Figure 1.

Effect of channel concentration on the efflux of calcein from reconstituted vesicles. The G22C mutant of E. coli MscL was reconstituted into calcein-containing vesicles containing a 1:1 molar ratio of DOPG:DOPC at the given molar ratios of total lipid to MscL. Samples were diluted into buffer, and a fluorescence baseline was recorded for 50 s, followed by the addition of 1 mM MTSET. Finally, 200 μMC₁₂E₈ was added to burst the vesicles and establish a value for the fluorescence intensity when all of the trapped calcein had been released. The amount of lipid was kept constant at 6.7 μmol. The trace labeled a shows an experiment for vesicles containing a 1:1 molar ratio of DOPG:DOPC in the absence of MscL. In (A), results are expressed as changes in absolute fluorescence intensities. In (B), results are expressed as a fraction of the observed change in fluorescence intensity between the initial value and that observed in the presence of 200 μM C₁₂E₈. The broken lines in (B) show best fits to a single exponential process.