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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-EM reconstruction of CPV at 21 Å resolution showing (a) a surface-shaded representation (adapted from Chipman et al., 1996 ▶) and (b) a central section (adapted from Tsao et al., 1991 ▶). The virus is about 280 Å in diameter. These reconstructions were based on icosahedral symmetry averaging, as was also the determination of the CPV crystal structure.
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fig3: Cryo-EM reconstruction of CPV at 21 Å resolution showing (a) a surface-shaded representation (adapted from Chipman et al., 1996 ▶) and (b) a central section (adapted from Tsao et al., 1991 ▶). The virus is about 280 Å in diameter. These reconstructions were based on icosahedral symmetry averaging, as was also the determination of the CPV crystal structure.

Mentions: Parvoviruses are small 260 Å diameter icosahedral non-enveloped single-stranded DNA viruses (Fig. 3 ▶) with a genome of about 5 kbp. Each of the 60 structurally identical 64 kDa subunits consists of an eight-stranded antiparallel β-barrel motif (Tsao et al., 1991 ▶) found in numerous viral capsid structures (Benson et al., 2004 ▶; Nandhagopal et al., 2002 ▶; Rossmann & Johnson, 1989 ▶; Fig. 4 ▶). The β-barrel has large insertions between β-strands. These insertions form most of the capsid surface and create small protruding ‘spikes’ around the icosahedral threefold axes in canine parvovirus (CPV; Tsao et al., 1991 ▶) and feline panleukopenia virus (FPV; Agbandje et al., 1993 ▶). CPV, which emerged as a natural variant of FPV in 1978 (Parrish & Kawaoka, 2005 ▶), has 99% sequence identity with FPV (Parrish et al., 1991 ▶). Both viruses bind to transferrin receptor (TfR; Hueffer, Parker et al., 2003 ▶) as a prelude to infecting their host cells. The viral surface in the vicinity of the spikes contains residues 93, 299 and 323, which are involved in host-range control, specific recognition of TfR and antibody binding (Chang et al., 1992 ▶; Hueffer, Govindasamy et al., 2003 ▶; Lawrence et al., 1999 ▶; Palermo et al., 2003 ▶).


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-EM reconstruction of CPV at 21 Å resolution showing (a) a surface-shaded representation (adapted from Chipman et al., 1996 ▶) and (b) a central section (adapted from Tsao et al., 1991 ▶). The virus is about 280 Å in diameter. These reconstructions were based on icosahedral symmetry averaging, as was also the determination of the CPV crystal structure.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig3: Cryo-EM reconstruction of CPV at 21 Å resolution showing (a) a surface-shaded representation (adapted from Chipman et al., 1996 ▶) and (b) a central section (adapted from Tsao et al., 1991 ▶). The virus is about 280 Å in diameter. These reconstructions were based on icosahedral symmetry averaging, as was also the determination of the CPV crystal structure.
Mentions: Parvoviruses are small 260 Å diameter icosahedral non-enveloped single-stranded DNA viruses (Fig. 3 ▶) with a genome of about 5 kbp. Each of the 60 structurally identical 64 kDa subunits consists of an eight-stranded antiparallel β-barrel motif (Tsao et al., 1991 ▶) found in numerous viral capsid structures (Benson et al., 2004 ▶; Nandhagopal et al., 2002 ▶; Rossmann & Johnson, 1989 ▶; Fig. 4 ▶). The β-barrel has large insertions between β-strands. These insertions form most of the capsid surface and create small protruding ‘spikes’ around the icosahedral threefold axes in canine parvovirus (CPV; Tsao et al., 1991 ▶) and feline panleukopenia virus (FPV; Agbandje et al., 1993 ▶). CPV, which emerged as a natural variant of FPV in 1978 (Parrish & Kawaoka, 2005 ▶), has 99% sequence identity with FPV (Parrish et al., 1991 ▶). Both viruses bind to transferrin receptor (TfR; Hueffer, Parker et al., 2003 ▶) as a prelude to infecting their host cells. The viral surface in the vicinity of the spikes contains residues 93, 299 and 323, which are involved in host-range control, specific recognition of TfR and antibody binding (Chang et al., 1992 ▶; Hueffer, Govindasamy et al., 2003 ▶; Lawrence et al., 1999 ▶; Palermo et al., 2003 ▶).

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