Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, England, UK.
Science. 2019 Feb 15;363(6428):740-744. doi: 10.1126/science.aav9370.
During trans-translation, transfer-messenger RNA (tmRNA) and small protein B (SmpB) together rescue ribosomes stalled on a truncated mRNA and tag the nascent polypeptide for degradation. We used cryo-electron microscopy to determine the structures of three key states of the tmRNA-SmpB-ribosome complex during trans translation at resolutions of 3.7 to 4.4 angstroms. The results show how tmRNA and SmpB act specifically on stalled ribosomes and how the circularized complex moves through the ribosome, enabling translation to switch from the old defective message to the reading frame on tmRNA.
在转译过程中，转移信使 RNA（tmRNA）和小蛋白 B（SmpB）共同拯救在截短的 mRNA 上停滞的核糖体，并标记新生多肽进行降解。我们使用冷冻电子显微镜在 3.7 到 4.4 埃的分辨率下确定了 tmRNA-SmpB-核糖体复合物在转译过程中的三个关键状态的结构。结果表明 tmRNA 和 SmpB 如何特异性地作用于停滞的核糖体，以及环状复合物如何在核糖体上移动，从而使翻译从旧的有缺陷的消息切换到 tmRNA 上的阅读框。
