| Autor: |
Epremyan KK; A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskiye Gory, 1-40, 119234 Moscow, Russia., Burlaka AA; Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Leninskiye Gory, 1-73, 119234 Moscow, Russia., Markova OV; A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskiye Gory, 1-40, 119234 Moscow, Russia., Galkina KV; A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskiye Gory, 1-40, 119234 Moscow, Russia., Knorre DA; A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskiye Gory, 1-40, 119234 Moscow, Russia. |
| Abstrakt: |
Unlike most animals, some fungi, including baker's yeast, inherit mitochondrial DNA (mtDNA) from both parents. When haploid yeast cells fuse, they form a heteroplasmic zygote, whose offspring retain one or the other variant of mtDNA. Meanwhile, some mutant mtDNA ( rho - ), with large deletions in the nucleotide sequence, can displace wild-type ( rho + ) mtDNA. Consequently, offspring of zygotes with such rho - mtDNA predominantly carry the mutant variant. This phenomenon is called suppressivity. In this study, we investigated how the suppressivity of rho - mtDNA depends on the mitochondrial and nuclear genomes of the rho + strain during crossing. Comparing two diverged laboratory strains, SK1 and W303 , we measured suppressivity in crosses with four rho - strains. One rho - strain showed significantly higher suppressivity when crossed with SK1 than with W303 . We then created cytoplasmic hybrids by swapping mtDNAs between these strains. Surprisingly, we found that the mtDNA of the rho + strain, rather than its nuclear DNA, determines high suppressivity in crosses of SK1 rho + with the rho - strain. Additionally, mtDNA replacement reduced respiration rate and growth rate on non-fermentable substrates while increasing the likelihood of functional mtDNA loss. Our data demonstrate that a mutant mtDNA variant's ability to displace another mitochondrial DNA variant in a heteroplasmic cell depends more on mtDNA sequences than on the biochemical and structural context created by the nuclear genome background. |
