Three protein binding sites form an enhancer that regulates sex- and fat body-specific transcription of Drosophila yolk protein genes.
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.
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Department of Biochemistry, Brandeis University, Waltham, MA 02254-9110, USA.
Wensink
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D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D022762:CCAAT-Enhancer-Binding Proteins; D004247:DNA / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics; D004527:Egg Proteins / Q000235:genetics*; D004742:Enhancer Elements, Genetic / Q000235:genetics*; D005216:Fat Body / Q000502:physiology; D005260:Female; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D017344:Genes, Insect / Q000235:genetics; D018095:Germ-Line Mutation / Q000502:physiology; D007301:Insect Hormones / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D012097:Repressor Proteins / Q000378:metabolism; D012733:Sex Differentiation / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics*
D022762:CCAAT-Enhancer-Binding Proteins; D004268:DNA-Binding Proteins; C070369:DSX protein, Drosophila; D029721:Drosophila Proteins; D004527:Egg Proteins; D007301:Insect Hormones; D012097:Repressor Proteins; D014157:Transcription Factors; C077246:slbo protein, Drosophila; D004247:DNA