Wisniewski J, Orosz A, Allada R, Wu C
Laboratory of Biochemistry, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Nucleic Acids Res. 1996 Jan 15;24(2):367-74. doi: 10.1093/nar/24.2.367.
The heat shock transcription factor (HSF) is constitutively expressed in Drosophila cells as an inactive monomer. Upon heat shock HSF undergoes trimerization and acquires high affinity DNA binding ability leading to specific interaction with its cognate elements in heat shock promoters. Here we show that the transactivation function of HSF is conferred by the extreme C-terminal region of the protein. Deletion analysis of HSF fragments fused to the GAL4 DNA-binding domain demonstrates that transactivation is dependent on HSF residues 610-691. This domain is located beyond the C-terminal heptad repeat (leucine zipper 4) whose presence or integrity is dispensable for transactivation. The transactivation domain is functional in the absence of heat shock and can be replaced by the extreme C-terminal region of human HSF1. The Drosophila and human HSF transactivation domains are both rich in hydrophobic and acidic residues and may be structurally conserved, despite limited sequence identity.
热休克转录因子（HSF）在果蝇细胞中以无活性的单体形式组成性表达。热休克时，HSF发生三聚化并获得高亲和力DNA结合能力，从而与热休克启动子中的同源元件发生特异性相互作用。在此我们表明，HSF的反式激活功能由该蛋白的极端C末端区域赋予。对与GAL4 DNA结合结构域融合的HSF片段进行缺失分析表明，反式激活依赖于HSF的610 - 691位残基。该结构域位于C末端七肽重复序列（亮氨酸拉链4）之外，其存在或完整性对于反式激活并非必需。反式激活结构域在无热休克时具有功能，并且可以被人HSF1的极端C末端区域替代。果蝇和人HSF的反式激活结构域都富含疏水和酸性残基，尽管序列一致性有限，但在结构上可能是保守的。
