A-L Only buffer (A), ferric iron (B), ferrous iron (C), ferrous iron-loaded DJA6 (D), DJA6J deletion (H), DJA6C224S (I), DJA6C241S (J), DJA6C267S (K), or DJA6C280S (L) was added to the reaction mixture (SUFBC2D complex, NFS2, SUFE1, MgCl2, NADPH and ATP). DMSO was added to the reaction mixture as a control to the iron chelator deferiprone (DFP) treatment (E). The reaction mixture containing ferrous iron-loaded DJA6 was treated with the iron chelator DFP (F). The reaction mixture containing ferrous iron was treated with the iron chelator DFP (G). UV-visible absorption spectra of the re-purified SUFBC2D complex from the reaction mixture were taken every 10 min for 50 min under anaerobic condition after addition of L-cysteine to initiate the reaction. A peak at 420 nm represents the iron-sulfur cluster in SUFBC2D complex. All data were based on three biological replicates, and similar results were observed. 