Protein structure determination by cryo-electron microscopy

Orateur : Janet VONCK (Department of Structural Biology, Max-Planck-Institut für Biophysik, Frankfurt)

Direct electron detection cameras have recently revolutionized the field of cryo-electron microscopy, making it now possible to calculate macromolecular structures without the need for crystallization. These cameras produce images with a much higher signal-to-noise ratio than traditional detectors (CCD cameras and photographic film) and allow the collection of “movies” in which beaminduced specimen movement can be determined and corrected. These images, together with new image processing tools, allow structure determination even for flexible and heterogeneous samples. For many complexes, resolutions of 6-8 Å can be achieved where secondary structure is visible. Maps better than 4.5 Å resolution allow de novo structure determination and below 3 Å atomic details like side chain rotamers and water molecules become visible. Several examples of recent high-resolution structures will be shown.

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