Fig. 3: Conformational dynamics of the telomeric G4 determines the BRCA2 binding.

a smFRET histograms of the four G4 substrates (TelG5TAA, TelG5, TelG5TTT, and TelG5TT) with Gaussian fits color-coded as in Fig. 2e. b Differential density histograms of the four G4 constructs upon incubation with 100 nM BRCA2OB. c EMSA results of BRCA2OB binding towards the four G4 substrates. The result is from the same gel, excluding unnecessary lanes. The experiments were repeated at least five times independently. d Transition density plots showing relative abundance of each transition (i.e., UF → NP, NP → UF, UF → P, P → UF, NP → P, and P → NP) in the absence of BRCA2OB. e A representative time trajectory of the TelG5TTT molecule undergoing direct transitions between the NP and P conformations (without BRCA2OB). f A comparative plot between the density of the NP-P direct transition (mean ± s.d., n = 3) measured by the smFRET assays (blue bars, left axis) and BRCA2OB binding intensity in EMSA (mean ± s.e.m., n ≥ 5) in c relative to TelG5 (gray bars, right axis). The experiments were repeated independently. g A molecular model of the BRCA2-G4 interaction. BRCA2 selectively binds to intermediates during structural rearrangement between the NP and P conformations. All smFRET and EMSA analyses were performed in the presence of 100 mM KCl.