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Crystal structures of MS2 capsids with mutations in the subunit FG loop
N J Stonehouse1, K Valegård, R Golmohammadi
1Department of Genetics, University of Leeds, UK.
Journal of Molecular Biology
|February 23, 1996
Summary
Mutations in the MS2 bacteriophage coat protein FG loop alter its conformation, affecting capsid assembly and stability. Proline 78
Area of Science:
- Structural biology
- Virology
- Biochemistry
Background:
- The bacteriophage MS2 coat protein forms a T=3 capsid shell.
- The F and G beta strands (FG loop) mediate inter-subunit contacts.
- FG loop conformations differ between subunit types (A/C vs. B).
Purpose of the Study:
- To investigate the role of the FG loop in MS2 capsid assembly.
- To understand the structural basis of capsid temperature stability.
- To probe the function of conserved proline residue Pro78.
Main Methods:
- X-ray crystallography of MS2 capsids.
- Site-directed mutagenesis of coat protein FG loop (P78N, E76D).
- Analysis of capsid structure and stability.
Main Results:
- Mutations P78N and E76D induced conformational changes in FG loops.
- These changes correlate with reduced capsid temperature stability.
- The P78N mutation resulted in a trans peptide bond, unlike the wild-type cis bond.
Conclusions:
- The FG loop conformation is critical for MS2 capsid assembly and stability.
- Proline 78 and its preceding peptide bond configuration influence structural integrity.
- Mutations impacting FG loop structure compromise capsid thermal stability.