Inducible acetylation of HSF1 at Lys80 within the DNA binding domain results in the disrupted DNA-binding ability thus causing the regulated release of the HSF1 trimers from DNA (Westerheide SD et al. 2009). This acetylation is reversible. Activation of the deacetylase and longevity factor SIRT1 was shown to prolong HSF1 binding to the heat shock promoter of hsp70 gene by maintaining HSF1 in a deacetylated state (Westerheide SD et al. 2009). Thus, the balance between deacetylase activity of SIRT1 and acetyltransferase activity of p300 determine the DNA-binding competent state of HSF1.