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Mutations in the mitochondrial ATP synthase gamma subunit suppress a slow-growth phenotype of yme1 yeast lacking
E R Weber1, R S Rooks, K S Shafer
1Department of Molecular Biology, University of Wyoming, Laramie 82071-3944, USA.
Abstract:
In Saccharomyces cerevisiae, inactivation of the nuclear gene YME1 causes several phenotypes associated with impairment of mitochondrial function. In addition to deficiencies in mitochondrial compartment integrity and respiratory growth, yme1 mutants grow extremely slowly in the absence of mitochondrial DNA. We have identified two genetic loci that, when mutated, act as dominant suppressors of the slow-growth phenotype of yme1 strains lacking mitochondrial DNA. These mutations only suppressed the slow-growth phenotype of yme1 strains lacking mitochondrial DNA and had no effect on other phenotypes associated with yme1 mutations. One allele of one linkage group had a collateral respiratory deficient phenotype that allowed the isolation of the wild-type gene. This suppressing mutation was in ATP3, a gene that encodes the gamma subunit of the mitochondrial ATP synthase. Recovery of two of the suppressing ATP3 alleles and subsequent sequence analysis placed the suppressing mutations at strictly conserved residues near the C terminus of Atp3p. Deletion of the ATP3 genomic locus resulted in an inability to utilize nonfermentable carbon sources. atp3 deletion strains lacking mitochondrial DNA grew slowly on glucose media but were not as compromised for growth as yme1 yeast lacking mitochondrial DNA.
Insights
Mutations in ATP3 suppress slow growth in yeast lacking mitochondrial DNA and YME1 function. This finding highlights ATP3
Area of Science:
- Mitochondrial biology
- Yeast genetics
Background:
- Nuclear gene YME1 inactivation impairs mitochondrial function in Saccharomyces cerevisiae.
- yme1 mutants exhibit slow growth without mitochondrial DNA, affecting compartment integrity and respiration.
Purpose of the Study:
- Identify genetic loci that suppress the slow-growth phenotype of yme1 mutants lacking mitochondrial DNA.
- Characterize the identified suppressor mutations and their effects on mitochondrial function.
Main Methods:
- Genetic screening for dominant suppressors of yme1 slow-growth phenotype.
- Allele recovery, sequencing, and functional analysis of suppressor genes.
- Deletion analysis of the identified suppressor gene (ATP3).
Main Results:
- Two genetic loci were identified as dominant suppressors of the yme1 slow-growth phenotype.
- One suppressor mutation was mapped to ATP3, encoding the gamma subunit of mitochondrial ATP synthase.
- Suppressing ATP3 mutations were located at conserved residues near the C terminus; ATP3 deletion caused slow growth in petite yeast.
Conclusions:
- Specific mutations in ATP3 can dominantly suppress the slow-growth defect of yme1 mutants lacking mitochondrial DNA.
- The gamma subunit of ATP synthase plays a role in mitigating growth defects associated with YME1 deficiency and mitochondrial dysfunction.
- These findings provide insights into the complex interplay between mitochondrial protein quality control and ATP synthesis in yeast.