RIBOSOMAL-RNA SYNTHESIS IN SACCHAROMYCES-CEREVISIAE
RIBOSOMAL-RNA SYNTHESIS IN SACCHAROMYCES-CEREVISIAE
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DOI：
10.1016/0022-2836(72)90279-3
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发表时间：
1972-01-01
影响因子：
5.6
通讯作者：
WARNER, JR
中科院分区：
文献类型：
--
作者：
UDEM, SA;WARNER, JR
酵母酿酒酵母代谢活跃的原生质球中的核糖体 RNA 生物合成被选为研究核-细胞质相互作用的模型系统。对短暂暴露于标记核苷期间合成的总细胞 RNA 的检查表明，除了成熟的核糖体 RNA 之外，还存在 35 s、27 s 和 20 s 三种大型、短寿命的 RNA 物种， 25 秒和 18 秒。很少或没有发现大于 35 s 的 RNA。这些RNA分子的合成动力学通过连续标记和脉冲追踪实验进行研究，使用[甲基-3H]甲硫氨酸仅标记核糖体种类。这些结果证明了以下前体-产物关系：在存在放线菌酮的情况下，导致成熟核糖体RNA的末端加工步骤受到严重抑制，表明核糖体前体RNA的成熟需要连续的蛋白质合成。使用二甲基亚砜的RNA变性研究表明，前体是比成熟rRNA更大的单个多核糖核苷酸链，而不是较小分子的聚集体或核糖体种类的构象异构体。这些 RNA 的分子大小通过丙烯酰胺凝胶中的电泳迁移率来估计。 35 s 前体为 2.5 × 106 道尔顿。它的裂解似乎是保守的，产生 1.6 × 106 和 0.8 × 106 道尔顿的中间分子。最终的成熟步骤产生 1.3 × 106 和 0.7 × 106 道尔顿的成熟 rRNA，同时损失约 20% 的原始前体分子。此外，得出的结论是，与 25 s RNA 非共价结合的小 RNA 种类 5.8 s（6 × 104 道尔顿）是在 27 s 前体分子的最终裂解过程中产生的。相比之下，5s RNA 是独立合成的。这些结果支持这样的论点：所有真核生物都类似地合成核糖体，并且酵母可能是研究细胞内通讯（特别是跨核膜通讯）的有用生物体。
Ribosomal RNA biosynthesis in metabolically active spheroplasts of the yeastSaccharomyces cerevisiaewas selected as a model system for the study of nucleo-cytoplasmic interactions.Examination of the total cellular RNA synthesized during short exposures to labeled nucleosides demonstrated the existence of three large, short-lived RNA species of 35 s, 27 s and 20 s, in addition to the mature ribosomal RNA's, 25 s and 18 s. Little or no RNA larger than 35 s is found. The kinetics of synthesis of these RNA molecules was pursued by continuous labeling and pulse-chase experiments, using [methyl-3H]methionine to label only ribosomal species. These results demonstrated the following precursor-product relationship: In the presence of cycloheximide the terminal processing steps leading to the mature ribosomal RNA's are severely inhibited, indicating that the maturation of ribosomal precursor RNA requires continuous protein synthesis.RNA denaturation studies using dimethyl sulfoxide showed the precursors to be single polyribonucleotide chains larger than the mature rRNA's, rather than aggregates of smaller molecules, or conformational isomers of the ribosomal species. Molecular sizes of these RNA's were estimated by electrophoretic mobility in acrylamide gels. The 35 s precursor is 2.5 × 106daltons. Its cleavage appears to be conservative, producing intermediate molecules of 1.6 × 106and 0.8 × 106daltons. The final maturation steps yield mature rRNA's of 1.3 × 106and 0.7 × 106daltons with the concomitant loss of about 20% of the original precursor molecule. In addition, it was concluded that the small RNA species, 5.8 s (6 × 104daltons) found non-covalently bound to the 25 s RNA, is generated during the final cleavage of the 27 s precursor molecule. In contrast, 5 s RNA is synthesized independently.These results support the contention that all eukaryotes synthesize ribosomes similarly and that yeast may be a useful organism for the investigation of intracellular communication, particularly across the nuclear membrane.