title: A trypanosomal pentatricopeptide repeat protein stabilizes the mitochondrial mRNAs of cytochrome oxidase subunits 1 and 2.
abstract: The pentatricopeptide repeat (PPR) protein family consists of organellar proteins predicted to bind to specific RNA sequences. Plants have hundreds of distinct PPR proteins, whereas other eukaryotes generally have many fewer. The genome of the parasitic protozoon Trypanosoma brucei is predicted to encode more than 30 different PPR proteins, which is an extraordinarily high number for a nonplant organism. Here we report the characterization T. brucei PPR9 (TbPPR9). Epitope tagging shows that the protein is exclusively mitochondrially localized. Interestingly, while in induced RNA interference cell lines TbPPR9 is efficiently downregulated, the level of its mRNA is not affected. Ablation of TbPPR9 selectively abolishes oxidative but not mitochondrial substrate-level phosphorylation. The molecular basis of this phenotype is the fact that TbPPR9 is required for the stability of the cytochrome oxidase subunit 1 (COX1) and COX2 mRNAs. This is supported by the observation that ablation of TbPPR9 destabilizes the COX complex but not the cytochrome bc1 or the ATP synthase complex. Moreover, it was shown by blue native gel electrophoresis that TbPPR9 is present in a large complex of unknown composition.
authors: Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland.
authors: Mascha
authors: M
authors: Pusnik
authors: André
authors: A
authors: Schneider
mesh_terms: D014450:Electron Transport Complex III / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000235:genetics* / Q000378:metabolism; D055785:Gene Knockdown Techniques; D008928:Mitochondria / Q000201:enzymology* / Q000235:genetics; D025261:Mitochondrial Proton-Translocating ATPases / Q000378:metabolism; D010085:Oxidative Phosphorylation; D055550:Protein Stability; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D020871:RNA Stability; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D014346:Trypanosoma brucei brucei / Q000201:enzymology* / Q000235:genetics; D039221:mRNA Cleavage and Polyadenylation Factors / Q000378:metabolism
chemical_list: D015800:Protozoan Proteins; D016601:RNA-Binding Proteins; D039221:mRNA Cleavage and Polyadenylation Factors; D003576:Electron Transport Complex IV; D025261:Mitochondrial Proton-Translocating ATPases; D014450:Electron Transport Complex III