smaug protein represses translation of unlocalized nanos mRNA in the Drosophila embryo.
smaug protein represses translation of unlocalized nanos mRNA in the Drosophila embryo.
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DOI：
10.1101/gad.10.20.2600
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发表时间：
1996-10
影响因子：
10.5
通讯作者：
Ciaig A. Smibert;Joan E. Wilson;K. Kerr;P. Macdonald
中科院分区：
文献类型：
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作者：
Ciaig A. Smibert;Joan E. Wilson;K. Kerr;P. Macdonald
nanos mRNA编码果蝇后体图案决定簇的局部成分，通常仅在胚胎的后极翻译，在那里mRNA集中。在这里，我们确定了两个类似的顺式作用序列在nanos mRNA 3'非翻译区，介导翻译抑制。这些序列结合135 kD的胚胎蛋白，smaug，我们把它们称为smaug识别元件（SRE）。SRE中的点突变的分析揭示了Smaug结合和翻译抑制之间的强相关性;不能在体外结合Smaug的突变体在体内不被抑制，而结合Smaug的突变体仍然被抑制。这些结果有力地表明，smaug在翻译抑制未定位的nanos mRNA中起作用。翻译抑制是必不可少的，因为表达具有突变的SRE的nanos mRNA的胚胎发育时具有前体图案缺陷并死亡，尽管RNA正确定位。
nanos mRNA, which encodes the localized component of the Drosophila posterior body patterning determinant, is normally translated only at the posterior pole of the embryo, where the mRNA is concentrated. Here we identify two similar cis-acting sequences in the nanos mRNA 3' untranslated region that mediate translational repression. These sequences bind an embryonic protein of 135 kD, smaug, and we refer to them as smaug recognition elements (SREs). Analysis of point mutations in the SREs reveals a strong correlation between smaug binding and translational repression; mutants unable to bind smaug in vitro are not repressed translationally in vivo, whereas mutants that do bind smaug remain repressed translationally. These results strongly suggest that smaug acts in translational repression of unlocalized nanos mRNA. Translational repression is essential, as embryos expressing a nanos mRNA with mutated SREs develop with anterior body patterning defects and die, despite correct localization of the RNA.