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Saccharomyces cerevisiae contains two functional citrate synthase genes
Molecular and Cellular Biology
|June 1, 1986
Summary
Yeast Saccharomyces cerevisiae has two genes for citrate synthase. Both CIT1 and CIT2 are needed to create citrate synthase deficiency, indicating each gene alone suffices for key metabolic roles.
Area of Science:
- Molecular Biology
- Biochemistry
- Yeast Genetics
Background:
- The tricarboxylic acid cycle is a central metabolic pathway occurring in mitochondria.
- Citrate synthase is a key enzyme in the tricarboxylic acid cycle.
- Previous research identified the CIT1 gene encoding citrate synthase in Saccharomyces cerevisiae.
Purpose of the Study:
- To isolate and characterize a second nuclear gene encoding citrate synthase in Saccharomyces cerevisiae.
- To investigate the functional redundancy and differential regulation of the two citrate synthase genes.
Main Methods:
- Immunological screening to identify the second gene.
- Gene disruption to create knockout strains.
- Analysis of growth phenotypes on various media.
- Transcriptional analysis under different nutrient conditions.
Main Results:
- A second nuclear gene, CIT2, encoding citrate synthase was isolated.
- Disruption of both CIT1 and CIT2 was required to produce severe citrate synthase deficiency phenotypes.
- Both CIT1 and CIT2 transcripts were repressed by glucose and glutamate.
- CIT1 transcription was derepressed by nonfermentable carbon sources, while CIT2 was not.
Conclusions:
- Saccharomyces cerevisiae possesses two functional genes for citrate synthase, CIT1 and CIT2.
- Either CIT1 or CIT2 can independently fulfill essential metabolic functions related to citrate synthase.
- The two genes exhibit distinct transcriptional regulation patterns in response to nutrient availability.