Organization of Passive and Active Membranes: An Exploration Using Mesoscale Computational Models

PhD defence by Adrià Bravo Vidal

Assessment Committee

Associate Professor Amin Doostmohammadi, Biocomplexity, University of Copenhagen (Chairperson)
Full Professor Nicolas Destainville, Université de Toulouse, Laboratoire de Physique Théorique, Université de Toulouse, 118 Route de Narbonne, 31062 Toulouse Cedex 4
Acting research director, Dmitry Fedosov, Theoretical Physics of Living Matter, Institute for Advanced Simulation, Forschungszentrum Jülich,

Supervisors

Associate Professor Pól Martin Bendix
Assistant Professor Weria Pezeshkian

Department

Niels Bohr Institute

Place

Building: Building C, Room: Auditorium A, Belgdamsvej 17, 2100 Copenhagen

Email address to gain access to the thesis: adria.vidal@nbi.ku.dk.
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Short description of the thesis

Biological membranes, made of lipids and proteins, surround cells and organelles. Only nanometers thick, they adopt complex shapes spanning microns. Membrane proteins collectively shape and organize the membrane by locally modifying its curvature and rigidity, yet how large-scale membrane behavior emerges from these local effects remains poorly understood. In this thesis, I use mesoscale simulations to address this question. First, I show that membrane undulations mediate multi-body forces that can drive the aggregation of stiff proteins. Second, I find that when proteins consume chemical energy to switch conformation, moderate activity stabilizes the membrane, while higher activity triggers a shape instability. Finally, I show that in wounded membranes, curvature-inducing proteins accumulate at the wound edge and reshape the surrounding membrane, but do not drive closure. These findings show how two protein features, curvature and rigidity, give rise to rich collective behavior.