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Isolation of omnipotent suppressors in an [eta+] yeast strain
J A All-Robyn1, D Kelley-Geraghty, E Griffin
1Department of Biological Sciences, University of Illinois, Chicago 60680.
Abstract:
Omnipotent suppressors decrease translational fidelity and cause misreading of nonsense codons. In the presence of the non-Mendelian factor [eta+], some alleles of previously isolated omnipotent suppressors are lethal. Thus the current search was conducted in an [eta+] strain in an effort to identify new suppressor loci. A new omnipotent suppressor, SUP39, and alleles of sup35, sup45, SUP44 and SUP46 were identified. Efficiencies of the dominant suppressors were dramatically reduced in strains that were cured of non-Mendelian factors by growth on guanidine hydrochloride. Wild-type alleles of SUP44 and SUP46 were cloned and these clones were used to facilitate the genetic analyses. SUP44 was shown to be on chromosome VII linked to cyh2, and SUP46 was clearly identified as distinct from the linked sup45.
Insights
Researchers identified a new omnipotent suppressor, SUP39, and other suppressor alleles in yeast strains with the [eta+] factor. Suppressor efficiency decreased when non-Mendelian factors were removed.
Area of Science:
- Genetics
- Molecular Biology
- Yeast Genetics
Background:
- Omnipotent suppressors are crucial genetic elements that reduce translational fidelity, leading to the misreading of nonsense codons.
- The presence of the non-Mendelian [eta+] factor can cause lethality in certain alleles of previously identified omnipotent suppressors.
- Identifying novel suppressor loci is essential for understanding translational control and genetic interactions.
Purpose of the Study:
- To identify new omnipotent suppressor loci in yeast strains harboring the [eta+] factor.
- To characterize the genetic interactions and functional properties of novel and known suppressors under specific genetic backgrounds.
Main Methods:
- Screening for new suppressor loci in [eta+] yeast strains.
- Genetic analysis of identified suppressors, including allelism tests and gene mapping.
- Cloning of wild-type alleles (SUP44, SUP46) to aid genetic characterization.
- Phenotypic analysis of suppressor efficiency in the presence and absence of non-Mendelian factors (e.g., after guanidine hydrochloride treatment).
Main Results:
- Discovery of a novel omnipotent suppressor, SUP39.
- Identification of new alleles for known suppressors: sup35, sup45, SUP44, and SUP46.
- Demonstration that the efficiency of dominant suppressors is significantly reduced in strains cured of non-Mendelian factors.
- Genetic mapping of SUP44 to chromosome VII, linked to cyh2, and confirmation that SUP46 is distinct from sup45.
Conclusions:
- The [eta+] factor influences the function and potential lethality of omnipotent suppressors.
- SUP39 represents a new locus involved in translational fidelity.
- Non-Mendelian factors play a significant role in modulating the activity of omnipotent suppressors.
- Detailed genetic characterization of SUP44 and SUP46 provides insights into their chromosomal location and distinct identities.