RAD51 separation of function mutation disables replication fork maintenance but preserves DSB repair

Mi Young Son; Ondrej Belan; Mario Spirek; Jakub Cibulka; Fedor Nikulenkov; You Young Kim; Sunyoung Hwang; Kyungjae Myung; Cristina Montagna; Tae Moon Kim; Lumir Krejci; Paul Hasty

doi:10.1016/j.isci.2024.109524

RAD51 separation of function mutation disables replication fork maintenance but preserves DSB repair

iScience. 2024 Mar 16;27(4):109524. doi: 10.1016/j.isci.2024.109524. eCollection 2024 Apr 19.

Authors

Mi Young Son¹, Ondrej Belan², Mario Spirek^{2

3}, Jakub Cibulka², Fedor Nikulenkov², You Young Kim⁴, Sunyoung Hwang⁴, Kyungjae Myung⁴, Cristina Montagna⁵, Tae Moon Kim^{1

4}, Lumir Krejci^{2

3}, Paul Hasty¹

Affiliations

¹ Department of Molecular Medicine, The Barshop Institute for Longevity and Aging Studies, The Cancer Therapy Research Center, UT Health San Antonio, San Antonio, TX 78229, USA.
² Department of Biology, Masaryk University, 625 00 Brno, Czech Republic.
³ National Centre for Biomolecular Research, Masaryk University, 625 00 Brno, Czech Republic.
⁴ Center for Genomic Integrity Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea.
⁵ Department of Genetics, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY 10461, USA.

Abstract

Homologous recombination (HR) protects replication forks (RFs) and repairs DNA double-strand breaks (DSBs). Within HR, BRCA2 regulates RAD51 via two interaction regions: the BRC repeats to form filaments on single-stranded DNA and exon 27 (Ex27) to stabilize the filament. Here, we identified a RAD51 S181P mutant that selectively disrupted the RAD51-Ex27 association while maintaining interaction with BRC repeat and proficiently forming filaments capable of DNA binding and strand invasion. Interestingly, RAD51 S181P was defective for RF protection/restart but proficient for DSB repair. Our data suggest that Ex27-mediated stabilization of RAD51 filaments is required for the protection of RFs, while it seems dispensable for the repair of DSBs.

Keywords: Genetics; Molecular biology; Molecular interaction; Properties of biomolecules.