Single-celled protists in the guts of animals thrive without the ‘powerhouse of the cell’

Almost all eukaryotic organisms, from plants and animals to fungi, can’t survive without mitochondria – the “powerhouses of the cell,” which generate chemical energy using oxygen. However, a new study by Lukáš Novák and Vladimír Hampl of Charles University, published in the journal PLOS Genetics, finds that multiple members of the oxymonads, a group of single-celled protists that live inside the guts of termites and other animals, have evolved to live quite happily without them.

Many groups of protists have evolved simplified mitochondria, but for a long time, scientists thought it was impossible for a species to completely lose them. The first eukaryotic organism discovered to live without mitochondria was an oxymonad isolated from the intestines of a chinchilla. In the new study, the research team looked to see if similar organisms had also shed them. They compared genomic data from the original oxymonad to multiple related species to see if they could decipher how the organisms evolved to live without this supposedly vital part of the cell.

The researchers showed that multiple oxymonads have gotten rid of their mitochondria – possibly the entire lineage. This event likely would have occurred at least 100 million years ago, before the ancestor of the oxymonads diversified into multiple species. The findings also demonstrate that it’s possible for  eukaryotic organisms to thrive without mitochondria, and to evolve into the wide range of shapes and specialized structures seen in oxymonads living today.

The authors add: "These microbes have been thriving without mitochondria since the age of dinosaurs."

#####

In your coverage, please use this URL to provide access to the freely available article in PLOS Genetics:

https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1011050

Citation: Novák LVF, Treitli SC, Pyrih J, Hałakuc P, Pipaliya SV, Vacek V, et al. (2023) Genomics of Preaxostyla Flagellates Illuminates the Path Towards the Loss of Mitochondria. PLoS Genetics 19(12): e1011050. https://doi.org/10.1371/journal.pgen.1011050

Author Countries: Canada, Czech Republic, France, Germany, Poland

Funding: This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 771592 to VH) and the Centre for research of pathogenicity and virulence of parasites (registration no. CZ.02.1.01/0.0/0.0/16_019/0000759). Research in Karnkowska lab was supported by EMBO Installation Grant 4150 and Ministry of Education and Science, Poland and the Interdisciplinary Centre for Mathematical and Computational Modelling (ICM) University of Warsaw under computational allocation no. G 72-16. Research in the Dacks Lab is supported by grants from the Natural Sciences and Research Council of Canada (RES0021028, RES0043758, and RES0046091) and SVP received salary support through Alberta Innovates Graduate Studentship (Doctoral) and Canadian Institutes of Health Research Canada Graduate Scholarships. LE was supported by an ERC Starting grant (803151). ME was supported by the Czech Science Foundation project 22-29633S. LVFN, SCT, JP, VV, OB, PS, and VH received a salary from ERC (771592). ME received a salary from the Czech Science Foundation (22-29633S). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.