Posttransscriptonal regulation of the nanos mRNA in Drosophila melanogaster

nanos mRNA编码果蝇胚胎后端发育的关键决定因素。Nanos处于严格的转录后控制之下：非定位的nanos RNA被去腺苷酸化并被抑制。去腺苷化和阻遏均由3' UTR中蛋白Smaug（Smaug应答元件，SRE）的结合位点控制。位于后极的Nanos RNA被Oskar激活。我们已经开发了一个无细胞系统，再现SRE依赖的翻译抑制和deadenylation以及激活奥斯卡。我们已经发现，一个阻遏物复合物组装在一个SRE依赖性的方式阻止翻译的起始在最早的可检测的阶段。阻遏物复合物的组装是缓慢的，需要ATP，并且复合物在动力学上异常稳定。阻遏物复合物含有Smaug和CCR 4-NOT复合物，一种已知的去腺苷酶。它还含有几种已知参与其他翻译抑制的蛋白质，特别是RNA依赖性ATP酶Me 31 B。我们现在想分析SRE依赖性阻遏物复合物的组成、它引起翻译阻遏和去腺苷化的机制以及复合物各个成分的作用。

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.