title: Acquisition of heat shock tolerance by regulation of intracellular redox states.
abstract: In the yeast Saccharomyces cerevisiae, a mild heat treatment strongly induces Hsp104p which provides acquisition of thermotolerance. The mechanism by which Hsp104p protects cells from the severe heat shock has not yet been completely elucidated. In this study, a pivotal role of Hsp104p as an efficient scavenger of the reactive oxygen species (ROS) is investigated. In our previous study, we reported that Hsp104p acted as a regulator in the mitochondrial respiration pathway. In this report, the recombinant wild-type and hypersensitive ras mutants (ira2Delta) with the extrachromosomal plasmids wild-type and mutant hsp104 genes were studied. The resulting strains successfully expressed both wild-type and mutant Hsp104p and showed the thermotolerance phenotype in the strain with the functional wild-type Hsp104p expressed. Upon treatment with H2O2 and menadione, the strains with the functional Hsp104p expressed showed higher survival rates than the other mutants, indicating the protective role of Hsp104p from the oxidative stress. Fluorescence measurement of the oxidation-dependent probe, 2',7'-dichlorofluoroscein diacetate (H2DCFDA), also indicated that Hsp104p significantly reduced the amount of ROS. Resistance to the oxidative stress was independent of the amount of the glutathione in the hyperactivated ras mutants. Taken all together, this study confirms that Hsp104p plays a crucial role in keeping cells from being damaged by the oxidative stress, thus acting as a modulator of the intracellular redox state.
authors.affiliation: Department of Applied Chemistry and Recombinant Protein Expression Center, Sejong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747, South Korea.
authors.forename: Jeonghoon
authors.initials: J
authors.lastname: Ueom
authors.forename: Soonhyun
authors.initials: S
authors.lastname: Kwon
authors.forename: Sunhee
authors.initials: S
authors.lastname: Kim
authors.forename: Youngkee
authors.initials: Y
authors.lastname: Chae
authors.forename: Kyunghee
authors.initials: K
authors.lastname: Lee
mesh_terms: D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D002478:Cells, Cultured; D005452:Fluoresceins; D016166:Free Radical Scavengers / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism*; D018869:Heat-Shock Response / Q000187:drug effects / Q000235:genetics*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism; D009154:Mutation / Q000187:drug effects / Q000235:genetics; D010084:Oxidation-Reduction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics*; D017382:Reactive Oxygen Species / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism*; D024483:Vitamin K 3 / Q000494:pharmacology; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D005452:Fluoresceins; D016166:Free Radical Scavengers; D006360:Heat-Shock Proteins; D017382:Reactive Oxygen Species; D029701:Saccharomyces cerevisiae Proteins; C070972:HsP104 protein, S cerevisiae; C029569:diacetyldichlorofluorescein; D024483:Vitamin K 3; D006861:Hydrogen Peroxide; D018631:ras Proteins; D005978:Glutathione