Evolution of hsp70 gene expression: a role for changes in AT-richness within promoters.
Evolution of hsp70 gene expression: a role for changes in AT-richness within promoters.
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Hsp70 基因表达的进化：启动子内 AT 丰富度变化的作用
DOI：
10.1371/journal.pone.0020308
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发表时间：
2011
期刊：
影响因子：
3.7
通讯作者：
Kang L
中科院分区：
文献类型：
--
作者：
Chen B;Jia T;Ma R;Zhang B;Kang L
在不同的生物体中，对热应激的适应与编码热休克蛋白（Hsp）的基因表达的变化有关。然而，潜在的遗传学仍然难以捉摸。在这里，我们表明，两个AT丰富的序列元件在启动子区的热休克蛋白70基因的苍蝇美洲斑潜蝇，是不存在的同类物种，南美斑潜蝇，具有显着的顺式调节的后果。我们研究了顺式调节的后果，这些元素（称为ATRS1和ATRS2）通过测量组成和热休克诱导的荧光素酶发光，他们驱动的细胞转染的构建体携带他们修改，删除，或完整的，在hsp70启动子融合到荧光素酶基因。元件影响表达水平显着，并以不同的方式：删除ATRS1增强的组成和热休克诱导的发光，这表明该元件抑制转录。有趣的是，用相同长度和A+T含量的随机序列替换该元素，获得了野生型发光模式，证明该元素的高A+T含量对其效应至关重要。删除ATRS2显着降低发光和几乎取消热休克诱导，所以没有取代的元素与随机序列匹配的元素的长度和A+T的内容，这表明ATRS2的转录和热休克诱导的影响涉及一个共同的机制，需要至少部分元素的特定的一级结构。最后，组成和热休克发光强烈减少时，两个假定的结合位点的Zeste转录因子内确定的ATRS 2通过定点突变改变，热休克诱导的发光增加时，Zeste过度表达，表明Zeste参与的影响映射到ATRS 2至少部分。富含AT的序列在启动子中很常见，我们的研究结果表明，它们应该在调控进化中发挥重要作用，因为它们可以显着影响表达，并以至少两种不同的方式限制启动子DNA。
In disparate organisms adaptation to thermal stress has been linked to changes in the expression of genes encoding heat-shock proteins (Hsp). The underlying genetics, however, remain elusive. We show here that two AT-rich sequence elements in the promoter region of the hsp70 gene of the fly Liriomyza sativae that are absent in the congeneric species, Liriomyza huidobrensis, have marked cis-regulatory consequences. We studied the cis-regulatory consequences of these elements (called ATRS1 and ATRS2) by measuring the constitutive and heat-shock-induced luciferase luminescence that they drive in cells transfected with constructs carrying them modified, deleted, or intact, in the hsp70 promoter fused to the luciferase gene. The elements affected expression level markedly and in different ways: Deleting ATRS1 augmented both the constitutive and the heat-shock-induced luminescence, suggesting that this element represses transcription. Interestingly, replacing the element with random sequences of the same length and A+T content delivered the wild-type luminescence pattern, proving that the element's high A+T content is crucial for its effects. Deleting ATRS2 decreased luminescence dramatically and almost abolished heat-shock inducibility and so did replacing the element with random sequences matching the element's length and A+T content, suggesting that ATRS2's effects on transcription and heat-shock inducibility involve a common mechanism requiring at least in part the element's specific primary structure. Finally, constitutive and heat-shock luminescence were reduced strongly when two putative binding sites for the Zeste transcription factor identified within ATRS2 were altered through site-directed mutagenesis, and the heat-shock-induced luminescence increased when Zeste was over-expressed, indicating that Zeste participates in the effects mapped to ATRS2 at least in part. AT-rich sequences are common in promoters and our results suggest that they should play important roles in regulatory evolution since they can affect expression markedly and constrain promoter DNA in at least two different ways.
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