Structural models of [2Fe–2S] BOLA1–GRX5 (A) and of [2Fe–2S] BOLA3–GRX5 (B) obtained by molecular docking from NMR mapping [21]. SmYrbA was superimposed on BolA homologs in BOLA1–GRX5 (C) and in BOLA3–GRX5 (D). GRX5, BOLA1, BOLA3 and SmYrbA structures are in red, green, blue and purple, respectively. The invariant C-terminal histidine residue (His⁶⁷, His⁹⁶ or His¹⁰² in SmYrbA, BOLA3 or BOLA1, respectively), conserved residues present in the [H/C]-loop (His³², Cys⁵⁹ or His⁶⁷ in SmYrbA, BOLA3 or BOLA1, respectively), the catalytic cysteine Cys⁶⁷ in GRX5 and GSH involved in Fe–S cluster binding are shown.