A folate inhibitor exploits metabolic differences in Pseudomonas aeruginosa for narrow-spectrum targeting

Connor Chain, Joseph P. Sheehan, Xincheng Xu, Soodabeh Ghaffari, Aneesh Godbole, Hahn Kim, Joel S. Freundlich, Joshua D. Rabinowitz, Zemer Gitai

Research output: Contribution to journalArticlepeer-review


Pseudomonas aeruginosa is a leading cause of hospital-acquired infections for which the development of antibiotics is urgently needed. Unlike most enteric bacteria, P. aeruginosa lacks enzymes required to scavenge exogenous thymine. An appealing strategy to selectively target P. aeruginosa is to disrupt thymidine synthesis while providing exogenous thymine. However, known antibiotics that perturb thymidine synthesis are largely inactive against P. aeruginosa. Here we characterize fluorofolin, a dihydrofolate reductase (DHFR) inhibitor derived from Irresistin-16, that exhibits significant activity against P. aeruginosa in culture and in a mouse thigh infection model. Fluorofolin is active against a wide range of clinical P. aeruginosa isolates resistant to known antibiotics. Metabolomics and in vitro assays using purified folA confirm that fluorofolin inhibits P. aeruginosa DHFR. Importantly, in the presence of thymine supplementation, fluorofolin activity is selective for P. aeruginosa. Resistance to fluorofolin can emerge through overexpression of the efflux pumps MexCD-OprJ and MexEF-OprN, but these mutants also decrease pathogenesis. Our findings demonstrate how understanding species-specific genetic differences can enable selective targeting of important pathogens while revealing trade-offs between resistance and pathogenesis.

Original languageEnglish (US)
Pages (from-to)1207-1219
Number of pages13
JournalNature Microbiology
Issue number5
StatePublished - May 2024

All Science Journal Classification (ASJC) codes

  • Applied Microbiology and Biotechnology
  • Microbiology (medical)
  • Genetics
  • Cell Biology
  • Microbiology
  • Immunology


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