Research Department "Molecular Structural Biology"
Cryoelectron microscopy offers the key to investigate the structure of large, complex and flexible protein assemblies in its natural environment in intact cells and in isolated form to the quasi-atomic level. Wolfgang Baumeister and his team of the research department "Molecular Structural Biology" have studied the 3D structure of the 26S proteasome (image) by an integrative approach of single particle electron microscopy, combining the classification of reconstructed 26S complexes in different conformational states, by structure modelling and the integration of atomic models of single protein components obtained by x-ray crystallography. The 26S proteasome consists of 66 protein subunits and recognizes, unfolds and degrades other protein molecules in a controlled manner. Large protein assemblies have important roles in the living cell, but they are often unstable, may exist only temporarily and can thus hardly be investigated in biochemical preparations in purified form. The department of Wolfgang Baumeister pioneered and developed the method of cryo-electron tomography which enables the reserches to visualize macromolecular structures in a functional and close-to-native state in frozen-hydrated cells. By recording micrographs from different viewing angles and integrating them to a 3D image (tomogram) the researchers study the structure of macromolecular assemblies in prokaryotic cells and of eukaryotic cellular components such as the nuclear pore complex, the actin filament network, and the pre- and postsynaptic structures of neurons in situ.