Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK.
Department of Molecular Biology, University Medical Center Göttingen, Göttingen, Germany.
Wiley Interdiscip Rev RNA. 2023 Jul-Aug;14(4):e1766. doi: 10.1002/wrna.1766. Epub 2022 Oct 18.
Ribosomes are essential macromolecular machines responsible for translating the genetic information encoded in mRNAs into proteins. Ribosomes are composed of ribosomal RNAs and proteins (rRNAs and RPs) and the rRNAs fulfill both catalytic and architectural functions. Excision of the mature eukaryotic rRNAs from their precursor transcript is achieved through a complex series of endoribonucleolytic cleavages and exoribonucleolytic processing steps that are precisely coordinated with other aspects of ribosome assembly. Many ribonucleases involved in pre-rRNA processing have been identified and pre-rRNA processing pathways are relatively well defined. However, momentous advances in cryo-electron microscopy have recently enabled structural snapshots of various pre-ribosomal particles from budding yeast (Saccharomyces cerevisiae) and human cells to be captured and, excitingly, these structures not only allow pre-rRNAs to be observed before and after cleavage events, but also enable ribonucleases to be visualized on their target RNAs. These structural views of pre-rRNA processing in action allow a new layer of understanding of rRNA maturation and how it is coordinated with other aspects of ribosome assembly. They illuminate mechanisms of target recognition by the diverse ribonucleases involved and reveal how the cleavage/processing activities of these enzymes are regulated. In this review, we discuss the new insights into pre-rRNA processing gained by structural analyses and the growing understanding of the mechanisms of ribonuclease regulation. This article is categorized under: Translation > Ribosome Biogenesis RNA Processing > rRNA Processing.
核糖体是负责将 mRNA 中编码的遗传信息翻译成蛋白质的重要大分子机器。核糖体由核糖体 RNA（rRNA）和蛋白质（rPs）组成，rRNA 同时具有催化和结构功能。真核生物 rRNA 前体从其前体转录本中的成熟 rRNA 的切除是通过一系列复杂的内切核酸酶切割和外切核酸酶加工步骤来实现的，这些步骤与核糖体组装的其他方面精确协调。已经鉴定出许多参与 pre-rRNA 加工的核糖核酸酶，并且 pre-rRNA 加工途径相对明确。然而，最近低温电子显微镜的巨大进展使得能够捕获来自酿酒酵母（Saccharomyces cerevisiae）和人类细胞的各种前核糖体颗粒的结构快照，令人兴奋的是，这些结构不仅允许在切割事件前后观察 pre-rRNA，还能够在其靶 RNA 上可视化核糖核酸酶。这些 pre-rRNA 加工的结构视图使人们对 rRNA 成熟及其如何与核糖体组装的其他方面协调有了新的认识。它们阐明了涉及的各种核糖核酸酶的靶标识别机制，并揭示了这些酶的切割/加工活性如何受到调节。在这篇综述中，我们讨论了结构分析获得的 pre-rRNA 加工新见解以及对核糖核酸酶调节机制的理解的不断提高。本文属于以下分类：翻译 > 核糖体生物发生 RNA 处理 > rRNA 处理。
