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Replication and preferential inheritance of hypersuppressive petite mitochondrial DNA

D M MacAlpine1, J Kolesar, K Okamoto

  • 1Department of Molecular Biology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-9148, USA.

The EMBO Journal
|April 4, 2001
PubMed

Insights

Hypersuppressive petite yeast mitochondrial DNA (mtDNA) is uniparentally inherited due to a promoter-dependent RNA-primed replication mechanism, not preferential segregation. This explains its unique inheritance pattern in crosses.

Area of Science:

  • Molecular Biology
  • Genetics
  • Yeast Biology

Background:

  • Wild-type yeast mitochondrial DNA (mtDNA) exhibits biparental inheritance.
  • Hypersuppressive petite mutants display uniparental mtDNA inheritance in crosses with wild-type strains.
  • The role of the conserved ori sequence in hypersuppressive petite mtDNA remains unclear.

Purpose of the Study:

  • To investigate the mechanism underlying the uniparental inheritance of hypersuppressive petite mtDNA.
  • To determine if the ori sequence confers a segregation or replication advantage.
  • To elucidate the role of the promoter within the ori sequence.

Main Methods:

  • Fluorescent in situ hybridization (FISH) to analyze mtDNA segregation in yeast crosses.
  • Analysis of DNA replication intermediates in wild-type and petite mtDNA.
  • Site-directed mutagenesis of the promoter within the ori sequence.

Main Results:

  • No preferential segregation of hypersuppressive petite mtDNA to zygotic buds was observed.
  • Single-stranded DNA circles and RNA-primed DNA replication intermediates were identified in hypersuppressive petite mtDNA.
  • Mutating the promoter abolished hypersuppressiveness and eliminated distinctive replication intermediates.

Conclusions:

  • Uniparental inheritance of hypersuppressive petite mtDNA is not due to preferential segregation.
  • Promoter-dependent RNA-primed replication is the likely mechanism driving hypersuppressive petite mtDNA inheritance.
  • This mechanism provides a replication advantage, leading to uniparental inheritance.

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