Massive mitochondrial DNA content in diplonemid and kinetoplastid protists

Julius Lukeš, Richard Wheeler, Dagmar Jirsová, Vojtěch David, John M. Archibald

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41 Citas (Scopus)

Resumen

The mitochondrial DNA of diplonemid and kinetoplastid protists is known for its suite of bizarre features, including the presence of concatenated circular molecules, extensive trans-splicing and various forms of RNA editing. Here we report on the existence of another remarkable characteristic: hyper-inflated DNA content. We estimated the total amount of mitochondrial DNA in four kinetoplastid species (Trypanosoma brucei, Trypanoplasma borreli, Cryptobia helicis, and Perkinsela sp.) and the diplonemid Diplonema papillatum. Staining with 4′,6-diamidino-2-phenylindole and RedDot1 followed by color deconvolution and quantification revealed massive inflation in the total amount of DNA in their organelles. This was further confirmed by electron microscopy. The most extreme case is the ∼260 Mbp of DNA in the mitochondrion of Diplonema, which greatly exceeds that in its nucleus; this is, to our knowledge, the largest amount of DNA described in any organelle. Perkinsela sp. has a total mitochondrial DNA content ~6.6× greater than its nuclear genome. This mass of DNA occupies most of the volume of the Perkinsela cell, despite the fact that it contains only six protein-coding genes. Why so much DNA? We propose that these bloated mitochondrial DNAs accumulated by a ratchet-like process. Despite their excessive nature, the synthesis and maintenance of these mtDNAs must incur a relatively low cost, considering that diplonemids are one of the most ubiquitous and speciose protist groups in the ocean.

Idioma originalEnglish
Páginas (desde-hasta)1267-1274
Número de páginas8
PublicaciónIUBMB Life
Volumen70
N.º12
DOI
EstadoPublished - dic. 2018

Nota bibliográfica

Funding Information:
This research was supported by the Czech Grant Agency (15-21974S), ERC CZ (LL1601) and ERD Funds, project OPVVV 16_019/0000759 (to J.L.), the Canadian Institutes of Health Research (MOP-115141) (to J.M.A.), and a Wellcome Trust Sir Henry Wellcome postdoctoral fellowship (103261/Z/13/Z) (to R.-J.W.). We thank two reviewers for helpful feedback on an earlier version of this manuscript.

Publisher Copyright:
© 2018 International Union of Biochemistry and Molecular Biology

ASJC Scopus Subject Areas

  • Biochemistry
  • Molecular Biology
  • Genetics
  • Clinical Biochemistry
  • Cell Biology

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't

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