Analysis of a fushi tarazu autoregulatory element : multiple sequence elements contribute to enhancer activity

Regulatory sequences or factors involved in the regulation of target genes of Drosophila homeodomain proteins are largely unknown. Here, we identify sequence elements that are involved in the function of the fushi tarazu (ftz) autoregulatory element AE, a direct in vivo target of the homeodomain protein ftz. A systematic deletion analysis of AE in transgenic embryos defines multiple elements that are redundantly involved in enhancer activity. Sequences juxtaposed to ftz binding sites are not strictly required for enhancer function. Several sequence motifs are conserved in other developmentally regulated genes of Drosophila melanogaster and in the AE homologue of Drosophila virilis. The D. virilis AE is functional in D. melanogaster. The sequence motifs identified here are candidate elements contributing to the target specificity of the homeodomain protein ftz.