Hu Ping, Wu Si, Hernandez Nouria
Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA .
Mol Cell. 2003 Sep;12(3):699-709. doi: 10.1016/j.molcel.2003.08.011.
In higher eukaryotes, RNA polymerase (pol) III is known to use different transcription factors to recognize three basic types of promoters, but in no case have these transcription factors been completely defined. We show that a highly purified pol III complex combined with the recombinant transcription factors SNAP(c), TBP, Brf2, and Bdp1 directs multiple rounds of transcription initiation and termination from the human U6 promoter. The pol III complex contains traces of CK2, and CK2 associates with the U6 promoter region in vivo. Transcription requires CK2 phosphorylation of the pol III complex. In contrast, CK2 phosphorylation of TBP, Brf2, and Bdp1 combined is inhibitory. The results define a minimum core machinery, the ultimate target of regulatory mechanisms, capable of directing all steps of the transcription process-initiation, elongation, and termination-by a metazoan RNA polymerase, and suggest positive and negative regulatory roles for CK2 in transcription by pol III.
在高等真核生物中，已知RNA聚合酶（pol）III使用不同的转录因子来识别三种基本类型的启动子，但在任何情况下，这些转录因子都未被完全定义。我们发现，一种高度纯化的pol III复合物与重组转录因子SNAP(c)、TBP、Brf2和Bdp1结合，可指导从人U6启动子进行多轮转录起始和终止。pol III复合物含有痕量的CK2，且CK2在体内与U6启动子区域相关联。转录需要CK2对pol III复合物进行磷酸化。相反，TBP、Brf2和Bdp1三者结合后的CK2磷酸化具有抑制作用。这些结果定义了一种最小核心机制，即调控机制的最终靶点，它能够指导后生动物RNA聚合酶转录过程的所有步骤——起始、延伸和终止，并表明CK2在pol III转录中具有正负调控作用。
