Thermodynamics of complex membranes: fluctuation-mediated clustering and active remodeling

Adrià Bravo Vidal, PhD Student, Biocomplexity Group, Niels Bohr Institute, Copenhagen

Biological membranes are complex, heterogeneous structures composed of a diverse mixture of lipids and proteins. These proteins diffuse on and interact locally with the membrane and their collective effect gives rise to rich emergent phenomena. In this talk, I present two analytical and simulation studies exploring how the collective effect of protein–membrane interactions drives lateral organization and shape change, both at and away from equilibrium. First, I show that protein-induced local stiffening alone is sufficient to drive protein clustering through fluctuation-mediated interactions. Second, I ask what happens when proteins are active, stochastically switching between conformational states. Depending on the switching rate, activity can either suppress or amplify membrane undulations across different wavelength regimes, and can even drive morphological instabilities absent at equilibrium. Both results highlight how simple local protein–membrane interactions can collectively give rise to surprisingly rich mechanical and morphological behavior.