Garcia-Santamarina S, Boronat S, Calvo IA, Rodriguez-Gabriel M, Ayte J, Molina H, Hidalgo E

Cysteine oxidation mediates oxidative stress toxicity and signaling. It has been long proposed that the thioredoxin system, which consists of thioredoxin and thioredoxin reductase, is not only involved in recycling classical thioredoxin substrates, such as ribonucleotide reductase, but it also regulates general cytoplasmic thiol homeostasis. To investigate such a role, ...

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we have performed a proteome-wide analysis of cells expressing or not the two components of the thioredoxin system. We have compared the reversibly oxidized thiol proteomes of wild-type Schizosaccharomyces pombe cells with mutants lacking thioredoxin or thioredoxin reductase. Specific thioredoxin substrates are reversibly-oxidized in both strain backgrounds; however, in the absence of thioredoxin reductase, thioredoxin can weakly recycle its substrates at the expense of an alternative electron donor. A massive thiol oxidation occurs only in cells lacking thioredoxin reductase, with 30% of all cysteine-containing peptides being reversibly oxidized; this oxidized cysteine proteome depends on the presence of thioredoxins. Our observations lead to the hypothesis that, in the absence of its reductase, the natural electron donor thioredoxin becomes a powerful oxidant and triggers general thiol oxidation.

Date: Nov. 02, 2012

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