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Structure of a multisubunit complex that promotes DNA branch migration
C A Parsons1, A Stasiak, R J Bennett
1Genetic Recombination Laboratory, Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Hertfordshire, UK.
Nature
|March 23, 1995
Summary
The RuvA and RuvB proteins in E. coli are crucial for DNA repair and genetic recombination. New research visualizes their complex, revealing a tripartite structure that drives DNA branch migration.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- RuvA and RuvB proteins are essential for DNA repair and genetic recombination in E. coli.
- These proteins are induced by DNA damage and facilitate heteroduplex DNA formation.
- RuvA targets the RuvB ATPase to Holliday junctions, promoting ATP-dependent branch migration.
Purpose of the Study:
- To elucidate the mechanism of branch migration mediated by the RuvAB complex.
- To visualize the structural organization of RuvAB at Holliday junctions.
- To propose a molecular model for the branch migration process.
Main Methods:
- In vitro biochemical assays.
- Electron microscopic visualization of the RuvAB complex.
- Structural analysis and molecular modeling.
Main Results:
- RuvA binds Holliday junctions and recruits RuvB hexamers.
- A tripartite complex forms with RuvA sandwiched between two RuvB rings.
- The Holliday junction adopts a square-planar structure within the complex.
- A molecular model for branch migration involving two RuvB ring motors was proposed.
Conclusions:
- The RuvAB complex forms a unique tripartite structure essential for DNA branch migration.
- The proposed model highlights the role of oppositely oriented RuvB ring motors in driving branch migration.
- Structural insights into RuvAB function advance understanding of DNA recombination and repair.