EzrA coordinates septal organization and nucleoid occlusion in Staphylococcus aureus

Abstract

Envelope biogenesis in Staphylococcus aureus is concentrated at the septum and encompasses peptidoglycan synthesis, teichoic acid production, and the targeted secretion and anchoring of YSIRK/GXXS signal peptide-bearing surface proteins. How S. aureus spatially restricts these processes to the dividing crosswall remains unclear. EzrA is a membrane-anchored protein structurally related to eukaryotic spectrins that has been implicated in linking cell division to envelope synthesis, yet its precise contribution remains undefined. Here, we show that EzrA spatially couples peptidoglycan synthesis with the surface display of septal proteins. In ezrA null cells, newly synthesized peptidoglycan is incorporated in a dispersed pattern rather than confined to the septum, teichoic acid synthesis is increased, and surface protein display is elevated. In wild-type cells, nascent peptidoglycan and nascent Staphylococcal protein A anchoring sites colocalize at the septum; this spatial coupling is lost in the absence of EzrA. ezrA null cells also exhibit impaired nucleoid occlusion, with septal ingression over the chromosome leading to chromosome guillotining. Together, these findings suggest that EzrA constitutes a spatial organizing system at the septum, coordinating multiple envelope biogenesis processes while linking septal organization to nucleoid occlusion, a parallel spatial positioning system, to ensure faithful chromosome segregation and cytokinesis.