Cramer Patrick
Gene Center, Ludwig-Maximilians-University of Munich, Department of Chemistry and Biochemistry, Feodor-Lynen-Str. 25, 81377 Munich, Germany.
Biochem Soc Symp. 2006(73):41-7. doi: 10.1042/bss0730041.
We have now completed an atomic crystallographic model of the 12-subunit yeast RNA polymerase II in elongation mode, with DNA and RNA in the active-centre cleft, and the NTP substrate at the growing end of the RNA. From these studies has emerged a detailed three-dimensional view of mRNA elongation. We have extended this structural analysis to a polymerase elongation complex bound by the transcript cleavage factor TFIIS (transcription factor IIS), which is required for polymerase escape from DNA arrest sites. A detailed model of this complex reveals a single tuneable active site for RNA polymerization and cleavage, and changes in the position of the RNA and polymerase domains, reflecting the dynamic nature of the elongation complex. An additional structure of a polymerase CTD (C-terminal domain) phosphopeptide bound by the 3'-RNA processing factor Pcf11 provides insights into the coupling of transcription elongation to mRNA processing. The structure of the CTD phosphatase Scp1 trapped in an intermediary enzymatic state explains CTD dephosphorylation during recycling of the polymerase. We also recently reported the first crystal structure of a Mediator subcomplex, which reveals an extended helical fold with a conserved hinge.
我们现已完成了处于延伸模式的12亚基酵母RNA聚合酶II的原子晶体学模型，活性中心裂隙中有DNA和RNA，RNA生长末端有NTP底物。通过这些研究，形成了mRNA延伸的详细三维视图。我们将这种结构分析扩展到了与转录切割因子TFIIS（转录因子IIS）结合的聚合酶延伸复合物，TFIIS是聚合酶从DNA停滞位点逃逸所必需的。该复合物的详细模型揭示了一个用于RNA聚合和切割的单一可调活性位点，以及RNA和聚合酶结构域位置的变化，反映了延伸复合物的动态性质。由3'-RNA加工因子Pcf11结合的聚合酶CTD（C末端结构域）磷酸肽的另一种结构，为转录延伸与mRNA加工的偶联提供了见解。处于中间酶状态的CTD磷酸酶Scp1的结构解释了聚合酶循环过程中的CTD去磷酸化。我们最近还报道了中介体亚复合物的首个晶体结构，其揭示了具有保守铰链的延伸螺旋折叠。
