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Novel mitochondrion‐related organelles in the anaerobic amoeba Mastigamoeba balamuthi
Author(s) -
Gill Erin E.,
DiazTriviño Sara,
Barberà Maria José,
Silberman Jeffrey D.,
Stechmann Alexandra,
Gaston Daniel,
Tamas Ivica,
Roger Andrew J.
Publication year - 2007
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2007.05979.x
Subject(s) - organelle , biology , eukaryote , entamoeba histolytica , mitochondrion , amoeba (genus) , proteome , entamoeba , microbiology and biotechnology , biochemistry , gene , genetics , genome
Summary Unicellular eukaryotes that lack mitochondria typically contain related organelles such as hydrogenosomes or mitosomes. To characterize the evolutionary diversity of these organelles, we conducted an expressed sequence tag (EST) survey on the free‐living amoeba Mastigamoeba balamuthi , a relative of the human parasite Entamoeba histolytica . From 19 182 ESTs, we identified 21 putative mitochondrial proteins implicated in protein import, amino acid interconversion and carbohydrate metabolism, two components of the iron–sulphur cluster (Fe‐S) assembly apparatus as well as two enzymes characteristic of hydrogenosomes. By immunofluorescence microscopy and subcellular fractionation, we show that mitochondrial chaperonin 60 is targeted to small abundant organelles within Mastigamoeba . In transmission electron micrographs, we identified double‐membraned compartments that likely correspond to these mitochondrion‐derived organelles, The predicted organellar proteome of the Mastigamoeba organelle indicates a unique spectrum of functions that collectively have never been observed in mitochondrion‐related organelles. However, like Entamoeba , the Fe‐S cluster assembly proteins in Mastigamoeba were acquired by lateral gene transfer from ε‐proteobacteria and do not possess obvious organellar targeting peptides. These data indicate that the loss of classical aerobic mitochondrial functions and acquisition of anaerobic enzymes and Fe‐S cluster assembly proteins occurred in a free‐living member of the eukaryote super‐kingdom Amoebozoa.