Green tea polyphenols function as prooxidants to activate oxidative-stress-responsive transcription factors in yeasts
Green tea polyphenols function as prooxidants to activate oxidative-stress-responsive transcription factors in yeasts
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DOI：
10.1128/aem.01963-06
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发表时间：
2007-01-01
影响因子：
4.4
通讯作者：
Inoue, Yoshiharu
中科院分区：
文献类型：
--
作者：
Maeta, Kazuhiro;Nomura, Wataru;Inoue, Yoshiharu
表没食子儿茶素没食子酸酯（EGCG）是绿色茶中含量最丰富的多酚类黄酮。儿茶素及其衍生物，包括EGCG，被广泛认为是抗氧化剂。在这里，我们证明了EGCG和绿色茶提取物（GTE）引起氧化应激相关的反应，在芽殖酵母酿酒酵母和裂殖酵母粟酒裂殖酵母在弱碱性条件下的氧化应激反应转录因子的激活。GTE和EGCG均能诱导Yap1在S.酿酒酵母，这是阻遏的过氧化氢酶，但不是通过添加超氧化物歧化酶。在S.酿酒酵母和Pap1，一个Yap1同源物，在S.粟酒分子内二硫键的形成已被提出是至关重要的H2O2诱导的核定位的Yap1，我们验证了半胱氨酸残基的Yap1在响应EGCG和GTE的重要性。此外，我们表明，EGCG和GTE产生过氧化氢在弱碱性介质中。最后，我们得出结论，茶多酚能够作为促氧化剂，在一定条件下引起酵母对氧化应激的反应。
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 H2O2-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 H2O2 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.