PMID:15250887

Citation	Ackerley, DF, Gonzalez, CF, Keyhan, M, Blake, R 2nd and Matin, A (2004) Mechanism of chromate reduction by the Escherichia coli protein, NfsA, and the role of different chromate reductases in minimizing oxidative stress during chromate reduction. Environ. Microbiol. 6:851-60
Abstract	Chromate [Cr(VI)] is a serious environmental pollutant, which is amenable to bacterial bioremediation. NfsA, the major oxygen-insensitive nitroreductase of Escherichia coli, is a flavoprotein that is able to reduce chromate to less soluble and less toxic Cr(III). We show that this process involves single-electron transfer, giving rise to a flavin semiquinone form of NfsA and Cr(V) as intermediates, which redox cycle, generating more reactive oxygen species (ROS) than a divalent chromate reducer, YieF. However, NfsA generates less ROS than a known one-electron chromate reducer, lipoyl dehydrogenase (LpDH), suggesting that NfsA employs a mixture of uni- and di-valent electron transfer steps. The presence of YieF, ChrR (another chromate reductase we previously characterized), or NfsA in an LpDH-catalysed chromate reduction reaction decreased ROS generation by c. 65, 40, or 20%, respectively, suggesting that these enzymes can pre-empt ROS generation by LpDH. We previously showed that ChrR protects Pseudomonas putida against chromate toxicity; here we show that NfsA or YieF overproduction can also increase the tolerance of E. coli to this compound.
Links	PubMed Online version:10.1111/j.1462-2920.2004.00639.x
Keywords	Amino Acid Sequence; Chromates/metabolism; Chromates/toxicity; Dihydrolipoamide Dehydrogenase/metabolism; Drug Resistance, Neoplasm; Electron Transport; Electron-Transferring Flavoproteins/metabolism; Escherichia coli/drug effects; Escherichia coli/metabolism; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Gene Dosage; Molecular Sequence Data; Nitroreductases/genetics; Nitroreductases/metabolism; Oxidation-Reduction; Oxidative Stress; Oxidoreductases/physiology; Pseudomonas/genetics; Reactive Oxygen Species/analysis; Sequence Homology, Amino Acid
edit table

Significance

You can help EcoliWiki by summarizing why this paper is useful

Useful Materials and Methods

You can help Ecoliwiki by describing the useful materials (strains, plasmids, antibodies, etc) described in this paper.

Annotations

<annotationlinks/>

EcoliWiki Links

Add links to pages that link here (e.g. gene, product, method pages)

References

See Help:References for how to manage references in EcoliWiki.