Different patterns of integral membrane protein localization during cell division in Bacillus subtilis

School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia Correspondence P. J. Lewis Peter.Lewis{at}newcastle.edu.au Cell division in rod-shaped bacteria nearly always occurs exactly at mid-cell and is dependent on the formation of the cytokinetic FtsZ ring and its associated division proteins. Many thousands of copies of division, or septum-specific proteins assemble at this site and may lead to the exclusion of other integral membrane proteins that are normally able to diffuse freely throughout the cytoplasmic membrane. In this study we have investigated the localization of a series of integral membrane proteins in Bacillus subtilis and we show that the recruitment of division and septum-specific proteins does not necessarily preclude the diffusion of other integral membrane proteins. However, some proteins, namely ATP synthase and succinate dehydrogenase, are reduced/absent from the mid-cell region at the onset of cell division, which may reflect an association with lipid domains rich in phosphatidylglycerol that are thought to be present at diminished levels at sites of cell division. Abbreviations: CFP, cyan fluorescent protein; CL, cardiolipin; CR, cleared region; GFP, green fluorescent protein; PE, phosphatidylethanolamine; PG, phosphatidylglycerol; YFP, yellow fluorescent protein