Single-molecule visualization of human RECQ5 interactions with single-stranded DNA recombination intermediates

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• RECQ5 is one of five human RecQ helicases.
• It is hypothesized to negatively regulate RAD51 in homologous DNA recombination.

Purpose of the Study:

• To investigate the behavior of RECQ5 on nucleoprotein complexes.
• To elucidate the mechanism by which RECQ5 interacts with and modulates RAD51.

Main Methods:

• Kinetic assays
• Single-molecule imaging
• Biochemical assays using wild-type and mutant proteins

Main Results:

• RECQ5 functions as an ATP-dependent motor protein translocating on RPA- and RAD51-coated ssDNA.
• RECQ5 efficiently dismantles RAD51-ssDNA filaments, with protein-protein interactions with RAD51 influencing translocation velocity.
• RECQ5 removes RAD51 mutants from ssDNA independently of RAD51 ATP hydrolysis, but does not translocate on dsDNA or dismantle RAD51-bound joint molecules.

Conclusions:

• RECQ5's substrate specificity, particularly its interaction with RAD51 and DNA structures, is crucial for its role in genome maintenance.
• RECQ5's ability to dismantle RAD51 filaments suggests a key regulatory role in DNA recombination pathways.