Can the different heat shock response thresholds found in fermenting and respiring yeast cells be attributed to their differential redox states?

• Published in: Yeast (Chichester, England) England), 2007-08, Vol.24 (8), p.653-666
• Main Authors: Moraitis, Christos, Curran, Brendan P G
• Format: Article
• Language: English
• Subjects: Saccharomyces cerevisiae
• ISSN: 0749-503X
• DOI: 10.1002/yea.1499

In this study we used a heat-shock (HS) reporter gene to demonstrate that respiring cells are intrinsically less sensitive (by 5 °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 H2O2. 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.