Related Experiment Videos
A multitude of suppressors of group II intron-splicing defects in yeast
M Waldherr1, A Ragnini, B Jank
1Institut für Mikrobiologie und Genetik, Universität Wien, Austria.
Abstract:
Disruption of the nuclear MRS2 gene (mrs2-1 mutation) causes a strong pet- phenotype in strains with mitochondrial group II introns, and a leaky pet- phenotype in strains without group II introns. MRS3 and MRS4, the genes for two mitochondrial-solute carrier proteins, can suppress both phenotypes when present in high-copy-number plasmids. In order to search for further multicopy suppressors of the mrs2-1 mutant phenotype, an yeast genomic DNA library, MW90, was constructed in YEp351 from a strain deleted for the MRS2, MRS3 and MRS4 genes. Ten different Sau3A DNA fragments that act as multicopy suppressors of the mrs2-1 respiratory-deficient phenotype were isolated from this library. Some of the newly isolated genes suppress the pet- phenotypes of mrs2-1 cells in strains with and without mitochondrial group II introns. Other genes, however, are suppressors only for the mitochondrial intron-less strains. This supports the notion that the MRS2 gene product is bifunctional i.e., it is essential for the splicing of group II introns and is also involved in processes of mitochondrial biogenesis other than RNA splicing.
Insights
Disrupting the MRS2 gene causes respiratory defects in yeast. Additional genes were identified that can suppress these defects, suggesting MRS2 has dual functions in mitochondrial biogenesis and intron splicing.
Area of Science:
- Molecular Biology
- Yeast Genetics
- Mitochondrial Biology
Background:
- The MRS2 gene is crucial for mitochondrial function in yeast.
- Mutations in MRS2 (mrs2-1) lead to respiratory-deficient (pet-) phenotypes.
- The severity of the pet- phenotype depends on the presence of mitochondrial group II introns.
Purpose of the Study:
- To identify novel multicopy suppressors of the mrs2-1 mutant phenotype.
- To further elucidate the functions of the MRS2 gene product.
Main Methods:
- Construction of a yeast genomic DNA library (MW90) from a strain lacking MRS2, MRS3, and MRS4.
- Screening the library for Sau3A DNA fragments that suppress the mrs2-1 pet- phenotype.
- Testing suppressor activity in yeast strains with and without mitochondrial group II introns.
Main Results:
- Ten novel multicopy suppressor DNA fragments were isolated.
- Some suppressors function in both intron-containing and intron-less strains.
- Other suppressors are specific to intron-less strains, indicating differential genetic interactions.
Conclusions:
- The MRS2 gene product likely possesses bifunctional activity.
- MRS2 is essential for mitochondrial group II intron splicing.
- MRS2 is also involved in mitochondrial biogenesis processes independent of RNA splicing.