Cowpea Chlorotic Mottle Virus
From Proteopedia
(→Self-Assembling Cowpea Chlorotic Mottle Virus Capsid: Nanoreactor and Scaffold for Molecular Synthesis) |
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The atoms of residues 27-49 are colored blue for clarity. | The atoms of residues 27-49 are colored blue for clarity. | ||
| - | Each hexamer consists of six beta strands that run parallel to each other and result in a pore in the center of the hexamer. Residues 29-33 line this pore and | + | Each hexamer consists of six beta strands that run parallel to each other and result in a pore in the center of the hexamer. Residues 29-33 line this pore and reinforce the hexamer subunits by the interaction of their side chains with adjacent residues. For example, the "side chain oxygens of Gln29 residues hydrogen bond with the main chain nitrogens of adjacent Gln29 residues, making a circular ring of interactions" and the "valine residues stack upon one another inside the the beta-tube forming a circle of hydrophobic bonds." |
In the <scene name='Cowpea_Chlorotic_Mottle_Virus/Interior_of_beta_barrel/1'>interior of beta barrel</scene>we can see these lining residues: glutamine 29 (in red), valine 31 (in orange), and valine 33 (in green). | In the <scene name='Cowpea_Chlorotic_Mottle_Virus/Interior_of_beta_barrel/1'>interior of beta barrel</scene>we can see these lining residues: glutamine 29 (in red), valine 31 (in orange), and valine 33 (in green). | ||
Pentamer capsomeres, on the other hand, are formed exclusively from the contribution of A subunit chains. | Pentamer capsomeres, on the other hand, are formed exclusively from the contribution of A subunit chains. | ||
| + | <scene name='Cowpea_Chlorotic_Mottle_Virus/Pentamer/1'>Pentamer capsomeres</scene> also contain the same beta barrel structure but the amino-terminus arms cluster to create 5-fold symmetry. The positively charged Lys 42 residue is colored in blue as a marker for the N-terminus arms. The 41 amino acids before this residue do not have detectable electron density for the techniques used to render the structure. | ||
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Hexamer formation predominates the structure. It serves as the nucleation point for capsid construction. | Hexamer formation predominates the structure. It serves as the nucleation point for capsid construction. | ||
Revision as of 06:46, 29 November 2011
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Self-Assembling Cowpea Chlorotic Mottle Virus Capsid: Nanoreactor and Scaffold for Molecular Synthesis
Introduction
General Capsid Structure
The viral capsid of CCMV is a complex of proteins stabilized by metal coordination between capsomeres and RNA binding on its internal surface. The viral genome encodes three capsid proteins that are chemically identical. These subunits, arbitrarily called A, B, and C, dimerize with each other and assemble into into hexamers and pentamers that comprise the viral capsomeres. The complete capsid structure takes the form of a truncated icosahedron (20 faces). It is described as a T=3 capsid, where the T value is an indicator of structural complexity. "A T-number or the triangulation number which determines the size of an icosahedron is defined as: T=h^2 + hk + k^2" -Fumio Arisaka, Tokyo Institute of Technology.
Capsomere Structure
The hexameric capsomeres are formed by the B and C subunits. The N-terminus arms (residue 27 through 49) of the subunits intertwine to form a ring structure. The N-terminus is therefore key to the hexamer composition.
The atoms of residues 27-49 are colored blue for clarity.
Each hexamer consists of six beta strands that run parallel to each other and result in a pore in the center of the hexamer. Residues 29-33 line this pore and reinforce the hexamer subunits by the interaction of their side chains with adjacent residues. For example, the "side chain oxygens of Gln29 residues hydrogen bond with the main chain nitrogens of adjacent Gln29 residues, making a circular ring of interactions" and the "valine residues stack upon one another inside the the beta-tube forming a circle of hydrophobic bonds."
In the we can see these lining residues: glutamine 29 (in red), valine 31 (in orange), and valine 33 (in green).
Pentamer capsomeres, on the other hand, are formed exclusively from the contribution of A subunit chains. also contain the same beta barrel structure but the amino-terminus arms cluster to create 5-fold symmetry. The positively charged Lys 42 residue is colored in blue as a marker for the N-terminus arms. The 41 amino acids before this residue do not have detectable electron density for the techniques used to render the structure.
Hexamer formation predominates the structure. It serves as the nucleation point for capsid construction.
- All Structural Content Derived from Speir et al.
"STRUCTURES OF THE NATIVE AND SWOLLEN FORMS OF COWPEA CHLOROTIC MOTTLE VIRUS DETERMINED BY X-RAY CRYSTALLOGRAPHY AND CRYO-ELECTRON MICROSCOPY"
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Inna Blyakhman, Michal Harel, Alexander Berchansky, Joel L. Sussman
