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HSF-type DNA-binding
Heat shock factor 3HTS.png
Structure of the dimeric DNA binding domain of the yeast heat shock factor (cyan and green) bound to DNA (brown) based on PDB 3HTS.
Identifiers
Symbol HSF_DNA-bind
Pfam PF00447
InterPro IPR000232
PROSITE PDOC00381
SCOP 1hks
Vertebrate heat shock transcription factor
Identifiers
Symbol Vert_HS_TF
Pfam PF06546
InterPro IPR010542

Heat shock factor (HSF), in molecular biology, is the name given to transcription factors that regulate the expression of the heat shock proteins.[1][2] A typical example is the heat shock factor of Drosophila melanogaster.[3]

Contents

Function

Heat shock factors (HSF) are transcriptional activators of heat shock genes.[3] They bind specifically to heat shock promoter elements, which are palindromic sequences rich with repetitive purine and pyrimidine motifs.[3] Under normal conditions, HSF is a homo-trimeric cytoplasmic protein, but heat shock activation results in relocalisation to the nucleus.[4]

Heat shock factor 1 (HSF-1) is the major regulator of heat shock protein transcription in eukaryotes. In the absence of cellular stress, HSF-1 is inhibited by association with heat shock proteins and is therefore not active. Cellular stresses, such as increased temperature, can cause proteins in the cell to misfold. Heat shock proteins bind to the misfolded proteins and dissociate from HSF-1. This allows HSF1 to form trimers and translocate to the cell nucleus and activate transcription.[5]

Structure

Each HSF monomer contains one C-terminal and three N-terminal leucine zipper repeats.[6] Point mutations in these regions result in disruption of cellular localisation, rendering the protein constitutively nuclear.[4] Two sequences flanking the N-terminal zippers fit the consensus of a bi-partite nuclear localization 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.[6] The DNA-binding component of HSF lies to the N-terminus of the first NLS region, and is referred to as the HSF domain.

Isoforms

Humans express the following heat shock factors:

gene protein
HSF1 heat shock transcription factor 1
HSF2 heat shock transcription factor 2
HSF2BP heat shock transcription factor 2 binding protein
HSF4 heat shock transcription factor 4
HSF5 heat shock transcription factor family member 5
HSFX1 heat shock transcription factor family, X linked 1
HSFX2 heat shock transcription factor family, X linked 2
HSFY1 heat shock transcription factor, Y-linked 1
HSFY2 heat shock transcription factor, Y-linked 2

References

  1. ^ Sorger PK (May 1991). "Heat shock factor and the heat shock response". Cell 65 (3): 363–6. doi:10.1016/0092-8674(91)90452-5. PMID 2018972.  
  2. ^ Morimoto RI (March 1993). "Cells in stress: transcriptional activation of heat shock genes". Science (journal) 259 (5100): 1409–10. doi:10.1126/science.8451637. PMID 8451637.  
  3. ^ a b c Clos J, Westwood JT, Becker PB, Wilson S, Lambert K, Wu C (November 1990). "Molecular cloning and expression of a hexameric Drosophila heat shock factor subject to negative regulation". Cell 63 (5): 1085–97. doi:10.1016/0092-8674(90)90511-C. PMID 2257625.  
  4. ^ a b Rabindran SK, Giorgi G, Clos J, Wu C (August 1991). "Molecular cloning and expression of a human heat shock factor, HSF1". Proc. Natl. Acad. Sci. U.S.A. 88 (16): 6906–10. doi:10.1073/pnas.88.16.6906. PMID 1871105. PMC 52202. http://www.pnas.org/cgi/pmidlookup?view=long&pmid=1871105.  
  5. ^ Prahlad, V, Morimoto RI (Dec 2008). "Integrating the stress response: lessons for neurodegenerative diseases from C. elegans". Trends in Cell Biology 19 (2): 52–61. doi:10.1016/j.tcb.2008.11.002. PMID 19112021.  
  6. ^ a b Schuetz TJ, Gallo GJ, Sheldon L, Tempst P, Kingston RE (August 1991). "Isolation of a cDNA for HSF2: evidence for two heat shock factor genes in humans". Proc. Natl. Acad. Sci. U.S.A. 88 (16): 6911–5. doi:10.1073/pnas.88.16.6911. PMID 1871106. PMC 52203. http://www.pnas.org/cgi/pmidlookup?view=long&pmid=1871106.  

This article includes text from the public domain Pfam and InterPro IPR000232

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