A Eukaryote without a Mitochondrial Organelle
Anna Karnkowska7, correspondence email, Vojtěch Vacek, Zuzana Zubáčová, Sebastian C. Treitli, Romana Petrželková, Laura Eme, Lukáš Novák, Vojtěch Žárský, Lael D. Barlow, Emily K. Herman, Petr Soukal, Miluše Hroudová, Pavel Doležal, Courtney W. Stairs, Andrew J. Roger, Marek Eliáš, Joel B. Dacks, Čestmír Vlček, Vladimír Hampl correspondence email
7Present address: Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
Publication stage: In Press Corrected Proof
Highlights
• Monocercomonoides sp. is a eukaryotic microorganism with no mitochondria
• The complete absence of mitochondria is a secondary loss, not an ancestral feature
• The essential mitochondrial ISC pathway was replaced by a bacterial SUF system
Summary
The presence of mitochondria and related organelles in every studied eukaryote supports the view that mitochondria are essential cellular components. Here, we report the genome sequence of a microbial eukaryote, the oxymonad Monocercomonoides sp., which revealed that this organism lacks all hallmark mitochondrial proteins. Crucially, the mitochondrial iron-sulfur cluster assembly pathway, thought to be conserved in virtually all eukaryotic cells, has been replaced by a cytosolic sulfur mobilization system (SUF) acquired by lateral gene transfer from bacteria. In the context of eukaryotic phylogeny, our data suggest that Monocercomonoides is not primitively amitochondrial but has lost the mitochondrion secondarily. This is the first example of a eukaryote lacking any form of a mitochondrion, demonstrating that this organelle is not absolutely essential for the viability of a eukaryotic cell.
Received: December 23, 2015; Received in revised form: March 5, 2016; Accepted: March 23, 2016; Published: May 12, 2016
© 2016 Elsevier Ltd. Published by Elsevier Inc. All rights reserved.
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