DNA binding and RAD51 engagement by the BRCA2 C-terminus orchestrate DNA repair and replication fork preservation

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• BRCA2 is a key tumor suppressor involved in DNA repair.
• It plays a role in homologous recombination and replication fork protection.

Purpose of the Study:

• To investigate the function of the BRCA2 C-terminal Recombinase Binding (CTRB) region.
• To determine the role of CTRB in DNA binding, RAD51 interaction, and homologous recombination.

Main Methods:

• Demonstrated DNA binding activity of the CTRB region.
• Assessed CTRB's effect on RAD51 strand exchange activity.
• Investigated functional synergy between CTRB and other BRCA2 domains.
• Evaluated the importance of CTRB's DNA binding and RAD51 interaction for homologous recombination and replication fork protection.

Main Results:

• The CTRB region of BRCA2 possesses DNA binding activity.
• CTRB alone stimulates RAD51-mediated strand exchange on RPA-coated single-stranded DNA (ssDNA).
• CTRB functionally synergizes with other BRCA2 domains for efficient DNA strand exchange.
• CTRB's DNA binding and RAD51 interaction are critical for homologous recombination and protecting replication forks from MRE11-mediated degradation.

Conclusions:

• The CTRB region is a crucial functional domain of BRCA2.
• CTRB's attributes are essential for genome repair and maintaining genomic stability.
• These findings elucidate BRCA2's functional plasticity and explain the embryonic lethality associated with Brca2 exon 27 deletion.