Regensburg 2016 – scientific programme
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BP: Fachverband Biologische Physik
BP 57: Membranes and Vesicles I
BP 57.4: Talk
Thursday, March 10, 2016, 10:30–10:45, H43
Acto-myosin dynamics drive local membrane component organization in an in vitro active composite layer — •Darius V. Köster1, Kabir Husain1, Elda Iljazi1, Peter Bieling2, Dyche Mullins2, Madan Rao1,3, and Satyajit Mayor1 — 1National Centre for Biological Sciences, Bangalore, India — 2University of California, San Francisco, USA — 3Raman Research Institute, Bangalore, India
Studies on the organisation of the cell surface have revealed a role for dynamic acto-myosin in membrane protein and lipid organization, suggesting that the cell surface behaves as an active composite. We reconstitute an analogous system in vitro that consists of a fluid lipid bilayer coupled via membrane-associated actin binding proteins to dynamic actin filaments and myosin motors. Varying actin concentration, filament length, and actin/myosin ratio in this minimal system revealed after consumption of a limited ATP pool a phase, characterized by a lattice of polar asters. During the self-organizing aster formation, advection drives transient clustering of membrane components. Increasing levels of ATP produces a constitutively remodelling state of the actin filaments which in turn drive active fluctuations of coupled membrane components, resembling those observed at the cell surface. In a multicomponent membrane bilayer, this remodelling acto-myosin layer contributes to distinct changes in the extent and dynamics of phase segregating domains. These results show how local membrane composition can be driven by active processes arising from acto-myosin which could have implications for the membrane organization in cells.