Temperature-controlled structural alterations of an RNA thermometer
Temperature-controlled structural alterations of an RNA thermometer
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DOI：
10.1074/jbc.m306874200
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发表时间：
2003-11-28
影响因子：
4.8
通讯作者：
Narberhaus, F
中科院分区：
文献类型：
--
作者：
Chowdhury, S;Ragaz, C;Narberhaus, F
已知mRNA的5 '-非翻译区中的温度响应结构控制热休克和毒力基因的翻译。许多根瘤菌热激基因的表达受一个保守序列元件ROSE的调控，该元件抑制热激基因的表达。这种顺式作用的非翻译mRNA被认为可以通过延伸的二级结构在低温下阻止核糖体进入，当温度升高时，二级结构部分融化。我们通过一系列体内和体外方法表明，ROSE是一种敏感的温度计，在30至40 ℃的生理相关温度范围内响应。预测破坏碱基配对的点突变在30 ℃下增强表达。补偿性突变恢复了阻遏，强调了感觉RNA二级结构的重要性。只有5 '-截短的ROSE变体的适度诱导表明个体茎环之间的相互作用协调温度传感。在互补寡核苷酸的存在下，ROSE的功能重要的茎环在热休克温度下对RNase H处理敏感。由于在UV和CD光谱中没有观察到主要的结构重排，因此建议涉及Shine-Dalgarno序列的细微结构变化介导翻译控制。感觉RNA的温度感知是一个有序的过程，很可能在没有辅助因子的帮助下发生。
Thermoresponsive structures in the 5'-untranslated region of mRNA are known to control translation of heat shock and virulence genes. Expression of many rhizobial heat shock genes is regulated by a conserved sequence element called ROSE for repression of heat shock gene expression. This cis-acting, untranslated mRNA is thought to prevent ribosome access at low temperature through an extended secondary structure, which partially melts when the temperature rises. We show here by a series of in vivo and in vitro approaches that ROSE is a sensitive thermometer responding in the physiologically relevant temperature range between 30 and 40 degreesC. Point mutations predicted to disrupt base pairing enhanced expression at 30 degreesC. Compensatory mutations restored repression, emphasizing the importance of secondary structures in the sensory RNA. Only moderate inducibility of a 5'-truncated ROSE variant suggests that interactions between individual stem loops coordinate temperature sensing. In the presence of a complementary oligonucleotide, the functionally important stem loop of ROSE was rendered susceptible to RNase H treatment at heat shock temperatures. Since major structural rearrangements were not observed during UV and CD spectroscopy, subtle structural changes involving the Shine-Dalgarno sequence are proposed to mediate translational control. Temperature perception by the sensory RNA is an ordered process that most likely occurs without the aid of accessory factors.