Journal Article

Fungal Hydrogenosomes Contain Mitochondrial Heat-Shock Proteins

Mark van der Giezen, Graeme M. Birdsey, David S. Horner, John Lucocq, Patricia L. Dyal, Marlene Benchimol, Christopher J. Danpure and T. Martin Embley

in Molecular Biology and Evolution

Published on behalf of Society for Molecular Biology and Evolution

Volume 20, issue 7, pages 1051-1061
Published in print July 2003 | ISSN: 0737-4038
Published online July 2003 | e-ISSN: 1537-1719 | DOI:

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At least three groups of anaerobic eukaryotes lack mitochondria and instead contain hydrogenosomes, peculiar organelles that make energy and excrete hydrogen. Published data indicate that ciliate and trichomonad hydrogenosomes share common ancestry with mitochondria, but the evolutionary origins of fungal hydrogenosomes have been controversial. We have now isolated full-length genes for heat shock proteins 60 and 70 from the anaerobic fungus Neocallimastix patriciarum, which phylogenetic analyses reveal share common ancestry with mitochondrial orthologues. In aerobic organisms these proteins function in mitochondrial import and protein folding. Homologous antibodies demonstrated the localization of both proteins to fungal hydrogenosomes. Moreover, both sequences contain amino-terminal extensions that in heterologous targeting experiments were shown to be necessary and sufficient to locate both proteins and green fluorescent protein to the mitochondria of mammalian cells. This finding, that fungal hydrogenosomes use mitochondrial targeting signals to import two proteins of mitochondrial ancestry that play key roles in aerobic mitochondria, provides further strong evidence that the fungal organelle is also of mitochondrial ancestry. The extraordinary capacity of eukaryotes to repeatedly evolve hydrogen-producing organelles apparently reflects a general ability to modify the biochemistry of the mitochondrial compartment.

Keywords: heat-shock proteins; hydrogenosomes; mitochondria; anaerobic eukaryotes; evolution

Journal Article.  6536 words.  Illustrated.

Subjects: Evolutionary Biology ; Molecular and Cell Biology