Fig. 1

SDAUF-Zn²⁺ structure and FXN-NFS1 interactions. a. Cryo-EM density of SDAUF-Zn²⁺ structure (NFS1/NFS1’ slate, ISD11/ISD11’ magenta, ACP/ACP’ light green, ISCU/ISCU’, Cyan, FXN/FXN’ orange). b. Cartoon representation of SDAUF-Zn²⁺ complex. 4′-phosphopantetheine acyl chain (8Q1, yellow), Zn²⁺ ion (ZN, red) and pyridoxal 5′-phosphate (PLP, wheat) are shown as sticks/spheres. c. Scattering data from a sample of SDAUF used in cryo-EM was collected (black points) and fit to the theoretical SAXS profile back-calculated from the SDAUF-Zn²⁺ cryo-EM structure (red line) with χ² = 1.98. d. The ab initio envelope calculated from SAXS data for the SDAUF sample was superimposed with the cryo-EM structure e. In the SDAUF complex, each FXN binds to a cavity formed by interface of NFS1 homodimer and one ISCU. FXN is shown as orange cartoon, while other subunits of the complex are shown as surface representation (colored by electrostatic potential). Yellow dotted lines denote protein boundaries. Source data for panel c are provided as a Source Data file