posted on 2019-06-10, 00:00authored byHyun Lee, Susan Boyle-Vavrab, Jinhong Ren, Jamie Jarusiewicz, Lalit Kumar Sharma, Daniel T. Hoagland, Shaohui Yin, Tian Zhu, Kirk E. Hevener, Isabel Ojeda, Richard E. Lee, Robert S. Daum, Michael E. Johnson
Methicillin-resistant Staphylococcus aureus (MRSA) strains that are resistant to all forms of penicillin have become an increasingly common and urgent problem threatening human health. They are responsible for a wide variety of infectious diseases ranging from minor skin abscesses to life-threatening severe infections. The vra operon that is conserved among S. aureus strains encodes a three-component signal transduction system (vraTSR) that is responsible for sensing and responding to cell-wall stress. We developed a novel and multi-faceted assay to identify compounds that potentiate the activity of oxacillin, essentially restoring efficacy of oxacillin against MRSA, and performed high-throughput screening (HTS) to identify oxacillin potentiators. HTS of 13,840 small molecule compounds from an antimicrobial-focused Life Chemicals library, using the MRSA cell-based assay, identified three different inhibitor scaffolds. Checkerboard assays for synergy with oxacillin, RT-PCR assays against vraR expression and direct confirmation of interaction with VraS by surface plasmon resonance (SPR) further verified them to be viable hit compounds. Subsequent structure-activity relationship (SAR) study of the best scaffold with diverse analogs was utilized to improve potency and provides a strong foundation for further development
We would like to thank NIH grant R33AI111760 and ALSAC, St. Jude Children's Research Hospital for funding support. The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright @ American Society for Microbiology.
Lee, Hyan., Boyle-Vavra, S., Ren, Jinhong., Jarusiewicz, Jamie., Sharma, Lalit. Kumar., Hoagland, Daniel, T., . . . Johnson, M. E. (2019). Identification of small molecules exhibiting oxacillin synergy through a novel assay for inhibition of vraTSR expression in methicillin resistant Staphylococcus aureus. Antimicrobial Agents and Chemotherapy.