Identification and chemogenetic profiling of two antimicrobial auranofin analogs in B. cenocepacia K56-2

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Maydaniuk, Dustin
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The Burkholderia cepacia complex (Bcc), a group of Gram-negative multi-drug resistant pathogens are notorious for causing persistent lung infections in people with cystic fibrosis and new antibiotics are needed to treat these infections. One way to find new antimicrobials is to repurpose old drugs for a new use. One such example of this auranofin, which has antimicrobial activity against Gram-positive bacteria, with low to no activity against Gram-negatives. Thus, to create novel antimicrobials for Gram-negatives, specifically Burkholderia cenocepacia, we synthesized chemical analogs of auranofin. I hypothesize auranofin analogs that will be bactericidal against B. cenocepacia K56-2 and other CF pathogens and that the mechanism of action of these antimicrobials can be determined through randomly barcode transposon sequencing (BarSeq). Two auranofin analogs with bactericidal activity against B. cenocepacia determined their mechanism of action. The two auranofin analogs are bactericidal, do not select for resistance, kill persisters, and are well-tolerated by C. elegans and Galleria in toxicity tests. They also inhibit the enzyme thioredoxin reductase. Interestingly, they do not inhibit the structurally and functionally similar protein glutathione reductase. The compounds also cause an increase in reactive oxygen species upon exposure. BarSeq identified the mechanism of action of these compounds include the glutathione system, potentially by protecting from the increase in reactive oxygen species, and purine metabolism, by altering the metabolic state of the bacterium. Thus, we have determined the mechanism of action of these novel therapeutics. We have also shown that BarSeq is able to determine the mechanism of action of novel antimicrobials.
Burkholderia, Auranofin, Antibiotic Resistance, BarSeq, Mechanism of Action