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Updated: May 19, 2026
07:24
In Vitro Disassembly of Influenza A Virus Capsids by Gradient Centrifugation
Published on: March 27, 2016
An unexpected twist in viral capsid maturation
Ilya Gertsman1, Lu Gan, Miklos Guttman
1Department of Molecular Biology, The Scripps Research Institute, La Jolla, California 92037, USA.
Nature
|February 11, 2009
Summary
The first bacteriophage procapsid structure reveals how viral shells expand and mature. This study of HK97 bacteriophage provides insights into the structural basis for exothermic maturation in double-stranded DNA viruses.
Area of Science:
- Structural Biology
- Virology
- Biochemistry
Background:
- Bacteriophage capsids undergo significant conformational changes during genome packaging.
- Mature bacteriophage capsids are well-characterized, but procapsid structures are largely unknown.
- Procapsids are essential intermediates for capsid maturation and genome packaging.
Purpose of the Study:
- To determine the X-ray structure of the HK97 bacteriophage procapsid (prohead II).
- To compare the procapsid structure with the mature HK97 capsid to understand maturation mechanisms.
- To elucidate the structural basis for the exothermic maturation process observed in bacteriophages.
Main Methods:
- X-ray crystallography (3.65 Å resolution) to determine the prohead II structure.
- Comparison with the previously solved mature HK97 capsid structure (3.44 Å resolution).
- Crystallographic and hydrogen/deuterium exchange data analysis to identify structural changes.
Main Results:
- The first atomic-resolution structure of a double-stranded DNA bacteriophage procapsid (prohead II) is presented.
- Significant differences in subunit tertiary structures between procapsid and mature capsid states were identified.
- Key subunit interactions at three-fold axes were found to be maintained during maturation, acting as hinges for conformational changes.
Conclusions:
- The structural comparison reveals an unprecedented expansion mechanism for bacteriophage capsid maturation.
- The observed tertiary structural changes provide a structural basis for the exothermic maturation process.
- This mechanism may be conserved in other double-stranded DNA bacteriophages and related viruses like herpesviruses.
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