Development of Oxadiazolone Activity-Based Probes Targeting FphE for Specific Detection of <i>Staphylococcus aureus</i> Infections

Abstract

<i>Staphylococcus aureus</i> (<i>S. aureus</i>) is a major human pathogen that is responsible for a wide range of systemic infections. Since its propensity to form biofilms <i>in vivo</i> poses formidable challenges for both detection and treatment, tools that can be used to specifically image <i>S. aureus</i> biofilms are highly valuable for clinical management. Here, we describe the development of oxadiazolone-based activity-based probes to target the <i>S. aureus</i>-specific serine hydrolase FphE. Because this enzyme lacks homologues in other bacteria, it is an ideal target for selective imaging of <i>S. aureus</i> infections. Using X-ray crystallography, direct cell labeling, and mouse models of infection, we demonstrate that oxadiazolone-based probes enable specific labeling of <i>S. aureus</i> bacteria through the direct covalent modification of the FphE active site serine. These results demonstrate the utility of the oxadizolone electrophile for activity-based probes and validate FphE as a target for the development of imaging contrast agents for the rapid detection of <i>S. aureus</i> infections.