TY - JOUR

T1 - A novel plant glutathione S-transferase/peroxidase suppresses Bax lethality in yeast

AU - Kampranis, S C

AU - Damianova, R

AU - Atallah, M

AU - Toby, G

AU - Kondi, G

AU - Tsichlis, P N

AU - Makris, A M

PY - 2000/9/22

Y1 - 2000/9/22

N2 - The mammalian inducer of apoptosis Bax is lethal when expressed in yeast and plant cells. To identify potential inhibitors of Bax in plants we transformed yeast cells expressing Bax with a tomato cDNA library and we selected for cells surviving after the induction of Bax. This genetic screen allows for the identification of plant genes, which inhibit either directly or indirectly the lethal phenotype of Bax. Using this method a number of cDNA clones were isolated, the more potent of which encodes a protein homologous to the class theta glutathione S-transferases. This Bax-inhibiting (BI) protein was expressed in Escherichia coli and found to possess glutathione S-transferase (GST) and weak glutathione peroxidase (GPX) activity. Expression of Bax in yeast decreases the intracellular levels of total glutathione, causes a substantial reduction of total cellular phospholipids, diminishes the mitochondrial membrane potential, and alters the intracellular redox potential. Co-expression of the BI-GST/GPX protein brought the total glutathione levels back to normal and re-established the mitochondrial membrane potential but had no effect on the phospholipid alterations. Moreover, expression of BI-GST/GPX in yeast was found to significantly enhance resistance to H(2)O(2)-induced stress. These results underline the relationship between oxidative stress and Bax-induced death in yeast cells and demonstrate that the yeast-based genetic strategy described here is a powerful tool for the isolation of novel antioxidant and antiapoptotic genes.

AB - The mammalian inducer of apoptosis Bax is lethal when expressed in yeast and plant cells. To identify potential inhibitors of Bax in plants we transformed yeast cells expressing Bax with a tomato cDNA library and we selected for cells surviving after the induction of Bax. This genetic screen allows for the identification of plant genes, which inhibit either directly or indirectly the lethal phenotype of Bax. Using this method a number of cDNA clones were isolated, the more potent of which encodes a protein homologous to the class theta glutathione S-transferases. This Bax-inhibiting (BI) protein was expressed in Escherichia coli and found to possess glutathione S-transferase (GST) and weak glutathione peroxidase (GPX) activity. Expression of Bax in yeast decreases the intracellular levels of total glutathione, causes a substantial reduction of total cellular phospholipids, diminishes the mitochondrial membrane potential, and alters the intracellular redox potential. Co-expression of the BI-GST/GPX protein brought the total glutathione levels back to normal and re-established the mitochondrial membrane potential but had no effect on the phospholipid alterations. Moreover, expression of BI-GST/GPX in yeast was found to significantly enhance resistance to H(2)O(2)-induced stress. These results underline the relationship between oxidative stress and Bax-induced death in yeast cells and demonstrate that the yeast-based genetic strategy described here is a powerful tool for the isolation of novel antioxidant and antiapoptotic genes.

KW - Amino Acid Sequence

KW - Apoptosis

KW - Cell Survival

KW - Gene Expression Regulation, Fungal

KW - Glutathione Transferase

KW - Molecular Sequence Data

KW - Oxidative Stress

KW - Plant Proteins

KW - Proto-Oncogene Proteins

KW - Proto-Oncogene Proteins c-bcl-2

KW - Saccharomyces cerevisiae

KW - Sequence Alignment

KW - bcl-2-Associated X Protein

U2 - 10.1074/jbc.M002359200

DO - 10.1074/jbc.M002359200

M3 - Journal article

C2 - 10859306

VL - 275

SP - 29207

EP - 29216

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 38

ER -