Chemical Proteomics Reveals Antibiotic Targets of Oxadiazolones in MRSA

Phenotypic screening is a powerful approach to identify novel antibiotics against methicillin-resistant Staphylococcus aureus (MRSA) infection, but elucidation of the targets responsible for antimicrobial activity is often challenging in the case of compounds with a polypharmacological mode-of-action. Here, we show that activity-based protein profiling maps the target interaction landscape of a series of 1,3,4-oxadiazole-3-ones, identified in a phenotypic screen to have high antibacterial potency against multidrug resistant S. aureus. In situ competitive and comparative chemical proteomics with a tailor-made activity-based probe, in combination with transposon and resistance studies, revealed several cysteine and serine hydrolases as relevant targets. Our data showcase oxadiazolones as novel antibacterial chemotype with a polypharmacological mode-of-action, in which FabH, FphC and AdhE play a central role.