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Analysis of gating transitions among the three major open states of the OpdK channel.

ABSTRACT: OpdK is an outer membrane protein of the pathogenic bacterium Pseudomonas aeruginosa. The recent crystal structure of this protein revealed a monomeric, 18-stranded ?-barrel with a kidney-shaped pore, whose constriction features a diameter of 8 Å. 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 ?-barrel membrane protein channels.

SUBMITTER: Cheneke BR

PROVIDER: S-EPMC3107985 | biostudies-literature | 2011 Jun

REPOSITORIES: biostudies-literature

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Analysis of gating transitions among the three major open states of the OpdK channel.

Cheneke Belete R BR van den Berg Bert B Movileanu Liviu L

Biochemistry 20110512 22

OpdK is an outer membrane protein of the pathogenic bacterium Pseudomonas aeruginosa. The recent crystal structure of this protein revealed a monomeric, 18-stranded β-barrel with a kidney-shaped pore, whose constriction features a diameter of 8 Å. 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 dis ...[more]

PMID: 21548584

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