Cryomicroscopy reconstruction

It is possible that the structure of HA2 in its low pH-converted form represents the results of multiple, sequential conformational changes (White and Wilson, 1987 Korte et al, 1999), and that, under certain conditions, intermediate states can be trapped. The first intermediate is likely to be one in which the fusion peptides have emerged from their buried positions. An electron cryomicroscopy reconstruction of HA exposed to low pH for short time periods at 4°C revealed relatively... 

Jimenez et al. (2002) proposed a molecular model for the insulin protofilament based on these data and on electron cryomicroscopy (cryo-EM) reconstructions of insulin fibrils. The fibrils show a number of twisted morphologies that seem to be alternative packings of similar protofilaments. The protofilaments have cross sections of 30x40 A. The authors suggest a complete conversion to / -structure and model the amyloid monomer as having four jS-strands (Fig. 3B). Each insulin chain contributes two of these jS-strands, and the chains align in a parallel stack, constrained by the interchain disulfide bonds. One pair of stacked /i-stran ds is curved... 

Akiba, T., Toyoshima, C., Matsunaga, T., Kawamoto, M., Kubota, T., Fukuyama, K., Namba, K., and Matsubara, H., 1996, Three-dimensional structure of bovine cytochrome bcl complex by electron cryomicroscopy and helical image reconstruction. Nature Struct. Biol. 3 553n561. 

Grimes et al., 1998 Reinisch et al, 2000 Wikoff et at, 2000). Likewise, advances in electron cryomicroscopy and image reconstruction techniques allow time-resolved investigations of structural transitions associated with capsid assembly and maturation (Conway et al., 2001 Lawton et al, 1997). These developments have been paralleled by refinements in the molecular approaches used for sample preparation, with the result that synthesis of assembly intermediates and end products has become routine for many viruses. 

Electron cryomicroscopy, 2, 94-101, 401-2 field depth/resolution graph for, 100 instrument choices in, 97-101 theoretical consideration of, 94-101 three dimensional reconstruction and, 101 Electron density maps, 42 Electron microscopy resolution (EM resolution), 45-46... 

Fig. 28-3. Structure of an alphavirus. Shown is the three-dimensional reconstruction of Sindbis virus at 28 A resolution from computer-processed images taken by electron cryomicroscopy, (a) The original electron micrograph shows virus particles in vitreous ice. (b) The surface view of the virus shows details of the 80 trimeric spikes, which are arranged in a T=4 icosahedron. Each spike protrudes 50 A from the virion surface and is believed to be composed of three E1-E2 glycoprotein heterodimers, (c) The cross-sectional view shows the outer surface spikes (yellow) and the internal nucleocapsid (blue), composed of the capsid and viral RNA. The space between the spikes and the nucleocapsid would be occupied by the lipid envelope. The green arrows mark visible points of interaction between the nucleocapsid and trans-membranal tails of the glycoprotein spikes, (d) The reconstructed capsid also exhibits a T=4 icosahedral symmetry. Computer models Courtesy of Angel M. Paredes, Cell Research Institute and Department of Microbiology, The University of Texas at Austin, Austin, Tex. Similar but not identical versions of these computer models were published in Paredes AM, Brown DT, Rothnagel R, et al. Three-dimensional structure of a membrane-containing virus. Proc Natl Acad Sci USA. 1993 90 9095-9099.

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