Mechanism of BCDX2-mediated RAD51 nucleation on short ssDNA stretches and fork DNA.

Autor:	Akita M; Department of Biology and National Centre for Biomolecular Research, Masaryk University, Brno, Czech Republic., Girvan P; Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, UK., Spirek M; Department of Biology and National Centre for Biomolecular Research, Masaryk University, Brno, Czech Republic., Novacek J; Cryo-Electron Microscopy and Tomography Core Facility, Central European Institute of Technology, Brno, Czech Republic., Rueda D; Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, UK.; Single Molecule Imaging Group, MRC-London Institute of Medical Sciences, London, UK., Prokop Z; Loschmidt Laboratories, Department of Experimental Biology and RECETOX, Faculty of Science, Masaryk University, Brno, Czech Republic.; International Clinical Research Center, St Anne's University Hospital, Brno, Czech Republic., Krejci L; Department of Biology and National Centre for Biomolecular Research, Masaryk University, Brno, Czech Republic.
Jazyk:	angličtina
Zdroj:	Nucleic acids research [Nucleic Acids Res] 2024 Oct 28; Vol. 52 (19), pp. 11738-11752.
DOI:	10.1093/nar/gkae770
Abstrakt:	Homologous recombination (HR) factors are crucial for DSB repair and processing stalled replication forks. RAD51 paralogs, including RAD51B, RAD51C, RAD51D, XRCC2 and XRCC3, have emerged as essential tumour suppressors, forming two subcomplexes, BCDX2 and CX3. Mutations in these genes are associated with cancer susceptibility and Fanconi anaemia, yet their biochemical activities remain unclear. This study reveals a linear arrangement of BCDX2 subunits compared to the RAD51 ring. BCDX2 shows a strong affinity towards single-stranded DNA (ssDNA) via unique binding mechanism compared to RAD51, and a contribution of DX2 subunits in binding branched DNA substrates. We demonstrate that BCDX2 facilitates RAD51 loading on ssDNA by suppressing the cooperative requirement of RAD51 binding to DNA and stabilizing the filament. Notably, BCDX2 also promotes RAD51 loading on short ssDNA and reversed replication fork substrates. Moreover, while mutants defective in ssDNA binding retain the ability to bind branched DNA substrates, they still facilitate RAD51 loading onto reversed replication forks. Our study provides mechanistic insights into how the BCDX2 complex stimulates the formation of BRCA2-independent RAD51 filaments on short stretches of ssDNA present at ssDNA gaps or stalled replication forks, highlighting its role in genome maintenance and DNA repair. (© The Author(s) 2024. Published by Oxford University Press on behalf of Nucleic Acids Research.)
Databáze:	MEDLINE
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