The Induction of Saccharomyces cerevisiae Hsp104 Synthesis by Heat Shock Is Controlled by Mitochondria (original) (raw)
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The Effect of Sodium Azide on Basic and Induced Thermotolerance in Saccharomyces cerevisiae
Russian Journal of Plant Physiology, 2004
The action mechanism of the mitochondrial inhibitor sodium azide on thermotolerance in Saccharomyces cerevisiae was studied. At ambient growth temperature, pretreatment with sodium azide was shown to improve the thermotolerance of parent cells and the hsp104 mutant. Treating with the inhibitor during a mild heat shock suppressed the development of induced thermotolerance due to the inhibition of heat shock protein (Hsp104) synthesis. Treating with the inhibitor immediately before lethal heat shock produced a variety of effects on thermotolerance depending on whether the yeast metabolism was oxidative or fermentative. The conclusions are: (1) the protective effect of sodium azide on the thermotolerance of S. cerevisiae cells grown on glucose-containing medium is not related to Hsp104 functioning, and (2) the mechanisms of basic and induced thermotolerance differ considerably.
The Journal of cell biology, 1996
SSH1, a newly identified member of the heat shock protein (hsp70) multigene family of the budding yeast Saccharomyces cerevisiae, encodes a protein localized to the mitochondrial matrix. Deletion of the SSH1 gene results in extremely slow growth at 23 degrees C or 30 degrees C, but nearly wild-type growth at 37 degrees C. The matrix of the mitochondria contains another hsp70, Ssc1, which is essential for growth and required for translocation of proteins into mitochondria. Unlike SSC1 mutants, an SSH1 mutant showed no detectable defects in import of several proteins from the cytosol to the matrix compared to wild type. Increased expression of Ssc1 partially suppressed the cold-sensitive growth defect of the SSH1 mutant, suggesting that when present in increased amounts, Ssc1 can at least partially carry out the normal functions of Ssh1. Spontaneous suppressors of the cold-sensitive phenotype of an SSH1 null mutant were obtained at a high frequency at 23 degrees C, and were all found ...
Heat Shock–Induced Changes in the Respiration of the Yeast Saccharomyces cerevisiae
Microbiology, 2001
The incubation of Saccharomyces cerevisiaeat elevated temperature (45°C) stimulated the respiration of yeast cells and decreased their survival rate. The respiration-deficient mutant of this yeast was found to be more tolerant to the elevated temperature than the wild-type strain. At the same time, the cultivation of the wild-type strain in an ethanol-containing medium enhanced the respiration, catalase activity, and thermotolerance of yeast cells, as compared with their growth in a glucose-containing medium. It is suggested that the enhanced respiration of yeast cells at 45°C leads to an intense accumulation of reactive oxygen species, which may be one of the reasons for the heat shock–induced cell death.
Biochemical and Biophysical Research Communications, 1998
Hsp100 protein family, is especially important for pro-TPN (tetrachloroisophthalonitrile) affected the tection against extremely stressful conditions such as growth in yeast Saccharomyces cerevisiae and enhigh temperatures and high concentrations of ethanol hanced the superoxide dismutase and glutathione re- . However, the mechanism of the Hsp104 function ductase activity under sublethal concentration. Conunder stressful conditions is not well understood. In versely, mild heat-shock treatment had no effect on this study, to examine the role of Hsp104, we demonthe enzyme activities. These show they inhibit the mestrated the intracellular localization of Hsp104 induced tabolism diversely: TPN is an oxidative stressor and by different types of conditions, i.e., heat and chemical mild heat-shock treatment leads to thermogenesis. We stress. One reason for this is that morphological analyhave earlier reported that on exposure to TPN under sis using electron and immunoelectron microscopy is sublethal concentration, heat-shock protein Hsp104 an efficient approach to determine the relationship bewas induced in the same way as in the mild heat-shock tween the Hsp104 synthesis and the intracellular orgatreatment (Fujita et al., Biochem. Biophys. Res. Comnella damaged by these stressors (Kawai, R. et al., unmun. (1995) 216, 1041-1047). However, intracellular localizations of Hsp104 showed different patterns in published data). each treated cell according to immunoelectron micrometallo-enzyme which plays a role in the detoxification
Journal of Biological Chemistry, 2002
Cells may sense heat shock via the accumulation of thermally misfolded proteins. To explore this possibility, we determined the effect of protein misfolding on gene expression in the absence of temperature changes. The imino acid analog azetidine-2-carboxylic acid (AZC) is incorporated into protein competitively with proline and causes reduced thermal stability or misfolding. We found that adding AZC to yeast at sublethal concentrations sufficient to arrest proliferation selectively induced expression of heat shock factor-regulated genes to a maximum of 27-fold and that these inductions were dependent on heat shock factor. AZC treatment also selectively repressed expression of the ribosomal protein genes, another heat shock factor-dependent process, to a maximum of 20-fold. AZC treatment thus strongly and selectively activates heat shock factor. AZC treatment causes this activation by misfolding proteins. Induction of HSP42 by AZC treatment required protein synthesis; treatment with ethanol, which can also misfold proteins, activated heat shock factor, but treatment with canavanine, an arginine analog less potent than AZC at misfolding proteins, did not. However, misfolded proteins did not strongly induce the stress response element regulon. We conclude that misfolded proteins are competent to specifically trigger activation of heat shock factor in response to heat shock.
Molecular and cellular biology, 2001
In the present study we sought to determine the source of heat-induced oxidative stress. We investigated the involvement of mitochondrial respiratory electron transport in post-diauxic-phase cells under conditions of lethal heat shock. Petite cells were thermosensitive, had increased nuclear mutation frequencies, and experienced elevated levels of oxidation of an intracellular probe following exposure to a temperature of 50 degrees C. Cells with a deletion in COQ7 leading to a deficiency in coenzyme Q had a much more severe thermosensitivity phenotype for these oxidative endpoints following heat stress compared to that of petite cells. In contrast, deletion of the external NADH dehydrogenases NDE1 and NDE2, which feed electrons from NADH into the electron transport chain, abrogated the levels of heat-induced intracellular fluorescence and nuclear mutation frequency. Mitochondria isolated from COQ7-deficient cells secreted more than 30 times as much H(2)O(2) at 42 as at 30 degrees C,...
Heat Shock Proteins in the “Hot” Mitochondrion: Identity and Putative Roles
BioEssays, 2019
The mitochondrion is known as the "powerhouse" of eukaryotic cells since it is the main site of adenosine 5′-triphosphate (ATP) production. Using a temperature-sensitive fluorescent probe, it has recently been suggested that the stray free energy, not captured into ATP, is potentially sufficient to sustain mitochondrial temperatures higher than the cellular environment, possibly reaching up to 50°C. By 50°C, some DNA and mitochondrial proteins may reach their melting temperatures; how then do these biomolecules maintain their structure and function? Further, the production of reactive oxygen species (ROS) accelerates with temperature, implying higher oxidative stresses in the mitochondrion than generally appreciated. Herein, it is proposed that mitochondrial heat shock proteins (particularly Hsp70), in addition to their roles in protein transport and folding, protect mitochondrial proteins and DNA from thermal and ROS damage. Other thermoprotectant mechanisms are also discussed.
PLOS ONE, 2019
Aggregation of the prion protein has strong implications in the human prion disease. Sup35p is a yeast prion, and has been used as a model protein to study the disease mechanism. We have studied the pattern of Sup35p aggregation inside live yeast cells under stress, by using confocal microscopy, fluorescence activated cell sorting and western blotting. Heat shock proteins are a family of proteins that are produced by yeast cells in response to exposure to stressful conditions. Many of the proteins behave as chaperones to combat stress-induced protein misfolding and aggregation. In spite of this, yeast also produce small molecules called osmolytes during stress. In our work, we tried to find the reason as to why yeast produce osmolytes and showed that the osmolytes are paramount to ameliorate the long-term effects of lethal stress in Saccharomyces cerevisiae, either in the presence or absence of Hsp104p.
Responses ofSaccharomyces cerevisiae to thermal stress
Biotechnology and Bioengineering, 2005
We studied the mechanisms involved in heat gradient-induced thermotolerance of Saccharomyces cerevisiae. Yeasts were slowly heated in a nutrient medium from 25 to 508C at 0.58C/min or immediately heat shocked at 508C, and both sets of cultures were maintained at this temperature for 1 h. Cells that had been slowly heated showed a 50-fold higher survival rate than the rapidly heated cells. Such thermotolerance was found not to be related to protein synthesis. Indeed Hsp104 a known protein involved in yeast thermal resistance induced by a preconditioning mild heat treatment, was not synthesized and cycloheximide addition, a protein synthesis inhibitor, did not affect the thermoprotective effect. Moreover, a rapid cooling from 50 to 258C applied immediately after the heat slope treatment inhibited the mechanisms involved in thermotolerance. Such observations lead us to conclude that heat gradient-induced thermal resistance is not directly linked to mechanisms involving intracellular molecules synthesis or activity such as proteins (Hsps, enzymes) or osmolytes (trehalose). Other factors such as plasma membrane phospholipid denaturation could be involved in this phenomenon.