Expression of a glutamate decarboxylase homologue is required for normal oxidative stress tolerance in Saccharomyces cerevisiae
Expression of a glutamate decarboxylase homologue is required for normal oxidative stress tolerance in Saccharomyces cerevisiae
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DOI：
10.1074/jbc.m007103200
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发表时间：
2001-01-05
影响因子：
4.8
通讯作者：
Moye-Rowley, WS
中科院分区：
文献类型：
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作者：
Coleman, ST;Fang, TK;Moye-Rowley, WS
γ-氨基丁酸酯(GABA)作为细胞间信号分子的作用已被广泛研究，但这种氨基酸代谢产物在细胞内代谢中的作用却知之甚少。在这项工作中，我们鉴定了酿酒酵母产生GABA的酶谷氨酸脱羧酶(GAD)的同源物，这是正常的氧化应激耐受所必需的。在含有完整谷氨酸分解代谢途径的细胞中，携带谷氨酸脱羧酶基因(GAD1)的高拷贝数质粒增加了对两种不同氧化剂过氧化氢和联胺的抗性。通过酵母酶与抗植物GAD的抗血清的交叉反应，证明了酿酒酵母GAD与以前研究的植物酶的结构相似。酵母GAD也和植物酶一样与钙调蛋白结合，这表明这种蛋白质的钙调节是保守的。在谷氨酸转化为琥珀酸的过程中，编码下游步骤的任一基因的缺失降低了正常细胞的氧化应激耐受性，并对高拷贝数GAD1具有上位性。编码琥珀酸半醛脱氢酶(UGA5)的基因被鉴定出来，并被发现是由过氧化氢诱导的。综上所述，这些数据强烈表明，谷氨酸分解代谢途径活性的增加可以缓冲细胞内氧化还原的变化。
The action of gamma -aminobutyrate (GABA) as an intercellular signaling molecule has been intensively studied, but the role of this amino acid metabolite in intracellular metabolism is poorly understood. In this work, we identify a Saccharomyces cerevisiae homologue of the GABA-producing enzyme glutamate decarboxylase (GAD) that is required for normal oxidative stress tolerance. A high copy number plasmid bearing the glutamate decarboxylase gene (GAD1) increases resistance to two different oxidants, H2O2 and diamide, in cells that contain an intact glutamate catabolic pathway. Structural similarity of the S. cerevisiae GAD to previously studied plant enzymes was demonstrated by the crossreaction of the yeast enzyme to a antiserum directed against the plant GAD. The yeast GAD also bound to calmodulin as did the plant enzyme, suggesting a conservation of calcium regulation of this protein. Loss of either gene encoding the downstream steps in the conversion of glutamate to succinate reduced oxidative stress tolerance in normal cells and was epistatic to high copy number GAD1. The gene encoding succinate semialdehyde dehydrogenase (UGA5) was identified and found to be induced by H2O2 exposure. Together, these data strongly suggest that increases in activity of the glutamate catabolic pathway can act to buffer redox changes in the cell.