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The role of cysteine in tellurate reduction and toxicity

Abstract

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 intracellular thiols are important in tellurate toxicity. X-ray absorption spectroscopy experiments demonstrated that cysteine reduces tellurate to elemental tellurium. This redox reaction was found to generate superoxide anions. These results indicate that tellurate reduction to Te(0) by cysteine is a source of ROS in the cytoplasm of tellurate-exposed cells.

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Acknowledgements

This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility, operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. We thank the MRCAT beamline staff for assistance during data collection at the synchrotron. MIB and KMK were supported by the Argonne Wetlands Hydrobiogeochemistry Scientific Focus Area funded by the Environmental System Science Program, Office of Biological and Environmental Research, Office of Science, U.S. Department of Energy (DOE), under contract DE-AC02-06CH11357. MRCAT/EnviroCAT operations are supported by DOE and the MRCAT/EnviroCAT member institutions.

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Correspondence to Jennifer L. Goff.

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Goff, J.L., Boyanov, M.I., Kemner, K.M. et al. The role of cysteine in tellurate reduction and toxicity. Biometals 34, 937–946 (2021). https://doi.org/10.1007/s10534-021-00319-8

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  • DOI: https://doi.org/10.1007/s10534-021-00319-8

Keywords

  • Escherichia coli
  • Metalloids
  • Tellurium
  • Tellurate
  • Tellurate toxicity