Loading strategies of ring-shaped nucleic acid translocases and helicases.
Loading strategies of ring-shaped nucleic acid translocases and helicases.
复制标题
环形核酸转位酶和解旋酶的加载策略。
DOI：
10.1016/j.sbi.2013.11.006
复制
发表时间：
2014
影响因子：
6.8
通讯作者：
Berger,JamesM
中科院分区：
文献类型：
--
作者：
O'Shea,ValerieL;Berger,JamesM
突出显示六聚体核酸移位酶和解旋酶形成环绕DNA或RNA的环。这些马达水解ATP以驱动核酸运动通过中心孔。环加载通过在核酸链上组装或打开预先形成的环而发生。辅助结构域可以在加载前帮助底物DNA或RNA识别。环加载是自我导向的或由辅助分子伴侣促进。环-成形的核酸移位酶和解旋酶催化核酸链的定向和进行性运动，以支持基本的交易，例如复制、转录和染色体分配。环解旋酶/移位酶系统通常组装为六聚体，其使用三磷酸核苷（NTP）水解的协调循环来使延伸的DNA或RNA底物移位通过中心孔。环的形成对底物寡核苷酸的接合提出了拓扑挑战，并且经常通过用于将特定马达引导到其各自的底物上的不同加载策略来克服。捕获不同装载中间体的最近结构研究已经开始揭示不同的解旋酶/移位酶环如何围绕底物组装或裂开以允许DNA或RNA链进入，以及在某些情况下专用分子伴侣如何促进这些事件。流行的机械模型和剩余的知识差距进行了讨论。
HighlightsHexameric nucleic-acid translocases and helicases form rings that encircle DNA or RNA.These motors hydrolyze ATP to power nucleic acid movement through a central pore.Ring loading occurs by assembly on nucleic acid strands or by opening pre-formed rings.Accessory domains can aid with substrate DNA or RNA recognition before loading.Ring loading is either self-directed or is facilitated by ancillary chaperones.Ring-shaped nucleic acid translocases and helicases catalyze the directed and processive movement of nucleic acid strands to support essential transactions such as replication, transcription, and chromosome partitioning. Assembled typically as hexamers, ring helicase/translocase systems use coordinated cycles of nucleoside triphosphate (NTP) hydrolysis to translocate extended DNA or RNA substrates through a central pore. Ring formation presents a topological challenge to the engagement of substrate oligonucleotides, and is frequently overcome by distinct loading strategies for shepherding specific motors onto their respective substrates. Recent structural studies that capture different loading intermediates have begun to reveal how different helicase/translocase rings either assemble around substrates or crack open to allow DNA or RNA strand entry, and how dedicated chaperones facilitate these events in some instances. Both prevailing mechanistic models and remaining knowledge gaps are discussed.