Curvature-driven lipid sorting needs proximity to a demixing point and is aided by proteins - Institut d'Optique Graduate School Accéder directement au contenu
Article Dans Une Revue Proceedings of the National Academy of Sciences of the United States of America Année : 2009

Curvature-driven lipid sorting needs proximity to a demixing point and is aided by proteins

Andrew Callan-Jones
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Pierre Nassoy
Jean-François Joanny
Jacques Prost
P. Bassereau
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Résumé

Sorting of lipids and proteins is a key process allowing eukaryotic cells to execute efficient and accurate intracellular transport and to maintain membrane homeostasis. It occurs during the formation of highly curved transport intermediates that shuttle between cell compartments. Protein sorting is reasonably well described, but lipid sorting is much less understood. Lipid sorting has been proposed to be mediated by a physical mechanism based on the coupling between membrane composition and high curvature of the transport intermediates. To test this hypothesis, we have performed a combination of fluorescence and force measurements on membrane tubes of controlled diameters pulled from giant unilamellar vesicles. A model based on membrane elasticity and nonideal solution theory has also been developed to explain our results. We quantitatively show, using 2 independent approaches, that a difference in lipid composition can build up between a curved and a noncurved membrane. Importantly, and consistent with our theory, lipid sorting occurs only if the system is close to a demixing point. Remarkably, this process is amplified when even a low fraction of lipids is clustered upon cholera toxin binding. This can be explained by the reduction of the entropic penalty of lipid sorting when some lipids are bound together by the toxin. Our results show that curvature-induced lipid sorting results from the collective behavior of lipids and is even amplified in the presence of lipid-clustering proteins. In addition, they suggest a generic mechanism by which proteins can facilitate lipid segregation in vivo.

Dates et versions

hal-00821354 , version 1 (09-05-2013)

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Citer

Benoît Sorre, Andrew Callan-Jones, Jean-Baptiste Manneville, Pierre Nassoy, Jean-François Joanny, et al.. Curvature-driven lipid sorting needs proximity to a demixing point and is aided by proteins. Proceedings of the National Academy of Sciences of the United States of America, 2009, 106 (14), pp.5622-5626. ⟨10.1073/pnas.0811243106⟩. ⟨hal-00821354⟩
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