A New Member Of The Thioredoxin Reductase Family From Early Oxygenic Photosynthetic Organisms.

Thioredoxins (Trxs) are key components of the redox system that regulates the activity of a spectrum of target proteins through dithiol-disulfide exchange reactions. Trxs are reduced by members of the Trx reductase (TR) family (Jacquot et al., 2009). NADP-dependent thioredoxin reductases (NTRs), the most common type, belong to the family of dimeric pyridine nucleotide disulfide oxidoreductase flavoproteins that use NADPH as the source of reducing equivalents. In oxyphotosynthetic organisms, in particular, NTRs coexist with the ferredoxin/thioredoxin system (FTS), composed of ferredoxin (Fdx), ferredoxin:thioredoxin reductase (FTR), and a Trx. FTRs convert the electron signal obtained from photoreduced Fdx to a thiol signal via a 4Fe-4S center and a redox-active disulfide catalytic center. FTR, in turn, reduces Trx.B.B.B. acknowledges support from an Alexander von Humboldt Research Award that catalyzed the launching of this project at the Ludwig-Maximilians-Universität in Munich. R.M.B. is supported by a Ramón y Cajal contract from the Spanish Ministerio de Economía y Competitividad. L.L.-M. is supported by a postdoctoral contract from Universidad de Sevilla.Peer Reviewe