Basal-level expression of the yeast HSP82 gene requires a heat shock regulatory element

Previous studies have shown that heat shock factor is constitutively bound to heat shock elements in Saccharomyces cerevisiae. We demonstrate that mutation of the heat shock element closest to the TATA box of the yeast HSP82 promoter abolishes basal-level transcription without markedly affecting inducibility. The mutated heat shock element no longer bound putative heat shock factor, either in vitro or in vivo, but still resided within a nuclease-hypersensitive site in the chromatin. Thus, constitutive binding of heat shock factor to heat shock elements in S. cerevisiae appears to functionally direct basal-level transcription.