Glycolysis mutants in Saccharomyces cerevisiae

Area of Science:

• Biochemistry
• Molecular Biology
• Yeast Genetics

Background:

• Understanding cellular metabolism is crucial for various biological processes.
• Yeast (Saccharomyces cerevisiae) serves as a model organism for studying fundamental metabolic pathways.
• Identifying specific enzyme functions aids in deciphering metabolic regulation.

Purpose of the Study:

• To isolate and characterize yeast mutants with altered glucose and pyruvate metabolism.
• To identify the specific enzymes affected in these mutants.
• To understand the genetic basis of glucose repression and pyruvate utilization.

Main Methods:

• Mutagenesis of Saccharomyces cerevisiae followed by phenotypic screening.
• Enrichment strategies including antibiotic treatment and nutrient starvation.
• Enzyme assays to determine the presence or absence of key glycolytic enzymes.
• Genetic analysis of mutant segregation in diploid strains.

Main Results:

• Isolation of mutants exhibiting growth on pyruvate but not glucose, or glucose-inhibited pyruvate growth.
• Identification of mutants lacking pyruvate kinase (pyk) and phosphoglucose isomerase (pgi).
• Characterization of double mutants (e.g., pyk hxk, pyk pfk, pyk gcr) with altered glycolytic enzyme profiles.
• Demonstration that mutations were recessive and segregated 2:2 in diploids.

Conclusions:

• Specific glycolytic enzyme deficiencies, such as pyruvate kinase, lead to distinct metabolic phenotypes in yeast.
• Genetic analysis confirms the allelic nature of the identified mutations.
• The study provides valuable genetic tools and insights into the regulation of glycolysis and carbon source utilization in S. cerevisiae.