ATP-mediated conformational changes in the RecA filament

Area of Science:

• Molecular biology
• Structural biology
• Biochemistry

Background:

• The crystal structure of E. coli RecA protein offers limited insight into homologous genetic recombination.
• Understanding RecA protein function is crucial for comprehending DNA repair mechanisms.

Purpose of the Study:

• To elucidate the mechanism of homologous genetic recombination by studying the RecA protein.
• To investigate the structural dynamics of RecA-DNA filaments in different functional states.

Main Methods:

• Utilized electron microscopy to reconstruct five distinct states of RecA-DNA filaments.
• Developed a model based on reconstructions to analyze nucleotide binding and protein conformation.

Main Results:

• Revealed that the C-terminal lobe of RecA is allosterically modulated by nucleotide binding.
• Demonstrated a significant rotation of the nucleotide-binding core in RecA-DNA filaments compared to crystal structures.
• Showed ATP binding occurs between subunits, explaining enhanced RecA activity in certain mutants.

Conclusions:

• The observed structural changes and allosteric coupling provide a mechanistic explanation for RecA's role in homologous recombination.
• The rotation model explains the cooperativity of ATP hydrolysis in RecA-DNA filaments.
• Structural insights advance the understanding of DNA repair and genetic recombination processes.