Electrophysiological Characterization of Transport Across Outer‐Membrane Channels from Gram‐Negative Bacteria in Presence of Lipopolysaccharides

Abstract

Multi‐drug resistance in Gram‐negative bacteria is often associated with low permeability of the outer membrane. To investigate the role of membrane channels in the uptake of antibiotics here, we show a robust approach using fusion of native outer membrane vesicles (OMV) into planar lipid bilayer, which moreover allows also characterization of membrane protein channels in their native environment. Two major membrane channels from E. coli , OmpF and OmpC, were overexpressed from the host and the corresponding OMVs were collected. Each OMV fusion revealed surprisingly single or only a few channel activities. The asymmetry of the OMV´s translates after fusion into the lipid membrane with the LPS dominantly present at the side of OMV addition. Compared to conventional reconstitution method, the channels fused from OMVs containing LPS have similar conductance but a much broader distribution and significantly lower permeation. We suggest using outer membrane vesicles as a fast and easy approach for functional and structural studies of membrane channels in the native membrane.