High-resolution mapping of DNase I-hypersensitive sites of Drosophila heat shock genes in Drosophila melanogaster and Saccharomyces cerevisiae.

High-resolution analysis of the chromatin structure of the promoter regions of five Drosophila heat shock genes showed a similar location for the hypersensitive sequences relative to the start of transcription. For each of the five genes examined--those coding for hsp27, hsp26, hsp23, hsp70, and hsp83--the DNase I-hypersensitive sites in Drosophila melanogaster nuclei mapped to two regions upstream of the coding region. These sites occurred on the average, 115 and 17 base pairs upstream from the start of transcription of the five heat shock genes examined. This latter site corresponded to sequences at or near the TATA consensus sequence. Sites even further upstream of the hsp27, hsp26, and hsp83 genes were also evident. Additionally, for the two genes examined--hsp70 and hsp83--the DNase I-hypersensitive sites were preserved, at least within this level of resolution (+/- 10 base pairs), when the Drosophila genes were integrated into the Saccharomyces cerevisiae genome. This result indicates that the signals responsible for generating these hypersensitive sites are inherent in the DNA sequences and, in this case, are not highly species specific.