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Dynamics of RecA filaments on single-stranded DNA
Marijn T J van Loenhout1, Thijn van der Heijden, Roland Kanaar
1Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.
Nucleic Acids Research
|May 12, 2009
Summary
RecA protein filament formation on single-stranded DNA requires ATP hydrolysis for dynamic activity. This process is crucial for homologous recombination, influencing filament structure and RecA-ssDNA interactions.
Area of Science:
- Molecular Biology
- Biochemistry
- Genetics
Background:
- RecA protein is central to homologous recombination, forming helical filaments on single-stranded DNA (ssDNA).
- ATP hydrolysis by RecA is critical for its dynamic activity and successful recombination.
- Previous studies primarily used double-stranded DNA (dsDNA), limiting understanding of RecA on its natural ssDNA substrate.
Purpose of the Study:
- To investigate the structure and kinetics of RecA filaments on long ssDNA molecules.
- To elucidate the role of ATP hydrolysis in RecA filament dynamics on ssDNA.
Main Methods:
- Single-molecule techniques were employed to directly probe RecA-ssDNA interactions.
- Filament nucleation and extension kinetics were analyzed.
- The effect of stretching force on RecA disassembly rates was measured.
- Reversible interconversion between ATP-bound and ADP-bound states was investigated.
Main Results:
- RecA ATPase activity is essential for forming long, continuous filaments on ssDNA.
- Filament nucleation and extension occur via a multimeric unit (Hill coefficient of 5.4).
- Applied stretching force reduces RecA disassembly rates from ssDNA.
- RecA-ssDNA filaments exhibit reversible transitions between extended (ATP-bound) and compressed (ADP-bound) states.
Conclusions:
- ATP hydrolysis significantly impacts the structure and dynamics of RecA filaments on ssDNA.
- These findings provide direct insights into RecA's function on its biologically relevant ssDNA substrate.
- The study reveals a force-dependent disassembly mechanism and ATP-driven conformational changes in RecA filaments.
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