FIGURE 1.

Properties of MscS pore: radius, resistance, surface polarity, hydration energy, and evolutionary conservancy. (a) Crystal structure of E. coli MscS (Bass et al., 2002) in a schematic representation. The pore region considered for continuum estimations and then included in MD simulations is highlighted yellow. (b) The cross section of the central pore region with its solvent-accessible surface (probe R = 1.4 Å) is colored according to the residue type: acidic (red), basic (blue), polar (green), and nonpolar (white). Positions of residues defining the polarity are indicated. (c) Effective pore radius R (black solid line) and specific resistance ρ (red solid line) as functions of z coordinate. A hypothetical widening of the constriction and the corresponding drop of resistance are shown by dotted lines. (d) The pore region is colored according to the relative conservation index for the YggB family (data from Pivetti et al., 2003). (e) The surface of the pore is colored according to the atomic solvation energies with hydrophilic atoms shown in blue. (f) Hydration energy (red) and free energies of dewetting calculated with the surface tension parameter σ = 70 (blue) and 20 mJ/m² (green). The initiation of the vapor phase formation was inferred in the narrowest part of the pore (dashed line).