1B-10 Subcellular localization of phosphatidylethanolamine in bacteria

Recently, we found that bacterial membranes have heterogeneous distribution of cardiolipin (CL) molecules in B. subtilis cells. By using the CL-specific fluorescent dye 10-N-nonyl-acridine orange (NAO), CL was localized clearly at the septal regions. We found further that phosphatidylethanolamine (PE) was localized mainly at the septal regions by using the tetracyclic polypeptide Ro09-0198 that bound specifically to PE and all phospholipids synthases fused to a green fluorescent protein were localized at the septal regions. The septal localizations of the phospholipids and the synthases might suggest the existence of some machinery to keep the phospholipids in the septal membrane from diffusing out to lateral ones. Similar PE-rich domains were observed at the septal regions in many Bacillus species. In E. coli membranes, however, PB was evenly distributed on the whole membranes and PB-rich domains were not observable unlike the septal localization of CL. Based on these findings, we will discuss on the possible mechanisms of the localization of the phospholipids.