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Updated: Aug 2, 2026
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Screening for Amyloid Aggregation by Semi-Denaturing Detergent-Agarose Gel Electrophoresis
Published on: July 16, 2008
Ssb1 chaperone is a [PSI+] prion-curing factor
A Chacinska1, B Szczesniak, N V Kochneva-Pervukhova
1Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5A, 02106 Warsaw, Poland.
Current Genetics
|June 19, 2001
Summary
Yeast strains lacking tRNA isopentenylation spontaneously develop a [PSI+] prion-like state. The SSB1 gene was identified as crucial, as its overexpression cures this prion phenotype.
Area of Science:
- Molecular Biology
- Yeast Genetics
- Prion Biology
Background:
- Nonsense suppressors (SUP7/SUP11) in yeast typically require tRNA modification for phenotypic expression.
- Deficiency in A37 isopentenylation of tRNA prevents the expression of these nonsense suppressors.
- Cytoplasmically inherited determinants can influence cellular phenotypes in yeast.
Purpose of the Study:
- To investigate the spontaneous development of nonsense suppressor phenotypes in yeast strains lacking tRNA isopentenylation.
- To identify genetic factors involved in regulating this [PSI+] prion-related suppressor phenotype.
- To determine the role of the identified gene in curing the [PSI+] prion.
Main Methods:
- Phenotypic analysis of yeast strains deficient in A37 isopentenylation.
- Screening of a yeast genomic library to identify genes affecting the suppressor phenotype.
- Assessing the effect of multicopy plasmid expression of candidate genes on the prion state.
Main Results:
- Yeast strains lacking A37 isopentenylation spontaneously exhibit a nonsense suppressor phenotype resembling the [PSI+] prion.
- The SSB1 gene was isolated through a screen for its ability to inactivate this [PSI+]-related suppressor.
- Overexpression of the Ssb1 chaperone from a multicopy plasmid effectively cures cells of the [PSI+] prion.
Conclusions:
- tRNA modification is essential for the proper regulation of nonsense suppressor phenotypes.
- The SSB1 chaperone plays a critical role in maintaining or curing the [PSI+] prion state in yeast.
- This study reveals a novel link between tRNA modification pathways and prion biology.
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