Ferredoxin/ferredoxin–thioredoxin reductase complex: Complete NMR mapping of the interaction site on ferredoxin by gallium substitution

The reduction of ferredoxin–thioredoxin reductase (FTR) by plant-type ferredoxin plays an important role in redox regulation in plants and cyanobacteria. Nuclear magnetic resonance (NMR) was used to map the binding sites on Synechocystis ferredoxin for FTR. A gallium-substituted structural analog of this [2Fe–2S] ferredoxin was obtained by reconstituting the apoprotein in a refolding buffer containing gallium. For the first time, the complete interaction interface of a [2Fe–2S] ferredoxin with a target enzyme has been mapped by NMR chemical shift perturbation with this diamagnetic structural analog.