Institute of Technology, University of Tartu, Tartu, 50411, Estonia.
Institute of Molecular and Cell Biology, University of Tartu, Tartu, 51010, Estonia.
Sci Rep. 2018 Aug 14;8(1):12136. doi: 10.1038/s41598-018-30562-y.
Coordination of DNA replication and cellular redox homeostasis mechanisms is essential for the sustained genome stability due to the sensitivity of replicating DNA to oxidation. However, substantial gaps remain in our knowledge of underlying molecular pathways. In this study, we characterise the interaction of Keap1, a central antioxidant response regulator in Metazoa, with the replicative helicase subunit protein MCM3. Our analysis suggests that structural determinants of the interaction of Keap1 with its critical downstream target - Nrf2 master transactivator of oxidative stress response genes - may have evolved in evolution to mimic the conserved helix-2-insert motif of MCM3. We show that this has led to a competition between MCM3 and Nrf2 proteins for Keap1 binding, and likely recruited MCM3 for the competitive binding dependent modulation of Keap1 controlled Nrf2 activities. We hypothesise that such mechanism could help to adjust the Keap1-Nrf2 antioxidant response pathway according to the proliferative and replicative status of the cell, with possible reciprocal implications also for the regulation of cellular functions of MCM3. Altogether this suggests about important role of Keap1-MCM3 interaction in the cross-talk between replisome and redox homeostasis machineries in metazoan cells.
DNA 复制与细胞氧化还原稳态机制的协调对于维持基因组稳定性至关重要，因为复制中的 DNA 对氧化很敏感。然而，我们对于潜在的分子途径的了解仍然存在很大的差距。在这项研究中，我们研究了 Metazoa 中抗氧化反应调节因子 Keap1 与复制解旋酶亚基蛋白 MCM3 的相互作用。我们的分析表明，Keap1 与其关键下游靶标-Nrf2（氧化应激反应基因的主要转录激活因子）相互作用的结构决定因素可能在进化中已经进化，以模拟 MCM3 的保守的螺旋-2-插入基序。我们表明，这导致了 MCM3 和 Nrf2 蛋白与 Keap1 结合的竞争，并且可能招募 MCM3 进行竞争结合依赖性的 Keap1 调控的 Nrf2 活性的调节。我们假设这种机制可以根据细胞的增殖和复制状态来调节 Keap1-Nrf2 抗氧化反应途径，这可能对 MCM3 的细胞功能调节也有相互影响。总之，这表明 Keap1-MCM3 相互作用在后生动物细胞的复制体和氧化还原稳态机制之间的串扰中起着重要作用。
