Activation of the DNA-Binding Ability of Human Heat Shock Transcription Factor 1 May Involve the Transition from an Intramolecular to an Intermolecular Triple-Stranded Coiled-Coil Structure

• DOI: 10.1128/mcb.14.11.7557-7568.1994
• Publication Date: 2021-06-10T00:59:36Z
• Authors: Jianru Zuo; Ruben Baler; Gerhard Dahl; Richard Voellmy
• Keywords: Repressor lexA; Heat shock factor; Coiled coil; HMG-box

Heat stress regulation of human heat shock genes is mediated by transcription factor hHSF1, which contains three 4-3 hydrophobic repeats (LZ1 to LZ3). In unstressed cells (37 degrees C), hHSF1 appears be in an inactive, monomeric state that may maintained through intramolecular interactions stabilized transient interaction with hsp70. (39 42 C) disrupts these interactions, and homotrimerizes acquires element DNA-binding ability. expressed Xenopus oocytes also assumes a monomeric, non-DNA-binding converted trimeric, form upon exposure the (35 37 C this organism). Because endogenous HSF activity low anti-hHSF1 antibody does not recognize HSF, we employed system for mapping regions are required maintenance state. The results mutagenesis analyses strongly suggest inactive monomer involving all leucine zippers triple-stranded coiled coil. Trimerization enable function facilitating cooperative binding domains motif. This view supported observations several different LexA domain-hHSF1 chimeras bind LexA-binding site heat-regulated fashion, single amino acid replacements disrupting integrity render constitutively trimeric DNA binding, itself binds stably only as dimer but our assays.