The roles of Rrp5p in the synthesis of yeast 18S and 5.8S rRNA can be functionally and physically separated
The roles of Rrp5p in the synthesis of yeast 18S and 5.8S rRNA can be functionally and physically separated
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DOI：
10.1017/s1355838299990313
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发表时间：
1999-06-01
期刊：
影响因子：
4.5
通讯作者：
Venema, J
中科院分区：
文献类型：
--
作者：
Eppens, NA;Rensen, S;Venema, J
酵母核仁蛋白Rrp 5 p是唯一已知的反式作用因子，其对于18 S rRNA和主要的短形式的5.8S（5.8S（s））rRNA的合成是必需的，其被认为在两组独立的前rRNA加工反应中产生。为了鉴定Rrp 5 p中任一加工途径所需的结构域，我们分析了一组8个缺失突变体，它们共同覆盖整个RRP 5序列。令人惊讶的是，只有一个缺失是致命的，这表明可以单独去除约80%的蛋白质区域，而不会破坏其基本的生物学功能。生物化学分析清楚地表明存在两个不同的功能结构域，从N-末端半部分去除三个连续片段中的每一个都特异性地抑制5.8S（s）rRNA的形成，而缺失蛋白质的C-末端区域的一部分仅阻断18 S rRNA的产生。后一种表型也是由同一C-末端区域内的温度敏感性突变引起的。通过突变分析鉴定的两个功能区域似乎与通过计算机分析检测到的结构域相关。它们甚至可以在物理上分离，如完全Rrp 5 p活性可以由两个连续的反式表达的蛋白片段提供的事实所证明的。
The yeast nucleolar protein Rrp5p is the only known trans-acting factor that is essential for the synthesis of both 18S rRNA and the major, short form of 5.8S (5.8S(s)) rRNA, which were thought to be produced in two independent sets of pre-rRNA processing reactions. To identify domains within Rrp5p required for either processing pathway, we have analyzed a set of eight deletion mutants that together cover the entire RRP5 sequence, Surprisingly, only one of the deletions is lethal, indicating that regions encompassing about 80% of the protein can be removed individually without disrupting its essential biological function. Biochemical analysis clearly demonstrated the presence of two distinct functional domains, Removal of each of three contiguous segments from the N-terminal half specifically inhibits the formation of 5.8S(s) rRNA, whereas deleting part of the C-terminaI region of the protein only blocks the production of 18S rRNA. The latter phenotype is also caused by a temperature-sensitive mutation within the same C-terminal region, The two functional regions identified by the mutational analysis appear to be correlated with the structural domains detected by computer analysis. They can even be physically separated, as demonstrated by the fact that full Rrp5p activity can be supplied by two contiguous protein fragments expressed in trans.