Effects of sodium chloride on membrane fusion and on the formation of aggregates of potassium channel KcsA in Escherichia coli membrane

In the current study, we found that NaCl induces fast vesicle fusion and aggregation of the bacterial potassium channel KcsA in Escherichia coli (E. coli) membranes. Conventional gel electrophoresis and tryptophan fluorescence experiments were performed to detect NaCl-induced aggregation or supramolecular complexes. Interestingly, in a planar lipid bilayer, increasing NaCl concentration dramatically increased the total internal current indicating enhanced vesicle fusion and transfer of high number of channels to the lipid bilayer. Such channels appeared in clusters of variable size which exhibited higher conductivity, increased open probability and efficient blocking by K+-channel blocker tetraethylammonium (TEA). Furthermore, NaCl-induced KcsA aggregation was found to be specific for E. coli membrane as compared to the artificial membrane system. Our preliminary data suggest the role of NaCl in the formation of KcsA aggregates as well as in the enhancement of membrane fusion capability in E. coli membranes.