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Proline transport in Saccharomyces cerevisiae
Journal of Bacteriology
|October 1, 1981
Summary
Researchers identified mutations in yeast Saccharomyces cerevisiae affecting proline transport. The put4 mutation disrupts high-affinity proline uptake, revealing the presence of inducible, low-affinity systems essential for growth on proline.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Yeast Saccharomyces cerevisiae utilizes proline as a nitrogen source.
- Proline transport systems are crucial for nutrient assimilation in yeast.
- Understanding these systems aids in metabolic engineering and genetic studies.
Purpose of the Study:
- To isolate and characterize mutants of S. cerevisiae with defects in proline transport.
- To investigate the mechanisms of proline uptake and utilization in yeast.
- To identify specific genes and pathways involved in proline transport.
Main Methods:
- Isolation of mutants resistant to toxic proline analogs (L-azetidine-2-carboxylate, 3,4-dehydro-DL-proline).
- Phenotypic analysis of mutant strains, including growth studies on proline-containing media.
- Kinetic studies to characterize proline transport systems (high-affinity and low-affinity).
Main Results:
- The put4 mutation confers a defect in the high-affinity proline transport system.
- Yeast possesses inducible low-affinity proline transport systems, confirmed by kinetic analysis.
- Both high- and low-affinity transport systems are regulated by ammonium and proline.
Conclusions:
- The put4 mutation is essential for high-affinity proline uptake in S. cerevisiae.
- Low-affinity proline transport systems compensate for high-affinity defects, especially at high proline concentrations.
- Histidine inhibits low-affinity proline transport, impacting growth in specific conditions.