Thèse de doctorat en Biophysique
Sous la direction de Pascal Martin.
Soutenue le 28-11-2012
à Paris 5 , dans le cadre de École doctorale Frontières de l'innovation en recherche et éducation (Paris) .
Le président du jury était Benoît Claude Forget.
Développement de systèmes biomimétiques pour l'étude des oscillations des moteurs moléculaires
Pas de résumé en français
Recent studies have suggested that minimal actomyosin systems have the intrinsic property to oscillate whensubjected to an elastic load. A similar situation can be found in various biological systems, leading, both in-vivoand in-vitro, to spontaneous oscillations. In particular, muscular systems as well as mechanosensitive hair-cellbundles in the inner ear have been shown to oscillate spontaneously as the result of active force production by anacto-myosin protein complex. We attempt to shed light on the mechanism behind the oscillatory activity of theacto-myosin system, in particular by determining the parameters that control the frequency and amplitude ofoscillation. The stiffness of the system, the total force developed by the motors and the type of motors have beenproposed as being influential in this respect. To investigate this effect, we make use of a modified motility assayconsisting of a motor-driven stiff polarized actin bundle subjected to an elastic load provided by opticaltweezers. During the course of this work, we also characterized auto-assembled magnetic bead columns andassessed their viability as molecular force sensors to study the oscillations. The fact that they can easily beorganized into large arrays makes them interesting as potential ‘high-throughput’ force sensors