Hfq binding changes the structure of Escherichia coli small noncoding RNAs OxyS and RprA, which are involved in the riboregulation of rpoS.
Hfq binding changes the structure of Escherichia coli small noncoding RNAs OxyS and RprA, which are involved in the riboregulation of rpoS.
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DOI：
10.1261/rna.034595.112
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发表时间：
2013-08
期刊：
影响因子：
--
通讯作者：
Callaghan AJ
中科院分区：
文献类型：
--
作者：
Henderson CA;Vincent HA;Casamento A;Stone CM;Phillips JO;Cary PD;Sobott F;Gowers DM;Taylor JEN;Callaghan AJ
大肠杆菌中许多小的非编码RNA需要RNA结合蛋白Hfq来发挥其调控功能。然而，Hfq所起的作用仍不清楚。本文使用多种生化和生物物理方法来表征Hfq在两种小rna的相反功能中的作用。OxyS和RprA是两个小的非编码rna (sRNAs)，它们调节rpoS的表达，编码一个可激活多种大肠杆菌应激反应基因转录的sigma因子。当RprA激活rpoS进行翻译时，OxyS下调转录本。至关重要的是，RNA结合蛋白Hfq是这两种sRNAs发挥功能所必需的，尽管Hfq所起的具体作用尚不清楚。我们利用生物化学和生物物理方法研究了RprA和OxyS与Hfq的相互作用。特别是，我们利用小角散射方法获得了Hfq-sRNA复合物的分子包膜，揭示了关键的分子细节。这些数据表明Hfq在复杂的形成过程中不会发生实质性的形状变化，而srna则会。我们将Hfq结合的影响和诱导的sRNA结构变化与RNase E降解的转录物稳定性联系起来。鉴于这些发现，我们讨论了Hfq在RprA和OxyS在rpoS调节中所起的相反调节功能中的作用。
Many small noncoding RNAs in E. coli require the RNA binding protein Hfq to exert their regulatory function. However, the role(s) played by Hfq remain unclear. This manuscript uses a variety of biochemical and biophysical approaches to characterize the role of Hfq in the opposing functions of two small RNAs. OxyS and RprA are two small noncoding RNAs (sRNAs) that modulate the expression of rpoS, encoding an alternative sigma factor that activates transcription of multiple Escherichia coli stress-response genes. While RprA activates rpoS for translation, OxyS down-regulates the transcript. Crucially, the RNA binding protein Hfq is required for both sRNAs to function, although the specific role played by Hfq remains unclear. We have investigated RprA and OxyS interactions with Hfq using biochemical and biophysical approaches. In particular, we have obtained the molecular envelopes of the Hfq–sRNA complexes using small-angle scattering methods, which reveal key molecular details. These data indicate that Hfq does not substantially change shape upon complex formation, whereas the sRNAs do. We link the impact of Hfq binding, and the sRNA structural changes induced, to transcript stability with respect to RNase E degradation. In light of these findings, we discuss the role of Hfq in the opposing regulatory functions played by RprA and OxyS in rpoS regulation.
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