Regensburg 2016 – scientific programme

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BP: Fachverband Biologische Physik

BP 57: Membranes and Vesicles I

BP 57.8: Talk

Thursday, March 10, 2016, 12:00–12:15, H43

Shaping the Endoplasmic Reticulum network in vitro — •Gernot Guigas, Csilla Ferencz, and Matthias Weiss — Experimental Physics I, University of Bayreuth

Many organelles in eucaryotic cells have complex shapes that deviate significantly from simple spheres. A prime example is the Endoplasmic Reticulum (ER) which forms an extensive network of membrane tubules throughout the cytoplasm of mammalian cells. In order to explore the self-assembly capacity of ER networks we have used an in-vitro reconstitution system and spinning disk confocal microscopy. In particular, we monitored how purified ER microsomes from Xenopus laevis eggs fuse in the presence of purified cytosol, ATP, and GTP. As a result, we observed that a complex network with an ER-like topology and a typical mesh size of some 10 micrometers grew almost instantly on the surface of the incubation chamber. In a subsequent relaxation process, single tubules of the network moved and rearranged until the network had reached a stable configuration. Tubular networks only grew on charged surfaces and they were most stable on surfaces with a medium elasticity. When vesicles were mixed with small silicon oil droplets, tubular networks with a significantly reduced mesh size formed on these droplets, i.e. the ER network structure resembled more closely the native form found in mammalian cells. We conclude from our experiments that ER microscomes have an inherent capacity to self-assemble into a network structure with a mesh size that is influenced by the surface on which the structure grows.