Lévy

Molecular Microscopy of Membranes (MMM)

Daniel Lévy
Scientific keywords: ABC transporters, electron microscopy, exosomes, membrane proteins, septins
Technics Used in the Lab: 2D and 3D cryo-electron microscopy, reconstitution of membrane proteins in liposomes, purification of membrane proteins

Our researches concentrate on the organization at the molecular level of the cell plasma membrane and of its components including lipids, transmembrane proteins and membrane bound proteins. We are using cryo-electron microscopy and cryo-tomography to describe at nanometric resolution the structure of purified membrane proteins, reconstituted into lipid model membranes, large and giant vesicles, or present in cell (Fig. 1). Membrane proteins of interest include e.g. ABC transporters involved in cell multidrugs resistance or septins involved in cell division and cellularization. In collaboration with the Team of G. Raposo (UMR 144), our project proposes to combine approaches of cell biology and of membrane biophysic to delineate the role of PMEL, a transmembrane protein in the formation of non-pathogenic amyloids fibers in exosomes (Fig. 2). Our team will develop a minimal in vitro membrane system able to reproduce the PMEL-associated amyloid fibers that could be enriched with partners newly identified in melanocyte. New approaches of 2D and 3D cellular and cryo-electron microscopy will be also developed to describe PMEL and the related amyloid fibers in reconstituted systems and in cellulo.

 

Fig. 1. Combined approaches to analyze membrane and membrane bound proteins by electron microscopy

Fig. 1. Combined approaches to analyze membrane and membrane bound
proteins by electron microscopy

 

Fig2-EqLevy

Fig. 2. Amyloid fibers nucleate from intraluminal vesicles of melanosomes as
observed in cell by tomography (B,C). Our goal is to exploit cryo electron
microscopy to study at high resolution the nucleation of fibrils at the membrane
of intraluminal vesicles (exosomes) by cryo-electron microscopy (D).