Heat shock factor (HSF) is a transcriptional activator of heat shock genes [ (PUBMED:2257625) (PUBMED:19864465) ]: it binds specifically to heat shock promoter elements, which are palindromic sequences rich with repetitive purine and pyrimidine motifs [ (PUBMED:2257625) ]. Under normal conditions, HSF is a homo-trimeric cytoplasmic protein, but heat shock activation results in relocalisation to the nucleus [ (PUBMED:1871105) ]. Each HSF monomer contains one C-terminal and three N-terminal leucine zipper repeats [ (PUBMED:1871106) ]. Point mutations in these regions result in disruption of cellular localisation, rendering the protein constitutively nuclear [ (PUBMED:1871105) ]. Two sequences flanking the N-terminal zippers fit the consensus of a bi- partite nuclear localisation signal (NLS). Interaction between the N- and C-terminal zippers may result in a structure that masks the NLS sequences: following activation of HSF, these may then be unmasked, resulting in relocalisation of the protein to the nucleus [ (PUBMED:1871106) ]. The DNA-binding component of HSF lies to the N terminus of the first NLS region, and is referred to as the HSF domain.
GO process:
regulation of transcription, DNA-templated (GO:0006355)
GO function:
DNA-binding transcription factor activity (GO:0003700), sequence-specific DNA binding (GO:0043565)
Family alignment:
There are 10788 HSF domains in 10729 proteins in SMART's nrdb database.
Click on the following links for more information.
Evolution (species in which this domain is found)
Taxonomic distribution of proteins containing HSF domain.
This tree includes only several representative species. The complete taxonomic breakdown of all proteins with HSF domain is also avaliable.
Click on the protein counts, or double click on taxonomic names to display all proteins containing HSF domain in the selected taxonomic class.
Cellular role (predicted cellular role)
Binding / catalysis: DNA-binding
Literature (relevant references for this domain)
Primary literature is listed below; Automatically-derived, secondary literature is also avaliable.
Crystal structure of the DNA binding domain of the heat shock transcription factor.
Science. 1994; 263: 224-7
Display abstract
The structure of the DNA binding domain, determined at 1.8 angstrom resolution, contains a three-helix bundle that is capped by a four-stranded antiparallel beta sheet. This structure is a variant of the helix-turn-helix motif, typified by catabolite activator protein. In the heat shock transcription factor, the first helix of the motif (alpha 2) has an alpha-helical bulge and a proline-induced kink. The angle between the two helices of the motif (alpha 2 and alpha 3) is about 20 degrees smaller than the average for canonical helix-turn-helix proteins. Nevertheless, the relative positions of the first and third helices of the bundle (alpha 1 and alpha 3) are conserved. It is proposed here that the first helix of the three-helix bundle be considered a component of the helix-turn-helix motif.
This information is based on mapping of SMART genomic protein database to KEGG orthologous groups. Percentage points are related to the number of proteins with HSF domain which could be assigned to a KEGG orthologous group, and not all proteins containing HSF domain. Please note that proteins can be included in multiple pathways, ie. the numbers above will not always add up to 100%.
