近日，国际学术期刊《the Journal of BioLogical Chemistry》在线发表上海交通大学微生物代谢国家重点实验室由德林教授研究组与中国农业科学院上海兽医研究所胡青海课题组合作发表关于DNA磷硫酰化修饰研究新进展文章，揭示了DNA解旋酶参与DNA磷硫酰化修饰过程。文章的题目是“DndEi exhibits helicase activity essential for DNA phosphorothioate modification and ATPase activity strongly stimulated by DNA substrate with a GAAC/GTTC motif”，博士生郑涛为论文第一作者。
DNA磷硫酰化是硫原子取代DNA骨架非桥联氧原子的一种新型表观遗传学修饰，这种修饰广泛存在于原核生物中，由磷硫酰化修饰基因dndA-E控制。最近，来自法国一个研究小组发现致病微生物Riemerella anatipestifer中存在一种新的DndE蛋白并命名为DndEi。DndEi比传统的DndE蛋白多1个结构域，但该结构域在DNA磷硫酰化修饰中的作用尚不清楚。
本研究通过对R. anatipestifer来源的磷硫酰化修饰基因DndEi生化性质和体内功能的全面分析，系统阐述了dndEi在DNA磷硫酰化修饰中的作用。研究表明DndEi中多出的结构域具有DNA解旋酶活性，体内缺失该结构域导致DNA磷硫酰化活性丧失，证明了该结构域对DNA磷硫酰化修饰是必需的。研究还发现DndEi具有ATP酶活性，并且，含有GAAC/GTTC序列的dna片段能极大的促进DndEi的ATP酶活性，而GAAC/GTTC正是DNA磷硫酰化修饰的保守序列。该研究首次揭示了DNA解旋酶参与DNA磷硫酰化修饰，为进一步深入理解DNA磷硫酰化的生物化学过程奠定了重要基础。
原文链接：
DndEi exhibits helicase activity essential for DNA phosphorothioate modification and ATPase activity strongly stimulated by DNA substrate with a GAAC/GTTC motif
原文摘要:
Phosphorothioate (PT) modification of DNA, in which the non-bridging oxygen of the backbone phosphate group is replaced by sulfur, is governed by the DndA-E proteins in prokaryotes. To better understand the biochemical mechanism of PT modification, functional analysis of the recently found PT-modifying enzymeDndEi, which has an additional domain compared to canonical DndE, from Riemerella anatipestifer is performed in this study. The additional domain is identified as an ATP-dependent DNA helicase, and functional deletion of this domain in vivo leads to PT modification deficiency, indicating an essential role of helicase activity in PT modification. Subsequent analysis reveals that the additional domain has an ATPase activity. Intriguingly, the ATPase activity is strongly stimulated by DNA substrate containing a GAAC/GTTC motif (i.e., the motif at which PT modifications occur in R. anatipestifer) when the additional domain and the other domain (homologous to canonical DndE) are co-expressed as a full-length DndEi. These results reveal that PT modification is a biochemical process with DNA strands separation and intense ATP hydrolysis.
doi:10.1074/jbc.M115.694018
（责任编辑：fangqi）
