A functional bacteria-derived restriction modification system in the mitochondrion of a heterotrophic protist

David S Milner, Jeremy G Wideman, Courtney W Stairs, Cory D Dunn, Thomas A Richards

Research output: Contribution to journalArticlepeer-review

Abstract

The overarching trend in mitochondrial genome evolution is functional streamlining coupled with gene loss; therefore, gene acquisition by mitochondria is considered to be exceedingly rare. Selfish elements in the form of self-splicing introns occur in many organellar genomes, but the wider diversity of selfish elements, and how they persist in the DNA of organelles, has not been explored. In the mitochondrial genome of a marine heterotrophic katablepharid protist, we identify a functional type II restriction modification (RM) system originating from a horizontal gene transfer (HGT) event involving bacteria related to flavobacteria. This RM system consists of an HpaII-like endonuclease and a cognate cytosine methyltransferase (CM). We demonstrate that these proteins are functional by heterologous expression in both bacterial and eukaryotic cells. These results suggest that a mitochondrial-encoded RM system can function as a toxin-antitoxin selfish element and that such elements could be co-opted by eukaryotic genomes to drive biased organellar inheritance.

Original languageEnglish
Article numbere3001126
Number of pages19
JournalPLoS Biology
Volume19
Issue number4
Early online date2021 Apr 23
DOIs
Publication statusPublished - 2021

Subject classification (UKÄ)

  • Microbiology

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