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Pseudo-atomic models of swollen CCMV from cryo-electron microscopy data
Hongjun Liu1, Chunxu Qu, John E Johnson
1Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
Journal of Structural Biology
|June 5, 2003
Summary
Cowpea chlorotic mottle virus (CCMV) capsid reversibly switches between compact and swollen forms. This structural change, driven by pH and metal ions, involves conserved pentamers and hexamers, with flexibility mainly in dimer interactions.
Area of Science:
- Structural biology
- Virology
- Biophysics
Background:
- Cowpea chlorotic mottle virus (CCMV) capsid exhibits reversible structural transitions.
- These conformational changes are influenced by pH and divalent metal ions.
- Previous studies utilized crystallography and cryo-electron microscopy to analyze compact and swollen forms.
Purpose of the Study:
- To interpret the 28-Å resolution electron density of the swollen CCMV form.
- To generate a pseudo-atomic model of the swollen viral particle.
- To elucidate the structural mechanisms underlying capsid conformational changes.
Main Methods:
- Utilized atomic models of unique viral subunits from crystallography.
- Interpreted 28-Å resolution electron density data of the swollen form.
- Employed energy minimization with incremental rigid body transformations (screw motion) for modeling.
Main Results:
- A pseudo-atomic model of the swollen CCMV capsid was produced.
- The quaternary structure model aligns with geometric constraints and intersubunit energies.
- Conserved pentamers and hexamers suggest flexibility arises from dimer interactions.
- A screw motion pathway for particle expansion was implied.
Conclusions:
- The study provides a detailed pseudo-atomic model of the swollen CCMV capsid.
- CCMV capsid flexibility is primarily accommodated by changes in dimer interactions.
- The findings offer insights into virus structural dynamics and assembly.