Analysis of Gating Transitions among the Three Major Open States of the OpdK Channel

作者：Cheneke Belete R; van den Berg Bert; Movileanu Liviu^*

来源：Biochemistry, 2011, 50(22): 4987-4997.

DOI：10.1021/bi200454j

OpdK is an outer membrane protein of the pathogenic bacterium Pseudomonas aeruginosa. The recent crystal structure of this protein revealed a monomeric, 18-stranded beta-barrel with a kidney-shaped pore, whose constriction features a diameter of 8 angstrom. Using systematic single-channel electrical recordings of this protein pore reconstituted into planar lipid bilayers under a broad range of ion concentrations, we were able to probe its discrete gating kinetics involving three major and functionally distinct conformations, in which a dominant open substate O(2) is accompanied by less thermodynamically stable substates O(1) and O(3). Single-channel electrical data enabled us to determine the alterations in the energetics and kinetics of the OpdK protein when experimental conditions were changed. In the future, such a semiquantitative analysis might provide a better understanding on the dynamics of current fluctuations of other beta-barrel membrane protein channels.

• 出版日期2011-6-7