Fig. 3: Solution state structure of Dri1.
a-b Experimental SAXS scattering profiles (binned using a nonuniform-step q-grid and vertically offset for clarity), and corresponding Guinier plots (linear fits displayed up to qmaxRg < 1.3). c P(r) distribution curves normalized to I(0) for the same set of Dri1 samples to qmax = 1.0 Å−1. d Rg values and approximate molecular weights of Dri1 samples calculated from Guinier analysis and by Bayesian inference with qmax = 0.3 Å-1, respectively. Confidence intervals are in parentheses. e SAXS-MD ensembles superimposed with DENSS envelopes calculated from SAXS data to qmax = 1.0 Å-1. f Iron K-edge EXAFS. Non-phase-corrected Fourier-transformed EXAFS of Dri1 and apo-Dri1. Note the Zn peak between 5 and 5.5 Å (indicated by a blue strip) in Dri1 absent in apo-Dri1. Inset: The corresponding k3-weighted EXAFs. g Fe EXAFS least-squares fitting parameters for Dri1.a The estimated standard deviations for distance are on the order of ± 0.02 Å. b Values of σ2 have been multiplied by 105. The value of S02 was set to 1 for all fits. Coordination numbers have an error of ± 20%. h Heme-bound Dri1, apo-Dri1, Zn-Dri1, Co-Dri1, Dri1 His79Ala-Arg90Ala, and Zn-Dri1 His79Ala-Arg90Ala measured by X-band CW-EPR at 10 K. Strong signal intensities at g = 6 indicate high spin (S = 5/2) iron species. The addition of either Co2+ or Zn2+ significantly reduces the g = 6 signal intensity (inset) and leads to features at g = 2.75, 2.27, and 1.72, corresponding to low spin (S = 1/2), 6-coordinated iron. The g = 4.3 signal likely originates from non-heme ferric iron contamination. All intensities are normalized by protein concentration. Source data are provided as a Source Data file.
