrification is generally considered to occur under micro-oxic or anoxic conditions. With this in mind, the physiological function and regulation of several steps in the denitrification of model α-proteobacteria are compared in the present review. Expression of the periplasmic nitrate reductase is quite variable, with this enzyme being maximally expressed under oxic conditions in some bacteria, but under micro-oxic conditions in others. Expression of nitrite and NO reductases in most denitrifiers is more tightly controlled, with expression only occurring under micro-oxic conditions. A possible exception to this may be Roseobacter denitrificans, but the physiological role of these enzymes under oxic conditions is uncertain.

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Compensatory periplasmic nitrate reductase activity supports anaerobic growth ofPseudomonas aeruginosaPAO1 in the absence of membrane nitrate reductase

Canadian Journal of Microbiology ◽

10.1139/w09-065 ◽

2009 ◽

Vol 55 (10) ◽

pp. 1133-1144 ◽

Cited By ~ 19

Author(s):

Nadine E. Van Alst ◽

Lani A. Sherrill ◽

Barbara H. Iglewski ◽

Constantine G. Haidaris

Keyword(s):

Nitrate Reductase ◽

Response Regulator ◽

Reductase Activity ◽

Transcriptional Start Site ◽

Atp Synthesis ◽

Anaerobic Growth ◽

Start Site ◽

Terminal Electron Acceptor ◽

Periplasmic Nitrate Reductase ◽

Growth Recovery

Nitrate serves as a terminal electron acceptor under anaerobic conditions in Pseudomonas aeruginosa . Reduction of nitrate to nitrite generates a transmembrane proton motive force allowing ATP synthesis and anaerobic growth. The inner membrane-bound nitrate reductase NarGHI is encoded within the narK1K2GHJI operon, and the periplasmic nitrate reductase NapAB is encoded within the napEFDABC operon. The roles of the 2 dissimilatory nitrate reductases in anaerobic growth, and the regulation of their expressions, were examined by use of a set of deletion mutants in P. aeruginosa PAO1. NarGHI mutants were unable to grow anaerobically, but plate cultures remained viable up to 120 h. In contrast, the nitrate sensor-response regulator mutant ΔnarXL displayed growth arrest initially, but resumed growth after 72 h and reached the early stationary phase in liquid culture after 120 h. Genetic, transcriptional, and biochemical studies demonstrated that anaerobic growth recovery by the NarXL mutant was the result of NapAB periplasmic nitrate reductase expression. A novel transcriptional start site for napEFDABC expression was identified in the NarXL mutant grown anaerobically. Furthermore, mutagenesis of a consensus NarL-binding site monomer upstream of the novel transcriptional start site restored anaerobic growth recovery in the NarXL mutant. The data suggest that during anaerobic growth of wild-type P. aeruginosa PAO1, the nitrate response regulator NarL directly represses expression of periplasmic nitrate reductase, while inducing maximal expression of membrane nitrate reductase.

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