FIGURE 6.

Membrane stability is compromised by recombinantly overproduced TatA. Fluorescence quenching with vesicles of either E. coli MC4100 producing mature HiPIP from pBW-mat-hip-strep (black traces from two experiments), or E. coli MC4100 overproducing TatA using the plasmid pBW-tatA-strep (gray traces from two experiments). HiPIP has been chosen as negative control to produce a similar size protein with the same rhamnose-inducible vector system. AU: arbitrary fluorescence intensity units; Quenching was started at the indicated time point by addition of 1 mm ATP and the pH gradient was abolished by addition of 25 μm CCCP (uncoupler). Note that the fluorescence quenching is ∼25% weaker when TatA was recombinantly produced.