title: Can the different heat shock response thresholds found in fermenting and respiring yeast cells be attributed to their differential redox states?
abstract: In this study we used a heat-shock (HS) reporter gene to demonstrate that respiring cells are intrinsically less sensitive (by 5 degrees C) than their fermenting counterparts to a sublethal heat shock. We also used an oxidant-sensitive fluorescent probe to demonstrate that this correlates with lower levels of sublethal reactive oxygen species (ROS) accumulation in heat-stressed respiring cells. Moreover, this relationship between HS induction of the reporter gene and ROS accumulation extends to respiring cells that have had their ROS levels modified by treatment with the anti-oxidant ascorbic acid and the pro-oxidant H(2)O(2). Thus, by demonstrating that the ROS/HSR correlation previously demonstrated in fermenting cells also holds for respiring cells (despite their greater HS insensitivity and higher level of intrinsic thermotolerance), we provide evidence that the intracellular redox state may influence both the sensitivity of the heat-shock response (HSR) and stress tolerance in the yeast Saccharomyces cerevisiae.
authors.affiliation: School of Biological and Chemical Sciences, Queen Mary College, University of London, Mile End Road, London E1 4NS, U.K.
authors.forename: Christos
authors.initials: C
authors.lastname: Moraitis
authors.forename: Brendan P G
authors.initials: BP
authors.lastname: Curran
mesh_terms: D001205:Ascorbic Acid / Q000494:pharmacology; D005285:Fermentation; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D017930:Genes, Reporter / Q000235:genetics; D018869:Heat-Shock Response / Q000502:physiology*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D017382:Reactive Oxygen Species / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D013696:Temperature; D017392:Thiobarbituric Acid Reactive Substances; D013997:Time Factors
chemical_list: D017382:Reactive Oxygen Species; D017392:Thiobarbituric Acid Reactive Substances; D006861:Hydrogen Peroxide; D001205:Ascorbic Acid