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Nanoroughness strongly impacts lipid mobility in supported membranes

Jeudi 11 avril 11:00 - Duree : 1 heure
Lieu : Science Building Room 036 - EPN campus - 71 avenue des Martyrs - Grenoble

Orateur : Jean-Paul RIEU (ILM – Institut Lumière et Matière, Université Claude Bernard Lyon 1, Villeurbanne, France ; 2Faculty of Sciences, Lebanese University, Lebanon)

In vivo, the surfaces to which lipid layers interact are generally not flat. Phospholipid multibilayers are found on the cartilage surface of articular joints (Hills and Butler, 1984) which exhibit large roughness. Lipid membranes also interact with rough supramolecular structures such as protein clusters and fibrils. How these features whose size ranges from a few nanometers to a few tens of nanometers impact lipid and protein mobility was still poorly investigated. We studied in this subtask 1.3 SPB deposited on etched surfaces bearing nanometric corrugations : silicon wafers etched by dry reactive ion etching and circular plane windows of borosilicate BK7 glass submitted to wet etching in a 1:1 sodium hydroxyde:ethanol solution. Surface roughness and mean curvature were carefully characterized by AFM imaging using ultrasharp tips. Neutron specular reflectivity supplemented this surface characterization, and indicated that the bilayers follow the large scale corrugations of the substrate. We measured the lateral mobility of lipids both in the fluid and gel phases by FRAP. While the mobility is independent of the roughness in the gel phase, it exhibits a five-fold decrease in the fluid phase when the roughness increases. These results are interpreted with a 2-phase model allowing for a strong decrease of the lipid mobility in highly curved or defect-induced gel-like nanoscale regions. This suggests an unexpected link between membrane nanoroughness and fluidity which is a key property for various cell functions such as signalling and adhesion and which probably has an important role for biolubrication.

Contact : tellier@ill.fr

Discipline évènement : (Biologie / Chimie) - Discipline évènement : (Physique)
Entité organisatrice : (ILL)
Nature évènement : (Séminaire)
Evènement répétitif : (General ILL Seminar - College 9)
Site de l'évènement : Polygone scientifique

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