Abstract

“Mechanosensitive channel of large conductance (MscL)” from Escherichia coli is one of the best characterized mechano-sensors in nature. It functions as a safety valve to protect the bacterial cell against severe osmotic downshifts. A sudden influx of water results in the build up of turgor pressure, generating tension in the membrane. Above a certain threshold value, the pressure results in the opening of the large, nonselective pore of MscL that allows efflux of ions, small solutes, and even some small proteins to prevent cell lysis.

We re-engineered MscL in order to operate it more easily in hybrid platforms. We managed to convert it into a light-sensitive valve, which opened and closed reversibly depending on the wavelength of the light in the absence of membrane tension. It was also possible to make a pH-sensitive valve out of it.

 The external control, sensitivity and tunability of this engineered channel present exciting opportunities from fundamental work to applications in lab-on-a-chip devices.