Nature2014-06-26 4:40 PM

线粒体核糖体的结构  Architecture of the large subunit of the mammalian mitochondrial ribosome

论文摘要 

通过有氧呼吸驱动真核细胞的线粒体源自原核生物,所含基因组要小得多,其基因组编码若干RNA分子和非常有限的一小类线粒体蛋白。哺乳动物细胞的线粒体核糖体的功能非常专一,是用于呼吸链的膜蛋白翻译的。Nenad Ban及同事通过低温电子显微镜以4.9 Å的分辨率获得了较大的39S线粒体核糖体亚单元的三维结构。他们的图像提供了关于这一核糖体内发生的相当大变化的详细信息,这些变化可能是为了帮助由线粒体基因组编码的非常憎水的蛋白的翻译的。

Abstract 

Mitochondrial ribosomes synthesize a number of highly hydrophobic proteins encoded on the genome of mitochondria, the organelles in eukaryotic cells that are responsible for energy conversion by oxidative phosphorylation. The ribosomes in mammalian mitochondria have undergone massive structural changes throughout their evolution, including ribosomal RNA shortening and acquisition of mitochondria-specific ribosomal proteins. Here we present the three-dimensional structure of the 39S large subunit of the porcine mitochondrial ribosome determined by cryo-electron microscopy at 4.9 Å resolution. The structure, combined with data from chemical crosslinking and mass spectrometry experiments, reveals the unique features of the 39S subunit at near-atomic resolution and provides detailed insight into the architecture of the polypeptide exit site. This region of the mitochondrial ribosome has been considerably remodelled compared to its bacterial counterpart, providing a specialized platform for the synthesis and membrane insertion of the highly hydrophobic protein components of the respiratory chain.

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