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Published on: October 14, 2011
Geometry of phage head construction
1School of Pharmacy, University of London, 29-39 Brunswick Square, London, WC1N 1AX, UK.
Journal of Molecular Biology
|October 26, 1999
Summary
Phage capsid assembly is driven by curvature, influencing head size and shape. This geometric principle explains procapsid formation, polyhead malformations, and the final angularization of mature phage heads.
Area of Science:
- Structural biology
- Biophysics
- Virology
Background:
- Phage capsid assembly is a complex process involving protein subunits forming a protective shell.
- Understanding the geometric principles governing capsid formation is crucial for deciphering viral structure and function.
Purpose of the Study:
- To review the process of phage capsid assembly, focusing on the role of curvature in determining head size and shape.
- To explore the influence of curvature on procapsid formation, malformations like polyheads, and the angularization of mature phage heads.
Main Methods:
- Geometric analysis of curvature (mean and Gaussian) in relation to capsid morphology.
- Review of experimental observations on procapsid and polyhead structures.
- Discussion of the implications of DNA packaging and inter-component symmetry mismatches.
Main Results:
- Spherical procapsids are favored by optimal curvature conditions, with thickness aiding size determination.
- Nucleation failures lead to malformations like polyheads, where subunit curvature results in constant mean curvature and lattice distortions.
- Head transformation involves enlargement and toughening, concentrating Gaussian curvature at vertices, explaining head angularization and subunit packing distortions.
Conclusions:
- Curvature is a key determinant of phage head size and shape throughout the assembly process.
- Geometric constraints explain the formation of procapsids, polyheads, and the angular morphology of mature phage heads.
- Symmetry mismatches between phage components are linked to DNA packaging mechanisms and channel structures.
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