The mRNA capping enzyme of Saccharomyces cerevisiae has dual specificity to interact with CTD of RNA Polymerase II
The mRNA capping enzyme of Saccharomyces cerevisiae has dual specificity to interact with CTD of RNA Polymerase II
复制标题
DOI：
10.1038/srep31294
复制
发表时间：
2016-08-09
影响因子：
4.6
通讯作者：
Akhtar, Md. Sohail
中科院分区：
文献类型：
--
作者：
Bharati, Akhilendra Pratap;Singh, Neha;Akhtar, Md. Sohail
RNA聚合酶II（RNAPII）在其最大的亚基Rpb 1上独特地具有延伸的羧基末端结构域（CTD），其包含具有潜在磷酸化位点的重复Tyr（1）Ser（2）Pro（3）Thr（4）Ser（5）Pro（6）Ser（7）基序。CTD的磷酸化充当用于mRNA生物发生的各种转录调节剂（包括mRNA加帽复合物）结合的信号。在真核生物中，新生转录物的5 ′加帽是第一个可检测的mRNA加工事件，并且对于生产性转录物延伸至关重要。已知加帽酶RNA鸟苷酰转移酶与转录RNAPII的结合主要由CTD促进，在Ser（5）（Ser（5 P））处磷酸化。本文报道了酿酒酵母RNA鸟苷酰转移酶（Ceg 1）具有双重特异性，不仅与CTD的Ser（5 P）相互作用，而且与CTD的Ser（7 P）相互作用。CTD的Ser（7）对于mRNA加帽复合物的无条件生长和有效引发是必需的。Ceg 1的Arg 159和Arg 185是与Ser（5 P）相互作用的关键残基，而CTD的Lys 175与Ser（7 P）相互作用。这些相互作用似乎是在一个特定的模式的Ser（5 P）S（e）r（7 P）Ser（5 P）在一个三-heptad CTD（YSPTSPPS YSPTSPSP YSPTSPPS），并提供了分子的见解Ceg 1-CTD相互作用的mRNA转录。
RNA Polymerase II (RNAPII) uniquely possesses an extended carboxy terminal domain (CTD) on its largest subunit, Rpb1, comprising a repetitive Tyr(1)Ser(2)Pro(3)Thr(4) Ser(5)Pro(6)Ser(7) motif with potential phosphorylation sites. The phosphorylation of the CTD serves as a signal for the binding of various transcription regulators for mRNA biogenesis including the mRNA capping complex. In eukaryotes, the 5 prime capping of the nascent transcript is the first detectable mRNA processing event, and is crucial for the productive transcript elongation. The binding of capping enzyme, RNA guanylyltransferases to the transcribing RNAPII is known to be primarily facilitated by the CTD, phosphorylated at Ser(5) (Ser(5P)). Here we report that the Saccharomyces cerevesiae RNA guanylyltransferase (Ceg1) has dual specificity and interacts not only with Ser(5P) but also with Ser(7P) of the CTD. The Ser(7) of CTD is essential for the unconditional growth and efficient priming of the mRNA capping complex. The Arg159 and Arg185 of Ceg1 are the key residues that interact with the Ser(5P), while the Lys175 with Ser(7P) of CTD. These interactions appear to be in a specific pattern of Ser(5P)S(e)r(7P)Ser(5P) in a tri-heptad CTD (YSPTSPPS YSPTSPSP YSPTSPPS) and provide molecular insights into the Ceg1-CTD interaction for mRNA transcription.