Limits...
From structure of the complex to understanding of the biology.

Rossmann MG, Arisaka F, Battisti AJ, Bowman VD, Chipman PR, Fokine A, Hafenstein S, Kanamaru S, Kostyuchenko VA, Mesyanzhinov VV, Shneider MM, Morais MC, Leiman PG, Palermo LM, Parrish CR, Xiao C - Acta Crystallogr. D Biol. Crystallogr. (2006)

Bottom Line: Both techniques lean heavily on imposing icosahedral symmetry, thereby obscuring any deviation from the assumed symmetry.However, tailed bacteriophages have icosahedral or prolate icosahedral heads that have one obvious unique vertex where the genome can enter for DNA packaging and exit when infecting a host cell.Comparisons are made between rhinoviruses that bind receptor molecules uniformly to all 60 equivalent binding sites, canine parvovirus, which appears to have a preferred receptor-binding site, and bacteriophage T4, which gains major biological advantages on account of its unique vertex and tail organelle.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biological Sciences, Purdue University, 915 West State Street, West Lafayette, IN 47907-2054, USA. mr@purdue.edu

ABSTRACT
The most extensive structural information on viruses relates to apparently icosahedral virions and is based on X-ray crystallography and on cryo-electron microscopy (cryo-EM) single-particle reconstructions. Both techniques lean heavily on imposing icosahedral symmetry, thereby obscuring any deviation from the assumed symmetry. However, tailed bacteriophages have icosahedral or prolate icosahedral heads that have one obvious unique vertex where the genome can enter for DNA packaging and exit when infecting a host cell. The presence of the tail allows cryo-EM reconstructions in which the special vertex is used to orient the head in a unique manner. Some very large dsDNA icosahedral viruses also develop special vertices thought to be required for infecting host cells. Similarly, preliminary cryo-EM data for the small ssDNA canine parvovirus complexed with receptor suggests that these viruses, previously considered to be accurately icosahedral, might have some asymmetric properties that generate one preferred receptor-binding site on the viral surface. Comparisons are made between rhinoviruses that bind receptor molecules uniformly to all 60 equivalent binding sites, canine parvovirus, which appears to have a preferred receptor-binding site, and bacteriophage T4, which gains major biological advantages on account of its unique vertex and tail organelle.

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Cryo-electron image reconstruction of human rhinovirus 16 (grey) complexed with domains D1 and D2 of ICAM-1 (yellow), the cellular molecule used by the virus for attachment and to initiate uncoating. (Adapted from Kolatkar et al., 1999 ▶.)
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fig2: Cryo-electron image reconstruction of human rhinovirus 16 (grey) complexed with domains D1 and D2 of ICAM-1 (yellow), the cellular molecule used by the virus for attachment and to initiate uncoating. (Adapted from Kolatkar et al., 1999 ▶.)

Mentions: Probably the structurally most studied group of viruses is the picornavirus family. This is both because these viruses were among the first viruses to be characterized and because of their small but highly symmetric shape, which makes them good candidates for crystallographic investigations (Acharya et al., 1989 ▶; Hogle et al., 1985 ▶; Luo et al., 1987 ▶; Rossmann et al., 1985 ▶). Their structure gave rise to the ‘canyon hypothesis’, which proposed that the cellular receptor would bind into a surface depression (the canyon), a site that is inaccessible to larger antibodies. Thus, the faster mutating surface amino acids would be able to escape the host’s neutralizing antibodies while conserving the receptor-binding site in the canyon. This prediction was subsequently verified by a series of studies using cryo-EM of various picornaviruses complexed with soluble fragments of their cellular receptor molecules (Fig. 2 ▶; Olson et al., 1993 ▶; Rossmann et al., 2002 ▶). Nevertheless, the rationale for the correct prediction has been questioned (Smith et al., 1996 ▶).


From structure of the complex to understanding of the biology.

Rossmann MG, Arisaka F, Battisti AJ, Bowman VD, Chipman PR, Fokine A, Hafenstein S, Kanamaru S, Kostyuchenko VA, Mesyanzhinov VV, Shneider MM, Morais MC, Leiman PG, Palermo LM, Parrish CR, Xiao C - Acta Crystallogr. D Biol. Crystallogr. (2006)

Cryo-electron image reconstruction of human rhinovirus 16 (grey) complexed with domains D1 and D2 of ICAM-1 (yellow), the cellular molecule used by the virus for attachment and to initiate uncoating. (Adapted from Kolatkar et al., 1999 ▶.)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2483488&req=5

fig2: Cryo-electron image reconstruction of human rhinovirus 16 (grey) complexed with domains D1 and D2 of ICAM-1 (yellow), the cellular molecule used by the virus for attachment and to initiate uncoating. (Adapted from Kolatkar et al., 1999 ▶.)
Mentions: Probably the structurally most studied group of viruses is the picornavirus family. This is both because these viruses were among the first viruses to be characterized and because of their small but highly symmetric shape, which makes them good candidates for crystallographic investigations (Acharya et al., 1989 ▶; Hogle et al., 1985 ▶; Luo et al., 1987 ▶; Rossmann et al., 1985 ▶). Their structure gave rise to the ‘canyon hypothesis’, which proposed that the cellular receptor would bind into a surface depression (the canyon), a site that is inaccessible to larger antibodies. Thus, the faster mutating surface amino acids would be able to escape the host’s neutralizing antibodies while conserving the receptor-binding site in the canyon. This prediction was subsequently verified by a series of studies using cryo-EM of various picornaviruses complexed with soluble fragments of their cellular receptor molecules (Fig. 2 ▶; Olson et al., 1993 ▶; Rossmann et al., 2002 ▶). Nevertheless, the rationale for the correct prediction has been questioned (Smith et al., 1996 ▶).

Bottom Line: Both techniques lean heavily on imposing icosahedral symmetry, thereby obscuring any deviation from the assumed symmetry.However, tailed bacteriophages have icosahedral or prolate icosahedral heads that have one obvious unique vertex where the genome can enter for DNA packaging and exit when infecting a host cell.Comparisons are made between rhinoviruses that bind receptor molecules uniformly to all 60 equivalent binding sites, canine parvovirus, which appears to have a preferred receptor-binding site, and bacteriophage T4, which gains major biological advantages on account of its unique vertex and tail organelle.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biological Sciences, Purdue University, 915 West State Street, West Lafayette, IN 47907-2054, USA. mr@purdue.edu

ABSTRACT
The most extensive structural information on viruses relates to apparently icosahedral virions and is based on X-ray crystallography and on cryo-electron microscopy (cryo-EM) single-particle reconstructions. Both techniques lean heavily on imposing icosahedral symmetry, thereby obscuring any deviation from the assumed symmetry. However, tailed bacteriophages have icosahedral or prolate icosahedral heads that have one obvious unique vertex where the genome can enter for DNA packaging and exit when infecting a host cell. The presence of the tail allows cryo-EM reconstructions in which the special vertex is used to orient the head in a unique manner. Some very large dsDNA icosahedral viruses also develop special vertices thought to be required for infecting host cells. Similarly, preliminary cryo-EM data for the small ssDNA canine parvovirus complexed with receptor suggests that these viruses, previously considered to be accurately icosahedral, might have some asymmetric properties that generate one preferred receptor-binding site on the viral surface. Comparisons are made between rhinoviruses that bind receptor molecules uniformly to all 60 equivalent binding sites, canine parvovirus, which appears to have a preferred receptor-binding site, and bacteriophage T4, which gains major biological advantages on account of its unique vertex and tail organelle.

Show MeSH
Related in: MedlinePlus