A two-step nucleotide-flipping mechanism enables kinetic discrimination of DNA lesions by AGT
A two-step nucleotide-flipping mechanism enables kinetic discrimination of DNA lesions by AGT
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DOI：
10.1073/pnas.0708058105
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发表时间：
2008-03-25
影响因子：
11.1
通讯作者：
Dinner, Aaron R.
中科院分区：
文献类型：
--
作者：
Hu, Jie;Ma, Ao;Dinner, Aaron R.
O-6-烷基鸟嘌呤-DNA烷基转移酶（AGT）通过将鸟嘌呤和胸腺嘧啶碱基翻转到其活性位点以将烷基损伤不可逆地转移到Cys-145来修复对人类基因组的损伤，但是该蛋白如何识别其靶点仍然未知。了解该系统中的分子识别，这可以作为许多核翻转蛋白的范例，这些蛋白在所有生命王国中调节基因和修复DNA，鉴于抑制剂正在临床试验中作为抗癌治疗剂，这一点尤为重要。最近推出的计算方法的收获和统计学特征的分子罕见事件的轨迹，现在使我们能够阐明的途径AGT和促进it. In对比以前提出的翻转机制的力量，核苷酸翻转，我们观察到一个两步的过程，促进动力学，而不是热力学，守门策略病变歧视。连接到最近的单分子研究的DNA修复蛋白滑动的DNA，以了解它们如何有效地感知碱基之间的微妙化学差异。
O-6-alkylguanine-DNA alkyltransferase (AGT) repairs damage to the human genome by flipping guanine and,thymine bases into its active site for irreversible transfer of alkyl lesions to Cys-145, but how the protein identifies its targets has remained unknown. Understanding molecular recognition in this system, which can serve as a paradigm for the many nucleoticle-flipping proteins that regulate genes and repair DNA in all kingdoms of life, is particularly important given that inhibitors are in clinical trials as anticancer therapeutics. Computational approaches introduced recently for harvesting and statistically characterizing trajectories of molecularly rare events now enable us to elucidate a pathway for nucleotide flipping by AGT and the forces that promote it. In contrast to previously proposed flipping mechanisms, we observe a two-step process that promotes a kinetic, rather than a thermodynamic, gate-keeping strategy for lesion discrimination. Connection is made to recent single-molecule studies of DNA-repair proteins sliding on DNA to understand how they sense subtle chemical differences between bases efficiently.