Role of thioredoxins in the response of Saccharomyces cerevisiae to oxidative stress induced by hydroperoxides

Abstract

SummaryGlutaredoxins and thioredoxins are highly conserved, small, heat-stable oxidoreductases. The yeast Saccharomyces cerevisiae contains two gene pairs encoding cytoplasmic glutaredoxins (GRX1, GRX2) and thioredoxins (TRX1, TRX2), and we have used multiple mutants to determine their roles in mediating resistance to oxidative stress caused by hydroperoxides. Our data indicate that TRX2 plays the predominant role, as mutants lacking TRX2 are hypersensitive, and mutants containing TRX2 are resistant to these oxidants. However, the requirement for TRX2 is only apparent during stationary phase growth, and we present three lines of evidence that the thioredoxin isoenzymes actually have redundant activities as antioxidants. First, the trx1 and trx2 mutants show wild-type resistance to hydroperoxide during exponential phase growth; secondly, overexpression of either TRX1 or TRX2 leads to increased resistance to hydroperoxides; and, thirdly, both Trx1 and Trx2 are equally able to act as cofactors for the thioredoxin peroxidase, Tsa1. The antioxidant activity of thioredoxins is required for both the survival of yeast cells as well as protection against oxidative stress during stationary phase growth, and correlates with an increase in the expression of both TRX1 and TRX2. We show that the requirement for thioredoxins during this growth phase is dependent on their activity as cofactors for the antioxidant enzyme Tsa1, and for regulation of the redox state and proteinbound levels of the low-molecular-weight antioxidant glutathione. IntroductionMany reports have highlighted the key role played by sul- dispensable during normal growth conditions (Luikenhuis et al., 1997). Unlike the thioredoxins, however, loss of glutaredoxins does not affect the cell cycle, nor does it result in any detectable aberrant growth phenotype.As in other species, yeast thioredoxins and glutaredoxins are active as antioxidants and play key roles in protection against oxidative stress induced by various reactive oxygen species (ROS). TRX2 was originally identified as a target gene of the yAP-1 transcriptional activator protein, which regulates the expression of a large number of antioxidants in response to oxidative stress (Kuge and Jones, 1994;Toone and Jones, 1999). Furthermore, TRX2 was shown to be essential for yAP-1-mediated resistance to hydroperoxides (Kuge and Jones, 1994). Thioredoxins are also required for the detoxification of ROS through their reactivity with thioredoxin peroxidases. A large number of thioredoxin peroxidase isoforms have been identified in yeast, including cytoplasmic (Tsa1, cTpx2/YDR453c, Tsa2/Ahp1/ YLR109), mitochondrial (mTpx/YBL064c) and nuclear (nTpx/YIL010w) (Chae et al., 1993;Jeong et al., 1999;Verdoucq et al., 1999;Park et al., 2000;Pedrajas et al., 2000). Enzyme analysis has confirmed that all the gene products display thioredoxin peroxidase activity, but their exact intracellular roles and targets remain unclear (Park et al., 2000). Strains deleted for both GRX1 and GRX2 lack heat-stable oxidoreductase activi...

Redox regulation of the yeast voltage-gated Ca2+ channel homolog Cch1p by glutathionylation of specific cysteine residues

“…We found that both grx1Δ and trx2Δ showed sensitivity to oxidative stress (Fig. 7M), which has also already been reported reported (Collinson et al, 2002;Garrido and Grant, 2002;Luikenhuis et al, 1998) while on α-factor exposure, grx1Δ and trx2Δ strains showed significantly higher growth as compared to WT strain (Fig. 7O) (controls are shown in Fig.…”

Role of the Yap Family in the Transcriptional Response to Oxidative Stress in Yeasts

“…For example, the gene TRX2 is a highly conserved oxydoreductase, required to maintain the redox homeostasis of the cell. In S. cerevisiae, thioredoxin TRX2 and thioredoxin reductase TRR1 were shown to be necessary to protect the cell against oxidative stress induced by the presence of ROS compounds in condition H 2 O 2 (Boisnard et al, 2009) or exposure to dithiothreitol (DTT) (Garrido and Grant, 2002). This agrees with the review of Rodrigues-Pousada et al (2010), in which Yap2p and Yap4p were described as involved in several types of stress responses, including oxidative stress (Cohen et al, 2002;Nevitt et al, 2004).…”

Involvement of glutaredoxin-1 and thioredoxin-1 in β-amyloid toxicity and Alzheimer's disease

“…26 In addition, a functional link between Grx and Trx expressions has also been described in yeast, where a lack of Trx causes a decrease in GSH levels, which are compensated for by an increased Grx expression. 27 A reduction of GSH levels has been previously demonstrated in AD brain, 28 suggesting the possibility of a similar mechanism.…”

“…Ab (25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) and Ab were purchased from Sigma-Aldrich (Stockholm, Sweden). Ab(1-42) was from US Peptide (Rancho Cucamonga, CA, USA) and dissolved in serum-free minimum essential medium (MEM).…”