title: Mitochondrial ribosomes in a trypanosome.
abstract: The nature, and even the existence, of trypanosome mitochondrial ribosomes has been the subject of some debate. We investigated this further in the insect trypanosome, Crithidia fasciculata. In sucrose gradients of parasite lysates, mitochondrial ribosomal RNA co-sediments at approximately 35S with nascent peptides synthesized in the presence of the cytosolic translational inhibitor, cycloheximide. Co-sedimenting peptides in this peak are much reduced when the parasites are treated with the bacterial translational inhibitor, chloramphenicol. In CsCl gradients this peak resolves at a buoyant density of 1.42 g/cm(3), a value typical for mito-ribosomes. Electron microscopy of peak material shows particles smaller than cytosolic ribosomes, but with characteristic ribosomal shapes. We propose that these particles represent the parasite's mitochondrial ribosomes.
authors.affiliation: Department of Molecular Biology, University of Umeå, Umeå S-901 87, Sweden. ivor.tittawella@molbiol.umu.se
authors.forename: Ivor
authors.initials: I
authors.lastname: Tittawella
authors.forename: Lubna
authors.initials: L
authors.lastname: Yasmin
authors.forename: Vladimir
authors.initials: V
authors.lastname: Baranov
mesh_terms: D000818:Animals; D002499:Centrifugation, Density Gradient; D016831:Crithidia fasciculata / Q000648:ultrastructure*; D008928:Mitochondria / Q000648:ultrastructure*; D010455:Peptides / Q000378:metabolism; D014176:Protein Biosynthesis; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D010455:Peptides