Ferredoxin-Thioredoxin Reductase: An Iron-Sulfur Enzyme Linking Light to Enzyme Regulation in Chloroplasts

The ferredoxin/thioredoxin system functions in oxygenic photosynthesis by linking light to the regulation of selected target enzymes (1). Here, the light signal is converted to reduced thioredoxin by way of ferredoxin, ferredoxin-thioredoxin reductase (FTR) and the photosynthetic electron transport chain, thereby changing the thiol status of target enzymes through transfer of net reducing equivalents. An oxidation of the SH groups formed in the light takes place in the dark in the presence of molecular oxygen.