2024/07/19(Fri) 15:00 -16:00 五樓第一會議室 5F, 1st Meeting Room
Title
Self-organized wave-like beating of actin bundles driven by myosin X motors
Speaker
Dr. Antony Lee (Institut Curie, Paris, France)Abstract
Large assemblies of biological filaments and molecular motors can exhibit emergent meso- and macro-scale behaviors that are not present at the single-molecule scale. As an example of self-organization in motor-filament systems, our group (Martin team, Physics of Cells and Cancer, Institut Curie) has recently shown that a wave-like beating behavior can emerge in vitro in an assembly of polymerizing actin filaments and myosin motors (Pochitaloff, Miranda, ..., Martin, Nature Physics, 2022). Despite the different molecular identity of the filaments and motors at work, the beating waveforms in this artificial system mimic those observed in eukaryotic flagella. Our minimal reconstituted system provides a powerful platform to study a fundamental question: how can motor activity be coordinated in space and time depending on the shape of the filament bundle, resulting in periodic wave-like oscillations?
Our assay relies on surface micropatterning of a nucleation promoting factor to control the geometry of actin polymerization into parallel filament networks. We studied how these filaments self-assemble in the presence of myosin X, which is involved in vivo in filopodia assembly and cargo transport along such parallel networks of actin filaments. We found that, as observed previously with heavy meromyosins II and V, myosin X can also drive the self-assembly of actin filaments into wave-like beating bundles. Similarly to myosin V, myosin X preferentially binds to the curved and dynamic tips of the bundles, which is suggestive of a general feedback mechanism based on curvature control of myosin affinity to actin. In addition, we observed motor streaming along the filaments, corresponding to processive motor motion towards the barbed ends of the actin filaments. Using FRAP experiments, we characterized how motor binding-unbinding kinetics and transport dynamics couple to dynamic shape changes associated to the beating phenomenon of the actin bundles. Altogether, our experiments are expected to shed light on coordination mechanisms in active motor-filament systems.
Language
演講語言 (Language): in English