Extended Data Fig. 6: SAXS analysis of Rb, E1A and the [E1AWT:Rb] complex.
From: Conformational buffering underlies functional selection in intrinsically disordered protein regions
a, I. Experimental SAXS intensity profile (black empty circles) versus theoretical profiles obtained from the crystal structure of the unliganded RbAB domain (PDB ID: 3POM) (red line) or a refined model where flexible loops were added (Allos-Mod-FoXS, blue line). Residuals are shown below the fits. II. Kratky plots of Rb at 4.0 mg/ml (blue line), 2.0 mg/ml (red line) and 1.0 mg/ml (black line). III. Orthogonal views of the RbAB crystal structure (red) and optimized model (blue) (RMSD = 1.7 Å). b, I. SAXS intensity profile of E1AWT (black circles) and the best fit from the EOM method (red line). Below, residual of the fit. II. Rg distribution of the E1AWT ensemble pool (black area) and EOM-selected ensemble (red area). III-IV. Kratky plots (III) or Guinier plots (IV) of E1AWT at 7.0 mg/ml (blue empty circles), 5.6 mg/ml (red empty circles) and 4.2 mg/ml (black empty circles). V. Overlay of SEC-SAXS profile of E1AWT (blue empty circles) and the merged curve from SAXS experiments at three concentrations (pink line). c, Theoretical SAXS profiles computed for a pool of 10250 [E1AWT:Rb] structures compared to experimental SAXS profiles and EOM fitting. Four fitting conditions are shown: I. 1000 generations with ensemble size N = 20, II. 1000 generations with N = 50, III. 500 generations with N = 20 and IV. 500 generations with N = 50. Left: experimental SAXS intensity profiles (grey circles) and EOM fitting (red lines). Middle: Rg distributions of pool ensembles (black line) and EOM-selected sub-ensembles (red line). Right: EOM-selected sub-ensembles. Fitting condition II is presented in Fig. 3. d, Calculated Rh for [E1AWT:Rb] (black) [E1AΔE:Rb] (green) and [E1AΔL:Rb] (blue) pool ensembles and the EOM-selected [E1AWT:Rb] sub-ensemble (red).
