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Mitochondria and hydrogenosomes are two forms of the same fundamental organelle

Lookup NU author(s): Emeritus Professor T. Martin Embley FMedSci FRSORCiD

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Abstract

Published data suggest that hydrogenosomes, organelles found in diverse anaerobic eukaryotes that make energy and hydrogen, were once mitochondria. As hydrogenosomes generally lack a genome, the conversion is probably one way. The sources of the key hydrogenosomal enzymes, pyruvate : ferredoxin oxidoreductase (PFO) and hydrogenase, are not resolved by current phylogenetic analyses, but it is likely that both were present at an early stage of eukaryotic evolution. Once thought to be restricted to a few unusual anaerobic eukaryotes, the proteins are intimately integrated into the fabric of diverse eukaryotic cells, where they are targeted to different cell compartments, and not just hydrogenosomes. There is no evidence supporting the view that PFO and hydrogenase originated from the mitochondrial endosymbiont, as posited by the hydrogen hypothesis for eukaryogenesis. Other organelles derived from mitochondria have now been described in anaerobic and parasitic microbial eukaryotes, including species that were once thought to have diverged before the mitochondrial symbiosis. It thus seems possible that all eukaryotes may eventually be shown to contain an organelle of mitochondrial ancestry, to which different types of biochemistry can be targeted. It remains to be seen if, despite their obvious differences, this family of organelles shares a common function of importance for the eukaryotic cell, other than energy production, that might provide the underlying selection pressure for organelle retention.


Publication metadata

Author(s): Embley TM, van der Giezen M, Horner DS, Dyal PL, Foster P

Publication type: Article

Publication status: Published

Journal: Philosophical Transactions of the Royal Society of London, B: Biological Sciences

Year: 2003

Volume: 358

Issue: 1429

Pages: 191-203

ISSN (print): 0962-8436

ISSN (electronic): 1471-2970

Publisher: Royal Society Publishing

PubMed id: 12594927

Notes: 22484190
0962-8436
Journal Article


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