Kim Minkyu, Suh Hyunsuk, Cho Eun-Jung, Buratowski Stephen
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA.
J Biol Chem. 2009 Sep 25;284(39):26421-6. doi: 10.1074/jbc.M109.028993. Epub 2009 Aug 13.
The C-terminal domain (CTD) of Rpb1, the largest subunit of RNA polymerase II, acts as a binding platform for various mRNA processing and histone-modifying enzymes that act co-transcriptionally. These factors are targeted to specific phosphorylation states of the CTD that predominate at different stages of transcription. Within the repeating sequence YSPTSPS, serines 2 and 5 are major phosphorylation sites, but serine 7 phosphorylation was recently discovered in mammalian cells. Here we show that CTD serine 7 is also phosphorylated in yeast and that Ser-7(P) chromatin immunoprecipitation patterns resemble those of Ser-5(P). The basal factor TFIIH can phosphorylate Ser-7 in vitro and is necessary for Ser-7(P) in vivo. Interestingly, deletion of the CTD Ser-5(P) phosphatase Rtr1 leads to an increase in Ser-5(P) but not Ser-7(P).
RNA聚合酶II最大亚基Rpb1的C末端结构域(CTD)作为多种mRNA加工和组蛋白修饰酶的结合平台,这些酶在转录过程中协同发挥作用。这些因子靶向CTD的特定磷酸化状态,这些状态在转录的不同阶段占主导。在重复序列YSPTSPS中,丝氨酸2和5是主要的磷酸化位点,但最近在哺乳动物细胞中发现了丝氨酸7的磷酸化。在这里,我们表明CTD丝氨酸7在酵母中也被磷酸化,并且Ser-7(P)染色质免疫沉淀模式与Ser-5(P)的模式相似。基础因子TFIIH可以在体外磷酸化Ser-7,并且对于体内Ser-7(P)的形成是必需的。有趣的是,CTD Ser-5(P)磷酸酶Rtr1的缺失导致Ser-5(P)增加,但不导致Ser-7(P)增加。