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Properties of a Saccharomyces cerevisiae mtDNA segment conferring high-frequency yeast transformation
Abstract:
The bakers' yeast Saccharomyces cerevisiae is a facultative anaerobe, tolerant to mutations in its mitochondrial genome. Individual cytoplasmic petite mutants retain genetic information derived from any portion of the parenteral mtDNA, prompting questions concerning distribution of the DNA replication origin(s) on the yeast mitochondrial genome. The experiments described in this paper were designated to test the possibility of using high-frequency yeast transformation as a selection for yeast mtDNA sequences conferring autonomously replicating function. A complete petite mitochondrial genome was inserted into the yeast vector YIp5, and the hybrid plasmid (YRMp1) was used to transform yeast. YRMp1 promoted high-frequency transformation of both wild-type yeast cells and petite mutant hosts lacking mtDNA and was maintained in each of these strains as a high-copy-number extrachromosomal element. The stability and copy-number properties of YRMp1 are similar to those of YRp12, a recombinant plasmid containing a yeast chromosomal autonomously replicating sequence.
Insights
Researchers explored yeast mitochondrial DNA replication origins using high-frequency transformation. A hybrid plasmid containing the petite mitochondrial genome successfully transformed yeast cells, indicating its autonomously replicating function.
Area of Science:
- Molecular Biology
- Genetics
- Yeast Biology
Background:
- Saccharomyces cerevisiae, a facultative anaerobe, exhibits tolerance to mitochondrial genome mutations.
- Cytoplasmic petite mutants retain parental mitochondrial DNA (mtDNA), raising questions about mtDNA replication origins.
Purpose of the Study:
- To investigate the distribution of DNA replication origins on the yeast mitochondrial genome.
- To utilize high-frequency yeast transformation as a method to identify yeast mtDNA sequences with autonomously replicating function.
Main Methods:
- Insertion of a complete petite mitochondrial genome into the yeast vector YIp5 to create a hybrid plasmid (YRMp1).
- Transformation of both wild-type yeast and petite mutant hosts lacking mtDNA with the YRMp1 plasmid.
Main Results:
- The YRMp1 plasmid facilitated high-frequency transformation in both wild-type and petite mutant yeast strains.
- YRMp1 was maintained as a high-copy-number extrachromosomal element in transformed yeast cells.
- The stability and copy-number characteristics of YRMp1 were comparable to a plasmid with a known yeast chromosomal autonomously replicating sequence.
Conclusions:
- The study demonstrates that yeast mtDNA contains sequences capable of conferring autonomously replicating function.
- High-frequency yeast transformation is a viable method for selecting and studying mtDNA replication origins.
- The findings contribute to understanding the organization and replication mechanisms of the yeast mitochondrial genome.