We used ribosome profiling to characterize the biological role of ribosome recycling factor (RRF) in Escherichia coli. As expected, RRF depletion leads to enrichment of post-termination 70S complexes in 3′-UTRs. We also observe that elongating ribosomes are unable to complete translation because they are blocked by non-recycled ribosomes at stop codons. Previous studies have suggested a role for recycling in translational coupling within operons; if a ribosome remains bound to an mRNA after termination, it may re-initiate downstream. We found, however, that RRF depletion did not significantly affect coupling efficiency in reporter assays or in ribosome density genome-wide. These findings argue that re-initiation is not a major mechanism of translational coupling in E. coli. Finally, RRF depletion has dramatic effects on the activity of ribosome rescue factors tmRNA and ArfA. Our results provide a global view of the effects of the loss of ribosome recycling on protein synthesis in E. coli.

中文翻译：

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核糖体回收对于大肠杆菌中的翻译偶联并不重要

我们使用核糖体分析来表征核糖体再循环因子 (RRF) 在大肠杆菌中的生物学作用。正如预期的那样，RRF 消耗导致 3'-UTR 中终止后 70S 复合物的富集。我们还观察到延长的核糖体无法完成翻译，因为它们在终止密码子处被非循环核糖体阻断。先前的研究表明，再循环在操纵子内的翻译耦合中发挥作用。如果核糖体在终止后仍与 mRNA 结合，则它可能会重新启动下游。然而，我们发现，RRF 消耗并未显着影响报告基因检测或全基因组核糖体密度的耦合效率。这些发现表明，重新启动不是大肠杆菌翻译偶联的主要机制。最后，RRF 耗竭对核糖体拯救因子 tmRNA 和 ArfA 的活性有显着影响。我们的结果提供了关于核糖体循环丧失对大肠杆菌蛋白质合成影响的全局视图。