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Specialized iNANO Lecture: Advances in segmented helical reconstruction

Dr. Carsten Sachse, PhD Group leader at EMBL Heidelberg, Heidelberg, Germany

2016.11.11 | Trine Møller Hansen

Date Fri 02 Dec
Time 13:15 14:00
Location iNANO AUD (1593-012), Gustav Wieds Vej 14, 8000 Aarhus C

Carsten Sache

Dr. Carsten Sachse, PhD, Group leader at EMBL Heidelberg, European Molecular Biology Laboratory, Structural and Computational Biology Unit,Heidelberg, Germany 

Advances in segmented helical reconstruction Advances in segmented helical reconstruction

As a result of recent advances in software and hardware, cryo-EM based structure determination in near native condition is currently undergoing a ‘resolution revolution’ in structural biology. In my talk, I will present our efforts on the structure elucidation of helical assemblies [1] as they present a fundamental architecture of structures involved in diverse cellular processes such as cytoskeleton assembly, endocytosis, signaling and autophagy. In my talk, I will provide an overview to segmented helical reconstruction covering the entire structure determination workflow from symmetry analysis to high-resolution structure refinement [2].

Further, I will illustrate based on previous and more recent examples of how direct electron detector technology and image processing have contributed to helical reconstruction [3] and have helped to reveal the functionality and versatility of helical organization for various processes in the cell. Recent developments in combining traditional Fourier-Bessel procedures with single-particle algorithms provide a versatile and comprehensive approach to structure determination of helical specimens [4].

I will present applications from a range of medium to high resolution structures. For example, we showed that autophagy receptor p62/SQSTM-1 assembles into flexible helical filaments that provide insights into the structural basis of polymer formation [5]. Recent hardware advancement by the introduction of direct electron detectors has significantly enhanced the image quality and together with improved image processing procedures has made segmented helical reconstruction a very productive cryo-EM structure determination method.

References: 

  1. Sachse, C. Single-particle based helical reconstruction—how to make the most of real and Fourier space. AIMS Biophysics 2, 219–244 (2015).
  2. Fromm, S. A. & Sachse, C. Cryo-EM Structure Determination Using Segmented Helical Image Reconstruction. Meth Enzymol 579, 307–328 (2016).
  3. Fromm, S. A., Bharat, T. A. M., Jakobi, A. J., Hagen, W. J. H. & Sachse, C. Seeing tobacco mosaic virus through direct electron detectors. J Struct Biol 189, 87–97 (2015).
  4. Desfosses, A., Ciuffa, R., Gutsche, I. & Sachse, C. SPRING - an image processing package for single-particle based helical reconstruction from electron cryomicrographs. J Struct Biol 185, 15–26 (2014).
  5. Ciuffa, R. et al. The selective autophagy receptor p62 forms a flexible filamentous helical scaffold. Cell Rep 11, 748–758 (2015).

Host: Associate professor Ebbe Sloth Andersen, iNANO & Department of Molecular Biology and Genetics, Aarhus University

Specialized iNANO Lectures