First Grenoble Practical Workshop on Helical Symmetry determination and Reconstruction

The workshop was dedicated to helical symmetry determination of biological polymers imaged by cryo-EM. Determining the helical parameters from a sample with helical symmetry(ies) is often the bottleneck for successful structure determination. The learning curve to get familiar with this process is steep and full of crevices. In this workshop, the participants who already had helical assemblies data in their hands through this process, were guided exploiting all possible information, including power spectra interpretation, 2D class-averages analysis and clue hunting from raw data inspection. The practicals covered the use of helixplorer (https://rico.ibs.fr/helixplorer/), but was not limited to this approach.
Although the main focus was on helical parameters determination, general reconstruction strategies were also discussed, including dealing with flexible helices, multiple symmetries, and merging of data from different symmetry filaments using subtraction approaches.
With 24 participants from all horizons (Europe, USA, China, young and experienced researchers), this course, organized by L. Estrosi (IBS/MEM) and A. Desfosses (IBS/MICA), was a success and will certainly be repeated next year.