Transcriptional control of Drosophila bicoid by Serendipity delta: cooperative binding sites, promoter context, and co-evolution.
Concentration of maternal BICOID (BCD) establishes the anterior pattern in the Drosophila embryo. Successive deletions in the bcd promoter allowed us to localize an enhancer sequence in the 5'-UTR and a down-regulating element downstream of the ATG initiator codon, and identify a 49 bp region sufficient to drive transcription of a reporter gene specifically in nurse cells. This fragment contains two binding sites for the Serendipity (Sry) d zinc finger activator, that mediate its cooperative binding. Both sites (sdbs) are essential for bcd expression. Further analysis showed that the bcd promoter configuration is decisive for Sry d activating function. Replacement of sdbs by binding sites for Sry b, the Sry d paralog, restores bcd transcription in sry d mutant ovaries, demonstrating that the functional divergence between these two proteins during evolution was mainly driven by changes in their DNA-specific recognition properties, resulting in the control of separate developmental pathways.
Ruez
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Centre de Biologie du Développement, UMR 5547 CNRS/UPS, Bat 4R3, 118 route de Narbonne, 31062, Toulouse cedex 4, France.
Payre
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Vincent
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D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D001665:Binding Sites; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics*; D004742:Enhancer Elements, Genetic; D019143:Evolution, Molecular; D005260:Female; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000096:biosynthesis* / Q000235:genetics; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010053:Ovary / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D015534:Trans-Activators / Q000096:biosynthesis* / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic
D029721:Drosophila Proteins; D018398:Homeodomain Proteins; C115207:Sry-beta protein, Drosophila; C090567:Sry-delta protein, Drosophila; D015534:Trans-Activators; D014157:Transcription Factors; C056478:bcd protein, Drosophila; D004247:DNA