title: 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 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 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 β-barrel membrane protein channels.
authors.affiliation: Department of Physics, Syracuse University, Syracuse, New York 13244-1130, United States.
authors.forename: Belete R
authors.initials: BR
authors.lastname: Cheneke
authors.forename: Bert
authors.initials: B
authors.lastname: van den Berg
authors.forename: Liviu
authors.initials: L
authors.lastname: Movileanu
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D015640:Ion Channel Gating / Q000502:physiology*; D007700:Kinetics; D008564:Membrane Potentials; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000378:metabolism; D013816:Thermodynamics
chemical_list: D001425:Bacterial Outer Membrane Proteins; D026901:Membrane Transport Proteins