Berlin 2015 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MI: Fachverband Mikrosonden

MI 1: Microanalysis and Microscopy of Biological Materials

MI 1.1: Hauptvortrag

Montag, 16. März 2015, 09:30–10:15, EMH 225

High-resolution electron cryo-microscopy of macromolecular protein complexes — •Werner Kühlbrandt — MPI of Biophysics, Frankfurt, Germany

We are witnessing a revolution in determining the structure of large protein complexes by electron cryo-microscopy (cryo-EM), precipitated by a new generation of direct electron detectors. The sensitivity and fast readout rate of these new cameras means that beam-induced movements can be overcome routinely. Three-dimensional density maps of a quality similar to or better than that achieved by x-ray crystallography are obtained. Two examples will be presented: the 3.3 Å structure of the nickel-iron hydrogen transferase Frh, an archaeal multi-enzyme complex involved in methanogenesis, and the 6.2 Å structure of an intact, functional mitochondrial F1-Fo ATP synthase. Both have defeated protein crystallography for years or decades.

The mitochondrial ATP synthase is an ancient nanomachine in the energy-converting membranes of all living organisms. In order to understand how this massive multiprotein assembly works in the cellular context, it is necessary to obtain detailed views of it in the membrane, which was achieved by electron cryo-tomography (cryo-ET) of whole mitochondria. The new direct electron detectors enabled us to obtain an 18 Å map of the ATP synthase in situ, doubling the resolution attained with conventional CCD detectors. Our results provide unique new insights into the functional arrangement of large membrane protein complexes in biological energy-converting membranes.