Eukaryote-specific rRNA expansion segments function in ribosome biogenesis.
Eukaryote-specific rRNA expansion segments function in ribosome biogenesis.
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DOI：
10.1261/rna.056705.116
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发表时间：
2016-08
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影响因子：
--
通讯作者：
Woolford JL Jr
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文献类型：
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作者：
Ramesh M;Woolford JL Jr
核糖体RNA（rRNA）的二级结构在所有生命界中基本上是保守的。然而，真核生物已经进化出相对于原核生物的rRNA序列的额外区块，称为扩展片段（ES）。ES的潜在作用的一个彻底的表征仍有待完成，可能是因为在强大的系统来研究rRNA突变体的可用性的限制。我们试图通过缺失突变系统地研究酿酒酵母25SrRNA中ES的潜在功能。我们删除了16个不同的真核生物特异性ES在酵母25S rRNA中的14个，并分析了它们的表型。我们的研究结果表明，除了两个测试的ES是必要的最佳生长和生产所需的25S rRNA，这表明ES在核糖体生物合成中发挥作用。此外，我们将扩展片段分为参与核糖体生物发生的早期核仁，中期和晚期核质步骤的组，通过测定它们的前rRNA加工表型。这项研究是同类研究中首次系统地鉴定真核生物特异性扩展片段的功能，表明它们在核糖体生物发生的特定步骤中发挥作用。表型的目录，我们确定，结合以前的调查的作用，核糖体蛋白质大亚基生物合成，使我们推断，组装核糖体是由不同的RNA和蛋白质结构附近的集群，参与特定步骤的核糖体生物合成。
The secondary structure of ribosomal RNA (rRNA) is largely conserved across all kingdoms of life. However, eukaryotes have evolved extra blocks of rRNA sequences, relative to those of prokaryotes, called expansion segments (ES). A thorough characterization of the potential roles of ES remains to be done, possibly because of limitations in the availability of robust systems to study rRNA mutants. We sought to systematically investigate the potential functions, if any, of the ES in 25S rRNA of Saccharomyces cerevisiae by deletion mutagenesis. We deleted 14 of the 16 different eukaryote-specific ES in yeast 25S rRNA individually and assayed their phenotypes. Our results show that all but two of the ES tested are necessary for optimal growth and are required for production of 25S rRNA, suggesting that ES play roles in ribosome biogenesis. Further, we classified expansion segments into groups that participate in early nucleolar, middle, and late nucleoplasmic steps of ribosome biogenesis, by assaying their pre-rRNA processing phenotypes. This study is the first of its kind to systematically identify the functions of eukaryote-specific expansion segments by showing that they play roles in specific steps of ribosome biogenesis. The catalog of phenotypes we identified, combined with previous investigations of the roles ribosomal proteins in large subunit biogenesis, leads us to infer that assembling ribosomes are composed of distinct RNA and protein structural neighborhood clusters that participate in specific steps of ribosome biogenesis.