Cryo-ME has become a major technique in structural biology in the last 5 years. It allows the determination of the three-dimensional structure of biological macromolecular complexes at a resolution close to atomic resolution without the use of crystals. Thanks to advances in image analysis methods, this technique also makes it possible to separate several conformations of the same biological object and to determine their structures.
In the classical way, we use our Glacios microscope to obtain the images we need. This will include testing to see if the samples are correct. Once this is done, in about 50% of cases the data acquired is sufficient to obtain 3D maps. When too many images are needed, when a high resolution is expected or if the complex studied is small, the grids that have been checked at Glacios are redirected to an even more powerful and stable microscope: typically a Titan Krios microscope like the one installed on CM01 at ESRF.
As specialists in cryo-electron microscopy and image analysis, we are strongly solicited at the IBS level, but also at the national level in a context where the number of instruments, allowing to go towards atomic resolutions, is limited.
At the IBS, our team collaborates with almost all the teams in the building. We have therefore been able to acquire very advanced expertise in the study of biological macromolecular complexes. These complexes can be very diverse in terms of size (from 100 kDa to several MDa), composition (monomeric or hetero-oligomeric), nature (membrane or non-membrane) or geometry (point or helical symmetry). The selection criterion applied for collaborations very often corresponds to the biological importance of the objects studied.
In parallel to these collaborations, we also provide our collaborators with the opportunity to train in certain aspects of cryo-electron microscopy.