The Drosophila hairy RNA localization signal modulates the kinetics of cytoplasmic mRNA transport
The Drosophila hairy RNA localization signal modulates the kinetics of cytoplasmic mRNA transport
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DOI：
10.1093/emboj/cdg230
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发表时间：
2003-05-15
期刊：
影响因子：
11.4
通讯作者：
Ish-Horowicz, D
中科院分区：
文献类型：
--
作者：
Bullock, SL;Zicha, D;Ish-Horowicz, D
在几种果蝇细胞类型中，mRNA的运输依赖于微管、分子马达动力蛋白和反式作用因子，包括平等主义者和双尾-D。然而，转录本识别的定位机制的分子基础是知之甚少。在这里，我们的特点毛配对规则RNA转录介导其顶端定位，使用体内注射荧光标记的mRNA到合胞胚盘胚胎的功能。我们表明，在3 '-非翻译区的121个核苷酸的元素是必要的，足以介导顶端运输。该信号包括两个基本的茎环结构，其中双链茎对于定位至关重要。茎内的碱基对身份不是必需的，但可以有助于本地化的效率，这表明特异性是由高阶结构介导的。使用延时显微镜，我们测量的动力学的本地化，并显示受损的本地化的突变信号是由于延迟形成的主动电机复合体，出乎意料的是，以较慢的运动。这些发现，以及共同注射野生型和突变型RNA的发现，表明分子马达的效率受到其货物特征的调节。
In several Drosophila cell types, mRNA transport depends on microtubules, the molecular motor dynein and trans-acting factors including Egalitarian and Bicaudal-D. However, the molecular basis of transcript recognition by the localization machinery is poorly understood. Here, we characterize the features of hairy pair-rule RNA transcripts that mediate their apical localization, using in vivo injection of fluorescently labelled mRNAs into syncytial blastoderm embryos. We show that a 121-nucleotide element within the 3'-untranslated region is necessary and sufficient to mediate apical transport. The signal comprises two essential stem-loop structures, in which double-stranded stems are crucial for localization. Base-pair identities within the stems are not essential, but can contribute to the efficiency of localization, suggesting that specificity is mediated by higher-order structure. Using time-lapse microscopy, we measure the kinetics of localization and show that impaired localization of mutant signals is due to delayed formation of active motor complexes and, unexpectedly, to slower movement. These findings, and those from co-injecting wild-type and mutant RNAs, suggest that the efficiency of molecular motors is modulated by the character of their cargoes.