title: Green tea polyphenols function as prooxidants to activate oxidative-stress-responsive transcription factors in yeasts.
abstract: Epigallocatechin gallate (EGCG) is the most abundant polyphenolic flavonoid in green tea. Catechin and its derivatives, including EGCG, are widely believed to function as antioxidants. Here we demonstrate that both EGCG and green tea extract (GTE) cause oxidative stress-related responses in the budding yeast Saccharomyces cerevisiae and the fission yeast Schizosaccharomyces pombe under weak alkaline conditions in terms of the activation of oxidative-stress-responsive transcription factors. GTE as well as EGCG induced the nuclear localization of Yap1 in S. cerevisiae, which was repressed by the addition of catalase but not by the addition of superoxide dismutase. The same phenomena were observed for the nucleocytoplasmic localization of Msn2 in S. cerevisiae and Pap1, a Yap1 homologue, in S. pombe. The formation of intramolecular disulfide bonds has been proposed to be crucial for the H(2)O(2)-induced nuclear localization of Yap1, and we verified the importance of cysteine residues of Yap1 in response to EGCG and GTE. Additionally, we show that EGCG and GTE produce H(2)O(2) in a weak alkaline medium. Finally, we conclude that tea polyphenols are able to act as prooxidants to cause a response to oxidative stress in yeasts under certain conditions.
authors.affiliation: Laboratory of Molecular Microbiology, Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Uji, Kyoto 611-0011, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Maeta
authors.forename: Wataru
authors.initials: W
authors.lastname: Nomura
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Takatsume
authors.forename: Shingo
authors.initials: S
authors.lastname: Izawa
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Inoue
mesh_terms: D028241:Camellia sinensis; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002467:Cell Nucleus / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology; D018869:Heat-Shock Response; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects*; D000073718:Pancreatitis-Associated Proteins; D010636:Phenols / Q000494:pharmacology; D010936:Plant Extracts; D059808:Polyphenols; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000187:drug effects* / Q000502:physiology; D029702:Schizosaccharomyces pombe Proteins; D013879:Thioredoxins / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation
chemical_list: D005419:Flavonoids; D008565:Membrane Proteins; D000073718:Pancreatitis-Associated Proteins; D010636:Phenols; D010936:Plant Extracts; D059808:Polyphenols; C000612141:REG3A protein, human; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; C516110:TRX2 protein, S cerevisiae; D014157:Transcription Factors; C086677:YAP1 protein, S cerevisiae; C516111:trx2 protein, S pombe; D013879:Thioredoxins; D002392:Catechin; D006861:Hydrogen Peroxide; C045651:epigallocatechin gallate