Diversity in DNA recognition by heat shock transcription factors (HSFs) from model organisms

Heat shock transcription factor (HSF), an evolutionarily conserved heat-responsive regulator, binds to heat shock elements (HSEs) comprising continuous inverted repeats of the pentamer nGAAn. Here, we analyzed DNA-binding ability, particularly for the discontinuously arranged nGAAn units, of HSFs from various organisms, including Arabidopsis thaliana, Caenorhabditis elegans, Drosophila melanogaster, and Danio rerio. Among these, only C. elegans HSF failed to bind the discontinuous nGAAn units, which suggests that the target genes of HSFs in many, but not all, organisms contain discontinuous HSEs, as well as continuous HSEs. Further analysis of alternatively spliced HSF isoforms showed the importance of the C-terminal region in HSF-HSE interaction.