1cwp
From Proteopedia
(New page: 200px<br /><applet load="1cwp" size="450" color="white" frame="true" align="right" spinBox="true" caption="1cwp, resolution 3.200Å" /> '''STRUCTURES OF THE N...) |
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| - | [[Image:1cwp.gif|left|200px]]<br /><applet load="1cwp" size=" | + | [[Image:1cwp.gif|left|200px]]<br /><applet load="1cwp" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1cwp, resolution 3.200Å" /> | caption="1cwp, resolution 3.200Å" /> | ||
'''STRUCTURES OF THE NATIVE AND SWOLLEN FORMS OF COWPEA CHLOROTIC MOTTLE VIRUS DETERMINED BY X-RAY CRYSTALLOGRAPHY AND CRYO-ELECTRON MICROSCOPY'''<br /> | '''STRUCTURES OF THE NATIVE AND SWOLLEN FORMS OF COWPEA CHLOROTIC MOTTLE VIRUS DETERMINED BY X-RAY CRYSTALLOGRAPHY AND CRYO-ELECTRON MICROSCOPY'''<br /> | ||
==Overview== | ==Overview== | ||
| - | BACKGROUND: RNA-protein interactions stabilize many viruses and also the | + | BACKGROUND: RNA-protein interactions stabilize many viruses and also the nucleoprotein cores of enveloped animal viruses (e.g. retroviruses). The nucleoprotein particles are frequently pleomorphic and generally unstable due to the lack of strong protein-protein interactions in their capsids. Principles governing their structures are unknown because crystals of such nucleoprotein particles that diffract to high resolution have not previously been produced. Cowpea chlorotic mottle virions (CCMV) are typical of particles stabilized by RNA-protein interactions and it has been found that crystals that diffract beyond 4.5 A resolution are difficult to grow. However, we report here the purification of CCMV with an exceptionally mild procedure and the growth of crystals that diffract X-rays to 3.2 A resolution. RESULTS: The 3.2 A X-ray structure of native CCMV, an icosahedral (T = 3) RNA plant virus, shows novel quaternary structure interactions based on interwoven carboxyterminal polypeptides that extend from canonical capsid beta-barrel subunits. Additional particle stability is provided by intercapsomere contacts between metal ion mediated carboxyl cages and by protein interactions with regions of ordered RNA. The structure of a metal-free, swollen form of the virus was determined by cryo-electron microscopy and image reconstruction. Modeling of this structure with the X-ray coordinates of the native subunits shows that the 29 A radial expansion is due to electrostatic repulsion at the carboxyl cages and is stopped short of complete disassembly by preservation of interwoven carboxyl termini and protein-RNA contacts. CONCLUSIONS: The CCMV capsid displays quaternary structural interactions that are unique compared with previously determined RNA virus structures. The loosely coupled hexamer and pentamer morphological units readily explain their versatile reassembly properties and the pH and metal ion dependent polymorphism observed in the virions. Association of capsomeres through inter-penetrating carboxy-terminal portions of the subunit polypeptides has been previously described only for the DNA tumor viruses, SV40 and polyoma. |
==About this Structure== | ==About this Structure== | ||
| - | 1CWP is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Cowpea_chlorotic_mottle_virus Cowpea chlorotic mottle virus]. Full crystallographic information is available from [http:// | + | 1CWP is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Cowpea_chlorotic_mottle_virus Cowpea chlorotic mottle virus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1CWP OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Cowpea chlorotic mottle virus]] | [[Category: Cowpea chlorotic mottle virus]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Baker, J | + | [[Category: Baker, J E.]] |
[[Category: Munshi, S.]] | [[Category: Munshi, S.]] | ||
| - | [[Category: Speir, J | + | [[Category: Speir, J E.Johnson J A.]] |
[[Category: Timothy, S.]] | [[Category: Timothy, S.]] | ||
[[Category: Wang, G.]] | [[Category: Wang, G.]] | ||
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[[Category: icosahedral virus]] | [[Category: icosahedral virus]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:10:31 2008'' |
Revision as of 10:10, 21 February 2008
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STRUCTURES OF THE NATIVE AND SWOLLEN FORMS OF COWPEA CHLOROTIC MOTTLE VIRUS DETERMINED BY X-RAY CRYSTALLOGRAPHY AND CRYO-ELECTRON MICROSCOPY
Overview
BACKGROUND: RNA-protein interactions stabilize many viruses and also the nucleoprotein cores of enveloped animal viruses (e.g. retroviruses). The nucleoprotein particles are frequently pleomorphic and generally unstable due to the lack of strong protein-protein interactions in their capsids. Principles governing their structures are unknown because crystals of such nucleoprotein particles that diffract to high resolution have not previously been produced. Cowpea chlorotic mottle virions (CCMV) are typical of particles stabilized by RNA-protein interactions and it has been found that crystals that diffract beyond 4.5 A resolution are difficult to grow. However, we report here the purification of CCMV with an exceptionally mild procedure and the growth of crystals that diffract X-rays to 3.2 A resolution. RESULTS: The 3.2 A X-ray structure of native CCMV, an icosahedral (T = 3) RNA plant virus, shows novel quaternary structure interactions based on interwoven carboxyterminal polypeptides that extend from canonical capsid beta-barrel subunits. Additional particle stability is provided by intercapsomere contacts between metal ion mediated carboxyl cages and by protein interactions with regions of ordered RNA. The structure of a metal-free, swollen form of the virus was determined by cryo-electron microscopy and image reconstruction. Modeling of this structure with the X-ray coordinates of the native subunits shows that the 29 A radial expansion is due to electrostatic repulsion at the carboxyl cages and is stopped short of complete disassembly by preservation of interwoven carboxyl termini and protein-RNA contacts. CONCLUSIONS: The CCMV capsid displays quaternary structural interactions that are unique compared with previously determined RNA virus structures. The loosely coupled hexamer and pentamer morphological units readily explain their versatile reassembly properties and the pH and metal ion dependent polymorphism observed in the virions. Association of capsomeres through inter-penetrating carboxy-terminal portions of the subunit polypeptides has been previously described only for the DNA tumor viruses, SV40 and polyoma.
About this Structure
1CWP is a Single protein structure of sequence from Cowpea chlorotic mottle virus. Full crystallographic information is available from OCA.
Reference
Structures of the native and swollen forms of cowpea chlorotic mottle virus determined by X-ray crystallography and cryo-electron microscopy., Speir JA, Munshi S, Wang G, Baker TS, Johnson JE, Structure. 1995 Jan 15;3(1):63-78. PMID:7743132
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