Stretch-activated composite ion channels in Bacillus subtilis.

The presence of ion-conducting pores in the membrane of Bacillus subtilis giant protoplasts was discovered using the patch-clamp technique. Membrane stretch caused the activation of several conductances with values in the nS range. The observations indicate the presence of substate levels and of aggregates of channels behaving in a cooperative manner. Following repeated stretch cycles, the channels exhibited spontaneous activity. The characteristics of the electrical phenomena afterwards changed in time in a manner suggesting the decay of the giant channels into lower-conductance species, presumably corresponding to building blocks of the giant stretch-activated channels.