Nitric oxide is an obligate bacterial nitrification intermediate produced by hydroxylamine oxidoreductase

Ammonia (NH )-oxidizing bacteria (AOB) emit substantial amounts of nitric oxide (NO) and nitrous oxide (N O), both of which contribute to the harmful environmental side effects of large-scale agriculture. The currently accepted model for AOB metabolism involves NH oxidation to nitrite (NO ) via a si...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS Vol. 114; no. 31; p. 8217
Main Authors: Caranto, Jonathan D, Lancaster, Kyle M
Format: Journal Article
Language:English
Published: United States 01.08.2017
Subjects:
nitric oxide
nitrification
enzymology
bioinorganic chemistry
ISSN:1091-6490, 1091-6490
Online Access:Get more information
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Summary:Ammonia (NH )-oxidizing bacteria (AOB) emit substantial amounts of nitric oxide (NO) and nitrous oxide (N O), both of which contribute to the harmful environmental side effects of large-scale agriculture. The currently accepted model for AOB metabolism involves NH oxidation to nitrite (NO ) via a single obligate intermediate, hydroxylamine (NH OH). Within this model, the multiheme enzyme hydroxylamine oxidoreductase (HAO) catalyzes the four-electron oxidation of NH OH to NO We provide evidence that HAO oxidizes NH OH by only three electrons to NO under both anaerobic and aerobic conditions. NO observed in HAO activity assays is a nonenzymatic product resulting from the oxidation of NO by O under aerobic conditions. Our present study implies that aerobic NH oxidation by AOB occurs via two obligate intermediates, NH OH and NO, necessitating a mediator of the third enzymatic step.
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ISSN:1091-6490
1091-6490
DOI:10.1073/pnas.1704504114