The Path to Thioredoxin and Redox Regulation Beyond Chloroplasts.

Once the ferredoxin/thioredoxin system was established as a mechanism linking light to the post-translational regulation of chloroplast enzymes, I considered that plants might harbor a light-independent mechanism utilizing this same enzyme chemistry based on thiol-disulfide redox transitions. After reflection, it occurred to me that such a mechanism could be fundamental to seeds of cereals that undergo dramatic change following exposure to oxygen during maturation and drying. The pursuit of this idea led to the discovery of a family of extraplastidic thioredoxins, designated the h-type, that resemble animal and bacterial counterparts in undergoing enzymatic reduction with NADPH. Current evidence suggests that h-type thioredoxins function broadly throughout the plant. Here I describe how the thioredoxin h field developed, its current status and potential for contributing material benefits to society.