1
|
Aphasizheva I, Maslov DA, Aphasizhev R. Kinetoplast DNA-encoded ribosomal protein S12: a possible functional link between mitochondrial RNA editing and translation in Trypanosoma brucei. RNA Biol 2013; 10:1679-88. [PMID: 24270388 DOI: 10.4161/rna.26733] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Mitochondrial ribosomes of Trypanosoma brucei are composed of 9S and 12S rRNAs, which are encoded by the kinetoplast genome, and more than 150 proteins encoded in the nucleus and imported from the cytoplasm. However, a single ribosomal protein RPS12 is encoded by the kinetoplast DNA (kDNA) in all trypanosomatid species examined. As typical for these organisms, the gene itself is cryptic and its transcript undergoes an extensive U-insertion/deletion editing. An evolutionary trend to reduce or eliminate RNA editing could be traced with other cryptogenes, but the invariably pan-edited RPS12 cryptogene is apparently spared. Here we inquired whether editing of RPS12 mRNA is essential for mitochondrial translation. By RNAi-mediated knockdowns of RNA editing complexes and inducible knock-in of a key editing enzyme in procyclic parasites, we could reversibly downregulate production of edited RPS12 mRNA and, by inference, synthesis of this protein. While inhibition of editing decreased edited mRNA levels, the translation of edited (Cyb) and unedited (COI) mRNAs was blocked. Furthermore, the population of SSU-related 45S complexes declined upon inactivation of editing and so did the amount of mRNA-bound ribosomes. In bloodstream parasites, which lack active electron transport chain but still require translation of ATP synthase subunit 6 mRNA (A6), both edited RPS12 and A6 mRNAs were detected in translation complexes. Collectively, our results indicate that a single ribosomal protein gene retained by the kinetoplast mitochondrion serves as a possible functional link between editing and translation processes and provide the rationale for the evolutionary conservation of RPS12 pan-editing.
Collapse
Affiliation(s)
- Inna Aphasizheva
- Department of Molecular and Cell Biology; Boston University Goldman School of Dental Medicine; Boston, MA USA
| | - Dmitri A Maslov
- Department of Biology; University of California at Riverside; Riverside, CA USA
| | - Ruslan Aphasizhev
- Department of Molecular and Cell Biology; Boston University Goldman School of Dental Medicine; Boston, MA USA
| |
Collapse
|
2
|
Paris Z, Horáková E, Rubio MAT, Sample P, Fleming IM, Armocida S, Lukeš J, Alfonzo JD. The T. brucei TRM5 methyltransferase plays an essential role in mitochondrial protein synthesis and function. RNA (NEW YORK, N.Y.) 2013; 19:649-658. [PMID: 23520175 PMCID: PMC3677280 DOI: 10.1261/rna.036665.112] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Accepted: 03/01/2013] [Indexed: 06/01/2023]
Abstract
All tRNAs undergo post-transcriptional chemical modifications as part of their natural maturation pathway. Some modifications, especially those in the anticodon loop, play important functions in translational efficiency and fidelity. Among these, 1-methylguanosine, at position 37 (m(1)G37) of the anticodon loop in several tRNAs, is evolutionarily conserved and participates in translational reading frame maintenance. In eukaryotes, the tRNA methyltransferase TRM5 is responsible for m(1)G formation in nucleus-encoded as well as mitochondria-encoded tRNAs, reflecting the universal importance of this modification for protein synthesis. However, it is not clear what role, if any, mitochondrial TRM5 serves in organisms that do not encode tRNAs in their mitochondrial genomes. These organisms may easily satisfy the m(1)G37 requirement through their robust mitochondrial tRNA import mechanisms. We have explored this possibility in the parasitic protist Trypanosoma brucei and show that down-regulation of TRM5 by RNAi leads to the expected disappearance of m(1)G37, but with surprisingly little effect on cytoplasmic translation. On the contrary, lack of TRM5 causes a marked growth phenotype and a significant decrease in mitochondrial functions, including protein synthesis. These results suggest mitochondrial TRM5 may be needed to mature unmethylated tRNAs that reach the mitochondria and that could pose a problem for translational fidelity. This study also reveals an unexpected lack of import specificity between some fully matured and potentially defective tRNA species.
Collapse
Affiliation(s)
- Zdeněk Paris
- Department of Microbiology, Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
| | - Eva Horáková
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, and Faculty of Sciences, University of South Bohemia, 37005 České Budějovice (Budweis), Czech Republic
| | - Mary Anne T. Rubio
- Department of Microbiology, Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
| | - Paul Sample
- Department of Microbiology, Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
| | - Ian M.C. Fleming
- Department of Microbiology, Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
| | - Stephanie Armocida
- Department of Microbiology, Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
| | - Julius Lukeš
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, and Faculty of Sciences, University of South Bohemia, 37005 České Budějovice (Budweis), Czech Republic
| | - Juan D. Alfonzo
- Department of Microbiology, Center for RNA Biology, The Ohio State University, Columbus, Ohio 43210, USA
- Ohio State Biochemistry Program, The Ohio State University, Columbus, Ohio 43210, USA
| |
Collapse
|
3
|
Roldán A, Comini MA, Crispo M, Krauth-Siegel RL. Lipoamide dehydrogenase is essential for both bloodstream and procyclic Trypanosoma brucei. Mol Microbiol 2011; 81:623-39. [DOI: 10.1111/j.1365-2958.2011.07721.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
|
4
|
Niemann M, Schneider A, Cristodero M. Mitochondrial translation in trypanosomatids: a novel target for chemotherapy? Trends Parasitol 2011; 27:429-33. [PMID: 21531629 DOI: 10.1016/j.pt.2011.03.011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 03/30/2011] [Accepted: 03/31/2011] [Indexed: 01/31/2023]
Abstract
Trypanosomatids cause widespread disease in humans and animals. Treatment of many of these diseases is hampered by the lack of efficient and safe drugs. New strategies for drug development are therefore urgently needed. It has long been known that the single mitochondrion of trypanosomatids exhibits many unique features. Recently, the mitochondrial translation machinery of trypanosomatids has been the focus of several studies, which revealed interesting variations to the mammalian system. It is the aim of this article to review these unique features and to discuss them in the larger biological context. It is our opinion that some of these features represent promising novel targets for chemotherapeutic intervention that should be studied in more detail.
Collapse
Affiliation(s)
- Moritz Niemann
- Department of Chemistry and Biochemistry, University of Bern, Freiestr. 3, 3012 Bern, Switzerland.
| | | | | |
Collapse
|