Related Experiment Videos
Hydrogen peroxide metabolism in yeasts
C Verduyn1, M L Giuseppin, W A Scheffers
1Department of Microbiology and Enzymology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, and Unilever Research Laboratory, Olivier van Noortlaan 120, 3133 AT Vlaardingen, The Netherlands.
Applied and Environmental Microbiology
|August 1, 1988
Summary
A catalase-negative yeast mutant effectively decomposes hydrogen peroxide (H2O2), highlighting cytochrome c peroxidase (CCP) as crucial for yeast H2O2 detoxification. Catalase competes with CCP only when H2O2 is peroxisomally generated.
Area of Science:
- Microbiology
- Biochemistry
- Enzymology
Background:
- Methanol metabolism in yeast generates hydrogen peroxide (H2O2), a toxic byproduct.
- Yeast possesses enzymes like catalase and cytochrome c peroxidase (CCP) to detoxify H2O2.
- The specific roles and interplay of these enzymes under different metabolic conditions require clarification.
Purpose of the Study:
- To investigate H2O2 detoxification mechanisms in Hansenula polymorpha, particularly in a catalase-negative mutant.
- To determine the role of cytochrome c peroxidase (CCP) in H2O2 decomposition.
- To compare H2O2 detoxification strategies between wild-type and mutant yeast, and across different yeast species.
Main Methods:
- Cultivation of a catalase-negative Hansenula polymorpha mutant and wild-type strains in chemostat cultures.
- Growth on various carbon sources including methanol, glucose, and hydrogen peroxide.
- Measurement of H2O2 consumption rates and enzyme activity assays (catalase, CCP, glutathione peroxidase).
Main Results:
- The catalase-negative mutant efficiently consumed both intracellularly generated and extracellular H2O2, reaching rates up to 8 mmol/g cells/h.
- Cytochrome c peroxidase (CCP) levels significantly increased in the mutant and in Saccharomyces cerevisiae when grown on H2O2, indicating its importance.
- In wild-type H. polymorpha, catalase levels correlated with methanol utilization, while CCP levels were independent, suggesting distinct roles.
Conclusions:
- Cytochrome c peroxidase (CCP) is a key enzyme for H2O2 detoxification in yeasts.
- Catalase is effective in H2O2 detoxification only when H2O2 is generated within peroxisomes, where catalase is localized.
- Yeast employs distinct enzymatic strategies for managing H2O2 based on its generation site and concentration.