The guanylyltransferase domain of mammalian mRNA capping enzyme binds to the phosphorylated carboxyl-terminal domain of RNA polymerase II
The guanylyltransferase domain of mammalian mRNA capping enzyme binds to the phosphorylated carboxyl-terminal domain of RNA polymerase II
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DOI：
10.1074/jbc.273.16.9577
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发表时间：
1998-04-17
影响因子：
4.8
通讯作者：
Shuman, S
中科院分区：
文献类型：
--
作者：
Ho, CK;Sriskanda, V;Shuman, S
我们对小鼠 mRNA 加帽酶 (Mce1) 进行了生化和遗传分析，Mce1 是一种具有 RNA 三磷酸酶和 RNA 鸟苷基转移酶活性的双功能蛋白，由 597 个氨基酸组成。主要结论如下：（i）哺乳动物加帽酶由自主且不重叠的功能域组成； (ii)鸟苷基转移酶结构域Mce1(211-597)在体外具有催化活性，并且在酵母体内具有功能，代替内源鸟苷基转移酶Ceg1； (iii) 鸟苷基转移酶结构域本身与磷酸化 RNA 聚合酶 II 羧基末端结构域 (CTD) 结合，而三磷酸酶结构域 Mce1(1-210) 不与 CTD 结合； (iv) 小鼠三磷酸酶活性位点半胱氨酸的突变在酵母中引起强烈的生长抑制表型，可能是通过将前 mRNA 末端隔离在非生产性复合物中或通过阻止内源酵母三磷酸酶接触 RNA 聚合酶 II。这些发现有助于建立一种新兴的 mRNA 生物合成模型，其中 RNA 加工酶通过与 CTD 接触而靶向新生聚合酶 II 转录物。鸟苷基转移酶和 CTD 之间的磷酸化依赖性相互作用从酵母到哺乳动物都是保守的。
We have conducted a biochemical and genetic analysis of mouse mRNA capping enzyme (Mce1), a bifunctional 597-amino acid protein with RNA triphosphatase and RNA guanylyltransferase activities. The principal conclusions are as follows: (i) the mammalian capping enzyme consists of autonomous and nonoverlapping functional domains; (ii) the guanylyltransferase domain Mce1(211-597) is catalytically active in vitro and functional in vivo in yeast in lieu of the endogenous guanylyltransferase Ceg1; (iii) the guanylyltransferase domain per se binds to the phosphorylated RNA polymerase II carboxyl-terminal domain (CTD), whereas the triphosphatase domain, Mce1(1-210), does not bind to the CTD; and (iv) a mutation of the active site cysteine of the mouse triphosphatase elicits a strong growth-suppressive phenotype in yeast, conceivably by sequestering pre-mRNA ends in a nonproductive complex or by blocking access of the endogenous yeast triphosphatase to RNA polymerase II. These findings contribute to an emerging model of mRNA biogenesis wherein RNA processing enzymes are targeted to nascent polymerase II transcripts through contacts with the CTD, The phosphorylation-dependent interaction between guanylyltransferase and the CTD is conserved from yeast to mammals.