Fudan University Shanghai Cancer Center, Department of Oncology and Institute of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai 200032, China; State Key Laboratory of Genetic Engineering, School of Life Sciences, Fudan University, Shanghai 200433, China.
Fudan University Shanghai Cancer Center, Department of Oncology and Institute of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai 200032, China.
Cell. 2013 Dec 19;155(7):1545-55. doi: 10.1016/j.cell.2013.11.020. Epub 2013 Dec 5.
TET proteins oxidize 5-methylcytosine (5mC) on DNA and play important roles in various biological processes. Mutations of TET2 are frequently observed in myeloid malignance. Here, we present the crystal structure of human TET2 bound to methylated DNA at 2.02 Å resolution. The structure shows that two zinc fingers bring the Cys-rich and DSBH domains together to form a compact catalytic domain. The Cys-rich domain stabilizes the DNA above the DSBH core. TET2 specifically recognizes CpG dinucleotide and shows substrate preference for 5mC in a CpG context. 5mC is inserted into the catalytic cavity with the methyl group orientated to catalytic Fe(II) for reaction. The methyl group is not involved in TET2-DNA contacts so that the catalytic cavity allows TET2 to accommodate 5mC derivatives for further oxidation. Mutations of Fe(II)/NOG-chelating, DNA-interacting, and zinc-chelating residues are frequently observed in human cancers. Our studies provide a structural basis for understanding the mechanisms of TET-mediated 5mC oxidation.
TET 蛋白可氧化 DNA 上的 5-甲基胞嘧啶（5mC），在各种生物学过程中发挥重要作用。TET2 的突变在髓系恶性肿瘤中经常观察到。在这里，我们展示了人源 TET2 与甲基化 DNA 结合的晶体结构，分辨率为 2.02Å。该结构表明，两个锌指将富含半胱氨酸和 DSBH 结构域结合在一起，形成一个紧凑的催化结构域。富含半胱氨酸的结构域稳定了位于 DSBH 核心上方的 DNA。TET2 特异性识别 CpG 二核苷酸，并在 CpG 背景下显示出对 5mC 的底物偏好。5mC 插入催化腔，甲基基团朝向催化 Fe(II)进行反应。甲基基团不参与 TET2-DNA 相互作用，因此催化腔允许 TET2 容纳 5mC 衍生物以进行进一步氧化。在人类癌症中经常观察到 Fe(II)/NOG 螯合、DNA 相互作用和锌螯合残基的突变。我们的研究为理解 TET 介导的 5mC 氧化机制提供了结构基础。
