Reduction of Cysteine Sulfinic Acid by Sulfiredoxin Is Specific to 2-Cys Peroxiredoxins

Abstract

Cysteine residues of certain peroxiredoxins (Prxs) undergo reversible oxidation to sulfinic acid (Cys-SO 2 H) and the reduction reaction is catalyzed by sulfiredoxin (Srx). Specific Cys residues of various other proteins are also oxidized to sulfinic acid, suggesting that formation of Cys-SO 2 H might be a novel posttranslational modification that contributes to regulation of protein function. To examine the susceptibility of sulfinic forms of proteins to reduction by Srx, we prepared such forms of all six mammalian Prx isoforms and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Purified sulfiredoxin reduced the sulfinic forms of the four 2-Cys members (Prx I to Prx IV) of the Prx family in vitro, but it did not affect those of Prx V, Prx VI, or GAPDH. Furthermore, Srx bound specifically to the four 2-Cys Prxs in vitro and in cells. Sulfinic forms of Prx I and Prx II, but not of Prx VI or GAPDH, present in H 2 O 2 -treated A549 cells were gradually reduced after removal of H 2 O 2 ; overexpression of Srx increased the rate of the reduction of Prx I and Prx II but did not induce that of Prx VI or GAPDH. These results suggest that reduction of Cys-SO 2 H by Srx is specific to 2-Cys Prx isoforms. For proteins such as Prx VI and GAPDH, sulfinic acid formation might be an irreversible process that causes protein damage.

The Peroxiredoxin Repair Proteins

“…Several lines of evidence support the selective binding of typical 2-Cys Prxs by Srx (Woo et al, 2005): (i) the GST-Srx fusion protein can bind the reduced and oxidized forms of PrxI-IV from HeLa cells with and without H 2 O 2 treatment, but not the atypical 2-Cys PrxV or the 1-Cys PrxVI; (ii) reduced hPrxI can compete for hyperoxidized hPrxI in the reductase antibody assay; (iii) a yeast two-hybrid screen indicated interactions only between Srx and PrxI-IV; and (iv) overexpression of Srx in A549 cells reduces the levels of hyperoxidzed PrxI-IV upon H 2 O 2 treatment, but not the other Prxs or glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Activity analyses using recombinant PrxI-6 have further confirmed that only the typical 2-Cys PrxI-IV are reduced.…”

“…At this time no further characterization of the sulfinic acid reductase activity of sestrins has been reported. Data presented from the Rhee laboratory in section 6.2 has shown that Srx is specific for typical 2-Cys Prxs (Woo et al, 2005).…”

“…In these studies three activity assays have been utilized: (i) sulfinic acid reductase activity based on the decrease in the immuno-reactive band to Prx-SO 2/3 -, (ii) ATPase activity corresponding to the increase in the amount of inorganic phosphate released, (iii) binding of Srx to Prx using the Srx-GST fusion and GSH-sepharose Chang et al, 2004;Woo et al, 2005;Jeong et al, 2006). The results from these studies suggest that the initial steps in the reaction may need to be reconsidered and evaluated by further experimentation.…”

“…Based on this analysis it is possible that the sestrins are responsible for the repair of the other Prx isozymes and other proteins. Another possibility is that the hyperoxidation of some proteins is irreversible (Woo et al, 2005).…”

Targeted disruption of the glutaredoxin 1 gene does not sensitize adult mice to tissue injury induced by ischemia/reperfusion and hyperoxia

“…Cysteine sulfinic acid is generally thought to represent an irreversible oxidative product of protein thiols that that can progress to the sulfonic acid oxidation state. However, recent data have documented an exception, showing that the sulfinic acid moiety in 2-Cys peroxiredoxins in cells under oxidative stress can be reduced by two ATP-dependent reductases, sulfiredoxin and sestrin [9][10][11][12].…”