David Lacoste

Research·05 / 06

Soft biological matter

The cytoskeleton and cell membranes are soft materials kept out of equilibrium by a constant consumption of energy. I studied how this activity changes their dynamics, their mechanics and their fluctuations.

Biofilaments · Active membranes · Electrokinetics · Protein diffusion

Biofilaments

Actin filaments and microtubules grow and shrink by adding and removing subunits that hydrolyse ATP or GTP. We built stochastic models of this non-equilibrium self-assembly, showed how random hydrolysis controls the dynamic instability of microtubules and the history-dependent depolymerization of actin, and studied bundles of filaments pushing against a barrier.

Active and driven membranes

Membranes containing light-activated ion pumps or ion channels are driven out of equilibrium. We showed how protein activity lowers membrane tension, and how an electric field changes the fluctuations, the elastic moduli and the stability of a lipid bilayer.

Membranes, cytoskeleton and proteins

We also studied membranes coupled to an elastic meshwork, which shows a jump in effective surface tension at the mesh size, and the mechanical factors, including protein shape, that control how fast a protein diffuses in a membrane.

Publications 16

All publications

Single filament dynamics

Filament bundle dynamics

Lateral diffusion of proteins in membranes

Membranes coupled to a cytoskeleton

Membranes with light-activated ion pumps

Membranes in an electric field