title: Giardia mitosomes and trichomonad hydrogenosomes share a common mode of protein targeting.
abstract: Mitochondria are archetypal organelles of endosymbiotic origin in eukaryotic cells. Some unicellular eukaryotes (protists) were considered to be primarily amitochondrial organisms that diverged from the eukaryotic lineage before the acquisition of the premitochondrial endosymbiont, but their amitochondrial status was recently challenged by the discovery of mitochondria-like double membrane-bound organelles called mitosomes. Here, we report that proteins targeted into mitosomes of Giardia intestinalis have targeting signals necessary and sufficient to be recognized by the mitosomal protein import machinery. Expression of these mitosomal proteins in Trichomonas vaginalis results in targeting to hydrogenosomes, a hydrogen-producing form of mitochondria. We identify, in Giardia and Trichomonas, proteins related to the component of the translocase in the inner membrane from mitochondria and the processing peptidase. A shared mode of protein targeting supports the hypothesis that mitosomes, hydrogenosomes, and mitochondria represent different forms of the same fundamental organelle having evolved under distinct selection pressures.
authors.affiliation: Department of Parasitology, Charles University, Vinicna 7, 128 44 Prague 2, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Dolezal
authors.forename: Ondrej
authors.initials: O
authors.lastname: Smíd
authors.forename: Petr
authors.initials: P
authors.lastname: Rada
authors.forename: Zuzana
authors.initials: Z
authors.lastname: Zubácová
authors.forename: Dejan
authors.initials: D
authors.lastname: Bursać
authors.forename: Robert
authors.initials: R
authors.lastname: Suták
authors.forename: Jana
authors.initials: J
authors.lastname: Nebesárová
authors.forename: Trevor
authors.initials: T
authors.lastname: Lithgow
authors.forename: Jan
authors.initials: J
authors.lastname: Tachezy
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001693:Biological Transport, Active; D019143:Evolution, Molecular; D005288:Ferredoxins / Q000235:genetics / Q000378:metabolism; D016829:Giardia lamblia / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D007506:Iron-Sulfur Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D015388:Organelles / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014246:Trichomonas vaginalis / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D005288:Ferredoxins; D007506:Iron-Sulfur Proteins; D015800:Protozoan Proteins; D011994:Recombinant Proteins