Table 1.
Experimental occurrences of MscS-like and MscL-like channels in patches of WT E. coli and V. cholerae
| Species | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
| No. MscS per patch | No. MscL per patch | p0.5MscS/p0.5MscL | MscS/µm2 (r = 1.5 µm) | MscL/µm2 (r = 1.5 µm) | Patch r*, µm (γ0.5 = 12 mN/m) | Patch area*, µm2 | MscS/µm2* | MscL/µm2* | |
| E coli | 46 ± 14 | 61 ± 40 | 0.60 ± 0.05 | 3.6 ± 1.8 | 4.3 ± 2.2 | 1.5 ± 0.3 | 14.7 ± 5 | 3.6 ± 1.8 | 4.3 ± 2.2 |
| V cholerae | 17 ± 9 | 164 ± 100 | 0.48 ± 0.04 | 1.2 ± 0.7 | 11 ± 4 | 1.37 ± 0.3 | 12.4 ± 6.3 | 1.5 ± 0.8 | 14 ± 5 |
Multiple traces, as shown in Fig. 2, were Rs corrected, and numbers of MscS-like and MscL-like channels as well as midpoint pressures for each population were determined. The pressure midpoint (p0.5) for Eco MscL was equated to membrane tension γ0.5 = 12 mN/m acting on channels, from where the radii of patch curvature and areas were calculated according to the law of Laplace (γ = Δpr/2). The densities (channels/µm2) were then deduced for MscS-like and MscL-like channels individually, first on the assumption that the average patch radius for V. cholerae preparations is the same as for E. coli (columns 4 and 5) and independently with the assumption that MscLs in both preparations gate with the same midpoint γ0.5 = 12 mN/m (columns 6 through 9). Data are presented as mean ± SD (n = 12 for E. coli and n = 19 for V. cholerae). The midpoint ratios p0.5MscS/p0.5MscL for the two species (column 3) are significantly different at a 0.006 level according to two-tailed unequal variance t test.