Background
Empirical evidence shows that under high hydrostatic pressure, the oxidative stress response is activated in Saccharomyces cerevisiae. However, the mechanisms involved in its antioxidant systems are unclear. In the current study, we aimed to explore the role of superoxide dismutase 1 (Sod1) in yeast able to grow under high pressure.
Conclusions
High pressure enhances O2•- production and Sod1 within the IMS plays a role in scavenging O2•- allowing the cells to grow under high pressure. General significance: Unlike external free radical-generating compounds, high-pressure treatment appeared to increase endogenous O2•- levels in yeast cells. Our experimental system offers a unique approach to investigating the physiological responses to mechanical and oxidative stresses in human body.
Methods
Wild type and sod1 mutant cells were cultured in high-pressure chambers under 25 MPa (~250 kg/cm2). The SOD activity in whole cell extracts and 6His-tagged Sod1 recombinant proteins was analyzed using an SOD assay kit. The O2•- generation in cells was estimated by fluorescence staining.
Results
Mutants lacking Sod1 or Ccs1, the copper chaperone for Sod1, displayed growth defects under 25 MPa. Of the various SOD1 mutations associated with familial amyotrophic lateral sclerosis, H46Q and S134N substitutions diminished SOD activity to levels comparable to those of catalytically deficient H63A and null mutants. The high-pressure sensitive sod1 mutants were also susceptible to sublethal levels of the O2•- generator paraquat. Exclusive localization of Sco2-Sod1 to the intermembrane space (IMS) of mitochondria partially restored the high-pressure growth ability in the sod1 mutants. Conclusions: High pressure enhances O2•- production and Sod1 within the IMS plays a role in scavenging O2•- allowing the cells to grow under high pressure. General significance: Unlike external free radical-generating compounds, high-pressure treatment appeared to increase endogenous O2•- levels in yeast cells. Our experimental system offers a unique approach to investigating the physiological responses to mechanical and oxidative stresses in human body.
Significance
Unlike external free radical-generating compounds, high-pressure treatment appeared to increase endogenous O2•- levels in yeast cells. Our experimental system offers a unique approach to investigating the physiological responses to mechanical and oxidative stresses in human body.