Okazaki Shoko, Tachibana Tsuyoshi, Naganuma Akira, Mano Nariyasu, Kuge Shusuke
Laboratory of Molecular and Biochemical Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan.
Mol Cell. 2007 Aug 17;27(4):675-88. doi: 10.1016/j.molcel.2007.06.035.
Redox reactions involving cysteine thiol-disulfide exchange are crucial for sensing intracellular levels of H(2)O(2). However, oxidation-sensitive dithiols are also sensitive to intracellular reducing agents, and disulfide bonds are thus transient. The yeast transcription factor Yap1 is activated by disulfide-induced structural changes in the nuclear export signal in a carboxy-terminal domain. We show herein that the activation of Yap1 by H(2)O(2) requires multistep formation of disulfide bonds. One disulfide bond forms within 15 s in an amino-terminal domain, and then disulfide bonds linking the two domains accumulate. The multiple interdomain disulfide bonds, which result in reduction-resistant Yap1, are required for transduction of the H(2)O(2) stress signal to induce the appropriate level and duration of specific transcription. Our results suggest both a mechanism wherein the H(2)O(2) levels might be sensed by Yap1 and the way in which the NADPH levels might be maintained by altering the redox status of Yap1.
涉及半胱氨酸硫醇 - 二硫键交换的氧化还原反应对于感知细胞内过氧化氢（H₂O₂）水平至关重要。然而，对氧化敏感的二硫醇也对细胞内还原剂敏感，因此二硫键是短暂的。酵母转录因子Yap1通过羧基末端结构域中核输出信号的二硫键诱导的结构变化而被激活。我们在此表明，H₂O₂对Yap1的激活需要二硫键的多步形成。一个二硫键在氨基末端结构域中15秒内形成，然后连接两个结构域的二硫键逐渐积累。多个结构域间的二硫键导致Yap1具有抗还原性，这是将H₂O₂应激信号转导以诱导特定转录的适当水平和持续时间所必需的。我们的结果既提出了一种Yap1可能感知H₂O₂水平的机制，也提出了通过改变Yap1的氧化还原状态来维持NADPH水平的方式。
