OMPF-LPP SIGNAL SEQUENCE MUTANTS WITH VARYING CHARGE HYDROPHOBICITY RATIOS PROVIDE EVIDENCE FOR A PHOSPHATIDYLGLYCEROL-SIGNAL SEQUENCE INTERACTION DURING PROTEIN TRANSLOCATION ACROSS THE ESCHERICHIA-COLI INNERMEMBRANE

Using inverted Escherichia coli inner membrane vesicles we have analyz ed the phosphatidylglycerol dependence of translocation of an OmpF-Lpp fusion protein carrying a signal sequence with varying positive charg e at the N terminus and a hydrophobic core of varying length. It is sh own that there is a direct relationship between the phosphatidylglycer ol requirement of translocation and the requirement within the translo cation process for positive charges on the signal sequence. This provi des further evidence that the negative head group of the lipid is requ ired for functional interaction with the positively charged N terminus of the signal sequence.