Three-dimensional electron cryo-microscopy as a powerful structural tool in molecular medicine.
Electron cryo-microscopy has established itself as a valuable method for the structure determination of protein molecules, protein complexes, and cell organelles. This contribution presents an introduction to the various aspects of three-dimensional electron cryomicroscopy. This includes the need for sample preservation in the microscope vacuum, strategies for minimizing radiation damage, methods of improving the poor signal-to-noise ratio in electron micrographs of unstained specimens, and the various methods of three-dimensional image reconstruction from projections. The various specimen types (e.g., flat and tubular two-dimensional crystals, protein filaments, individual protein molecules, and large complexes) require different means of three-dimensional reconstruction, and we review the five major reconstruction techniques (electron crystallography, helical reconstruction, icosahedral reconstruction, single-particle reconstruction, and electron tomography), with an emphasis on electron crystallography. Several medically relevant three-dimensional protein structures are chosen to illustrate the potential of electron cryo-microscopy and image reconstruction techniques. Among the structural methods, electron cryo-microscopy is the only tool for studying objects that range in size from small proteins over macromolecular complexes to cell organelles or even cells.
Auer
M
M
Skirball Institute of Biomolecular Medicine, New York University Medical Center, NY 10016, USA. auer@saturn.med.nyu.edu
D020285:Cryoelectron Microscopy / Q000295:instrumentation / Q000379:methods*; D018360:Crystallography, X-Ray; D006801:Humans; D021621:Imaging, Three-Dimensional; D009682:Magnetic Resonance Spectroscopy; D008854:Microscopy, Electron; D015394:Molecular Structure; D011506:Proteins / Q000737:chemistry / Q000648:ultrastructure; D011978:Receptors, Nicotinic / Q000737:chemistry / Q000378:metabolism; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism; D014780:Viruses / Q000737:chemistry / Q000648:ultrastructure
D011506:Proteins; D011978:Receptors, Nicotinic