Voltage-Dependent Inactivation of MscS Occurs Independently of the Positively Charged Residues in the Transmembrane Domain

Figure 2

Characteristics of the wild-type and mutant MscS expressed in PB111 (ΔmscS) cells. (a) PB111 cells expressing the wild-type MscS. Channel current (upper) and pressure applied through a pipette (bottom) are shown. The insets show the magnification of the MscS and MscL traces indicated by arrowhead and arrow, respectively. Membrane voltage: +20 mV. (b) The gating threshold ratio (MscS/MscL) of the wild-type and mutant MscS at various voltages (−100 to +40 mV). Values are expressed as mean ± SEM (standard error of the mean) (–7). (c) Effects of hypoosmotic shock on MJF455 (ΔmscSΔmscL) cells expressing MscS or harboring an empty vector (pB10b) (mean ± SEM, ). No significant difference was observed between the wild-type and mutant MscS. The asterisks indicate significant difference from the wild-type ( by t-test).