Mechanisms of chlorate toxicity and resistance in Pseudomonas aeruginosa
Abstract
Pseudomonas aeruginosa is an opportunistic bacterial pathogen that often encounters hypoxic/anoxic environments within the host, which increases its tolerance to many conventional antibiotics. Towards identifying novel treatments, we explored the therapeutic potential of chlorate, a pro-drug that kills hypoxic/anoxic, antibiotic-tolerant P. aeruginosa populations. While chlorate itself is relatively nontoxic, it is enzymatically reduced to the toxic oxidizing agent, chlorite, by hypoxically-induced nitrate reductase. To better assess chlorate's therapeutic potential, we investigated mechanisms of chlorate toxicity and resistance in P. aeruginosa. We used transposon mutagenesis to identify genes that alter P. aeruginosa fitness during chlorate treatment, finding that methionine sulfoxide reductases (Msr), which repair oxidized methionine residues, support survival during chlorate stress. Chlorate treatment leads to proteome-wide methionine oxidation, which is exacerbated in a ∆msrA∆msrB strain. In response to chlorate, P. aeruginosa upregulates proteins involved in a wide range of functions, including metabolism, DNA replication/repair, protein repair, transcription, and translation, and these newly synthesized proteins are particularly vulnerable to methionine oxidation. The addition of exogenous methionine partially rescues P. aeruginosa survival during chlorate treatment, suggesting that widespread methionine oxidation contributes to death. Finally, we found that mutations that decrease nitrate reductase activity are a common mechanism of chlorate resistance.
Additional Information
© 2022 John Wiley & Sons. Accepted manuscript online: 08 August 2022. Manuscript accepted: 04 August 2022. Manuscript revised: 31 July 2022. Manuscript received: 25 April 2022. Grants to D.K.N. from the NIH (1R21AI146987-02) and the Doren Family Foundation supported this research. M.A.S. was supported by a postdoctoral fellowship from the Cystic Fibrosis Foundation (SPERO19F0). We thank Megan Bergkessel (University of Dundee) for help with Tn-seq analyses, including providing custom scripts, and Nathan Dalleska and the Resnick Water and Environment Laboratory (Caltech) for help with metabolite analyses. We also thank John Bettinger for providing the python code used to analyze methionine oxidation levels via the ¹⁸O-H₂O₂ labeling method that he and colleagues developed (Bettinger et al.) The Proteome Exploration Laboratory was supported by NIH OD010788, NIH OD020013, the Betty and Gordon Moore Foundation through grant GBMF775 and the Beckman Institute at Caltech. Data Availability Statement: The proteomic data that supports the findings of this study are openly available in PRIDE at http://www.ebi.ac.uk/pride, accession number PXD033396.Attached Files
Accepted Version - Molecular_Microbiology_-_2022_-_Spero_-_Mechanisms_of_chlorate_toxicity_and_resistance_in_Pseudomonas_aeruginosa.pdf
Supplemental Material - mmi14972-sup-0001-figs1-s3.docx
Supplemental Material - mmi14972-sup-0002-tables1.xlsx
Supplemental Material - mmi14972-sup-0003-tables2.xlsx
Supplemental Material - mmi14972-sup-0004-tables3.xlsx
Supplemental Material - mmi14972-sup-0005-tables4.xlsx
Supplemental Material - mmi14972-sup-0006-tables5.xlsx
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Additional details
- PMCID
- PMC9589919
- Eprint ID
- 116160
- Resolver ID
- CaltechAUTHORS:20220808-223822000
- NIH
- 1R21AI146987-02
- Doren Family Foundation
- Cystic Fibrosis Foundation
- SPERO19F0
- NIH
- OD010788
- NIH
- OD020013
- Gordon and Betty Moore Foundation
- GBMF775
- Caltech Beckman Institute
- Created
-
2022-08-09Created from EPrint's datestamp field
- Updated
-
2023-06-17Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences, Resnick Sustainability Institute, Division of Biology and Biological Engineering, Division of Biology and Biological Engineering