Thioredoxin-related protein of 14 kDa is an efficient L-cystine reductase and S-denitrosylase

Abstract

Thioredoxin-related protein of 14 kDa (TRP14, also called TXNDC17 for thioredoxin domain containing 17, or TXNL5 for thioredoxinlike 5) is an evolutionarily well-conserved member of the thioredoxin (Trx)-fold protein family that lacks activity with classical Trx1 substrates. However, we discovered here that human TRP14 has a high enzymatic activity in reduction of L-cystine, where the catalytic efficiency (2,217 min) coupled to Trx reductase 1 (TrxR1) using NADPH was fivefold higher compared with Trx1 (418 min). Moreover, the L-cystine reduction with TRP14 was in contrast to that of Trx1 fully maintained in the presence of a protein disulfide substrate of Trx1 such as insulin, suggesting that TRP14 is a more dedicated L-cystine reductase compared with Trx1. We also found that TRP14 is an efficient S-denitrosylase with similar efficiency as Trx1 in catalyzing TrxR1-dependent denitrosylation of S-nitrosylated glutathione or of HEK293 cell-derived S-nitrosoproteins. Consequently, nitrosylated and thereby inactivated caspase 3 or cathepsin B could be reactivated through either Trx1-or TRP14-catalyzed denitrosylation reactions. TRP14 was also, in contrast to Trx1, completely resistant to inactivation by high concentrations of hydrogen peroxide. The oxidoreductase activities of TRP14 thereby complement those of Trx1 and must therefore be considered for the full understanding of enzymatic control of cellular thiols and nitrosothiols.redox regulation | nitric oxide | sulfur metabolism | oxidative stress

Role of sulfiredoxin as a peroxiredoxin-2 denitrosylase in human iPSC-derived dopaminergic neurons

“…For example, in addition to having broad-spectrum protein disulfide reductase activity, thioredoxin 1 is also a denitrosylase for a large range of nitrosoproteins (28,29). Additionally, the thioredoxin-related protein of 14 kDa (TRP14) has recently been reported to mediate reduction as well as denitrosylation of specific substrates (30). The enzyme GSNO reductase has also been reported to mediate protein denitrosylation (31,32), as have carbonyl reductase 1 and protein disulfide isomerase (33).…”

The cysteine proteome

“…Furthermore, redox proteomics studies with inhibition of thioredoxin reductase (TrxR) show that many protein Cys are simultaneously oxidized [49]. Along with the above evidence for compartmentalization, and recent data showing that redox pathways can switch due to abundance of reactive targets [50], these observations indicate that interactions within the Cys proteome are best described as a network with spatial determinants [6, 7]. Redox signaling pathways are present within this network, characterized by being localized [51] and having rapid flux compared to the relatively slow and distributed election flow of the overall Cys proteome.…”

Dual targeting of the thioredoxin and glutathione systems in cancer and HIV

“…Whereas both GSH and Trxs (Trx1 and -2 and Trx-related protein 14 [TRP14]) catalyze the direct removal of NO groups from proteins, the activity of GSH is dependent on a class of denitrosylases (S-nitrosoglutathione reductases [GSNORs]), which metabolize the GSNO formed in the denitrosylation reaction (7). The proteins that are denitrosylated by Trx-and GSH-dependent mechanisms are largely nonoverlapping (7,14,15). Even among the denitrosylating Trxs, substrate specificity is evident.…”