Structural Basis for Finding OG Lesions and Avoiding Undamaged G by the DNA Glycosylase MutY
Structural Basis for Finding OG Lesions and Avoiding Undamaged G by the DNA Glycosylase MutY
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DOI：
10.1021/acschembio.9b00639
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发表时间：
2020-01-01
影响因子：
4
通讯作者：
Horvat, Martin P.
中科院分区：
文献类型：
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作者：
Russelburg, L. Peyton;Murray, Valerie L. O'Shea;Horvat, Martin P.
腺嘌呤糖基化酶MutY选择性地启动OG:A损伤的修复，相比之下，避免G:A错配。区分这些密切相关底物的能力依赖于MutY的c端结构域，其结构类似于MutT。为了了解底物特异性的机制，我们将MutY与高亲和的阿扎里糖过渡态类似物对面含有G的DNA进行结晶。我们的结构表明G被OG位点容纳，并突出了丝氨酸残基在OG与G歧视中的作用。通过突变分析评估了Ser308及其邻近残基的功能意义，揭示了c端结构域β环对细胞突变抑制和体外生化性能的重要作用。该环包含残基Phe307、Ser308和His309（嗜脂嗜热地杆菌序列位置），在MutT中保守，但在MutT和其他DNA修复酶中不存在，因此可能作为化学生物探针可利用的MutY特异性靶标。
The adenine glycosylase MutY selectively initiates repair of OG:A lesions and, by comparison, avoids G:A mispairs. The ability to distinguish these closely related substrates relies on the C-terminal domain of MutY, which structurally resembles MutT. To understand the mechanism for substrate specificity, we crystallized MutY in complex with DNA containing G across from the high-affinity azaribose transition state analogue. Our structure shows that G is accommodated by the OG site and highlights the role of a serine residue in OG versus G discrimination. The functional significance of Ser308 and its neighboring residues was evaluated by mutational analysis, revealing the critical importance of a beta loop in the C-terminal domain for mutation suppression in cells, and biochemical performance in vitro. This loop comprising residues Phe307, Ser308, and His309 (Geobacillus stearothermophilus sequence positions) is conserved in MutY but absent in MutT and other DNA repair enzymes and may therefore serve as a MutY-specific target exploitable by chemical biological probes.