Erdman S E, Chen H J, Burtis K C
Section of Molecular and Cellular Biology, University of California, Davis 95616, USA.
Genetics. 1996 Dec;144(4):1639-52. doi: 10.1093/genetics/144.4.1639.
The doublesex (dsx) gene of Drosophila melanogaster encodes both male-specific (DSXM) and female-specific (DSXF) polypeptides, which are required for normal differentiation of numerous sexually dimorphic somatic traits. The DSX polypeptides are transcription factors and have been shown previously to bind through a zinc finger-like domain to specific sites in an enhancer regulating sex-specific expression of yolk protein genes. We have determined the consensus target sequence for this DNA binding domain to be a palindromic sequence AGNNACTAAATGTNNTC composed of two half-sites around a central (A/T) base pair. As predicted by the symmetric nature of this site, we have found that the DSX proteins exist as dimers in vivo and have mapped two independent dimerization domains by the yeast two-hybrid method; one in the non-sex-specific amino-terminal region of the protein and one that includes the partially sex-specific carboxy-terminal domains of both the male and female polypeptides. We have further identified a missense mutation that eliminates dsx function in female flies, and shown that the same mutation prevents dimerization of DSXF in the yeast two-hybrid system, indicating a critical role for dimerization in dsx function in vivo.
黑腹果蝇的双性基因（doublesex，dsx）编码雄性特异性（DSXM）和雌性特异性（DSXF）多肽，这些多肽是许多性二态性体细胞特征正常分化所必需的。DSX多肽是转录因子，先前已证明它们通过类似锌指的结构域与调控卵黄蛋白基因性别特异性表达的增强子中的特定位点结合。我们已确定该DNA结合结构域的共有靶序列为回文序列AGNNACTAAATGTNNTC，它由围绕中心（A/T）碱基对的两个半位点组成。正如该位点的对称性质所预测的那样，我们发现DSX蛋白在体内以二聚体形式存在，并通过酵母双杂交方法定位了两个独立的二聚化结构域；一个在蛋白的非性别特异性氨基末端区域，另一个包括雄性和雌性多肽的部分性别特异性羧基末端结构域。我们进一步鉴定了一个错义突变，该突变消除了雌性果蝇中的dsx功能，并表明相同的突变在酵母双杂交系统中阻止了DSXF的二聚化，这表明二聚化在dsx体内功能中起关键作用。
