The mechanosensitive channel of small conductance (MscS) from Escherichia coli (E. coli) gates in response to mechanical tension that is generated from hypo-osmotic shock. The gating mechanism of E. coli MscS, in response to mechanical tension, is similar to that of a Jack-in-the-Box, the channel springs into the open state when the applied extrinsic tension overcomes the intrinsic lateral tension of the membrane. E. coli MscS is the founding member of the MscS superfamily, a superfamily of 15 subfamilies that all contain significant homology to the pore lining helix of E. coli MscS. When MscS is activated by tension at low pH the rate of desensitization is on the order of seconds. However, when MscS gates in response to applied tension at physiological pH the rate of desensitization is on the order of minutes. This significant alteration in the rate of desensitization for MscS due to alterations in pH suggests that a residue or region of the protein is responsible for this modulation. To identify the region of the channel that evokes pH sensitivity we will use asymmetric and symmetric pH patch buffer in patch clamp electrophysiology. Patch clamp electrophysiology allows for the direct observation of single channels opening and closing in response to the applied tension. A through understanding of the pH modulation for bacterial mechanosensitive channels gives additional insight into their role in bacterial survival in rapidly changing environments.

Understanding the pH modulation in the E. coli mechanosensitive channel of small conductance (MscS)

2019 Spring National Meeting

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