Haem synthesis during mitochondrogenesis in yeast

Area of Science:

• Biochemistry
• Molecular Biology
• Yeast Metabolism

Background:

• Glucose repression is a critical regulatory mechanism in Saccharomyces cerevisiae.
• Understanding the enzymes involved in heme biosynthesis, like delta-aminolaevulate synthetase and delta-aminolaevulate dehydratase, is crucial for yeast metabolic studies.

Purpose of the Study:

• To investigate the activities of delta-aminolaevulate synthetase and delta-aminolaevulate dehydratase in Saccharomyces cerevisiae.
• To elucidate the enzymes' roles during glucose repression and de-repression phases.
• To correlate enzyme activity with cellular respiration changes.

Main Methods:

• Assay of delta-aminolaevulate synthetase and delta-aminolaevulate dehydratase activities.
• Culturing Saccharomyces cerevisiae under conditions of glucose repression and de-repression.
• Monitoring oxygen uptake in response to glucose depletion and enzyme activity.

Main Results:

• Delta-aminolaevulate dehydratase activity increased in parallel with oxygen uptake during glucose de-repression.
• Delta-aminolaevulate synthetase exhibited oscillatory behavior, with activity spikes preceding increased oxygen consumption.
• Both enzyme activities were reduced by glucose or cycloheximide, but not by chloramphenicol.

Conclusions:

• Delta-aminolaevulate synthetase and dehydratase activities are tightly regulated by glucose availability in Saccharomyces cerevisiae.
• The oscillatory nature of delta-aminolaevulate synthetase suggests a complex regulatory feedback mechanism.
• These enzymes play significant roles in yeast metabolic adaptation to changing nutrient conditions and are sensitive to protein synthesis inhibition.