Crystal structure of a phage Twort group I ribozyme-product complex
Crystal structure of a phage Twort group I ribozyme-product complex
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DOI：
10.1038/nsmb868
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发表时间：
2005-01-01
影响因子：
16.8
通讯作者：
Chase, E
中科院分区：
文献类型：
--
作者：
Golden, BL;Kim, H;Chase, E
I组内含子是能够协调导致自我剪接的两个连续磷酸酯交换反应的催化RNA。为了理解I组内含子活性位点如何促进催化，我们已经解决了来自噬菌体Twort的orf 142-I2内含子的活性核酶的结构，该内含子以3.6埃的分辨率结合到四核苷酸产物RNA上。除了所有I组内含子的三个保守结构域特征之外，Twort核酶具有噬菌体内含子的外围插入特征。这些元件形成一个环，完全包围了活性位点，在活性位点处，一系列堆叠的碱基三联体形成了一个适合鸟苷的口袋。活性位点的结构揭示了催化金属的三个潜在的结合位点，并在组织催化活性位点中调用鸟苷底物的2个羟基的作用。
Group I introns are catalytic RNAs capable of orchestrating two sequential phosphotransesterification reactions that result in self-splicing. To understand how the group I intron active site facilitates catalysis, we have solved the structure of an active ribozyme derived from the orf142-I2 intron from phage Twort bound to a four-nucleotide product RNA at a resolution of 3.6 Angstrom. In addition to the three conserved domains characteristic of all group I introns, the Twort ribozyme has peripheral insertions characteristic of phage introns. These elements form a ring that completely envelops the active site, where a snug pocket for guanosine is formed by a series of stacked base triples. The structure of the active site reveals three potential binding sites for catalytic metals, and invokes a role for the 2 hydroxyl of the guanosine substrate in organization of the active site for catalysis.