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Dynamic pathways of-1 translational frameshifting

机译：1个平移移码的动态途径

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摘要

Spontaneous changes in the reading frame of translation are rare (frequency of 10~(-3) to 10~(-4) per codon), but can be induced by specific features in the messenger RNA (mRNA). In the presence of mRNA secondary structures, a heptanucleotide 'slippery sequence' usually defined by the motif X XXY YYZ, and (in some prokaryotic cases) mRNA sequences that base pair with the 3' end of the 16S ribosomal rRNA (internal Shine-Dalgarno sequences), there is an increased probability that a specific programmed change of frame occurs, wherein the ribosome shifts one nucleotide backwards into an overlapping reading frame (- 1 frame) and continues by translating a new sequence of amino acids. Despite extensive biochemical and genetic studies, there is no clear mechanistic description for frameshifting. Here we apply single-molecule fluorescence to track the compositional and conformational dynamics of individual ribosomes at each codon during translation of a frameshift-inducing mRNA from the dnaX gene in Escherichia coli Ribosomes that frameshift into the -1 frame are characterized by a tenfold longer pause in elongation compared to non-frameshifted ribosomes, which translate through unperturbed. During the pause, interactions of the ribosome with the mRNA stimulatory elements uncouple EF-G catalysed translocation from normal ribosomal subunit reverse-rotation, leaving the ribosome in a non-canonical intersubunit rotated state with an exposed codon in the aminoacyl-tRNA site (A site). tRNA~(Lys) sampling and accommodation to the empty A site and EF-G action either leads to the slippage of the tRNAs into the - 1 frame or maintains the ribosome into the 0 frame. Our results provide a general mechanistic and conformational framework for - 1 frameshifting, highlighting multiple kinetic branchpoints during elongation.
机译：翻译阅读框的自发变化很少（每个密码子10〜（-3）至10〜（-4）的频率），但可以由信使RNA（mRNA）中的特定特征诱导。在存在mRNA二级结构的情况下，通常由基序X XXY YYZ定义的七核苷酸“滑序列”，以及（在某些原核细胞中）与16S核糖体rRNA 3'末端碱基配对的mRNA序列（内部Shine-Dalgarno序列），发生特定的程序化框架变化的可能性增加，其中核糖体将一个核苷酸向后移动到重叠的阅读框架（-1框架）中，并通过翻译新的氨基酸序列继续进行。尽管进行了广泛的生化和遗传研究，但对于移框没有明确的机理描述。在这里，我们应用单分子荧光来追踪大肠杆菌核糖体中dnaX基因的移码诱导mRNA的翻译过程中，移入-1帧的特征在于每个密码子的核糖体在每个密码子的组成和构象动力学，其特征是移码时间延长了十倍与未移码的核糖体相比，其延伸率不受干扰。在暂停期间，核糖体与mRNA刺激元件的相互作用将EF-G催化的易位与正常核糖体亚基反向旋转解偶联，使核糖体处于非规范亚基旋转状态，并在氨酰基tRNA位点暴露了密码子（A现场）。 tRNA〜（Lys）采样并适应空的A位点和EF-G作用要么导致tRNA滑入-1帧，要么将核糖体保持在0帧。我们的结果为-1移码提供了一个通用的机械和构象框架，突出了延伸过程中的多个动力学分支点。

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  • 来源
    《Nature》 |2014年第7514期|328-332|共5页
  • 作者

    Jin Chen; Alexey Petrov; Magnus Johansson; Albert Tsai; Sean E. OLeary; Joseph D. Puglisi;

  • 作者单位

    Department of Applied Physics, Stanford University, Stanford, California 94305-4090, USA,Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305-5126, USA;

    Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305-5126, USA;

    Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305-5126, USA;

    Department of Applied Physics, Stanford University, Stanford, California 94305-4090, USA,Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305-5126, USA;

    Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305-5126, USA;

    Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305-5126, USA;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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