A model for the mechanism of polymerase translocation
A model for the mechanism of polymerase translocation
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DOI：
10.1006/jmbi.1996.0707
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发表时间：
1997-01-10
影响因子：
5.6
通讯作者：
Sousa, R
中科院分区：
文献类型：
--
作者：
Guajardo, R;Sousa, R
详细阐述了聚合酶易位的一般机制。该机制的核心特征是，在核苷单磷酸掺入的每个循环后建立快速易位平衡，使得聚合酶通过在模板上的所有可接近位置之间的扩散滑动来分布自身，相对占据由相对自由能决定。虽然易位的替代模型尚未完全开发出来，但目前用于描述此步骤的大部分语言表明与聚合酶中的构象转变耦合的主动机制。例如，最近一项关于大肠杆菌 RNA 聚合酶在转录过程中产生力的研究表明，它是一种类似于肌球蛋白运动蛋白驱动蛋白的机械酶。虽然所提出的机制并不排除聚合酶易位过程中的构象转变，但它表明它们可能是不必要的，并且可以根据活性位点对三磷酸核苷的亲和力以及结合在模板上不同位置的聚合酶的相对自由能来解释易位。这种机制做出了具体的预测，并通过不同的聚合酶（如大肠杆菌 DNAP I、噬菌体 T7 RNAP 和大肠杆菌 RNAP）进行实验证实。 (C) 1997 学术出版社有限公司
A general mechanism for polymerase translocation is elaborated. The central feature of this mechanism is that a rapid translocational equilibrium is established after each cycle of nucleoside monophosphate incorporation such that the polymerase distributes itself by diffusional sliding between all accessible positions on the template with relative occupancy determined by relative free energy. While alternative models for translocation have not been fully developed, much of the language currently used to describe this step suggests an active mechanism coupled to conformational transitions in the polymerase. For example, a recent study of force generation by Escherichia coli RNA polymerase during transcription suggests that it is a mechanoenzyme analogous to kinesin of myosin motor proteins. While the proposed mechanism does not rule out conformational transitions during polymerase translocation, it suggests that they may be unnecessary and that translocation can be explained in terms of the affinity of the active site for nucleoside triphosphate and the relative free energies of the polymerase bound at different positions on the template. This mechanism makes specific predictions which are borne out experimentally with polymerases as distinct as E. coli DNAP I, phage T7 RNAP, and E. coli RNAP. (C) 1997 Academic Press Limited