Probing transport of charged β-lactamase inhibitors through OmpC, a membrane channel from E. coli

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• 作者：Ishan Ghai ; Mathias Winterhalter ; Richard Wagner ; ^{ri.wagner@jacobs-university.de}
• 关键词：Bacterial outer membrane ; OmpC ; Permeation ; Zero current potential ; Electrophoretic mobilities ; β-lacatamase inhibitor
• 刊名：Biochemical and Biophysical Research Communications
• 出版年：2017
• 出版时间：26 February 2017
• 年：2017
• 卷：484
• 期：1
• 页码：51-55
• 全文大小：740 K
• 卷排序：484

文摘

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=0mVVm=0mV was about n=200n=200 molecules/s per OmpC single pore.