Journal: Nature Communications
Article Title: BRCA2 stabilises RAD51 and DMC1 nucleoprotein filaments through a conserved interaction mode
doi: 10.1038/s41467-024-52699-3
Figure Lengend Snippet: a Model of the BRCA2 Ex27-RAD51 filament structure generated by docking BRCA2 Ex27-RAD51 1:2 complex AlphaFold2 models (Supplementary Fig. ) onto a previously reported structure of the RAD51 filament (PDB accession: 8BSC) . b The modelled BRCA2 Ex27 peptide includes the PhePP motif (boxed), and a long extension that runs along the interface between adjacent RAD51 promoters, shrouding the F86 self-association interaction. c The PhePP motif is predicted to bind in the same manner as the BRCA2 Ex14-DMC1 interaction, involving FxPP amino-acids F3298, P3300 and P3301. d Amylose pull-downs of RAD51 ΔN following recombinant co-expression with MBP-BRCA2 Ex14, Ex27 and its AAA mutant (F3298A, P3300A, P3301A), BRC4 and free MBP (empty). The MBP-BRCA2 fusion proteins exhibited some degradation to free MBP and intermediate species (MBP fused to a partially degraded peptide), which was more pronounced for Ex14 and Ex27 than for BRC4. e EMSAs in which ( i ) RAD51-ssDNA binding was disrupted by equimolar quantities of BRC4 (dashed, boxed). ( ii ) BRCA2 Ex27 but not ( iii ) BRCA2 Ex14-AAA mutant protected against BRC4-mediated disruption (dashed, boxed), and ( iv ) RAD51 L180E mutant underwent similar disruption, but ( v ) was not protected by BRCA2 Ex27. BRCA2 peptide concentrations are shown as molar ratios with respect to RAD51 protomers. Arrowheads, free ssDNA; yellow arrows, RAD51-ssDNA complexes; red arrows, BRCA2-RAD51-ssDNA complexes. The ssDNA substrate is a 100-nucleotide random sequence (provided in Methods). The same EMSAs performed using a 100-nucleotide polydT ssDNA substrate, in which complete protection is conferred by Ex27 and abrogated upon mutation, are shown in Supplementary Fig. . d , e Gel images are representative of at least three replicates. Source data are provided as a Source Data file.
Article Snippet: All other BRCA2 peptide sequences utilised in experiments (other than affinity pulldown experiments) were synthesised by Severn Biotech including BRC4 (amino acids 1519-1551), BRCA2 Ex14-Tr (amino acids 2401-2414), BRCA2 Ex27 (amino acids 3270-3315) and BRCA2 Ex27-AAA (amino acids 3270-3315 harbouring F3308A, P3310A and P3311A mutations).
Techniques: Generated, Recombinant, Expressing, Mutagenesis, Binding Assay, Disruption, Sequencing