Dresden 2006 – scientific programme
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AKB: Biologische Physik
AKB 18: Ion Channels and Nanopores
AKB 18.4: Talk
Wednesday, March 29, 2006, 16:30–16:45, ZEU 255
Antibiotic translocation through OmpF — •Tivadar Mach1, Karin Türk1, Luminita Damian1, Sergei M Bezrukov2, and Mathias Winterhalter1 — 1International University Bremen, Germany — 2National Institutes of Health, Bethesda, MD, USA
The first step for antibiotics to reach their target in gram-negative bacteria is crossing the outer membrane. Several studies have concluded that general diffusion porin OmpF plays an important role in the uptake of some antibiotics, and that this uptake can often be considered the limiting step in their functionality. We use the analysis of the ion current through a single trimeric OmpF porin reconstituted into a planar lipid bilayer to study binding and translocation of fluoroquinolone antibiotics of different structure and hydrophobicity. Because the size of the antibiotic molecules is close to the size of the constriction zone in the OmpF pore, longer residence times of the fluoroquinolones in the channel cause random transient blockages in the ion current. Analysing these fluctuations we calculate chemical binding constants, affinity, and transfer probability. Our findings complete and corroborate earlier indications and indirect measurements of pathways of entry, providing a test-case for a direct, controlled measurement method also to be expanded to other antibiotic structures.