<p>In <i>Saccharomyces cerevisiae</i>, an asymmetrical division model, mitochondrial (mt) DNA typically exists in a homoplasmic state, but mutations frequently occur. Rolling-circle replication, mediated by the mtDNA recombinase Mhr1p, forms tandem concatemers that are selectively transmitted to budding cells. In crosses between haploids with wild-type (ρ<sup>+</sup>) and hypersuppressive (HS) ρ<sup>−</sup> mtDNA, ρ<sup>−</sup> progeny are predominantly produced due to the replicative advantage of mtDNA with large deletions. We investigated the effects of caloric restriction (CR; 0.5% glucose medium) on mitochondrial distribution and found that ρ<sup>+</sup> mtDNA-mitochondria are pre-selected in zygotes and transmitted into buds prior to mitochondrial fusion. This process, termed ρ<sup>+</sup> mtDNA-mitochondrial preselection and transmission (ρ<sup>+</sup> mtDNA-MPT), was validated by confocal imaging and flow cytometry analyses. The rate of ρ<sup>+</sup> progeny increased under CR conditions compared to glucose-abundant media, suggesting that CR enhances ρ<sup>+</sup> mtDNA-MPT and promotes the formation of wild-type mtDNA homoplasmy via an Mhr1p-dependent mechanism, which dominates mtDNA inheritance.</p>

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Caloric restriction enhances inheritance of wild-type mitochondrial DNA in Saccharomyces cerevisiae

  • Wenjuan Zhu,
  • Minoru Yoshida,
  • Feng Ling

摘要

In Saccharomyces cerevisiae, an asymmetrical division model, mitochondrial (mt) DNA typically exists in a homoplasmic state, but mutations frequently occur. Rolling-circle replication, mediated by the mtDNA recombinase Mhr1p, forms tandem concatemers that are selectively transmitted to budding cells. In crosses between haploids with wild-type (ρ+) and hypersuppressive (HS) ρ mtDNA, ρ progeny are predominantly produced due to the replicative advantage of mtDNA with large deletions. We investigated the effects of caloric restriction (CR; 0.5% glucose medium) on mitochondrial distribution and found that ρ+ mtDNA-mitochondria are pre-selected in zygotes and transmitted into buds prior to mitochondrial fusion. This process, termed ρ+ mtDNA-mitochondrial preselection and transmission (ρ+ mtDNA-MPT), was validated by confocal imaging and flow cytometry analyses. The rate of ρ+ progeny increased under CR conditions compared to glucose-abundant media, suggesting that CR enhances ρ+ mtDNA-MPT and promotes the formation of wild-type mtDNA homoplasmy via an Mhr1p-dependent mechanism, which dominates mtDNA inheritance.