Structural and mechanistic insights into an archaeal DNA-guided Argonaute protein
Structural and mechanistic insights into an archaeal DNA-guided Argonaute protein
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DOI：
10.1038/nmicrobiol.2017.35
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发表时间：
2017-03
影响因子：
28.3
通讯作者：
S. Willkomm;C. A. Oellig;Adrian Zander;T. Restle;R. Keegan;Dina Grohmann;S. Schneider
中科院分区：
文献类型：
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作者：
S. Willkomm;C. A. Oellig;Adrian Zander;T. Restle;R. Keegan;Dina Grohmann;S. Schneider
真核生物中的精氨酸(AGO)蛋白被认为是转录后基因沉默的关键分子1，而最近对原核生物AGOS的研究暗示了它们在抵御入侵DNA 2，3中的作用。在这里，我们介绍了载脂蛋白酶的晶体结构和古代雅纳什甲烷球菌(Mj)AGO的二元AGO-导向复合体。引导DNA的结合会导致大的结构重排。这包括包含开关螺旋的铰链区的结构转换，这已被证明对人类Ago2的动态目标搜索过程4-6是关键的。为了确定对MjAgo功能至关重要的关键残基，我们分析了几个MjAgo突变体的影响。我们观察到，特别是3‘和5’核苷酸的性质，以及开关螺旋，似乎影响MjAgo的切割活性。综上所述，我们提供了洞察的分子机制，驱动DNA引导的DNA沉默的古生菌。
Argonaute (Ago) proteins in eukaryotes are known as key players in post-transcriptional gene silencing 1, while recent studies on prokaryotic Agos hint at their role in the protection against invading DNA 2, 3. Here, we present crystal structures of the apo enzyme and a binary Ago-guide complex of the archaeal Methanocaldococcus jannaschii (Mj) Ago. Binding of a guide DNA leads to large structural rearrangements. This includes the structural transformation of a hinge region containing a switch helix, which has been shown for human Ago2 to be critical for the dynamic target search process 4–6. To identify key residues crucial for MjAgo function, we analysed the effect of several MjAgo mutants. We observe that the nature of the 3′ and 5′ nucleotides in particular, as well as the switch helix, appear to impact MjAgo cleavage activity. In summary, we provide insights into the molecular mechanisms that drive DNA-guided DNA silencing by an archaeal Ago.