The role of phosphatidic acid in cell division of an E. coli mutant lacking phosphatidylglycerol (PG) and cardiolipin (CL)

Anionic phospholipids, PG and CL, participate in the binding of amphitropic cell division proteins at the bacterial membrane. Behavior of these proteins was studied in E. coli pgsA null mutant UE54, which completely lacks PG and CL. The cells grew slower and were shorter than cells of its parent UE53. In the majority of cells FtsZ‐GFP was properly localized at mid‐cell, however some aberrant localization was also detected. Pole‐to‐pole movement of GFP‐MinD was slower than in the wild type. The increased level of phosphatidic acid (PA) found in UE54 might substitute for CL and PG in the regulation of division proteins. To test this hypothesis IPTG‐induced expression of a GFP‐tagged PH domain of oxysterol‐binding protein exhibiting selective binding to PA and its PA‐insensitive derivative were expressed in cells. Our preliminary results indicate an increase in PA at the cell poles in UE54, which correlates with CL‐domains found in wild type cells. We conclude that PA might substitute for CL and PG in membrane interaction of division proteins. Supported by NIH grant GM 20478 (to WD).