The human RAD52 complex undergoes phase separation and facilitates bundling and end-to-end tethering of RAD51...

Area of Science:

• Molecular Biology
• Cancer Research
• Biochemistry

Background:

• Human RAD52 is a target for cancer synthetic lethality, potentially substituting for BRCA2 in homologous recombination.
• RAD52's mechanism in substituting BRCA2 functions is not fully understood.
• RAD52 forms a multivalent protein complex that promotes supramolecular assembly.

Purpose of the Study:

• To investigate the mechanistic details of RAD52 function in homologous recombination.
• To explore RAD52's role in organizing DNA repair factors and promoting filament assembly.

Main Methods:

• Fluorescence microscopy
• Single-molecule super-resolution imaging (DNA-PAINT)
• Atomic force microscopy

Main Results:

• RAD52 undergoes homotypic phase separation, forming condensates that recruit ssDNA, RPA, and RAD51.
• RAD52 phase separation is regulated by ssDNA and RPA.
• RAD52 promotes RAD51-ssDNA fibrillar structures, which are bundles of RAD51 nucleoprotein filaments.
• RAD52 induces end-to-end tethering of RAD51 nucleoprotein filaments.

Conclusions:

• RAD52's phase separation and ability to organize RAD51 filaments are key to its cellular functions.
• These findings provide insights into RAD52's role in homologous recombination and DNA repair.
• Understanding RAD52's macromolecular organization may lead to novel cancer therapies.