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Induction of distinct [URE3] yeast prion strains
M Schlumpberger1, S B Prusiner, I Herskowitz
1Institute for Neurodegenerative Diseases, University of California, San Francisco, California 94143-0518, USA.
Molecular and Cellular Biology
|September 21, 2001
Summary
Researchers identified novel variants of the [URE3] prion in yeast, differing in Ure2 protein activity and response to curing agents. This discovery offers new insights into prion strain diversity and aggregation mechanisms.
Area of Science:
- Yeast genetics
- Prion biology
- Molecular cell biology
Background:
- The [URE3] element in Saccharomyces cerevisiae is a non-Mendelian genetic factor arising from the prion-like conversion of Ure2 protein (Ure2p).
- This conversion inactivates Ure2p, enabling yeast cells to utilize ureidosuccinic acid under ammonia, a phenotype useful for prion state selection.
Purpose of the Study:
- To develop a novel reporter system for monitoring Ure2p function and studying [URE3] prion variants.
- To investigate the induction and characteristics of different [URE3] prion strains.
Main Methods:
- Development of a reporter system using the ADE2 gene controlled by the DAL5 regulatory region for colony color-based Ure2p function monitoring.
- Overexpression of the N-terminal Ure2p prion domain (UPD) and full-length Ure2p to induce and analyze [URE3] prion variants.
- Characterization of prion variants based on residual Ure2p activity and susceptibility to curing agents.
Main Results:
- Two distinct [URE3] prion variants, type A (conventional) and type B (novel), were induced by full-length Ure2p overexpression.
- Type B [URE3] exhibited higher residual Ure2p activity and was efficiently cured by a UPD-green fluorescent protein fusion protein.
- Overexpression of UPD specifically induced type B [URE3], while both type A and B strains maintained stable characteristics, suggesting aggregation-dependent strain variation.
Conclusions:
- The study identified and characterized novel [URE3] prion variants in yeast, demonstrating strain diversity.
- Different Ure2p aggregation modes likely underlie the observed prion strain variations.
- A novel reporter system and counterselection procedure were developed for studying and manipulating [URE3] prions.
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