Analysis of the crystal structure of an active MCM hexamer.
Analysis of the crystal structure of an active MCM hexamer.
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DOI：
10.7554/elife.03433
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发表时间：
2014-09-29
期刊：
影响因子：
7.7
通讯作者：
Enemark EJ
中科院分区：
文献类型：
--
作者：
Miller JM;Arachea BT;Epling LB;Enemark EJ
在以前的研究文章中，我们提出了MCM解旋酶激活机制，但在讨论ATP酶结构域时受到限制，因为它不存在于晶体结构中。在这里，我们提出了一个几乎全长MCM六聚体的晶体结构，是解旋酶活性，因此具有所有功能的DNA解旋必不可少的。该结构是硫磺硫化叶菌N-末端结构域和激烈火球菌ATP酶结构域的嵌合体。我们讨论了三个主要的发现：1）一种新的构象的A-亚结构域，可以发挥作用的MCM调节; 2）一个普遍保守的谷氨酰胺在N-末端变构通讯环与AAA+结构域螺旋-2-插入（h2 i）的相互作用;和3）一个凹进的结合口袋MCM ssDNA结合基序的影响h2 i。我们认为，在解旋酶激活过程中，h2 i钳在领先的链，以促进链保留和调节ATP水解。DOI：http://dx.doi.org/10.7554/eLife.03433.001网站
In a previous Research article, we suggested an MCM helicase activation mechanism, but were limited in discussing the ATPase domain because it was absent from the crystal structure. Here we present the crystal structure of a nearly full-length MCM hexamer that is helicase-active and thus has all features essential for unwinding DNA. The structure is a chimera of Sulfolobus solfataricus N-terminal domain and Pyrococcus furiosus ATPase domain. We discuss three major findings: 1) a novel conformation for the A-subdomain that could play a role in MCM regulation; 2) interaction of a universally conserved glutamine in the N-terminal Allosteric Communication Loop with the AAA+ domain helix-2-insert (h2i); and 3) a recessed binding pocket for the MCM ssDNA-binding motif influenced by the h2i. We suggest that during helicase activation, the h2i clamps down on the leading strand to facilitate strand retention and regulate ATP hydrolysis. DOI: http://dx.doi.org/10.7554/eLife.03433.001