Extended Data Fig. 3: Cryo-EM analysis.

a, Top left, the 3.26 Å-resolution cryo-EM density map of Cdiff Eσ^A/Fdx. Top right, a cross-section of the structure, showing the Fdx. Bottom, same views as above, but colored by local resolution, The boxed region is magnified and displayed as an inset. Density for Fdx is outlined in red¹⁵. b, Gold-standard FSC plots of the Cdiff Eσ^A/Fdx complex from cryoSPARC⁴². The dotted line represents the gold-standard 0.143 FSC cutoff which indicates a nominal resolution of 3.26 Å. c, Angular distribution calculated in cryoSPARC for Cdiff Eσ^A /Fdx particle projections. Heat map shows number of particles for each viewing angle (less = blue, more = red)⁴². d, Cross-validation FSC plots for map-to-model fitting were calculated between the refined structure of Cdiff Eσ^A/Fdx and the half-map used for refinement (work, red), the other half-map (free, blue), and the full map (black). The dotted black line represents the 0.5 FSC cutoff determined for the full map⁵².