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Updated: Jun 21, 2026
Competitive Genomic Screens of Barcoded Yeast Libraries
Published on: August 11, 2011
Genome-wide screen of genes required for caffeine tolerance in fission yeast
Isabel A Calvo1, Natalia Gabrielli, Iván Iglesias-Baena
1Oxidative Stress and Cell Cycle Group, Universitat Pompeu Fabra, Barcelona, Spain.
Background:
An excess of caffeine is cytotoxic to all eukaryotic cell types. We aim to study how cells become tolerant to a toxic dose of this drug, and the relationship between caffeine and oxidative stress pathways.
Methodology/Principal Findings:
We searched for Schizosaccharomyces pombe mutants with inhibited growth on caffeine-containing plates. We screened a collection of 2,700 haploid mutant cells, of which 98 were sensitive to caffeine. The genes mutated in these sensitive clones were involved in a number of cellular roles including the H(2)O(2)-induced Pap1 and Sty1 stress pathways, the integrity and calcineurin pathways, cell morphology and chromatin remodeling. We have investigated the role of the oxidative stress pathways in sensing and promoting survival to caffeine. The Pap1 and the Sty1 pathways are both required for normal tolerance to caffeine, but only the Sty1 pathway is activated by the drug. Cells lacking Pap1 are sensitive to caffeine due to the decreased expression of the efflux pump Hba2. Indeed, ?hba2 cells are sensitive to caffeine, and constitutive activation of the Pap1 pathway enhances resistance to caffeine in an Hba2-dependent manner.
Conclusions/Significance:
With our caffeine-sensitive, genome-wide screen of an S. pombe deletion collection, we have demonstrated the importance of some oxidative stress pathway components on wild-type tolerance to the drug.
Insights
Caffeine is toxic to cells, but this study identified key oxidative stress pathways in yeast that help cells tolerate high doses. These pathways, including Pap1 and Sty1, are crucial for survival and involve the Hba2 efflux pump.
Area of Science:
- Cell Biology
- Genetics
- Biochemistry
Background:
- Caffeine exhibits cytotoxicity across eukaryotic cell types.
- Understanding cellular tolerance mechanisms to toxic compounds is essential.
- Investigating the interplay between caffeine and oxidative stress pathways is crucial.
Purpose of the Study:
- To identify genes and pathways conferring tolerance to toxic caffeine doses in yeast.
- To elucidate the role of oxidative stress pathways in caffeine tolerance.
- To determine the relationship between caffeine exposure and cellular defense mechanisms.
Main Methods:
- Genome-wide screening of 2,700 haploid mutant yeast strains for caffeine sensitivity.
- Analysis of genes involved in stress response, cell morphology, and chromatin remodeling.
- Functional investigation of oxidative stress pathways (Pap1, Sty1) and the Hba2 efflux pump.
Main Results:
- 98 yeast mutants sensitive to caffeine were identified, with mutations in stress, integrity, and chromatin remodeling pathways.
- The Pap1 and Sty1 oxidative stress pathways are critical for caffeine tolerance.
- Sty1 pathway activation by caffeine was observed, while Pap1's role involves Hba2 efflux pump expression.
Conclusions:
- A genome-wide screen revealed the significance of oxidative stress pathways in yeast's tolerance to caffeine.
- Components of the Pap1 and Sty1 pathways are vital for cellular survival under caffeine stress.
- The Hba2 efflux pump, regulated by the Pap1 pathway, plays a key role in mediating caffeine resistance.
