Comparison of the binding sites of plant ferredoxin for two ferredoxin‐dependent enzymes

Abstract

Differential chemical modification of acidic residues was used to map the binding site of plant ferredoxin (Fd) for the chloroplast enzyme ferredoxin:thioredoxin reductase (FTR). Binding of FTR to Fd inhibits chemical modification of Fd residues D34, D65, E92, E93, E94 and C-terminal A97. The binding site demarcated by these residues differs from that for ferredoxin:NADP⁺ reductase (FNR). The FTR site includes C-terminal residues but not helix 24–31, which is part of the FNR site. Both sites enclose the [2Fe-2S] cluster.