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Updated: May 18, 2026
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High-throughput Screening for Protein-based Inheritance in S. cerevisiae
Published on: August 8, 2017
Sex, prions, and plasmids in yeast
Amy C Kelly1, Frank P Shewmaker, Dmitry Kryndushkin
1Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Summary
Yeast prions like [PIN+] can spread through mating, even if they cause harm. Genetic diversity in yeast, particularly in the RNQ1 gene, likely evolved to protect against these infectious protein elements.
Area of Science:
- Molecular biology
- Genetics
- Prion biology
Background:
- Prions are infectious proteins that can cause disease.
- Yeast prions, such as [PSI+], [URE3], and [PIN+], are self-propagating protein aggregates.
- The prevalence and spread of prions in natural populations are not fully understood.
Purpose of the Study:
- To investigate the prevalence of yeast prions in wild yeast strains.
- To understand the mechanisms of prion transmission and their impact on host fitness.
- To explore the role of genetic variation in prion resistance.
Main Methods:
- Screening of 70 wild yeast strains for the presence of [PSI+], [URE3], and [PIN+] prions.
- Estimation of outcross mating frequency using 2-μm DNA plasmid carriage and heterozygosity at the RNQ1 locus.
- Analysis of RNQ1 polymorphisms, including premature stop codons and sequence variations, for their effect on [PIN+] propagation.
Main Results:
- The [PIN+] prion was found in approximately 16% of wild yeast strains, while [PSI+] and [URE3] were not detected.
- The detriment of carrying [PSI+], [URE3], or [PIN+] was estimated to be greater than 1%.
- RNQ1 polymorphisms, including those that prevent [PIN+] propagation or create a transmission barrier, were identified. Strains carrying [PIN+] were more likely to be heterozygous at RNQ1, suggesting sexual transmission.
Conclusions:
- The [PIN+] prion is present in natural yeast populations and spreads via mating.
- Genetic polymorphism in the RNQ1 gene likely provides a defense mechanism against the detrimental effects of the [PIN+] prion.
- Natural selection may favor RNQ1 variants that confer resistance to prion infection.
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