title: Facilitated permeation of antibiotics across membrane channels--interaction of the quinolone moxifloxacin with the OmpF channel.
abstract: The facilitated influx of moxifloxacin through the most abundant channel in the outer cell wall of gram-negative bacteria was investigated. Molecular modeling provided atomic details of the interaction with the channel surface, revealed the preferred orientation of the antibiotic along its pathway, and gave an estimated time necessary for translocation. High-resolution conductance measurements on single OmpF trimers allowed the passages of individual moxifloxacin molecules to be counted. The average mean residence time of 50 micros is in agreement with the predicted strong interaction from the modeling. In contrast, control measurements with nalidixic acid, a hydrophobic antibiotic that rather permeates across the lipid membrane, revealed a negligible interaction. The spectral overlap of tryptophan with moxifloxacin was suitable for a FRET study of the protein-antibiotic interaction. Combining molecular dynamics simulations with selective quenching identified an interaction of moxifloxacin with Trp61 inside the OmpF channel, whereas nalidixic acid showed preferential interaction with Trp214 on the channel exterior. An understanding of the detailed molecular interactions between the antibiotic and its preferred channel may be used to develop new antibiotics with improved uptake kinetics.
authors.affiliation: Jacobs University Bremen, Campus Ring 1, D-28759 Bremen, Germany. t.mach@jacobs-university.de
authors.forename: Tivadar
authors.initials: T
authors.lastname: Mach
authors.forename: Patricia
authors.initials: P
authors.lastname: Neves
authors.forename: Enrico
authors.initials: E
authors.lastname: Spiga
authors.forename: Helge
authors.initials: H
authors.lastname: Weingart
authors.forename: Mathias
authors.initials: M
authors.lastname: Winterhalter
authors.forename: Paolo
authors.initials: P
authors.lastname: Ruggerone
authors.forename: Matteo
authors.initials: M
authors.lastname: Ceccarelli
authors.forename: Paula
authors.initials: P
authors.lastname: Gameiro
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000378:metabolism*; D001372:Aza Compounds / Q000737:chemistry* / Q000378:metabolism*; D024841:Fluoroquinolones; D008958:Models, Molecular; D000077266:Moxifloxacin; D018272:Porins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011804:Quinolines / Q000737:chemistry* / Q000378:metabolism*; D015363:Quinolones / Q000737:chemistry* / Q000378:metabolism; D013050:Spectrometry, Fluorescence
chemical_list: D000900:Anti-Bacterial Agents; D001372:Aza Compounds; D024841:Fluoroquinolones; C109237:OmpF protein; D018272:Porins; D011804:Quinolines; D015363:Quinolones; D000077266:Moxifloxacin