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Complementation of soluble phosphofructokinase activity in yeast mutants.
1Molecular Biology Unit, Tata Institute of Fundamental Research, Bombay, India.
European Journal of Biochemistry
|August 15, 1991
Summary
Genetic and biochemical analyses reveal that both catalytic and regulatory subunits are crucial for soluble phosphofructokinase (PFK I) activity in yeast. Neither subunit is active alone; only their heteromeric complex reconstitutes enzyme function.
Area of Science:
- Biochemistry
- Molecular Biology
- Yeast Genetics
Background:
- Soluble phosphofructokinase (PFK I) is a key glycolytic enzyme.
- Mutations can affect enzyme activity and kinetics.
- Understanding subunit function is critical for enzyme activity.
Purpose of the Study:
- To genetically and biochemically analyze mutations in yeast PFK I.
- To determine the roles of catalytic and regulatory subunits in enzyme activity.
- To investigate subunit interactions and their contribution to enzyme function.
Main Methods:
- Genetic complementation and allele-testing of yeast mutants.
- Biochemical assays to measure enzyme activity.
- Reconstitution of enzyme activity from cell-free extracts.
- Sedimentation studies and Western blot analysis.
Main Results:
- Mutations in either catalytic or regulatory subunits can abolish or alter PFK I activity.
- Both subunits are essential for detectable in vitro enzyme activity.
- Mixing extracts from mutants lacking individual subunits reconstitutes active PFK I.
- The reconstituted enzyme is a heteromeric complex identical to wild-type PFK I.
Conclusions:
- The heteromeric complex of catalytic and regulatory subunits is essential for PFK I activity.
- Individual subunits lack enzymatic activity in vitro.
- Subunit interactions are critical for the functional assembly of PFK I.