Crystal structure of thymine DNA glycosylase conjugated to SUMO-1
Crystal structure of thymine DNA glycosylase conjugated to SUMO-1
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DOI：
10.1038/nature03634
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发表时间：
2005-06-16
期刊：
影响因子：
64.8
通讯作者：
Shirakawa, M
中科院分区：
文献类型：
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作者：
Baba, D;Maita, N;Shirakawa, M
小泛素样修饰物（SUMO）家族的成员可以通过类似于泛素缀合中使用的酶促途径共价连接到靶蛋白的赖氨酸残基（1），并且参与不依赖于通过蛋白酶体或溶酶体的降解信号传导的各种细胞事件（2-5）。然而，对SUMO修饰诱导蛋白质功能转移的分子机制知之甚少。在DNA错配修复过程中，尿嘧啶/胸腺嘧啶DNA糖基化酶TDG的SUMO缀合促进TDG从碱基切除后产生的脱碱基（AP）位点释放，并协调其转移至AP核酸内切酶1，后者催化修复途径中的下一步（6）。在这里，我们报告的晶体结构的中心区域的人TDG共轭SUMO-1在2.1埃分辨率。该结构揭示了从蛋白质表面突出的螺旋，这可能会干扰产物DNA，从而促进TDG从DNA分子中解离。该螺旋通过TDG和SUMO-1之间的共价和非共价接触形成。非共价接触对于从产物DNA中释放也是必不可少的，如通过诱变验证的。
Members of the small ubiquitin-like modifier ( SUMO) family can be covalently attached to the lysine residue of a target protein through an enzymatic pathway similar to that used in ubiquitin conjugation(1), and are involved in various cellular events that do not rely on degradative signalling via the proteasome or lysosome(2-5). However, little is known about the molecular mechanisms of SUMO-modification-induced protein functional transfer. During DNA mismatch repair, SUMO conjugation of the uracil/ thymine DNA glycosylase TDG promotes the release of TDG from the abasic (AP) site created after base excision, and coordinates its transfer to AP endonuclease 1, which catalyses the next step in the repair pathway(6). Here we report the crystal structure of the central region of human TDG conjugated to SUMO-1 at 2.1 angstrom resolution. The structure reveals a helix protruding from the protein surface, which presumably interferes with the product DNA and thus promotes the dissociation of TDG from the DNA molecule. This helix is formed by covalent and non-covalent contacts between TDG and SUMO-1. The non-covalent contacts are also essential for release from the product DNA, as verified by mutagenesis.