The Effect of Dipole Potential of Lipid Bilayers on the Properties of Ion Channels Formed by Cyclic Lipodepsipeptide Syringomycin E

摘要

The effect of membrane dipole potential (φ_d) on the properties of ion channels formed in bilayerlipid membranes by syringomycin E (SRE), a toxin produced by Pseudomonas syringae, has been studied. Ithas been shown that φ_daffects the conductance and lifetime of elementary SRE channels as well their clusterorganization, in particular, the number of elementary channels synchronously opened in the cluster and the life-time of these clusters. The channel-forming activity of SRE was found to be 9d-dependent. The analysis ofexperimental data has revealed that (i) the mechanisms of the observed effects involve the dipole–dipole andcharge–dipole interactions responsible for the cooperative functioning of the elementary SRE channels; (ii)about 95% of membrane dipole potential is shielded in the SRE pore; and (iii) the channel-forming activity ofSRE is mainly determined by the gating charge of the SRE channels. At the same time, the partition coefficientfor the toxin distribution between the membrane and aqueous phase as well as the chemical component of thechannel formation work are also responsible for the 9d-dependence of the SRE channel forming activity.