Staphylococcus aureus DivIBis a peptidoglycan‐binding protein that is required for a morphological checkpoint in cell division

SummaryBacterial cell division is a fundamental process that requires the coordinated actions of a number of proteins which form a complex macromolecular machine known as the divisome. The membrane‐spanning proteinsDivIBand its orthologueFtsQare crucial divisome components inGram‐positive andGram‐negative bacteria respectively. However, the role of almost all of the integral division proteins, includingDivIB, still remains largely unknown. Here we show that the extracellular domain ofDivIBis able to bind peptidoglycan and have mapped the binding to its β subdomain. Conditional mutational studies show thatdivIBis essential forStaphylococcus aureusgrowth, while phenotypic analyses following depletion ofDivIBresults in a block in the completion, but not initiation, of septum formation. Localisation studies suggest thatDivIBonly transiently localises to the division site and may mark previous sites of septation. We propose thatDivIBis required for a molecular checkpoint during division to ensure the correct assembly of the divisome at midcell and to prevent hydrolytic growth of the cell in the absence of a completed septum.