Dresden 2014 – scientific programme

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BP: Fachverband Biologische Physik

BP 38: Active cell and tissue mechanics (focus session) II

BP 38.2: Talk

Thursday, April 3, 2014, 15:30–15:45, HÜL 386

Transduction channel's gating controls friction on vibrating hair-cell bundles in the ear — •Volker Bormuth¹, Jérémie Barral¹, Jean-François Joanny¹, Frank Jülicher², and Pascal Martin¹ — ¹Laboratoire Physico-Chimie Curie, CNRS, Institut Curie, UPMC; 75005 Paris, France — ²2Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany

Hearing starts when sound-evoked mechanical vibrations of the hair-cell bundle activate mechanosensitive ion channels, giving birth to an electrical signal. As for any mechanical machine, friction impedes movements of the hair bundle and thus constrains the sensitivity and frequency selectivity of auditory transduction. Using dynamic force measurements on single hair-cell bundles, we demonstrate here that the opening and closing of the transduction channels produce internal friction forces that can dominate viscous drag on the micrometric hair-bundle structure. A theoretical analysis reveals that channel friction arises from coupling the dynamics of the conformational change associated with channel gating to tip-link tension. We propose that this intrinsic source of friction contributes to the process that sets the hair cell's characteristic frequency of responsiveness.