Three-dimensional reconstruction of the stacked-disk aggregate of tobacco mosaic virus protein from electron micrographs

The three-dimensional structure of the stacked-disk rod of tobacco mosaic virus protein has been reconstructed to a resolution of about 2 nm from electron microscope images. Closed rings of seventeen protein subunits (compared with 16 ⅓ in one turn of the virus helix) are stacked in polar fashion, the stacking being accompanied by an axial perturbation of periodicity 5.3 nm connecting successive pairs of rings into disks. The axial perturbation consists of a movement towards each other of the outer parts of the subunits in the two rings comprising a disk, together with a movement of the inner parts in the opposite direction. This could be explained either by a bending of parts of the subunits in the appropriate directions or by a bodily tilting of the subunits in the two rings in opposite directions.

1999 ◽  
Vol 354 (1383) ◽  
pp. 659-664 ◽  
Author(s):  
Roger N. Beachy

In 1986 we reported that transgenic plants which accumulate the coat protein of tobacco mosaic virus (TMV) are protected from infection by TMV, and by closely related tobamoviruses. The phenomenon is referred to as coat–protein–mediated resistance (CP–MR), and bears certain similarities to cross protection, a phenomenon described by plant pathologists early in this century. Our studies of CP–MR against TMV have demonstrated that transgenically expressed CP interferes with disassembly of TMV particles in the inoculated transgenic cell. However, there is little resistance to local, cell–to–cell spread of infection. CP–MR involves interaction between the transgenic CP and the CP of the challenge virus, and resistance to TMV is greater than to tobamoviruses that have CP genes more distantly related to the transgene. Using the known coordinates of the three–dimensional structure of TMV we developed mutant forms of CP that have stronger inter–subunit interactions, and confer increased levels of CP–MR compared with wild–type CP. Similarly, it is predicted that understanding the cellular and structural basis of CP–MR will lead to the development of variant CP transgenes that each can confer high levels of resistance against a range of tobamoviruses.


Nature ◽  
1963 ◽  
Vol 200 (4910) ◽  
pp. 932-934 ◽  
Author(s):  
R. MacLEOD ◽  
G. J. HILLS ◽  
ROY MARKHAM

1993 ◽  
Vol 231 (2) ◽  
pp. 375-391 ◽  
Author(s):  
Steven B. Larson ◽  
Stanley Koszelak ◽  
John Day ◽  
Aaron Greenwood ◽  
J.Allan Dodds ◽  
...  

Author(s):  
Robert Glaeser ◽  
Thomas Bauer ◽  
David Grano

In transmission electron microscopy, the 3-dimensional structure of an object is usually obtained in one of two ways. For objects which can be included in one specimen, as for example with elements included in freeze- dried whole mounts and examined with a high voltage microscope, stereo pairs can be obtained which exhibit the 3-D structure of the element. For objects which can not be included in one specimen, the 3-D shape is obtained by reconstruction from serial sections. However, without stereo imagery, only detail which remains constant within the thickness of the section can be used in the reconstruction; consequently, the choice is between a low resolution reconstruction using a few thick sections and a better resolution reconstruction using many thin sections, generally a tedious chore. This paper describes an approach to 3-D reconstruction which uses stereo images of serial thick sections to reconstruct an object including detail which changes within the depth of an individual thick section.


Author(s):  
Irwin Bendet ◽  
Nabil Rizk

Preliminary results reported last year on the ion etching of tobacco mosaic virus indicated that the diameter of the virus decreased more rapidly at 10KV than at 5KV, perhaps reaching a constant value before disappearing completely.In order to follow the effects of ion etching on TMV more quantitatively we have designed and built a second apparatus (Fig. 1), which incorporates monitoring devices for measuring ion current and vacuum as well as accelerating voltage. In addition, the beam diameter has been increased to approximately 1 cm., so that ten electron microscope grids can be exposed to the beam simultaneously.


Author(s):  
J.L. Williams ◽  
K. Heathcote ◽  
E.J. Greer

High Voltage Electron Microscope already offers exciting experimental possibilities to Biologists and Materials Scientists because the increased specimen thickness allows direct observation of three dimensional structure and dynamic experiments on effectively bulk specimens. This microscope is designed to give maximum accessibility and space in the specimen region for the special stages which are required. At the same time it provides an ease of operation similar to a conventional instrument.


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