Complete RNA polymerase II elongation complex structure and its interactions with NTP and TFIIS
Complete RNA polymerase II elongation complex structure and its interactions with NTP and TFIIS
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DOI：
10.1016/j.molcel.2004.11.040
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发表时间：
2004-12-22
期刊：
影响因子：
16
通讯作者：
Cramer, P
中科院分区：
文献类型：
--
作者：
Kettenberger, H;Armache, KJ;Cramer, P
完整的12亚基RNA聚合酶（pol）II结合到转录泡和产物RNA的晶体结构揭示了进入的模板和非模板DNA，一个7个碱基对的DNA/RNA杂交体，以及分离DNA和RNA的各3个核苷酸。该复合物采用后易位状态，并容纳共结晶的核苷三磷酸（NTP）底物。NTP结合在活性位点孔中与DNA模板碱基相互作用的位置处。NTP周围的残基在所有细胞RNA聚合酶中是保守的，这表明NTP选择和掺入的普遍机制。DNA-DNA和DNA-RNA链的分离可以用pol II诱导的双链体畸变来解释。四个蛋白质环分隔活性中心裂缝，有助于嵌入杂交体，防止链重新结合，并创建RNA出口隧道。延伸因子TFIIS的结合使活性中心的RNA重新排列，可能将延伸复合物转化为不太容易停滞的替代状态。
The crystal structure of the complete 12 subunit RNA polymerase (pol) II bound to a transcription bubble and product RNA reveals incoming template and non-template DNA, a seven base pair DNA/RNA hybrid, and three nucleotides each of separating DNA and RNA. The complex adopts the posttranslocation state and accommodates a cocrystallized nucleoside triphosphate (NTP) substrate. The NTP binds in the active site pore at a position to interact with a DNA template base. Residues surrounding the NTP are conserved in all cellular RNA polymerases, suggesting a universal mechanism of NTP selection and incorporation. DNA-DNA and DNA-RNA strand separation may be explained by pol II-induced duplex distortions. Four protein loops partition the active center cleft, contribute to embedding the hybrid, prevent strand reassociation, and create an RNA exit tunnel. Binding of the elongation factor TFIIS realigns RNA in the active center, possibly converting the elongation complex to an alternative state less prone to stalling.