Structures of phi29 DNA polymerase complexed with substrate:: The mechanism of translocation in B-family polymerases
Structures of phi29 DNA polymerase complexed with substrate:: The mechanism of translocation in B-family polymerases
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DOI：
10.1038/sj.emboj.7601780
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发表时间：
2007-07-25
期刊：
影响因子：
11.4
通讯作者：
Steitz, Thomas A.
中科院分区：
文献类型：
--
作者：
Berman, Andrea J.;Kamtekar, Satwik;Steitz, Thomas A.
复制型DNA聚合酶（DNAP）以进行性方式沿模板DNA沿着移动。易位机制的结构基础在聚合酶的A-家族中比在复制型聚合酶的B-家族中得到更好的研究。为了解决这个问题，我们已经确定了X射线晶体结构的phi 29 DNAP，一个成员的蛋白质引发的亚组的B-家族的聚合酶，与引物模板DNA复合的存在或不存在的传入核苷三磷酸，前和后易位状态，分别。这些结构的比较揭示了易位的机制，似乎是由两个保守的酪氨酸残基到插入位点的协调运动促进。这不同于A家族聚合酶所采用的机制，其中保守的酪氨酸在易位步骤期间移动到模板和插入位点中。来自这两个家族的聚合酶也以非常不同的方式与下游单链模板DNA相互作用。
Replicative DNA polymerases (DNAPs) move along template DNA in a processive manner. The structural basis of the mechanism of translocation has been better studied in the A-family of polymerases than in the B-family of replicative polymerases. To address this issue, we have determined the X-ray crystal structures of phi29 DNAP, a member of the protein-primed subgroup of the B-family of polymerases, complexed with primer-template DNA in the presence or absence of the incoming nucleoside triphosphate, the pre- and post-translocated states, respectively. Comparison of these structures reveals a mechanism of translocation that appears to be facilitated by the coordinated movement of two conserved tyrosine residues into the insertion site. This differs from the mechanism employed by the A-family polymerases, in which a conserved tyrosine moves into the templating and insertion sites during the translocation step. Polymerases from the two families also interact with downstream single-stranded template DNA in very different ways.