Maintenance of Transcription-Translation Coupling by Elongation Factor P.
Maintenance of Transcription-Translation Coupling by Elongation Factor P.
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DOI：
10.1128/mbio.01373-16
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发表时间：
2016-09-13
期刊：
影响因子：
6.4
通讯作者：
Ibba M
中科院分区：
文献类型：
--
作者：
Elgamal S;Artsimovitch I;Ibba M
在翻译和转录之间紧密耦合的条件下，核糖体通过阻止内在终止子发夹的形成和转录终止因子Rho的加载来实现全长mRNA的合成。虽然以前的研究都集中在转录因子，我们研究了大肠杆菌延伸因子P（EF-P），有效翻译含有连续脯氨酸密码子的mRNA所需的延伸因子，在维持耦合的翻译和转录的作用。在缺乏EF-P的情况下，Rho利用（rut）位点的存在导致聚脯氨酸编码mRNA的翻译减少约30倍。Rho抑制剂Psu的共表达完全恢复了翻译。EF-P还显示在编码内在终止子的mRNA的合成和翻译期间抑制过早终止。EF-P损失对聚脯氨酸mRNA表达的影响通过RNA聚合酶中的取代而增强，所述取代加速转录。先前报道的核糖体分析和全球蛋白质组学数据的分析确定了几个候选基因簇，其中EF-P可以防止过早的转录终止。在体内探测允许检测一些预测的提前终止产品在EF-P的情况下。我们的研究结果支持一个模型，其中EF-P保持耦合的翻译和转录减少核糖体失速在聚脯氨酸基序。促进核糖体通过路障易位以防止解偶联后过早转录终止的其他调节剂仍有待鉴定。细菌的mRNA和蛋白质合成通常是紧密结合的，核糖体结合新合成的Shine-Dalgarno序列，然后翻译新生的mRNA，因为它们从RNA聚合酶中出现。虽然以前的研究主要集中在转录因子的作用，在这里，我们调查是否翻译因子也可以发挥作用，保持耦合和防止过早的转录终止。使用聚脯氨酸合成增强子延伸因子P，我们发现通过潜在的停滞基序快速翻译是提供核糖体和RNA聚合酶之间的有效偶联所必需的。这些发现表明，翻译增强子可以通过防止转录的过早终止在基因表达中发挥重要作用。
Under conditions of tight coupling between translation and transcription, the ribosome enables synthesis of full-length mRNAs by preventing both formation of intrinsic terminator hairpins and loading of the transcription termination factor Rho. While previous studies have focused on transcription factors, we investigated the role of Escherichia coli elongation factor P (EF-P), an elongation factor required for efficient translation of mRNAs containing consecutive proline codons, in maintaining coupled translation and transcription. In the absence of EF-P, the presence of Rho utilization (rut) sites led to an ~30-fold decrease in translation of polyproline-encoding mRNAs. Coexpression of the Rho inhibitor Psu fully restored translation. EF-P was also shown to inhibit premature termination during synthesis and translation of mRNAs encoding intrinsic terminators. The effects of EF-P loss on expression of polyproline mRNAs were augmented by a substitution in RNA polymerase that accelerates transcription. Analyses of previously reported ribosome profiling and global proteomic data identified several candidate gene clusters where EF-P could act to prevent premature transcription termination. In vivo probing allowed detection of some predicted premature termination products in the absence of EF-P. Our findings support a model in which EF-P maintains coupling of translation and transcription by decreasing ribosome stalling at polyproline motifs. Other regulators that facilitate ribosome translocation through roadblocks to prevent premature transcription termination upon uncoupling remain to be identified. Bacterial mRNA and protein syntheses are often tightly coupled, with ribosomes binding newly synthesized Shine-Dalgarno sequences and then translating nascent mRNAs as they emerge from RNA polymerase. While previous studies have mainly focused on the roles of transcription factors, here we investigated whether translation factors can also play a role in maintaining coupling and preventing premature transcription termination. Using the polyproline synthesis enhancer elongation factor P, we found that rapid translation through potential stalling motifs is required to provide efficient coupling between ribosomes and RNA polymerase. These findings show that translation enhancers can play an important role in gene expression by preventing premature termination of transcription.