From structure of the complex to understanding of the biology.
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.
Rossmann
Michael G
MG
Department of Biological Sciences, Purdue University, 915 West State Street, West Lafayette, IN 47907-2054, USA. mr@purdue.edu
Arisaka
Fumio
F
Battisti
Anthony J
AJ
Bowman
Valorie D
VD
Chipman
Paul R
PR
Fokine
Andrei
A
Hafenstein
Susan
S
Kanamaru
Shuji
S
Kostyuchenko
Victor A
VA
Mesyanzhinov
Vadim V
VV
Shneider
Mikhail M
MM
Morais
Marc C
MC
Leiman
Petr G
PG
Palermo
Laura M
LM
Parrish
Colin R
CR
Xiao
Chuan
C
D001435:Bacteriophages / Q000737:chemistry* / Q000648:ultrastructure; D001665:Binding Sites; D002213:Capsid / Q000737:chemistry; D020285:Cryoelectron Microscopy / Q000379:methods*; D003460:Crystallization; D018360:Crystallography, X-Ray / Q000379:methods*; D004247:DNA / Q000737:chemistry; D042003:DNA Packaging; D008958:Models, Molecular; D008968:Molecular Conformation; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D014771:Virion / Q000737:chemistry; D019065:Virus Assembly; D014780:Viruses / Q000737:chemistry* / Q000648:ultrastructure*
D004247:DNA