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Single-molecule characterization of compressed RecA nucleoprotein filaments
Aleksandr Alekseev1, Natalia Morozova1, Alexey Vedyaykin1
1Peter the Great St. Petersburg Polytechnic University, Saint Petersburg, 195251, Russia.
Biochemical and Biophysical Research Communications
|May 14, 2022
Summary
RecA protein filaments, crucial for DNA repair, can adopt different structures. This study shows that only the 3:1 RecA-DNA ratio allows conversion between inactive and active states, impacting DNA recombination processes.
Area of Science:
- Biochemistry
- Molecular Biology
- Genetics
Background:
- RecA protein is essential for homologous recombination in bacteria, mediating DNA repair, transformation, and SOS response.
- RecA forms nucleoprotein filaments on single-stranded DNA, exhibiting conserved architecture across species.
- These filaments dynamically switch between stretched and compressed conformations, influenced by ATP binding and hydrolysis, though the functional significance remains unclear.
Purpose of the Study:
- To investigate the characteristics of inactive RecA nucleoprotein filaments formed without nucleotide cofactors.
- To elucidate the role of different RecA-DNA stoichiometries in filament conformation and interconvertibility.
Main Methods:
- Utilized a single-molecule approach to study de novo RecA nucleoprotein filaments.
- Analyzed RecA-DNA binding stoichiometry under varying assembly conditions in the absence of nucleotides.
Main Results:
- Inactive RecA-DNA filaments can exhibit either 5:1 or 3:1 nucleotide-to-monomer stoichiometry, dependent on assembly conditions.
- Only the 3:1 stoichiometry facilitates direct interconversion with the active, ATP-bound RecA conformation.
- The 5:1 stoichiometry, while possible for inactive filaments, does not allow this dynamic switching.
Conclusions:
- RecA filament conformation and stoichiometry are condition-dependent.
- The 3:1 RecA-DNA stoichiometry is critical for the dynamic interconversion between inactive and active filament states.
- Understanding these conformational dynamics is key to comprehending RecA's roles in DNA metabolism.
