#41 - En route to dynamic life processes by SNARE-mediated fusion of polymer and hybrid membranes.
Lado Otrin (Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg)
Tuesday, 01 Dec 21:15 - 22:00 CET
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Title: En route to dynamic life processes by SNARE-mediated fusion of polymer and hybrid membranes
Author(s): Lado Otrina, Agata Witkowskab, Nika Marušiča, Ziliang Zhaoc, Rafael B. Lirac, Fotis L. Kyrilisd, Farzad Hamdid, Ivan Ivanova, Reinhard Lipowskyc, Panagiotis L. Kastritisd, Rumiana Dimovac, Kai Sundmachera, Reinhard Jahnb, Tanja Vidaković-Kocha
Affiliation(s): aMax Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany; bMax Planck Institute for Biophysical Chemistry, Göttingen, Germany; cMax Planck Institute of Colloids and Interfaces, Potsdam
dMartin Luther University Halle-Wittenberg, Halle/Saale
Abstract: Membrane fusion is an essential process behind the formation, assembly and maintenance of life as we know it. In eukaryotes, it´s role in fertilization is often poetically described as the spark of creation. Meanwhile, the process of membrane fusion is crucial also for the more commonly occurring cell functions, such as cell transport and trafficking, cell growth and others. The fusion of more traditional lipid membranes can be facilitated by a variety of fusogens, for example SNAP receptor (SNARE) proteins. However, the substitution of said membrane type for the one, which would exhibit higher stability and functional durability, for example polymer-based one, is often a desired design feature in synthetic biology. In this context, SNARE-mediated fusion would be indispensable for the stepwise integration of membrane protein assemblies with delicate configuration, such as artificial respiratory chains and others, and would, furthermore, enable the controlled growth of synthetic compartments. Nevertheless, to this day, SNAREs were not successfully inserted into polymer-based membranes and the SNARE-mediated fusion of those remains unexplored. In the presented work, we developed functionalization of polymer and lipid/polymer hybrid membranes with the fusogenic SNAREs, reconstituted with the remarkable integration efficiency and correct orientation. Furthermore, in said membranes, we either match or improve the efficiency of membrane mixing, otherwise observed in lipid membranes, and discuss it in the context of biophysical parameters such as membrane charge and stiffness. For the first time, we showcase nature-like full vesicle fusion with content mixing via integration and functional coupling between two complex respiratory enzymes, bacterial terminal oxidase and ATP synthase. We investigate in more detail the mechanisms governing this multi-stage process by examining pore opening dynamics and fusion intermediates of polymer and hybrid fusion via cryo-EM.