Glycogenolytic enzymes in sporulating yeast

Area of Science:

• Biochemistry
• Molecular Biology
• Yeast Genetics

Background:

• During meiosis in Saccharomyces cerevisiae, glycogen synthesis is followed by degradation during spore maturation.
• Understanding the enzymes involved in this metabolic shift is crucial for comprehending yeast sporulation.

Purpose of the Study:

• To detect and characterize the enzyme activity responsible for glycogen catabolism during yeast sporulation.
• To determine the substrate specificity and properties of the glycogenolytic enzyme.

Main Methods:

• Assaying enzyme activity in sporulating and vegetative yeast strains.
• Partial purification of the glycogenolytic enzyme.
• Enzyme characterization using various substrates like glycogen, amylose, and dextrins.
• Sephadex G-150 chromatography for enzyme resolution.

Main Results:

• A specific glycogen catabolic enzyme activity was detected in sporulating yeast, absent in vegetative cells.
• The enzyme activity increased during sporulation and was higher in intact asci than in isolated spores.
• The enzyme preparation degraded glycogen and amylose, releasing glucose, and exhibited both alpha-1,4- and alpha-1,6-glucosidase activities.
• Chromatography resolved the activity into two components, potentially a glucamylase and a debranching enzyme.

Conclusions:

• The study identified a sporulation-specific enzyme responsible for glycogen degradation in Saccharomyces cerevisiae.
• This enzyme possesses both glucamylase and debranching activities, crucial for spore maturation.
• The findings provide insight into the metabolic regulation during yeast meiosis.