An W, Wensink P C
Department of Biochemistry, Brandeis University, Waltham, MA 02254-9110, USA.
EMBO J. 1995 Mar 15;14(6):1221-30. doi: 10.1002/j.1460-2075.1995.tb07105.x.
Transcription of the Drosophila yolk protein (Yp) genes is regulated by the somatic sex determination pathway. A gene at the bottom of this pathway, doublesex, encodes the female-specific DSXF and male-specific DSXM proteins that bind to and regulate transcription from several sites in the Yp genes. We report site-directed mutagenesis, protein binding and germline transformation experiments that identify and characterize the activity of a single binding site (dsxA) for the doublesex proteins and two binding sites for other regulatory proteins. A single copy of the three sites is sufficient to direct the sex and fat body specificities of Yp transcription. The sites form an enhancer with two strongly synergistic enhancer elements. One element (22 bp) consists of dsxA and an overlapping site, bzip1, that binds the DmC/EBP (slbo) protein, a member of the bZIP family of transcriptional activators. The other element is an 11 bp binding site (ref1) for an unknown protein. Tissue-specific activation requires strong cooperation between the ref1 site and the bzip1 or dsxA sites. Sex specificity is regulated exclusively by the dsxA site which connects the sex determination pathway to the target gene through DSXM repression and DSXF activation.
果蝇卵黄蛋白（Yp）基因的转录受体细胞性别决定途径调控。该途径底部的一个基因——双性基因，编码雌性特异性的DSXF和雄性特异性的DSXM蛋白，它们与Yp基因中的多个位点结合并调控转录。我们报告了定点诱变、蛋白质结合和种系转化实验，这些实验鉴定并表征了双性蛋白的单个结合位点（dsxA）以及其他调控蛋白的两个结合位点的活性。这三个位点的单拷贝足以指导Yp转录的性别和脂肪体特异性。这些位点形成了一个具有两个强协同增强子元件的增强子。一个元件（22 bp）由dsxA和一个重叠位点bzip1组成，bzip1可结合DmC/EBP（slbo）蛋白，它是转录激活因子bZIP家族的成员。另一个元件是一个11 bp的未知蛋白结合位点（ref1）。组织特异性激活需要ref1位点与bzip1或dsxA位点之间的强协同作用。性别特异性仅由dsxA位点调控，该位点通过DSXM抑制和DSXF激活将性别决定途径与靶基因连接起来。
