Department of Cell Biology and Physiology, Washington University School of Medicine, 600 South Euclid Avenue, Campus Box 8228, St. Louis, MO, 63110, USA.
Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, 94305-5126, USA.
Nat Commun. 2019 Dec 18;10(1):5774. doi: 10.1038/s41467-019-13810-1.
Translation initiation is a major rate-limiting step for protein synthesis. However, recent studies strongly suggest that the efficiency of protein synthesis is additionally regulated by multiple factors that impact the elongation phase. To assess the influence of early elongation on protein synthesis, we employed a library of more than 250,000 reporters combined with in vitro and in vivo protein expression assays. Here we report that the identity of the amino acids encoded by codons 3 to 5 impact protein yield. This effect is independent of tRNA abundance, translation initiation efficiency, or overall mRNA structure. Single-molecule measurements of translation kinetics revealed pausing of the ribosome and aborted protein synthesis on codons 4 and 5 of distinct amino acid and nucleotide compositions. Finally, introduction of preferred sequence motifs only at specific codon positions improves protein synthesis efficiency for recombinant proteins. Collectively, our data underscore the critical role of early elongation events in translational control of gene expression.
翻译起始是蛋白质合成的主要限速步骤。然而，最近的研究强烈表明，蛋白质合成的效率还受到多种因素的调节，这些因素影响延伸阶段。为了评估早期延伸对蛋白质合成的影响，我们使用了一个由超过 250000 个报告基因组成的文库，结合体外和体内蛋白质表达测定。在这里，我们报告说密码子 3 到 5 编码的氨基酸的身份影响蛋白质产量。这种效应不依赖于 tRNA 丰度、翻译起始效率或整体 mRNA 结构。翻译动力学的单分子测量显示，核糖体在不同氨基酸和核苷酸组成的密码子 4 和 5 处暂停，并中止蛋白质合成。最后，仅在特定密码子位置引入优选序列基序可提高重组蛋白的蛋白质合成效率。总的来说，我们的数据强调了早期延伸事件在基因表达的翻译调控中的关键作用。
