Related Experiment Videos
Single-molecule study of RuvAB-mediated Holliday-junction migration
A Dawid1, V Croquette, M Grigoriev
1Laboratoire Pierre Aigrain, Unité Mixte de Recherche 8551, Ecole Normale Supérieure, 24 Rue Lhomond, 75005 Paris, France.
Summary
The RuvAB complex acts as a DNA motor, driving continuous branch migration of Holliday junctions during genetic recombination and DNA repair. This process occurs at an average speed of 43 bp/sec, even under varying loads.
Area of Science:
- Molecular Biology
- Genetics
- Biophysics
Background:
- Branch migration of Holliday junctions is crucial for genetic recombination and DNA repair.
- The RuvAB complex in Escherichia coli functions as a molecular motor to drive this process.
Purpose of the Study:
- To investigate the RuvAB complex's role in directing Holliday junction branch migration.
- To quantify the speed and processivity of RuvAB-mediated branch migration using single-molecule techniques.
Main Methods:
- Utilized magnetic tweezers to study individual Holliday junctions formed between homologous DNA molecules.
- Measured RuvAB-directed branch migration rates at 37°C with 1 mM ATP.
- Assessed migration rates under varying applied forces (loads).
Main Results:
- Directly demonstrated RuvAB as a highly processive DNA motor protein.
- Observed continuous and unidirectional branch migration over several kilobases.
- Measured an average migration rate of approximately 43 bp/sec at zero load.
- Found minimal load dependence within a force range of -3.4 pN to +3.4 pN.
Conclusions:
- RuvAB efficiently drives continuous, unidirectional branch migration of Holliday junctions.
- The motor protein exhibits robust performance across a range of applied forces, essential for its biological function in DNA repair and recombination.