Dresden 2009 – scientific programme

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BP: Fachverband Biologische Physik

BP 25: Membranes

BP 25.1: Invited Talk

Friday, March 27, 2009, 10:15–10:45, HÜL 186

Role of membrane curvature in membrane trafficking — •Patricia Bassereau, Benoit Sorre, Andrew Callan-Jones, Gerbrand Koster, Aurélien Roux, Martin Lenz, Jean-François Joanny, and Jacques Prost — Institut Curie, Lab. PhysicoChimie Curie, Paris, France

Similar to proteins, most membrane lipids are transported by carriers (vesicles or tubules) with typical 50-100nm diameters that bud off from a donor membrane. During budding, sorting occurs: some lipids and proteins are selectively incorporated into these transport intermediates. It has been proposed that components can be dynamically sorted due to membrane curving during coat formation. In order to test this hypothesis, we have pulled membrane nanotubes with controlled diameters (15-500 nm) from Giant Vesicles (GUV). We will show that curvature-induced lipid sorting only occurs if the membrane is close to a demixing point. In addition, for these compositions, lipid sorting is further amplified when even a low fraction of lipids is clustered upon cholera toxin binding, suggesting that lipid-clustering proteins may play an important role in curvature-induced sorting in biological membranes. Another aspect of the role of curvature in membrane trafficking can be studied with these nanotubes. Dynamin is a protein, which assembles in helicoidal structures around the neck of vesicles during budding and induces fission upon GTP hydrolysis. We will show that dynamin assembly can occur only when the neck diameter is below a threshold value. This curvature-dependent polymerization mechanism guaranties a correct timing for carrier budding.