Solution structure of the Set2-Rpb1 interacting domain of human Set2 and its interaction with the hyperphosphorylated C-terminal domain of Rpb1
Solution structure of the Set2-Rpb1 interacting domain of human Set2 and its interaction with the hyperphosphorylated C-terminal domain of Rpb1
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DOI：
10.1073/pnas.0506350102
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发表时间：
2005-12-06
影响因子：
11.1
通讯作者：
Zhou, P
中科院分区：
文献类型：
--
作者：
Li, M;Phatnani, HP;Zhou, P
RNA聚合酶II最大亚基的C末端重复结构域(CTD)的磷酸化状态随着聚合酶转录基因的变化而变化，不同形式的磷酸化CTD(PCTD)向延伸的聚合酶招募不同的核因子。最近发现酵母中的Set2组蛋白甲基转移酶通过一个新的结构域与延伸的RNA聚合酶II的PCTD结合，称为Set2-Rpb1相互作用(SRI)结构域。在这里，我们报道了人类Set2中SRI结构域(HSRI结构域)的溶液结构，它采用了一个左转的三螺旋束，与其他结构特征的PCTD相互作用结构域截然不同。核磁共振滴定实验将HSRI结构域的结合表面映射到螺旋1和2，Biacore结合研究表明该结构域更好地与含有两个或更多七肽重复的磷酸化CTD肽结合。点突变研究确定了五个对PCTD结合至关重要的残基。鉴于这些点突变对不同CTD磷酸肽结合的不同影响，我们提出了HSRI结构域与PCTD相互作用的模型。
The phosphorylation state of the C-terminal repeat domain (CTD) of the largest subunit of RNA polymerase II changes as polymerase transcribes a gene, and the distinct forms of the phospho-CTD (PCTD) recruit different nuclear factors to elongating polymerase. The Set2 histone methyltransferase from yeast was recently shown to bind the PCTD of elongating RNA polymerase II by means of a novel domain termed the Set2-Rpb1 interacting (SRI) domain. Here, we report the solution structure of the SRI domain in human Set2 (hSRI domain), which adopts a left-turned three-helix bundle distinctly different from other structurally characterized PCTD-interacting domains. NMR titration experiments mapped the binding surface of the hSRI domain to helices 1 and 2, and Biacore binding studies showed that the domain binds preferably to [Ser-2 + Ser-5]-phosphorylated CTD peptides containing two or more heptad repeats. Point-mutagenesis studies identified five residues critical for PCTD binding. In view of the differential effects of these point mutations on binding to different CTD phosphopeptides, we propose a model for the hSRI domain interaction with the PCTD.