title: Probing transport of charged β-lactamase inhibitors through OmpC, a membrane channel from E. coli.
abstract: One of the major causes of antibiotic resistance in the Gram-negative bacteria is the low permeability across the outer membrane. Currently a main bottleneck in the development of effective antibiotics is the lack of a general method to quantify permeation which would allow screening for optimal scaffolds. Here, we present a permeation assay based on conventional electrophysiology. The method mainly involves application of concentration gradients of charged molecules with different electrophoretic mobilities through a membrane channel. Thus the unbalanced flux creates an electrostatic potential which provides direct information on relative ion fluxes. The experimental approach applied here involves measuring zero-current-potentials and the corresponding single channel conductance. For OmpC and the β-lactamase inhibitor avibactam at a 10 μm gradient the calculated flux rate at Vm=0mV was about n=200 molecules/s per OmpC single pore.
authors.affiliation: Department of Life Sciences and Chemistry, Jacobs University Bremen, 28719 Bremen, Germany.
authors.forename: Ishan
authors.initials: I
authors.lastname: Ghai
authors.affiliation: Department of Life Sciences and Chemistry, Jacobs University Bremen, 28719 Bremen, Germany.
authors.forename: Mathias
authors.initials: M
authors.lastname: Winterhalter
authors.affiliation: Department of Life Sciences and Chemistry, Jacobs University Bremen, 28719 Bremen, Germany. Electronic address: ri.wagner@jacobs-university.de.
authors.forename: Richard
authors.initials: R
authors.lastname: Wagner
mesh_terms: D029968:Escherichia coli Proteins / Q000378:metabolism*; D007473:Ion Channels / Q000378:metabolism*; D008051:Lipid Bilayers; D015335:Molecular Probes; D018272:Porins / Q000378:metabolism*; D065093:beta-Lactamase Inhibitors / Q000494:pharmacology*
chemical_list: D029968:Escherichia coli Proteins; D007473:Ion Channels; D008051:Lipid Bilayers; D015335:Molecular Probes; C113724:OmpC protein; D018272:Porins; D065093:beta-Lactamase Inhibitors
keywords: Bacterial outer membrane; Electrophoretic mobilities; OmpC; Permeation; Zero current potential; β-lacatamase inhibitor