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Bacteriophage P22 scaffolding protein forms oligomers in solution
M H Parker1, W F Stafford, P E Prevelige
1Dept. of Microbiology, Univ. of Alabama at Birmingham, 35294, USA.
Journal of Molecular Biology
|May 9, 1997
Summary
Salmonella typhimurium bacteriophage P22 scaffolding protein oligomers, not monomers, drive procapsid assembly. Dimers and higher-order structures are key to viral coat protein polymerization.
Area of Science:
- Structural biology
- Virology
- Biochemistry
Background:
- The scaffolding protein of Salmonella typhimurium bacteriophage P22 is crucial for viral procapsid assembly.
- Previous studies indicated variable reaction orders in assembly kinetics, suggesting oligomeric forms of scaffolding protein are involved.
Purpose of the Study:
- To investigate the oligomeric states of P22 scaffolding protein and their role in procapsid assembly.
- To determine if dimers or higher-order oligomers are the active species in viral assembly.
Main Methods:
- Analytical ultracentrifugation to analyze scaffolding protein oligomerization.
- In vitro assembly assays using wild-type and mutant scaffolding proteins.
- Kinetic analysis of procapsid formation.
Main Results:
- Scaffolding protein exists in a monomer/dimer/tetramer equilibrium, with higher stability at lower temperatures.
- Under assembly conditions, dimers are present in significant concentrations alongside monomers.
- A disulfide-linked dimeric mutant showed enhanced assembly rates compared to wild-type.
Conclusions:
- Dimeric and potentially higher-order oligomeric forms of P22 scaffolding protein are the active species in procapsid assembly.
- Oligomerization state significantly influences the efficiency of viral coat protein polymerization.