Elsevier

Virology

Volume 186, Issue 2, February 1992, Pages 655-668
Virology

Regular article
Cauliflower mosaic virus: A 420 subunit (T = 7), multilayer structure

https://doi.org/10.1016/0042-6822(92)90032-KGet rights and content

Abstract

The structures of the Cabb-B and CM 1841 strains of cauliflower mosaic virus (CaMV) have been solved to about 3 nm resolution from unstained, frozen-hydrated samples that were examined with low-irradiation cryo-electron microscopy and three-dimensional image reconstruction procedures. CaMV is highly susceptible to distortions. Spherical particles, with a maximum diameter of 53.8 nm, are composed of three concentric layers (I–III) of solvent-excluded density that surround a large, solvent-filled cavity (∼ 27 nm dia.). The outermost layer (I) contains 72 capsomeric morphological units, with 12 pentavalent pentamers and 60 hexavalent hexamers for a total of 420 subunits (37–42 kDa each) arranged with T = 7 icosahedral symmetry. CaMV is the first example of a T = 7 virus that obeys the rules of stoichiometry proposed for isometric viruses by Caspar and Klug (1962, Cold Spring Harb. Symp. Quant. Biol. 27, 1–24), although the hexameric capsomers exhibit marked departure from the regular sixfold symmetry expected for a structure in which the capsid protein subunits are quasi-equivalently related. The double-stranded DNA genome is distributed in layers II and III along with a portion of the viral protein. The CaMV reconstructions are consistent with the model based on neutron diffraction studies (Kruse et al., 1987, Virology 159, 166–168) and, together, these structural models are discussed in relation to a replication-assembly model (Hull et al., 1987, J. Cell Sci. (Suppl.) 7, 213–229). Remarkable agreement between the reconstructions of CaMV Cabb-B and CM 1841 suggests that other strains of CaMV adopt the same basic structure.

References (67)

  • Z.X. Gong et al.

    Crystallization of cauliflower mosaic virus

    Virology

    (1990)
  • P. Hahn et al.

    Phosphorylated proteins in cauliflower mosaic virus

    Virology

    (1980)
  • P. Hahn et al.

    Evidence for a 58-kilodalton polypeptide as precursor of the coat protein of cauliflower mosaic virus

    Virology

    (1982)
  • G.L. Hills et al.

    Morphology of broccoli necrotic yellow virus

    J. Ultrastruc. Res.

    (1968)
  • T. Hohn et al.

    Reverse transcription in a plant virus

    Trends Biochem. Sci.

    (1985)
  • R. Hull et al.

    The coat proteins of cauliflower mosaic virus

    Virology

    (1976)
  • T. Itoh et al.

    Conformational changes in cauliflower mosaic virus

    Virology

    (1969)
  • J. Kruse et al.

    A neutron scattering study of the structure of compact and swollen forms of southern bean mosaic virus

    Virology

    (1982)
  • J. Kruse et al.

    The spherically averaged structure of a DNA isometric plant virus: Cauliflower mosaic virus

    Virology

    (1987)
  • A.J. Maule et al.

    The pattern of accumulation of cauliflower mosaic virus-specific products in infected turnips

    Virology

    (1989)
  • J.M. Mesnard et al.

    The cauliflower mosaic virus gene III product is a non-sequence-specific DNA binding protein

    Virology

    (1990)
  • N.H. Olson et al.

    Magnification calibration and the determination of spherical virus diameters using cryo-microscopy

    Ultramicroscopy

    (1989)
  • D. Rodríguez et al.

    An electron microscopic study of cauliflower mosaic virus-induced viroplasms: unusual structures within the virioplasm matrix with possible functional significance in the viral replication cycle

    J. Ultrastructure and Mol. Structure Res.

    (1988)
  • R.J. Shepherd et al.

    Double-stranded DNA from cauliflower mosaic virus

    Virology

    (1970)
  • N. Tezuka et al.

    Stepwise degradation of cauliflower mosaic virus by pronase

    Virology

    (1972)
  • R. Al Am et al.

    The structure of cauliflower mosaic virus. I. pH-induced structural changes

    Virology

    (1979)
  • R. Al Ani et al.

    The structure of cauliflower mosaic virus. II. Identity and location of the viral polypeptides

    Virology

    (1979)
  • T.S. Baker et al.

    Reconstruction of the three-dimensional structure of simian virus 40 and visualization of the chromatin core

  • T.S. Baker et al.

    Three-dimensional structures of maturable and abortive capsids of equine herpesvirus 1 from cryoelectron microscopy

    J. Virol.

    (1990)
  • J.M. Berg

    Protein metal-binding domains in nucleic acid binding protein

    Science

    (1986)
  • N. Brisson et al.

    Expression of a bacterial gene in plants by using a viral vector

    Nature

    (1984)
  • A.A. Brunt et al.

    The composition of cauliflower mosaic virus protein

    J. Gen. Virol.

    (1975)
  • D.L.D. Caspar et al.

    Physical principles in the construction of regular viruses

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