Towards atomic resolution structural determination by single-particle cryo-electron microscopy.
Recent advances in cryo-electron microscopy and single-particle reconstruction (collectively referred to as 'cryoEM') have made it possible to determine the three-dimensional (3D) structures of several macromolecular complexes at near-atomic resolution ( approximately 3.8-4.5A). These achievements were accomplished by overcoming the challenges in sample handling, instrumentation, image processing, and model building. At near-atomic resolution, many detailed structural features can be resolved, such as the turns and deep grooves of helices, strand separation in beta sheets, and densities for loops and bulky amino acid side chains. Such structural data of the cytoplasmic polyhedrosis virus (CPV), the Epsilon 15 bacteriophage and the GroEL complex have provided valuable constraints for atomic model building using integrative tools, thus significantly enhancing the value of the cryoEM structures. The CPV structure revealed a drastic conformational change from a helix to a beta hairpin associated with RNA packaging and replication, coupling of RNA processing and release, and the long sought-after polyhedrin-binding domain. These latest advances in single-particle cryoEM provide exciting opportunities for the 3D structural determination of viruses and macromolecular complexes that are either too large or too heterogeneous to be investigated by conventional X-ray crystallography or nuclear magnetic resonance (NMR) methods.
Zhou
Z Hong
ZH
Department of Microbiology, Immunology & Molecular Genetics and the California NanoSystems Institute, University of California at Los Angeles, 237 BSRB, 615 Charles E. Young Dr. S., Los Angeles, CA 90095-7364, USA. Hong.Zhou@UCLA.edu
D020285:Cryoelectron Microscopy / Q000295:instrumentation / Q000379:methods*; D007091:Image Processing, Computer-Assisted; D046911:Macromolecular Substances / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008968:Molecular Conformation
D046911:Macromolecular Substances