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. 2018 Oct 1;9:1389. doi: 10.3389/fphys.2018.01389

FIGURE 1.

FIGURE 1

Introduction of cysteine residues into TM3b and the Cyto-helix alters the gating characteristics. (A) Schematic of the MscS channel from E. coli (PDB code 2OAU). Left: side view of an individual MscS subunit with the positions of the transmembrane helices (TM1, TM2, TM3a, and TM3b). The Cyto-helix, middle-β, and C-terminal are labeled. Middle: side view of the MscS heptamer. Right: enlarged side view of the TM3b and Cyto-helix region. Red, TM3b; blue, Cyto-helix. (B) Thresholds for MscS gating as determined by patch clamp (mean ± SEM, n = 6; ∗∗∗p < 0.001 vs. WT MscS). Single-channel recordings and gating threshold measurements were performed using strain MJF429 expressing MscS channels. (C) Representative single-channel activity traces for WT, N117C, and N167C. Lower trace: negative pressure application. ∗MscS activity; #MscL activity.