Nilsson Jakob, Sengupta Jayati, Gursky Richard, Nissen Poul, Frank Joachim
Department of Molecular Biology, University of Aarhus, Gustav Wieds vej 10C, DK-8000 Aarhus C, Denmark.
J Mol Biol. 2007 Jun 1;369(2):429-38. doi: 10.1016/j.jmb.2007.03.035. Epub 2007 Mar 20.
Compared to the prokaryotic 70 S ribosome, the eukaryotic 80 S ribosome contains additional ribosomal proteins and extra segments of rRNA, referred to as rRNA expansion segments (ES). These eukaryotic-specific rRNA ES are mainly on the periphery of the 80 S ribosome, as revealed by cryo-electron microscopy (cryo-EM) studies, but their precise function is not known. To address the question of whether the rRNA ES are structurally conserved among 80 S ribosomes of different fungi we performed cryo-electron microscopy on 80 S ribosomes from the thermophilic fungus Thermomyces lanuginosus and compared it to the Saccharomyces cerevisiae 80 S ribosome. Our analysis reveals general structural conservation of the rRNA expansion segments but also changes in ES27 and ES7/39, as well as the absence of a tertiary interaction between ES3 and ES6 in T. lanuginosus. The differences provide a hint on the role of rRNA ES in regulating translation. Furthermore, we show that the stalk region and interactions with elongation factor 2 (eEF2) are different in T. lanuginosus, exhibiting a more extensive contact with domain I of eEF2.
与原核生物的70S核糖体相比，真核生物的80S核糖体含有额外的核糖体蛋白和rRNA的额外片段，称为rRNA扩展片段（ES）。冷冻电子显微镜（cryo-EM）研究表明，这些真核生物特有的rRNA ES主要位于80S核糖体的外围，但其确切功能尚不清楚。为了解决不同真菌的80S核糖体中rRNA ES在结构上是否保守的问题，我们对嗜热真菌嗜热栖热菌的80S核糖体进行了冷冻电子显微镜观察，并将其与酿酒酵母的80S核糖体进行了比较。我们的分析揭示了rRNA扩展片段的总体结构保守性，但也发现了ES27和ES7/39的变化，以及嗜热栖热菌中ES3和ES6之间不存在三级相互作用。这些差异为rRNA ES在调节翻译中的作用提供了线索。此外，我们表明嗜热栖热菌的柄区以及与延伸因子2（eEF2）的相互作用有所不同，与eEF2的结构域I表现出更广泛的接触。
