Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
Mol Cell. 2013 Sep 26;51(6):850-8. doi: 10.1016/j.molcel.2013.08.015. Epub 2013 Sep 12.
The C-terminal domain (CTD) of Rpb1, the largest subunit of RNA polymerase II (RNApII), coordinates recruitment of RNA- and chromatin-modifying factors to transcription complexes. It is unclear whether the CTD communicates with the catalytic core region of Rpb1 and thus must be physically connected, or instead can function as an independent domain. To address this question, CTD was transferred to other RNApII subunits. Fusions to Rpb4 or Rpb6, two RNApII subunits located near the original position of CTD, support viability in a strain carrying a truncated Rpb1. In contrast, CTD fusion to Rpb9 on the other side of RNApII does not. Rpb4-CTD and Rpb6-CTD proteins are functional for phosphorylation and recruitment of various factors, albeit with some restrictions and minor defects. Normal CTD functions are not transferred to RNApI or RNApIII by Rbp6-CTD. These results show that, with some spatial constraints, CTD can function even when disconnected from Rpb1.
RNA 聚合酶 II（RNApII）大亚基 Rpb1 的 C 端结构域（CTD）协调 RNA 和染色质修饰因子向转录复合物的募集。目前尚不清楚 CTD 是否与 Rpb1 的催化核心区域相互作用，因此必须物理连接，还是可以作为独立的结构域发挥作用。为了解决这个问题，将 CTD 转移到其他 RNApII 亚基上。与 CTD 原始位置附近的两个 RNApII 亚基 Rpb4 或 Rpb6 的融合支持在携带截短 Rpb1 的菌株中存活。相比之下，在 RNApII 另一侧的 Rpb9 上的 CTD 融合则不行。Rpb4-CTD 和 Rpb6-CTD 蛋白可用于磷酸化和各种因子的募集，但存在一些限制和较小的缺陷。Rpb6-CTD 不能将正常的 CTD 功能转移到 RNApI 或 RNApIII。这些结果表明，在存在一些空间限制的情况下，即使与 Rpb1 断开连接，CTD 也能发挥作用。
