Cooperative conformational transitions keep RecA filament active during ATPase cycle

Area of Science:

• Molecular Biology
• Biochemistry
• Structural Biology

Background:

• The RecA filament's active conformation is essential for homologous recombination.
• RecA mediates DNA homology search and strand exchange, requiring ATP binding and hydrolysis.
• The dynamics of RecA filament conformational changes during ATP hydrolysis are not well understood.

Purpose of the Study:

• To investigate the coupling between ATP hydrolysis and RecA filament dynamics.
• To elucidate the real-time structural changes and cooperativity within the RecA filament.

Main Methods:

• Single-molecule fluorescence techniques were employed.
• Real-time observation of RecA filament structural dynamics during ATP hydrolysis.

Main Results:

• Observed cooperative structural changes between neighboring monomers in the RecA filament in real-time.
• Demonstrated that cooperativity creates a window for nucleotide cofactor exchange.
• Showed that this process maintains the active filament conformation during ATP hydrolysis cycles.

Conclusions:

• RecA filament dynamics are coupled to ATP hydrolysis through cooperative structural changes.
• Neighboring monomer cooperativity is crucial for maintaining the active RecA filament conformation.
• This mechanism ensures efficient homologous recombination by regulating nucleotide cofactor exchange.