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AKB: Biologische Physik

AKB 40: Poster Session II

AKB 40.46: Poster

Mittwoch, 29. März 2006, 16:30–19:30, P3

Temperature dependent voltage-induced gating of OmpF — •Catalin Chimerel¹, Liviu Movileanu², and Mathias Winterhalter¹ — ¹International University Bremen, Germany — ²Syracuse University, New York, USA

OmpF porin is a trimeric β-barrel channel from the outer cell wall of E.coli. A characteristic of the channel is its complete closure at transmembrane voltages (~ 130 mV at room temperature), which depend on the experimental conditions. We employed single-channel and macroscopic current recordings in planar lipid bilayers to examine the gating fluctuations leading to transient or permanent closure as a function of applied voltage in a temperature range between 2 and 72 ^∘C. The OmpF single-channel conductance, the amplitude of the gating blockades, and the lifetime of the closure sub-states were strongly temperature-dependent. Increasing the temperature increases the number of short-lived fluctuations, their lifetime, and the OmpF single-channel conductance in a non-linear manner, but decreases the threshold transmembrane voltage above which a complete closure occurs. These data reveal different mechanisms for channel closure that are discussed.