Autolysin-mediated peptidoglycan hydrolysis is required for the surface display of <i>Staphylococcus aureus</i> cell wall-anchored proteins

Abstract

Peptidoglycan hydrolases, or autolysins, play a critical role in cell wall remodeling and degradation, facilitating bacterial growth, cell division, and cell separation. In <i>Staphylococcus aureus,</i> 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 <i>S. aureus</i> cell wall-anchored proteins, including the fibronectin-binding proteins (FnBPs) and protein A (Spa). As such, disrupting autolysin function reduced the affinity of <i>S. aureus</i> for host cell ligands, and negatively impacted early stages of bacterial colonization in a systemic model of <i>S. aureus</i> 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 <i>S. aureus</i> 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 <i>S. aureus</i> infections.