Journal
BIOCHEMICAL JOURNAL
Volume 454, Issue -, Pages 217-225Publisher
PORTLAND PRESS LTD
DOI: 10.1042/BJ20121806
Keywords
antioxidant enzyme; chaperone; Hsp104; oxidative stress; prion; RNQ1
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Funding
- Department of Science and Technology
- Council for Scientific and Industrial Research (CSIR)
- Department of Science & Technology Innovation in Science Pursuit for Inspired Research (DST-INSPIRE) programme
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Maintenance of cellular redox homoeostasis forms an important part of the cellular defence mechanism and continued cell viability. Despite extensive studies, the role of the chaperone Hsp104 (heat-shock protein of 102 kDa) in propagation of misfolded protein aggregates in the cell and generation of oxidative stress remains poorly understood. Expression of RNQ1-RFP in Saccharomyces cerevisiae cells led to the generation of the prion form of the protein and increased oxidative stress. In the present study, we show that disruption of Hsp104 in an isogenic yeast strain led to solubilization of RNQ1-RFP. This reduced the oxidative stress generated in the cell. The higher level of oxidative stress in the Hsp104-containing (parental) strain correlated with lower activity of almost all of the intracellular antioxidant enzymes assayed. Surprisingly, this did not correspond with the gene expression analysis data. To compensate for the decrease in protein translation induced by a high level of reactive oxygen species, transcriptional up-regulation takes place. This explains the discrepancy observed between the transcription level and functional enzymatic product. Our results show that in a Delta Hsp104 strain, due to lower oxidative stress, no such mismatch is observed, corresponding with higher cell viability. Thus Hsp104 is indirectly responsible for enhancing the oxidative stress in a prion-rich environment.
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