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Title: Mechanisms of Chromium and Uranium Toxicity in Pseudomonas stutzeri RCH2 Grown under Anaerobic Nitrate-Reducing Conditions

Abstract

Chromium and uranium are highly toxic metals that contaminate many natural environments. We investigated their mechanisms of toxicity under anaerobic conditions using nitrate-reducing Pseudomonas stutzeri RCH2, which was originally isolated from a chromium-contaminated aquifer. A random barcode transposon site sequencing library of RCH2 was grown in the presence of the chromate oxyanion (Cr[VI]O$$2-\atop{4}$$) or uranyl oxycation (U[VI]O$$2+\atop{2}$$). Strains lacking genes required for a functional nitrate reductase had decreased fitness as both metals interacted with heme-containing enzymes required for the later steps in the denitrification pathway after nitrate is reduced to nitrite. Cr[VI]-resistance also required genes in the homologous recombination and nucleotide excision DNA repair pathways, showing that DNA is a target of Cr[VI] even under anaerobic conditions. The reduced thiol pool was also identified as a target of Cr[VI] toxicity and psest_2088, a gene of previously unknown function, was shown to have a role in the reduction of sulfite to sulfide. U[VI] resistance mechanisms involved exopolysaccharide synthesis and the universal stress protein UspA. Finally, as the first genome-wide fitness analysis of Cr[VI] and U[VI] toxicity under anaerobic conditions, this study provides new insight into the impact of Cr[VI] and U[VI] on an environmental isolate from a chromium contaminated site, as well as into the role of a ubiquitous protein, Psest_2088.

Authors:
 [1];  [1];  [1];  [2];  [3];  [1];  [1];  [2];  [3];  [3];  [2];  [1]
  1. Univ. of Georgia, Athens, GA (United States). Dept. of Biochemistry and Molecular Biology
  2. Univ. of Missouri, Columbia, MO (United States). Dept. of Biochemistry
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Environmental Genomics and Systems Biology Division
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1476524
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Frontiers in Microbiology
Additional Journal Information:
Journal Volume: 8; Journal Issue: AUG; Journal ID: ISSN 1664-302X
Publisher:
Frontiers Research Foundation
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 59 BASIC BIOLOGICAL SCIENCES; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; anaerobes; nitrate reductase; transposon mutagenesis; metals; heavy; contaminated groundwater

Citation Formats

Thorgersen, Michael P., Lancaster, W. Andrew, Ge, Xiaoxuan, Zane, Grant M., Wetmore, Kelly M., Vaccaro, Brian J., Poole, Farris L., Younkin, Adam D., Deutschbauer, Adam M., Arkin, Adam P., Wall, Judy D., and Adams, Michael W. W.. Mechanisms of Chromium and Uranium Toxicity in Pseudomonas stutzeri RCH2 Grown under Anaerobic Nitrate-Reducing Conditions. United States: N. p., 2017. Web. doi:10.3389/fmicb.2017.01529.
Thorgersen, Michael P., Lancaster, W. Andrew, Ge, Xiaoxuan, Zane, Grant M., Wetmore, Kelly M., Vaccaro, Brian J., Poole, Farris L., Younkin, Adam D., Deutschbauer, Adam M., Arkin, Adam P., Wall, Judy D., & Adams, Michael W. W.. Mechanisms of Chromium and Uranium Toxicity in Pseudomonas stutzeri RCH2 Grown under Anaerobic Nitrate-Reducing Conditions. United States. doi:10.3389/fmicb.2017.01529.
Thorgersen, Michael P., Lancaster, W. Andrew, Ge, Xiaoxuan, Zane, Grant M., Wetmore, Kelly M., Vaccaro, Brian J., Poole, Farris L., Younkin, Adam D., Deutschbauer, Adam M., Arkin, Adam P., Wall, Judy D., and Adams, Michael W. W.. Thu . "Mechanisms of Chromium and Uranium Toxicity in Pseudomonas stutzeri RCH2 Grown under Anaerobic Nitrate-Reducing Conditions". United States. doi:10.3389/fmicb.2017.01529. https://www.osti.gov/servlets/purl/1476524.
@article{osti_1476524,
title = {Mechanisms of Chromium and Uranium Toxicity in Pseudomonas stutzeri RCH2 Grown under Anaerobic Nitrate-Reducing Conditions},
author = {Thorgersen, Michael P. and Lancaster, W. Andrew and Ge, Xiaoxuan and Zane, Grant M. and Wetmore, Kelly M. and Vaccaro, Brian J. and Poole, Farris L. and Younkin, Adam D. and Deutschbauer, Adam M. and Arkin, Adam P. and Wall, Judy D. and Adams, Michael W. W.},
abstractNote = {Chromium and uranium are highly toxic metals that contaminate many natural environments. We investigated their mechanisms of toxicity under anaerobic conditions using nitrate-reducing Pseudomonas stutzeri RCH2, which was originally isolated from a chromium-contaminated aquifer. A random barcode transposon site sequencing library of RCH2 was grown in the presence of the chromate oxyanion (Cr[VI]O$2-\atop{4}$) or uranyl oxycation (U[VI]O$2+\atop{2}$). Strains lacking genes required for a functional nitrate reductase had decreased fitness as both metals interacted with heme-containing enzymes required for the later steps in the denitrification pathway after nitrate is reduced to nitrite. Cr[VI]-resistance also required genes in the homologous recombination and nucleotide excision DNA repair pathways, showing that DNA is a target of Cr[VI] even under anaerobic conditions. The reduced thiol pool was also identified as a target of Cr[VI] toxicity and psest_2088, a gene of previously unknown function, was shown to have a role in the reduction of sulfite to sulfide. U[VI] resistance mechanisms involved exopolysaccharide synthesis and the universal stress protein UspA. Finally, as the first genome-wide fitness analysis of Cr[VI] and U[VI] toxicity under anaerobic conditions, this study provides new insight into the impact of Cr[VI] and U[VI] on an environmental isolate from a chromium contaminated site, as well as into the role of a ubiquitous protein, Psest_2088.},
doi = {10.3389/fmicb.2017.01529},
journal = {Frontiers in Microbiology},
number = AUG,
volume = 8,
place = {United States},
year = {Thu Aug 10 00:00:00 EDT 2017},
month = {Thu Aug 10 00:00:00 EDT 2017}
}

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Works referenced in this record:

Rapid Quantification of Mutant Fitness in Diverse Bacteria by Sequencing Randomly Bar-Coded Transposons
journal, May 2015

  • Wetmore, Kelly M.; Price, Morgan N.; Waters, Robert J.
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