Mitochondrial-nuclear co-evolution leads to hybrid incompatibility through pentatricopeptide repeat proteins

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Han-Ying Jhuang1,2, Hsin-Yi Lee1,3, Jun-Yi Leu4,2

  • 1Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan.

EMBO Reports
|December 7, 2016
PubMed

Insights

Mitochondrial-nuclear incompatibility, a cause of reproductive isolation, is driven by fast co-evolution between PPR proteins and mitochondrial RNA. This study identifies Ccm1 and 15S rRNA as key players in yeast hybrid incompatibility.

Area of Science:

  • Evolutionary Biology
  • Genetics
  • Molecular Biology

Background:

  • Mitochondrial-nuclear incompatibility significantly contributes to reproductive isolation between species.
  • The precise mechanisms and evolutionary drivers of this incompatibility are not fully understood.

Purpose of the Study:

  • To investigate the molecular basis of hybrid incompatibility between Saccharomyces cerevisiae and Saccharomyces bayanus.
  • To identify specific proteins and RNA molecules involved in this interspecies reproductive barrier.

Main Methods:

  • Identified a pentatricopeptide repeat-containing (PPR) protein, Ccm1, and its interaction with 15S rRNA.
  • Assessed binding affinity between S. bayanus-Ccm1 and S. cerevisiae-15S rRNA.
  • Analyzed the impact of mutations on PPR protein function and compatibility within Saccharomyces sensu stricto yeasts.

Main Results:

  • S. bayanus-Ccm1 exhibits reduced binding affinity to S. cerevisiae-15S rRNA, causing respiratory defects in hybrid yeast.
  • Single mutations in PPR motifs can rescue this incompatibility, highlighting the adaptability of PPR proteins.
  • Approximately two-thirds of examined PPR proteins in related Saccharomyces species showed detectable incompatibility.

Conclusions:

  • Fast co-evolution between flexible PPR proteins and mitochondrial RNA substrates is a likely common driver of mitochondrial-nuclear hybrid incompatibility.
  • PPR proteins and their RNA targets are crucial in the speciation process through reproductive isolation.
Keywords:
PPR proteinhybrid incompatibilitymitochondrial–nuclear co‐evolutionyeast speciation

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