Autolysin-mediated peptidoglycan hydrolysis is required for the surface display of cell wall-anchored proteins.

Peptidoglycan hydrolases, or autolysins, play a critical role in cell wall remodeling and degradation, facilitating bacterial growth, cell division, and cell separation. In the so-called "major" autolysin, Atl, has long been associated with host adhesion; however, the molecular basis underlying this phenomenon remains understudied. To investigate, we used the type V glycopeptide antibiotic complestatin, which binds to peptidoglycan and blocks the activity of autolysins, as a chemical probe of autolysin function. We also generated a chromosomally encoded, catalytically inactive variant of the Atl enzyme. Autolysin-mediated peptidoglycan hydrolysis, in particular Atl-mediated daughter cell separation, was shown to be critical for maintaining optimal surface levels of cell wall-anchored proteins, including the fibronectin-binding proteins (FnBPs) and protein A (Spa). As such, disrupting autolysin function reduced the affinity of for host cell ligands, and negatively impacted early stages of bacterial colonization in a systemic model of infection. Phenotypic studies revealed that Spa was sequestered at the septum of complestatin-treated cells, highlighting that autolysins are required to liberate Spa during cell division. In summary, we reveal the hydrolytic activities of autolysins are associated with the surface display of cell wall-anchored proteins. We demonstrate that by blocking autolysin function, type V glycopeptide antibiotics are promising antivirulence agents for the development of strategies to control infections.