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Modulation of human heat shock factor trimerization by the linker domain
1Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0606, USA. dthiele@umich.edu
The Journal of Biological Chemistry
|June 8, 1999
Summary
The human heat shock transcription factor 1 (HSF1) remains inactive as a monomer due to its linker region. Mutations in this linker promote HSF1 trimerization, activating its function under stress conditions.
Area of Science:
- Molecular Biology
- Genetics
- Cellular Stress Response
Background:
- Heat shock transcription factors (HSFs) regulate gene expression in response to cellular stress.
- Human HSF1 exists as an inactive monomer under basal conditions, transitioning to an active trimer upon stress.
Purpose of the Study:
- To identify regions of human HSF1 critical for maintaining monomeric stability under unstressed conditions.
- To investigate the role of the HSF1 linker region in regulating its monomer-trimer equilibrium.
Main Methods:
- Functional complementation assays in bakers' yeast.
- Analysis of HSF1-HSF2 chimeras.
- Point mutagenesis studies.
- Expression in human 293 cells.
Main Results:
- Mutations in the HSF1 linker region enable homotrimerization and rescue of yeast viability.
- A specific N-terminal portion of the HSF1 linker is essential for maintaining the monomeric state in yeast and human cells.
- The HSF1 linker does not influence DNA binding preferences in vivo.
Conclusions:
- The linker region of human HSF1 is a key regulator of its monomer-trimer equilibrium.
- This linker region plays a crucial role in HSF1 inactivation under basal conditions, independent of DNA binding specificity.