Separate FeS scaffold and carrier functions for SufB2C2 and SufA during in vitro maturation of [2Fe2S] Fdx

► SufB2C2 acts as a scaffold to enhance Fdx cluster formation. ► SufA acts as an intermediate during FeS cluster transfer. ► ATP suppresses cluster transfer from SufBC2D to SufA. ► SufA does not function as a de novo cluster scaffold.