IN-VITRO ANALYSIS OF THE STOP-TRANSFER PROCESS DURING TRANSLOCATION ACROSS THE CYTOPLASMIC MEMBRANE OF ESCHERICHIA-COLI

In this study, using a derivative of proOmpA containing an artificial stop-transfer sequence (proOmpA2xH1), we analyzed the process of stop- transfer during translocation across the cytoplasmic membrane of Esche richia coli. ProOmpA2xH1 did not interfere with the transit of wild-ty pe proOmpA. When proOmpA2xH1 was anchored in the membrane, membrane-in serted SecA was deinserted with the reversion of the inverted topology of SecG. Cross-linking experiments revealed that the anchored proOmpA 2xH1 that does not interact with either SecY or SecA. These results, t aken together, suggest that proOmpA2xH1 leaves the translocation pathw ay by means of a specific interaction between the stop-transfer sequen ce and the translocational channel.