Posttransscriptonal regulation of the nanos mRNA in Drosophila melanogaster

Nanos信使核糖核酸编码果蝇胚胎后端发育的关键决定因素。Nanos受到严格的转录后调控：非本地化的Nanos RNA是死烯化的，并在翻译上受到抑制。去烯化和阻遏都是由3‘UTR中Smaug(Smaug Response Elements，SRE)蛋白的结合位点控制的。定位于后极的Nanos RNA被奥斯卡激活。我们已经开发了一个无细胞系统，它可以复制依赖SRE的翻译抑制和去烯化以及由Oskar激活。我们发现，以SRE依赖的方式组装的抑制子复合体阻止了翻译的启动。抑制物复合体的组装很慢，需要三磷酸腺苷，而且复合体的动力学非常稳定。抑制子复合体包含Smaug和CCR4-非复合体，这是一种已知的死烯基酶。它还包含几种已知参与其他翻译抑制情况的蛋白质，特别是依赖RNA的ATPase Me31B。我们现在想分析依赖SRE的阻遏物复合体的组成，它导致翻译抑制和去烯化的机制，以及复合体的单个成分的作用。

The nanos mRNA encodes a key determinant for development of the posterior end of the Drosophila embryo. Nanos is under strict posttranscriptional control: Non-localized nanos RNA is deadenylated and translationally repressed. Both deadenylation and repression are governed by binding sites for the protein Smaug (Smaug response elements, SREs) in the 3' UTR. Nanos RNA localized at the posterior pole is activated by Oskar. We have developed a cell-free system that reproduces SRE-dependent translational repression and deadenylation as well as activation by Oskar. We have found that a repressor complex assembled in an SRE-dependent manner prevents the initiation of translation at the earliest detectable stage. Assembly of the repressor complex is slow and requires ATP, and the complex is kinetically unusually stable. The repressor complex contains Smaug and the CCR4-NOT complex, a known deadenylase. It also contains several proteins known to be involved in other cases of translational repression, in particular the RNA-dependent ATPase Me31B. We now want to analyze the composition of the SRE-dependent repressor complex, the mechanism by which it causes translational repression and deadenylation and the roles of individual components of the complex.