Hübel A, Lee J H, Wu C, Schöffl F
Universität Tübingen, Biologisches Institut, Lehrstuhl für Allgemeine Genetik, Germany.
Mol Gen Genet. 1995 Jul 28;248(2):136-41. doi: 10.1007/BF02190794.
Heat shock factors (HSF) are the transcriptional activators of the heat shock response. The conversion of constitutively expressed HSF to a form that can bind DNA requires the trimerization of the protein, involving leucine zipper interactions as shown for yeast, Drosophila, chicken and human HSFs. Like other metazoan HSFs, the endogenous Arabidopsis HSF displays heat shock-inducible DNA-binding activity in gel retardation assays. The heat shock-inducible binding of a recombinant Arabidopsis HSF (ATHSF1) expressed in Arabidopsis plants suggests that ATHSF1 is the major heat shock factor regulating the heat stress response. However, on transient expression in Drosophila and human cells, ATHSF1 fails to exhibit proper regulation, as demonstrated by constitutive binding to DNA, and by constitutive expression of a chloramphenicol acetyltransferase (CAT) reporter gene under the control of the Drosophila hsp70 promoter. These results suggest that the regulation of ATHSF1 is normally dependent on a specific factor that inhibits the DNA-binding and transcriptional activities under non-heat shock conditions.
热休克因子（HSF）是热休克反应的转录激活因子。组成型表达的HSF转变为能够结合DNA的形式需要蛋白质三聚化，这涉及到亮氨酸拉链相互作用，酵母、果蝇、鸡和人类的HSF均如此。与其他后生动物的HSF一样，在凝胶阻滞试验中，内源性拟南芥HSF表现出热休克诱导的DNA结合活性。在拟南芥植物中表达的重组拟南芥HSF（ATHSF1）的热休克诱导结合表明，ATHSF1是调节热应激反应的主要热休克因子。然而，在果蝇和人类细胞中瞬时表达时，ATHSF1未能表现出适当的调节，这体现在其与DNA的组成型结合以及在果蝇hsp70启动子控制下氯霉素乙酰转移酶（CAT）报告基因的组成型表达上。这些结果表明，ATHSF1的调节通常依赖于一种特定因子，该因子在非热休克条件下抑制DNA结合和转录活性。
