Purification of OmpU from Vibrio cholerae classical strain 569B: evidence for the formation of large cation-selective ion-permeable channels by OmpU.

摘要: The outer membrane of the classical Vibrio cholerae strain 569B was isolated by sucrose density centrifugation. simple treatment or cell envelopes with different detergents allowed purification two proteins, 38 kDa OmpU and 25 OmpV. Furthermore, a 35 protein (probably OmpA-like protein) purified two-fold envelope 2% SDS solution. A subsequent wash SDS-pellet Genapol buffer yielded in protein, which formed SDS-resistant oligomers (66 kDa). pellet contained Reconstitution experiments lipid bilayer membranes demonstrated that channel-forming component, whereas OmpV had small ability if any. channels appeared to be large water-filled single-channel conductance about 2 nS 1 M KCl for monomer trimer, means they have larger cross-section than enterobacterial porins. showed rapid switching between open closed configuration. They were slightly cation-selective, suggests contain an excess negatively charged amino groups.