title: Replacement of a Drosophila Polycomb response element core, and in situ analysis of its DNA motifs.
abstract: Long-term repression of homeotic genes in the fruit fly is accomplished by proteins of the Polycomb Group, acting at Polycomb response elements (PREs). Here we use gene conversion to mutate specific DNA motifs within a PRE to test their relevance, and we exchange PREs to test their specificity. Previously we showed that removal of a 185 bp core sequence from the bithoraxoid PRE of the bithorax complex results in posteriorly directed segmental transformations. Mutating multiple binding sites for either the PHO or the GAF proteins separately in the core bithoraxoid PRE resulted in only rare and subtle transformations in adult flies. However, when both sets of sites were mutated, the transformations were similar in strength and penetrance to those caused by the deletion of the 185 bp core region. In contrast, mutating the singly occurring binding site of another DNA-binding protein, DSP1 (reportedly essential for PRE-activity), had no similar effect in combination with mutated PHO or GAF sites. Two minimal PREs from other segment-specific regulatory domains of the bithorax complex could substitute for the bithoraxoid PRE core. Our in situ analysis suggests that core PREs are interchangeable, and the cooperation between PHO and GAF binding sites is indispensable for silencing.
authors: Institute of Genetics, Biological Research Center of the Hungarian Academy of Sciences, Szeged 6701, Hungary.
authors: Gabriella
authors: G
authors: Kozma
authors: Welcome
authors: W
authors: Bender
authors: László
authors: L
authors: Sipos
mesh_terms: D000818:Animals; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000235:genetics; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000033:anatomy & histology / Q000235:genetics*; D005260:Female; D005785:Gene Conversion; D005801:Genes, Homeobox; D006609:High Mobility Group Proteins / Q000235:genetics; D006801:Humans; D009154:Mutation; D010641:Phenotype; D063150:Polycomb Repressive Complex 1; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins / Q000378:metabolism*; D020218:Response Elements; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; C104348:DSP1 protein, Drosophila; D029721:Drosophila Proteins; D006609:High Mobility Group Proteins; C066770:Pc protein, Drosophila; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C063460:Trl protein, Drosophila; C113295:pho protein, Drosophila; D063150:Polycomb Repressive Complex 1