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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
Summary
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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