Schizosaccharomyces pombe homologue of glutathione peroxidase, which does not contain selenocysteine, is induced by several stresses and works as an antioxidant

Abstract

We have cloned a gene of Schizosaccharomyces pombe homologues to the glutathione peroxidase gene. The cloned gene, named gpx1+, encoded a protein that was 158 amino acids in length and had a molecular mass of 18 kDa. The gpx1+ gene is homologous with many glutathione peroxidase genes but the selenocysteine codon (UGA) position of mammalian genes is a cysteine codon (UGU) in S. pombe. gpx1+ mRNA was induced by various stresses, including oxidative stress, osmostress and heat stress. These stresses activate the Wis1–Sty1/Spc1 MAP kinase cascade in S. pombe. Transcriptional factors Atf1 and Pap1 are under the control of this MAP kinase. In the disruption of the atf1+ gene, gpx1+ was not transcribed or induced. However, the expression of gpx1+ was not affected by the disruption of the pap1+ gene. These results indicated that gpx1+ was under the control of transcription factor Atf1. Catalase can detoxicate H2O2 in the same way as GPx and the disruptant of the catalase gene of S. pombe is hypersensitive to H2O2. The catalase gene disruptant of S. pombe harbouring multicopy plasmid containing gpx1+ restored the hypersensitivity to H2O2 of the catalase gene disruptant. These results suggest that Gpx1 acts as a scavenger of H2O2 in vivo. The nucleotide sequence reported in this paper has been submitted to DDBJ/EMBL/GenBank, with Accession No. AB012395. Copyright © 1999 John Wiley & Sons, Ltd.

Global Transcriptional Responses of Fission Yeast to Environmental Stress

“…Sty1p regulates stress-dependent transcription, at least in part, through a b-ZIP transcription factor, Atf1p (Takeda et al, 1995;Shiozaki and Russell, 1996;Wilkinson et al, 1996;Yamada et al, 1999;Nguyen et al, 2000). This is analogous to the situation in mammalian cells where the transactivation potential of ATF2, a homolog of Atf1p, is regulated by the JNK and p38 protein kinases (Tibbles and Woodgett, 1999).…”

The Srk1 Protein Kinase Is a Target for the Sty1 Stress-activated MAPK in Fission Yeast

“…Atf1 is phosphorylated by Sty1 in response to stress, and, although Pap1 does not appear to be a direct target of Sty1, H 2 O 2 -induced nuclear accumulation of Pap1 is impaired in a sty1 Ϫ mutant at all but very low concentrations of H 2 O 2 (7, 20 -22, 24). Analysis of the phenotypes of pap1 Ϫ and atf1 Ϫ mutants has suggested that Pap1 controls the response to a range of drugs and heavy metals, and low level oxidative stress (18,20,22,24), and that Atf1 is important in regulating the response to osmotic stress, nutrient deprivation, and high levels of oxidative stress (16,19,21,23,24). However, although there is considerable overlap in the phenotypes of the pap1 Ϫ and atf1 Ϫ mutants with the sty1 Ϫ mutant, several phenotypes appear to be Sty1-specific including sensitivity to DNA damaging agents and the G 2 cell cycle delay.…”

Activation of the Oxidative Stress Regulator PpYap1 through Conserved Cysteine Residues during Methanol Metabolism in the YeastPichia pastoris

“…Therefore, PpGPX1 is both an upstream activator and a target of PpYAP1, suggesting that it combines the functions of ScGPX2 and ScGPX3. This H 2 O 2 signal relay system (PpGpx1-PpYap1-PpGPX1 expression) is not only distinct from that of S. cerevisiae (ScGpx3-ScYap1-ScGPX2 expression) but also from that of S. pombe (SpTpx1-Pap1-SpTPX1 or SpAtf1-SpGPX1 expression), 35,37) since no P. pastoris homolog of SpATF1 could be identified, and PpTsa1 (the homolog of SpTpx1) did not regulate the PpYap1 pathway during H 2 O 2 stress (Fig. 3). Fig.…”

“…36,37) Also, we found the P. pastoris homolog of thioredoxin peroxidase, PpTsa1, from the genome sequence database.…”

“…In the other pathway, the SpGPX1 gene is induced, and this induction is under the control of another bZIP transcription factor, Atf1, but not Pap1. 37) In the absence of PpGpx1, P. pastoris (Ppgpx1Á) became very sensitive to H 2 O 2 (Fig. 3A) and tBOOH (Fig.…”