Small Molecule Inhibitors of the BfrB–Bfd Interaction Decrease Pseudomonas aeruginosa Fitness and Potentiate Fluoroquinolone Activity
Year: 2019
Type: article
Abstract: The iron storage protein bacterioferritin (BfrB) is central to bacterial iron homeostasis. The mobilization of iron from BfrB, which requires binding by a cognate ferredoxin (Bfd), is essential to the regulation of cytosolic iron levels in P. aeruginosa. This paper describes the structure-guided development of small molecule inhibitors of the BfrB–Bfd protein–protein interaction. The process was initiated by screening a fragment library and followed by obtaining the structure of a fragment hit bound to BfrB. The structural insights were used to develop a series of 4-(benzylamino)- and 4-((3-phenylpropyl)amino)-isoindoline-1,3-dione analogs that selectively bind BfrB at the Bfd binding site. Challenging P. aeruginosa cells with the 4-substituted isoindoline analogs revealed a dose-dependent growth phenotype. Further investigation determined that the analogs elicit a pyoverdin hyperproduction phenotype that is consistent with blockade of the BfrB–Bfd interaction and ensuing irreversible accumulation of iron in BfrB, with concomitant depletion of iron in the cytosol. The irreversible accumulation of iron in BfrB prompted by the 4-substituted isoindoline analogs was confirmed by visualization of BfrB-iron in P. aeruginosa cell lysates separated on native PAGE gels and stained for iron with Ferene S. Challenging P. aeruginosa cultures with a combination of commercial fluoroquinolone and our isoindoline analogs results in significantly lower cell survival relative to treatment with either antibiotic or analog alone. Collectively, these findings furnish proof of concept for the usefulness of small molecule probes designed to dysregulate bacterial iron homeostasis by targeting a protein–protein interaction pivotal for iron storage in the bacterial cell.
DOI: 10.1021/jacs.9b00394
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $5,000
Funders: National Science Foundation, U.S. Department of Energy, Industrial Macromolecular Crystallography Association Collaborative Access Team, National Institutes of Health, Office of Science, National Institute of General Medical Sciences, National Institute of Allergy and Infectious Diseases, National Institute of Diabetes and Digestive and Kidney Diseases, Division of Molecular and Cellular Biosciences, Basic Energy Sciences
Awards: G102163711, G1286251239, Protein Structure and Function, G2237872364, G2287611682, G262962599, G409777406, G426311843, G498139845, G513797252, G5387317844, G5607048534, Protein interactions regulate iron storage and utilization in bacteria, Chemical tools for perturbing iron homeostasis in P. aeruginosa, G6848031779, G6918803902, G7583137537, G8546385581, G8583206708, G8854876071, G9000188091, Center for Cystic Fibrosis Translational Research in the Post-CFTR modulator Era, G969889393, G993149817
OpenAlex ID: W4233096475