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Proc Natl Acad Sci U S A. 2015 Apr 7;112(14):4453-8. doi: 10.1073/pnas.1504022112. Epub 2015 Mar 23.

Auranofin exerts broad-spectrum bactericidal activities by targeting thiol-redox homeostasis.

Author information

1
California Institute for Biomedical Research, La Jolla, CA 92037;
2
Howard Hughes Medical Institute and Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461;
3
Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037; and.
4
Department of Pediatrics and Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California at San Diego, La Jolla, CA 92093.
5
California Institute for Biomedical Research, La Jolla, CA 92037; Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037; and schultz@scripps.edu fwang@calibr.org.
6
California Institute for Biomedical Research, La Jolla, CA 92037; schultz@scripps.edu fwang@calibr.org.

Abstract

Infections caused by antibiotic-resistant bacteria are a rising public health threat and make the identification of new antibiotics a priority. From a cell-based screen for bactericidal compounds against Mycobacterium tuberculosis under nutrient-deprivation conditions we identified auranofin, an orally bioavailable FDA-approved antirheumatic drug, as having potent bactericidal activities against both replicating and nonreplicating M. tuberculosis. We also found that auranofin is active against other Gram-positive bacteria, including Bacillus subtilis and Enterococcus faecalis, and drug-sensitive and drug-resistant strains of Enterococcus faecium and Staphylococcus aureus. Our biochemical studies showed that auranofin inhibits the bacterial thioredoxin reductase, a protein essential in many Gram-positive bacteria for maintaining the thiol-redox balance and protecting against reactive oxidative species. Auranofin decreases the reducing capacity of target bacteria, thereby sensitizing them to oxidative stress. Finally, auranofin was efficacious in a murine model of methicillin-resistant S. aureus infection. These results suggest that the thioredoxin-mediated redox cascade of Gram-positive pathogens is a valid target for the development of antibacterial drugs, and that the existing clinical agent auranofin may be repurposed to aid in the treatment of several important antibiotic-resistant pathogens.

KEYWORDS:

Gram-positive; MRSA; auranofin; tuberculosis

PMID:
25831516
PMCID:
PMC4394260
DOI:
10.1073/pnas.1504022112
[Indexed for MEDLINE]
Free PMC Article

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