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Nature:哺乳动物线粒体核糖体的结构

摘要 : Nenad Ban及同事通过低温电子显微镜以高分辨率(3.4 Å)获得了39S大线粒体核糖体亚单元的结构。他们还能确定50个核糖体蛋白、肽基转移酶中心、这一活性点内的tRNA、以及“出口隧道”(exit tunnel)内的新生肽链的位置。

 nature13895-f3

线粒体核糖体具有与胞质核糖体不同的RNA和蛋白组成。Nenad Ban及同事通过低温电子显微镜以高分辨率(3.4 Å)获得了39S大线粒体核糖体亚单元的结构。他们还能确定50个核糖体蛋白、肽基转移酶中心、这一活性点内的tRNA、以及“出口隧道”(exit tunnel)内的新生肽链的位置。这一核糖体亚单元的一个未曾料到的特征是,一个线粒体tRNA取代了 5S 核糖体RNA,后者在胞质大核糖体亚单元中起一个结构方面的作用。

原文摘要:

The complete structure of the large subunit of the mammalian mitochondrial ribosome

Basil J. Greber, Daniel Boehringer, Marc Leibundgut, Philipp Bieri, Alexander Leitner,Nikolaus Schmitz, Ruedi Aebersold & Nenad Ban

Mitochondrial ribosomes (mitoribosomes) are extensively modified ribosomes of bacterial descent specialized for the synthesis and insertion of membrane proteins that are critical for energy conversion and ATP production inside mitochondria1. Mammalian mitoribosomes, which comprise 39S and 28S subunits2, have diverged markedly from the bacterial ribosomes from which they are derived, rendering them unique compared to bacterial, eukaryotic cytosolic and fungal mitochondrial ribosomes3, 4, 5. We have previously determined at 4.9 Å resolution the architecture of the porcine (Sus scrofa) 39S subunit6, which is highly homologous to the human mitoribosomal large subunit. Here we present the complete atomic structure of the porcine 39S large mitoribosomal subunit determined in the context of a stalled translating mitoribosome at 3.4 Å resolution by cryo-electron microscopy and chemical crosslinking/mass spectrometry. The structure reveals the locations and the detailed folds of 50 mitoribosomal proteins, shows the highly conserved mitoribosomal peptidyl transferase active site in complex with its substrate transfer RNAs, and defines the path of the nascent chain in mammalian mitoribosomes along their idiosyncratic exit tunnel. Furthermore, we present evidence that a mitochondrial tRNA has become an integral component of the central protuberance of the 39S subunit wher it architecturally substitutes for the absence of the 5S ribosomal RNA, a ubiquitous component of all cytoplasmic ribosomes.(doi:10.1038/nature13895

对应Nature杂志: 2014年11月13日Nature杂志精选

来源: Nature中文 浏览次数:75

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