The speed of RNA transcription and metabolite binding kinetics operate an FMN riboswitch
The speed of RNA transcription and metabolite binding kinetics operate an FMN riboswitch
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DOI：
10.1016/j.molcel.2005.02.032
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发表时间：
2005-04-01
期刊：
影响因子：
16
通讯作者：
Crothers, DM
中科院分区：
文献类型：
--
作者：
Wickiser, JK;Winkler, WC;Crothers, DM
核糖开关是遗传控制元件，通常位于信使 RNA 的非翻译区域。这些折叠的 RNA 直接结合代谢物并发生调节基因表达的变构变化。来自枯草芽孢杆菌 ribDEAHT 操纵子的黄素单核苷酸 (FMN) 依赖性核糖开关使用转录终止机制，其中 RNA-FMN 复合物的形成导致内在终止子茎的形成。我们评估了 RNA 转录速度以及 FMN 与新生 mRNA 结合的动力学对于核糖开关功能的重要性。在 RNA 聚合酶需要在继续转录和转录终止之间做出选择之前，核糖开关不会与 FMN 达到热力学平衡。因此，这种核糖开关是动力学驱动的，其功能更像是“分子熔断器”。对于利用转录终止机制的核糖开关来说，这种对配体缔合动力学和 RNA 聚合速度的依赖可能很常见。
Riboswitches are genetic control elements that usually reside in untranslated regions of messenger RNAs. These folded RNAs directly bind metabolites and undergo allosteric changes that modulate gene expression. A flavin mononucleotide (FMN)-dependent riboswitch from the ribDEAHT operon of Bacillus subtilis uses a transcription termination mechanism wherein formation of an RNA-FMN complex causes formation of an intrinsic terminator stem. We assessed the importance of RNA transcription speed and the kinetics of FMN binding to the nascent mRNA for riboswitch function. The riboswitch does not attain thermodynamic equilibrium with FMN before RNA polymerase needs to make a choice between continued transcription and transcription termination. Therefore, this riboswitch is kinetically driven, and functions more like a "molecular fuse." This reliance on the kinetics of ligand association and RNA polymerization speed might be common for riboswitches that utilize transcription termination mechanisms.