Stress induction of HSP30, the plasma membrane heat shock protein gene of Saccharomyces cerevisiae, appears not to use known stress-regulated transcription factors

More than one transcription factor contributes to the Saccharomyces cerevis iae heat shock response. Many genes are induced through the activation of h eat shock factor (Hsf1), a protein that is constitutively bound to heat sho ck promoter elements (HSEs). Other genes are switched on by Msn2/Msn4-depen dent activation of a quite separate promoter element (the stress response e lement, STRE). While Hsf1 directs gene activation mainly in response to hea t stress, STRE-directed transcription is stimulated not only by heat but al so by several other stresses, starvation included. HSP30, encoding the plas ma membrane heat shock protein, is shown in this study to be activated by s everal stresses. It is most strongly induced with heat shock, ethanol and w eak organic acid exposure. The HSP30 promoter has no good agreement to the HSE consensus and its stress activation is unaffected by a mutation (hsf1-m 3) that causes defective heat shock activation of Hsf1-dependent genes. Act ivation of HSP30 occurs with some, but not all, STRE-inducing stresses and is largely unaffected either by loss of the Msn2/Msn4 transcription factors or with mutation of all STRE-like consensus sequences of the promoter. Str ess activation of HSP30 appears therefore to involve as yet unidentified co mponents of the yeast transcriptional apparatus.