Riboswitches are RNA sensors that have been shown to modulate the expression of downstream genes by altering their structure upon metabolite binding. Riboswitches are unique among cellular regulators in that metabolite detection is strictly performed using RNA interactions with the sensed metabolite and in which no regulatory protein is needed to mediate the interaction. However, recent studies have shed light on riboswitch control mechanisms relying on protein regulators to harness metabolite binding for the mediation of gene expression, thereby increasing the range of cellular factors involved in riboswitch regulation. The interaction between riboswitches and proteins adds another level of evolutionary pressure as riboswitches must maintain key residues for metabolite detection, structural switching and protein binding sites. Here, we review regulatory mechanisms involving Escherichia coli riboswitches that have recently been shown to rely on regulatory proteins. We also discuss the implication of such protein-based riboswitch regulatory mechanisms for genetic regulation.

中文翻译：

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核糖开关调节机制：RNA，代谢产物和调节蛋白。

核糖开关是RNA传感器，已显示可通过在代谢物结合后改变下游基因的结构来调节下游基因的表达。核糖开关在细胞调节剂之间是独特的，因为代谢产物的检测必须使用与感测的代谢产物的RNA相互作用来严格进行，并且不需要调节蛋白来介导相互作用。然而，最近的研究揭示了依赖蛋白质调节剂的核糖开关控制机制利用代谢物结合来介导基因表达，从而增加了参与核糖开关调节的细胞因子的范围。核糖开关与蛋白质之间的相互作用增加了另一水平的进化压力，因为核糖开关必须维持用于代谢物检测，结构转换和蛋白质结合位点的关键残基。这里，我们回顾了涉及大肠杆菌核糖开关的调节机制，最近已证明它们依赖于调节蛋白。我们还讨论了这种基于蛋白质的核糖开关调控机制对遗传调控的影响。