The capacity to form H-DNA cannot substitute for GAGA factor binding to a (CT)n*(GA)n regulatory site.
Previous studies of the Drosophila melanogaster hsp26 gene promoter have demonstrated the importance of a homopurine*homopyrimidine segment [primarily (CT)n*(GA)n] for chromatin structure formation and gene activation. (CT)n regions are known to bind GAGA factor, a dominant enhancer of PEV thought to play a role in generating an accessible chromatin structure. The (CT)n region can also form an H-DNA structure in vitro under acidic pH and negative supercoiling; a detailed map of that structure is reported here. To test whether the (CT)n sequence can function through H-DNA in vivo, we have analyzed a series of hsp26-lacZ transgenes with altered sequences in this region. The results indicate that a 25 bp mirror repeat within the homopurine.homopyrimidine region, while adequate for H-DNA formation, is neither necessary nor sufficient for positive regulation of hsp26 when GAGA factor-binding sites have been eliminated. The ability to form H-DNA cannot substitute for GAGA factor binding to the (CT)n sequence.
Lu
Quinn
Q
Department of Biology, Washington University, St Louis, MO 63130, USA.
Teare
John M
JM
Granok
Howard
H
Swede
Marci J
MJ
Xu
Jenny
J
Elgin
Sarah C R
SC
D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D004247:DNA / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins; D018900:Dinucleotide Repeats / Q000235:genetics*; D029721:Drosophila Proteins; D005260:Female; D006360:Heat-Shock Proteins / Q000235:genetics; D018398:Homeodomain Proteins / Q000378:metabolism*; D007763:Lac Operon / Q000235:genetics; D008297:Male; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009154:Mutation; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D014157:Transcription Factors / Q000378:metabolism*
D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D006360:Heat-Shock Proteins; D018398:Homeodomain Proteins; D009841:Oligonucleotides; D014157:Transcription Factors; C063460:Trl protein, Drosophila; C051802:triplex DNA; D004247:DNA