Bending of promoter DNA on binding of heat shock transcription factor

The Drosophila heat-shock transcription factor (HSTF) has been shown to bind to three domains of the heat shock protein 70 gene (hsp 70) control region. The most critical of these for transcriptional activation appears to be the one closest to the TATA-homology region. This domain, spanning sequences from -40 to -95, consists of two contiguous HSTF binding sites (sites 1 and 2) that are occupied in a cooperative manner (see Fig. 1). Recent alkylation interference and protection studies suggest a conformational change occurs in the protein-DNA complex at site 1 upon sequential HSTF binding at site 2 (ref. 5). We report here that HSTF binding to a single site or to both contiguous sites results in the introduction of a specific DNA bend within this domain of the hsp 70 promoter.