The role of cysteine in tellurate reduction and toxicity

  title={The role of cysteine in tellurate reduction and toxicity},
  author={Jennifer L. Goff and Maxim I. Boyanov and Kenneth M. Kemner and Nathan W. Yee},
The tellurium oxyanion tellurate is toxic to living organisms even at low concentrations; however, its mechanism of toxicity is poorly understood. Here, we show that exposure of Escherichia coli K-12 to tellurate results in reduction to elemental tellurium (Te[0]) and the formation of intracellular reactive oxygen species (ROS). Toxicity assays performed with E. coli indicated that pre-oxidation of the intracellular thiol pools increases cellular resistance to tellurate—suggesting that… 
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Tellurite reduction by Escherichia coli NDH-II dehydrogenase results in superoxide production in membranes of toxicant-exposed cells

This communication shows that the E. coli ndh gene, encoding NDH-II dehydrogenase, is significantly induced in toxicant-exposed cells and that the enzyme displays tellurite-reducing activity that results in increased superoxide levels in vitro.

Tellurite-mediated thiol oxidation in Escherichia coli.

The results establish that the Te(r) determinants play an important role in maintaining homeostasis of the intracellular reducing environment within gram-negative cells through specific reactions with either TeO3(2-) or thiol:tellurium products.

Glutathione is a target in tellurite toxicity and is protected by tellurite resistance determinants in Escherichia coli.

The presence of plasmid-borne tellurite-resistance determinants kilA and ter protect against the loss of reduced glutathione by as much as 60% over a 2 h exposure, likely key to the resistance mechanism of these determinants.

Tellurate enters Escherichia coli K-12 cells via the SulT-type sulfate transporter CysPUWA

Results indicate that tellurate enters E. coli cells to cause toxic effects via the CysPUWA sulfate transporter, and that implementation of the mutation restored tellurate sensitivity and uptake.

Bacterial Toxicity of Potassium Tellurite: Unveiling an Ancient Enigma

Biochemical, genetic, enzymatic and molecular approaches were used to demonstrate, for the first time, that tellurite (TeO(3) (2-)) toxicity in E. coli involves superoxide formation. This radical is

Tellurite-mediated disabling of [4Fe-4S] clusters of Escherichia coli dehydratases.

Results suggest that tellurite inactivates enzymes of this kind via a superoxide-dependent disabling of their [4Fe-4S] catalytic clusters.

Evidence for a tellurite-dependent generation of reactive oxygen species and absence of a tellurite-mediated adaptive response to oxidative stress in cells of Pseudomonas pseudoalcaligenes KF707

It is concluded that in P. pseudoalcaligenes KF707 cells, the TeO32− acts as a pro-oxidant by stimulating ROS production; the release of superoxide oxyanions is directly linked to the mechanism of toxicity; and TeO 32− is unable to induce an adaptive response to oxidative stress.

Monounsaturated Fatty Acids Are Substrates for Aldehyde Generation in Tellurite-Exposed Escherichia coli

Aldehyde amounts and markers of oxidative damage decreased upon exposure to E. coli containing low MUFA ratios, which was paralleled by a concomitant increase in resistance to ROS-generating compounds.

Tellurite: history, oxidative stress, and molecular mechanisms of resistance.

This review traces the history of Te in its biological interactions, its enigmatic toxicity, importance in cellular oxidative stress, and interaction in cysteine metabolism.