Watching how accessory proteins regulate filament growth in real time

Using the optical epilator pliers, researchers from the National University of Taiwan observed individual affairs events in real time, offering new information on the molecular regulation of homologous recombination.

Their new study has published in Nucleic acid search reveals how accessory proteins regulate the growth of the RAD51 filament, a critical step in homologous recombination and DNA repair.

Research, led by Professor Hung-Wen Li (Department of Chemistry) and Professor Peter Chi (Institute of Biochemical Sciences), BRIDGES Biophysics and BioCocemistry to meet one of the central DNA repair challenges: how RAD51 is gathered on real-time DNA.

Traditional structural techniques capture only static or averaged views of protein clusters, leaving an unanswered oligomer forms stimulating the growth of the filament.

To overcome this, the team applied optical tweezers with a single molecule, which use laser beams focused to handle DNA molecules attached to microscopic balls. Like the RAD51 proteins linked and extended along the DNA, the resulting length changes have been followed with nanometric accuracy, allowing researchers to directly observe the growth of the step by step.

This approach revealed a regulatory role that striking accessory proteins. RAD51 alone was mainly assembled in octameric units, but in the presence of the SWI5-SFR1 complex, the assembly has moved to tetramères. This remodeling stabilized the RAD51 filaments, which makes the assembly process more uniform and effective.

These ideas highlight how accessory proteins refine recombination to protect the integrity of the genome. Beyond the progress of our understanding of DNA repair, the results have implications for cancer biology and genome editing technologies.

“This work shows how the single molecule platforms, associated with interdisciplinary collaboration, can shed light on fundamental biological processes in unprecedented details,” said Professor Hung-Wen Li.