Related Experiment Videos
Model of RecA-mediated homologous recognition
Kevin D Dorfman1, Renaud Fulconis, Marie Dutreix
1Laboratoire Physicochimie-Curie, CNRS/UMR 168, Institut Curie, 26 Rue d'Ulm, F-75248 Paris Cedex 5, France.
Physical Review Letters
|February 9, 2005
Summary
Homologous DNA search involves RecA protein filament interactions. DNA stretching and thermal activation facilitate recognition, suggesting a three base-pair seed initiates the process.
Area of Science:
- Biophysics
- Molecular Biology
- Genetics
Background:
- RecA protein facilitates homologous recombination by binding to single-stranded DNA (ssDNA) and searching for complementary sequences within double-stranded DNA (dsDNA).
- The search process is influenced by the distinct structural properties of dsDNA and the RecA-ssDNA nucleofilament, particularly their differing helical pitches.
Purpose of the Study:
- To theoretically investigate the mechanism of homology search between dsDNA and RecA-ssDNA nucleofilaments.
- To elucidate the role of DNA structural dynamics and thermal fluctuations in facilitating this search.
Main Methods:
- Theoretical modeling of the homology search process.
- Analytical first-passage-time analysis to describe the kinetics of DNA search.
- Consideration of DNA's polymeric nature and thermally activated conformational changes.
Main Results:
- The study highlights the importance of dsDNA stretching from the B state to the metastable S state to overcome pitch differences with the RecA-ssDNA filament.
- Analytical results align well with existing experimental data.
- New dependencies on intracellular fluid viscosity and ionic strength are predicted.
Conclusions:
- Homology search is a dynamic process involving DNA conformational changes.
- The findings suggest that initial homologous recognition is mediated by a small seed region of three base pairs.