Multiple Layers of Regulation of Human Heat Shock Transcription Factor 1
| Autor: | Jianru Zuo, Richard Voellmy, D. Rungger |
|---|---|
| Rok vydání: | 1995 |
| Předmět: |
Transcriptional Activation
Transcription Genetic Protein Conformation Xenopus DNA Mutational Analysis Regulatory Sequences Nucleic Acid Biology Transfection DNA-binding protein Structure-Activity Relationship Protein structure Heat Shock Transcription Factors Transcription (biology) Heat shock protein Animals Humans Nuclear protein Molecular Biology Transcription factor Heat-Shock Proteins Sequence Deletion Nuclear Proteins Cell Biology biology.organism_classification Molecular biology Cell Compartmentation Cell biology DNA-Binding Proteins Heat shock factor Research Article HeLa Cells Transcription Factors |
| Zdroj: | Molecular and Cellular Biology. 15:4319-4330 |
| ISSN: | 1098-5549 |
| DOI: | 10.1128/mcb.15.8.4319 |
| Popis: | Upon heat stress, monomeric human heat shock transcription factor 1 (hHSF1) is converted to a trimer, acquires DNA-binding ability, is transported to the nucleus, and becomes transcriptionally competent. It was not known previously whether these regulatory changes are caused by a single activation event or whether they occur independently from one another, providing a multilayered control that may prevent inadvertant activation of hHSF1. Comparison of wild-type and mutant hHSF1 expressed in Xenopus oocytes and human HeLa cells suggested that retention of hHSF1 in the monomeric form depends on hydrophobic repeats (LZ1 to LZ3) and a carboxy-terminal sequence element in hHSF1 as well as on the presence of a titratable factor in the cell. Oligomerization of hHSF1 appears to induce DNA-binding activity as well as to uncover an amino-terminally located nuclear localization signal. A mechanism distinct from that controlling oligomerization regulates the transcriptional competence of hHSF1. Components of this mechanism were mapped to a region, including LZ2 and nearby sequences downstream from LZ2, that is clearly separated from the carboxy-terminally located transcription activation domain(s). We propose the existence of a fold-back structure that masks the transcription activation domain in the unstressed cell but is opened up by modification of hHSF1 and/or binding of a factor facilitating hHSF1 unfolding in the stressed cell. Activation of hHSF1 appears to involve at least two independently regulated structural transitions. |
| Databáze: | OpenAIRE |
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