Mechanism for the alteration of the substrate specificities of template-independent RNA polymerases.
Mechanism for the alteration of the substrate specificities of template-independent RNA polymerases.
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DOI：
10.1016/j.str.2010.12.006
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发表时间：
2011-02
期刊：
影响因子：
5.7
通讯作者：
Y. Toh;D. Takeshita;Takashi Nagaike;T. Numata;K. Tomita
中科院分区：
文献类型：
--
作者：
Y. Toh;D. Takeshita;Takashi Nagaike;T. Numata;K. Tomita
多聚腺苷酸聚合酶（PAP）以腺苷三磷酸（ATP）为底物，在没有核酸模板的情况下，将多聚腺苷酸尾加到RNA的3′-末端。真细菌PAP选择底物的机制仍不清楚。对大肠杆菌iPAP（EcPAP）的结构和生物化学研究表明，EcPAP的核碱基相互作用口袋的形状和大小由分子内氢网络维持，使其适合仅容纳ATP，使用单个氨基酸Arg 197。口袋结构由催化结构域和RNA结合结构域之间的相互作用维持。EcPAP具有一个灵活的碱性C-末端区域，该区域有助于最佳的RNA易位，以便将5′-单磷酸腺苷（AMP）进行性地修饰到RNA的3′-末端。EcPAP结构与其他模板非依赖性RNA聚合酶的结构的比较表明，保守的催化核心结构域以外的结构域的变化改变了模板非依赖性RNA聚合酶的底物特异性。
PolyA polymerase (PAP) adds a polyA tail onto the 3′-end of RNAs without a nucleic acid template, using adenosine-5′-triphosphate (ATP) as a substrate. The mechanism for the substrate selection by eubacterial PAP remains obscure. Structural and biochemical studies ofEscherichia coliPAP (EcPAP) revealed that the shape and size of the nucleobase-interacting pocket of EcPAP are maintained by an intra-molecular hydrogen-network, making it suitable for the accommodation of only ATP, using a single amino acid, Arg197. The pocket structure is sustained by interactions between the catalytic domain and the RNA-binding domain. EcPAP has a flexible basic C-terminal region that contributes to optimal RNA translocation for processive adenosine 5′-monophosphate (AMP) incorporations onto the 3′-end of RNAs. A comparison of the EcPAP structure with those of other template-independent RNA polymerases suggests that structural changes of domain(s) outside the conserved catalytic core domain altered the substrate specificities of the template-independent RNA polymerases.