Crystal Structure of Tetrameric Arabidopsis MYC2 Reveals the Mechanism of Enhanced Interaction with DNA
Crystal Structure of Tetrameric Arabidopsis MYC2 Reveals the Mechanism of Enhanced Interaction with DNA
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四聚体拟南芥 MYC2 的晶体结构揭示了增强与 DNA 相互作用的机制
DOI：
10.1016/j.celrep.2017.04.057
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发表时间：
2017-05-16
期刊：
影响因子：
8.8
通讯作者：
Su, Xiao-Dong
中科院分区：
文献类型：
--
作者：
Lian, Teng-fei;Xu, Yong-ping;Su, Xiao-Dong
茉莉酸是一种重要的植物激素，在调节植物生长和响应环境胁迫中起着重要作用。在JA信号通路中，核心转录因子是一类碱性螺旋-环-螺旋（bHLH）蛋白，包括MYC 2、MYC 3和MYC 4，它们具有不同的调节能力。在这里，我们报告的2.7埃晶体结构的MYC 2 bHLH结构域与G盒DNA复合，显示一个顺式四聚体结构。生物化学分析证实，全长MYC 2在溶液和DNA结合状态下形成稳定的同源四聚体，而MYC 3仅形成同源二聚体。等温滴定量热法（ITC）分析表明，四聚体增强DNA结合亲和力，荧光共振能量转移（FRET）分析表明四聚体MYC 2的DNA成环潜力。荧光素酶检测进一步证实了四聚体在转录调控中的重要性。我们的研究为MYC转录因子的调控差异提供了一个机制上的解释。
Jasmonates (JAs) are essential plant hormones that play important roles in the regulation of plant growth and the response to environmental stress. In the JA signaling pathway, the core transcription factors are a class of basic helix-loop-helix (bHLH) proteins, including MYC2, MYC3, and MYC4, that have different regulatory capacities. Here, we report the 2.7 angstrom crystal structure of the MYC2 bHLH domain complexed with G-box DNA, showing a cis-tetrameric structure. Biochemical assays confirmed that full-length MYC2 forms a stable homo-tetramer both in solution and in DNA-bound states, whereas MYC3 forms only a homodimer. Isothermal titration calorimetry (ITC) assays demonstrated that tetramerization enhanced DNA binding affinity, and fluorescence resonance energy transfer (FRET) assay indicated DNA looping potential of tetrameric MYC2. Luciferase assay further confirmed the importance of tetramerization in transcriptional regulation. Our studies provide a mechanistic explanation for the regulatory differences of MYC transcription factors.