Fig. 3. Analysis of the [4Fe-4S] cluster environment.

(A) Likely positions of mutated residues (gray) in the S24F and L28H AfFNR variants. Both mutations should influence the interaction of the Cys²³-Cys²⁹ loop (green) with the top of the DNA binding domain (blue). (B) Intramolecular connections between the [4Fe-4S] cluster and the Asp¹³⁰-Arg¹⁴⁰ salt bridges. Helices A, B, and C (Fig. 2B) are represented by cylinders.