Lumen geometry of ion channels formed by Vibrio cholerae EL Tor cytolysin elucidated by nonelectrolyte exclusion.

摘要: Abstract Vibrio cholerae EL Tor cytolysin, a water-soluble protein with molecular mass of 63 kDa, forms small pores in target cell membranes. In this communication, planar lipid bilayers under voltage clamp conditions were used to investigate the geometric properties pores. It was established that all cytolysin channels inserted into membranes same orientation. Sharp asymmetry I-V curve fully open persisting at high electrolyte concentrations indicated geometry channel lumen. Using nonelectrolyte exclusion method, evidence obtained cis opening had larger diameter (≤1.9 nm) than trans (≤1.6 nm). The lumen appeared constricted, ≤1.2 nm. Cup-shaped deduced for both openings, which be connected each other via central narrow part. latter contributed significantly total electrical resistance and determined discontinuous character filling nonelectrolytes. Comparisons formed by cytolysins two V. biotypes (EL non-O1) ion possessed similar geometry.