Visualization of higher-order autophagy assemblies by cryo-EM
Dr Carsten SACHSE
Structural and Computational Biology Unit, EMBL, Heidelberg, Germany
Monday, June 18th 2018 - 2 p.m.
- Conference room E1031, CBI
Hosted by Integrated structural Biology, Albert WEIXLBAUMER
Cryo-EM has become the method of choice to study the structures of large helical assemblies up to atomic resolution. I will present medium to high resolution oligomeric and polymeric cryo-EM structures that have advanced our understanding of the molecular mechanism of how cargo is recognized by the selective autophagy machinery. Throughout the talk, I will focus on the methodological advances that have led to the high-resolution structure elucidation . These developments have taken us to address more general problems of improving cryo-EM map interpretation by local sharpening . We show that autophagy receptor p62/SQSTM-1 assembles into flexible helical filaments and provides insights into the molecular basis of polymer formation . EM based structure elucidation in vitro and in situ reveals large oligomeric and polymeric cargo receptor complexes giving rise to higher-order structures that constitute the scaffold for autophagosome formation . The organization of small receptor proteins into helical assemblies constitutes a cellular mechanism for high selectivity in cargo recognition and a fundamental architecture that enables cargo encapsulation of various sizes from molecular to cellular scale.
 S. A. Fromm and C. Sachse, “Cryo-EM Structure Determination Using Segmented Helical Image Reconstruction.,” Meth Enzymol, vol. 579, pp. 307–328, 2016.
 A. J. Jakobi, M. Wilmanns, and C. Sachse, “Model-based local density sharpening of cryo-EM maps.,” eLife, vol. 6, p. 213, Oct. 2017.
 R. Ciuffa, T. Lamark, A. K. Tarafder, A. Guesdon, S. Rybina, W. J. H. Hagen, T. Johansen, and C. Sachse, “The selective autophagy receptor p62 forms a flexible filamentous helical scaffold.,” Cell Rep, vol. 11, no. 5, pp. 748–758, May 2015.
 C. Bertipaglia, S. Schneider, A. J. Jakobi, A. K. Tarafder, Y. S. Bykov, A. Picco, W. Kukulski, J. Kosinski, W. J. Hagen, A. C. Ravichandran, M. Wilmanns, M. Kaksonen, J. A. Briggs, and C. Sachse, “Higher-order assemblies of oligomeric cargo receptor complexes form the membrane scaffold of the Cvt vesicle.,” EMBO Rep, vol. 17, no. 7, pp. 1044–1060, Jul. 2016.