title: [Redox-dependent changes in structure and function of hHSF1].
abstract: To evaluate the effects of cysteine-SH-directed regents on the redox status, structure and function of human heat shock transcription factor 1 (hHSF1), treatment in vitro of hHSF1 with 0.3 0.5 mmol/L oxidizing reagent diamide (DM) and treatment in vivo of HeLa cells with 1 mmol/L buthionine sulfoximine (BSO), an inhibitor of gamma-glutamylcysteine synthetase, promoted the formation of a compact, intramolecularly disulfide-crosslinked, stable monomeric form of ox-hHSF1, and blocked the trimerization and activation of HSF1. The effects of diamine were dose-dependent and readily could be completely reversed by adding 0.4 0.5 mmol/L reducing reagent dithiothreitol (DTT) to the samples prior to gel electrophoresis. Computer modeling of the alpha-helical coiled-coil domains of the HSF1 monomer and trimer showed that the alignment of the N- and C-terminal hydrophobic repeats of HSF1 monomer could bring C(3)(Cys(153))close to C(4) and C(5)(Cys(373) and Cys(378), respectively), in positions permissible for disulfide bond formation under appropriate experimental conditions. The results suggest that redox-dependent thiol-disulfide exchange can provide a mechanism for regulation the conformation and activity of hHSF1.
authors.affiliation: The First Hospital Affiliated to Sun Yat-Sen University, Guangzhou, 510080 China. zhenglin2@hotmail.com
authors.forename: Zheng
authors.initials: Z
authors.lastname: Lin
authors.forename: Fan
authors.initials: F
authors.lastname: Huang
authors.forename: Zhong-Fu
authors.initials: ZF
authors.lastname: Ma
authors.forename: Kang
authors.initials: K
authors.lastname: Xu
authors.forename: Alice Y
authors.initials: AY
authors.lastname: Liu
mesh_terms: D019328:Buthionine Sulfoximine / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D003958:Diamide / Q000494:pharmacology; D004229:Dithiothreitol / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005721:Glutamate-Cysteine Ligase / Q000037:antagonists & inhibitors; D006367:HeLa Cells; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D010084:Oxidation-Reduction; D011485:Protein Binding / Q000187:drug effects; D011487:Protein Conformation; D014157:Transcription Factors
chemical_list: D004268:DNA-Binding Proteins; C000619706:HSF1 protein, human; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; D014157:Transcription Factors; D003958:Diamide; D019328:Buthionine Sulfoximine; D005721:Glutamate-Cysteine Ligase; D004229:Dithiothreitol