Woolhead Cheryl A, Johnson Arthur E, Bernstein Harris D
Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
Mol Cell. 2006 Jun 9;22(5):587-98. doi: 10.1016/j.molcel.2006.05.021.
When the export of E. coli SecM is blocked, a 17 amino acid motif near the C terminus of the protein induces a translation arrest from within the ribosome tunnel. Here we used a recently described application of fluorescence resonance energy transfer (FRET) to gain insight into the mechanism of translation arrest. We found that the SecM C terminus adopted a compact conformation upon synthesis of the arrest motif. This conformational change did not occur spontaneously, but rather was induced by the ribosome. Translation arrest required both compaction of the SecM C terminus and the presence of key residues in the arrest motif. Further analysis showed that the arrested peptidyl-tRNA was resistant to puromycin treatment and revealed additional changes in the ribosome-nascent SecM complex. Based on these observations, we propose that translation arrest results from a series of reciprocal interactions between the ribosome and the C terminus of the nascent SecM polypeptide.
当大肠杆菌SecM的输出受阻时，该蛋白质C末端附近的一个17个氨基酸的基序会从核糖体隧道内部诱导翻译停滞。在这里，我们使用了最近描述的荧光共振能量转移（FRET）应用来深入了解翻译停滞的机制。我们发现，在停滞基序合成后，SecM的C末端采取了紧凑的构象。这种构象变化不是自发发生的，而是由核糖体诱导的。翻译停滞既需要SecM C末端的紧凑化，也需要停滞基序中关键残基的存在。进一步的分析表明，停滞的肽基-tRNA对嘌呤霉素处理具有抗性，并揭示了核糖体-新生SecM复合物中的其他变化。基于这些观察结果，我们提出翻译停滞是由核糖体与新生SecM多肽的C末端之间的一系列相互作用导致的。
