1
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Wenger C, Harsman A, Niemann M, Oeljeklaus S, von Känel C, Calderaro S, Warscheid B, Schneider A. The Mba1 homologue of Trypanosoma brucei is involved in the biogenesis of oxidative phosphorylation complexes. Mol Microbiol 2023; 119:537-550. [PMID: 36829306 DOI: 10.1111/mmi.15048] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 02/16/2023] [Accepted: 02/21/2023] [Indexed: 02/26/2023]
Abstract
Consistent with other eukaryotes, the Trypanosoma brucei mitochondrial genome encodes mainly hydrophobic core subunits of the oxidative phosphorylation system. These proteins must be co-translationally inserted into the inner mitochondrial membrane and are synthesized by the highly unique trypanosomal mitoribosomes, which have a much higher protein to RNA ratio than any other ribosome. Here, we show that the trypanosomal orthologue of the mitoribosome receptor Mba1 (TbMba1) is essential for normal growth of procyclic trypanosomes but redundant in the bloodstream form, which lacks an oxidative phosphorylation system. Proteomic analyses of TbMba1-depleted mitochondria from procyclic cells revealed reduced levels of many components of the oxidative phosphorylation system, most of which belong to the cytochrome c oxidase (Cox) complex, three subunits of which are mitochondrially encoded. However, the integrity of the mitoribosome and its interaction with the inner membrane were not affected. Pull-down experiments showed that TbMba1 forms a dynamic interaction network that includes the trypanosomal Mdm38/Letm1 orthologue and a trypanosome-specific factor that stabilizes the CoxI and CoxII mRNAs. In summary, our study suggests that the function of Mba1 in the biogenesis of membrane subunits of OXPHOS complexes is conserved among yeast, mammals and trypanosomes, which belong to two eukaryotic supergroups.
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Affiliation(s)
- Christoph Wenger
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
| | - Anke Harsman
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
| | - Moritz Niemann
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
| | - Silke Oeljeklaus
- Faculty of Chemistry and Pharmacy, Biochemistry II, Theodor Boveri-Institute, University of Würzburg, Würzburg, Germany
| | - Corinne von Känel
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
| | - Salvatore Calderaro
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland
| | - Bettina Warscheid
- Faculty of Chemistry and Pharmacy, Biochemistry II, Theodor Boveri-Institute, University of Würzburg, Würzburg, Germany.,CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - André Schneider
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Bern, Switzerland.,Institute for Advanced Study (Wissenschaftskolleg) Berlin, Berlin, Germany
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2
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Dubey AP, Tylec BL, McAdams NM, Sortino K, Read L. Trypanosome RNAEditing Substrate Binding Complex integrity and function depends on the upstream action of RESC10. Nucleic Acids Res 2021; 49:3557-3572. [PMID: 33677542 PMCID: PMC8034615 DOI: 10.1093/nar/gkab129] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 02/11/2021] [Accepted: 02/17/2021] [Indexed: 01/17/2023] Open
Abstract
Uridine insertion/deletion editing of mitochondrial mRNAs is a characteristic feature of kinetoplastids, including Trypanosoma brucei. Editing is directed by trans-acting gRNAs and catalyzed by related RNA Editing Core Complexes (RECCs). The non-catalytic RNA Editing Substrate Binding Complex (RESC) coordinates interactions between RECC, gRNA and mRNA. RESC is a dynamic complex comprising GRBC (Guide RNA Binding Complex) and heterogeneous REMCs (RNA Editing Mediator Complexes). Here, we show that RESC10 is an essential, low abundance, RNA binding protein that exhibits RNase-sensitive and RNase-insensitive interactions with RESC proteins, albeit its minimal in vivo interaction with RESC13. RESC10 RNAi causes extensive RESC disorganization, including disruption of intra-GRBC protein-protein interactions, as well as mRNA depletion from GRBC and accumulation on REMCs. Analysis of mitochondrial RNAs at single nucleotide resolution reveals transcript-specific effects: RESC10 dramatically impacts editing progression in pan-edited RPS12 mRNA, but is critical for editing initiation in mRNAs with internally initiating gRNAs, pointing to distinct initiation mechanisms for these RNA classes. Correlations between sites at which editing pauses in RESC10 depleted cells and those in knockdowns of previously studied RESC proteins suggest that RESC10 acts upstream of these factors and that RESC is particularly important in promoting transitions between uridine insertion and deletion RECCs.
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Affiliation(s)
- Ashutosh P Dubey
- Department of Microbiology and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14203, USA
| | - Brianna L Tylec
- Department of Microbiology and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14203, USA
| | - Natalie M McAdams
- Department of Microbiology and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14203, USA
| | - Katherine Sortino
- Department of Microbiology and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14203, USA
| | - Laurie K Read
- Department of Microbiology and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14203, USA
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3
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Trenaman A, Glover L, Hutchinson S, Horn D. A post-transcriptional respiratome regulon in trypanosomes. Nucleic Acids Res 2019; 47:7063-7077. [PMID: 31127277 PMCID: PMC6648352 DOI: 10.1093/nar/gkz455] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Revised: 04/25/2019] [Accepted: 05/10/2019] [Indexed: 12/21/2022] Open
Abstract
Post-transcriptional regulons coordinate the expression of groups of genes in eukaryotic cells, yet relatively few have been characterized. Parasitic trypanosomatids are particularly good models for studies on such mechanisms because they exhibit almost exclusive polycistronic, and unregulated, transcription. Here, we identify the Trypanosoma brucei ZC3H39/40 RNA-binding proteins as regulators of the respiratome; the mitochondrial electron transport chain (complexes I-IV) and the FoF1-ATP synthase (complex V). A high-throughput RNAi screen initially implicated both ZC3H proteins in variant surface glycoprotein (VSG) gene silencing. This link was confirmed and both proteins were shown to form a cytoplasmic ZC3H39/40 complex. Transcriptome and mRNA-interactome analyses indicated that the impact on VSG silencing was indirect, while the ZC3H39/40 complex specifically bound and stabilized transcripts encoding respiratome-complexes. Quantitative proteomic analyses revealed specific positive control of >20 components from complexes I, II and V. Our findings establish a link between the mitochondrial respiratome and VSG gene silencing in bloodstream form T. brucei. They also reveal a major respiratome regulon controlled by the conserved trypanosomatid ZC3H39/40 RNA-binding proteins.
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Affiliation(s)
- Anna Trenaman
- The Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Lucy Glover
- The Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Sebastian Hutchinson
- The Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - David Horn
- The Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
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4
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Maslov DA. Separating the Wheat from the Chaff: RNA Editing and Selection of Translatable mRNA in Trypanosome Mitochondria. Pathogens 2019; 8:E105. [PMID: 31323762 PMCID: PMC6789859 DOI: 10.3390/pathogens8030105] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 07/14/2019] [Accepted: 07/16/2019] [Indexed: 11/16/2022] Open
Abstract
In the mitochondria of trypanosomes and related kinetoplastid protists, most mRNAs undergo a long and sophisticated maturation pathway before they can be productively translated by mitochondrial ribosomes. Some of the aspects of this pathway (identity of the promotors, transcription initiation, and termination signals) remain obscure, and some (post-transcriptional modification by U-insertion/deletion, RNA editing, 3'-end maturation) have been illuminated by research during the last decades. The RNA editing creates an open reading frame for a productive translation, but the fully edited mRNA often represents a minor fraction in the pool of pre-edited and partially edited precursors. Therefore, it has been expected that the final stages of the mRNA processing generate molecular hallmarks, which allow for the efficient and selective recognition of translation-competent templates. The general contours and several important details of this process have become known only recently and represent the subject of this review.
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Affiliation(s)
- Dmitri A Maslov
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA 92521, USA.
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5
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Kamba PF, Dickson DA, White NA, Ekstrom JL, Koslowsky DJ, Hoogstraten CG. The 27 kDa Trypanosoma brucei Pentatricopeptide Repeat Protein is a G-tract Specific RNA Binding Protein. Sci Rep 2018; 8:16989. [PMID: 30451852 PMCID: PMC6242908 DOI: 10.1038/s41598-018-34377-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 10/15/2018] [Indexed: 01/30/2023] Open
Abstract
Pentatricopeptide repeat (PPR) proteins, a helical repeat family of organellar RNA binding proteins, play essential roles in post-transcriptional RNA processing. In Trypanosoma brucei, an expanded family of PPR proteins localize to the parasite’s single mitochondrion, where they are believed to perform important roles in both RNA processing and translation. We studied the RNA binding specificity of the simplest T. brucei PPR protein (KRIPP11) using electrophoretic mobility shift assays, fluorescence anisotropy, circular dichroism spectroscopy, and in vitro selection. We found KRIPP11 to be an RNA binding protein with specificity for sequences of four or more consecutive guanosine residues (G-tracts). Such G-tracts are dramatically enriched in T. brucei mitochondrial transcripts that are destined for extensive uridine insertion/deletion editing but are not present in mRNAs following editing. We further found that the quadruplex oligoguanosine RNA conformation is preferentially recognized by KRIPP11 over other conformational forms, and is bound without disruption of the quadruplex structure. In combination with prior data demonstrating association of KRIPP11 with the small ribosomal subunit, these results suggest possible roles for KRIPP11 in bridging mRNA maturation and translation or in facilitating translation of unusual dual-coded open reading frames.
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Affiliation(s)
- Pakoyo F Kamba
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, 48824-1319, USA.,Graduate Program in Cell and Molecular Biology, Michigan State University, East Lansing, Michigan, 48824-1319, USA.,Makerere University, Kampala, Uganda
| | - David A Dickson
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, 48824-1319, USA.,Sackler School of Graduate Biomedical Sciences, Tufts University, Medford, Massachusetts, USA
| | - Neil A White
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, 48824-1319, USA.,Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut, USA
| | - Jennifer L Ekstrom
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, 48824-1319, USA.,Department of Food Science and Human Nutrition, Michigan State University, East Lansing, Michigan, USA
| | - Donna J Koslowsky
- Graduate Program in Cell and Molecular Biology, Michigan State University, East Lansing, Michigan, 48824-1319, USA.,Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan, 48824-1319, USA
| | - Charles G Hoogstraten
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, 48824-1319, USA.
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6
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Thomas JA, Baker N, Hutchinson S, Dominicus C, Trenaman A, Glover L, Alsford S, Horn D. Insights into antitrypanosomal drug mode-of-action from cytology-based profiling. PLoS Negl Trop Dis 2018; 12:e0006980. [PMID: 30475806 PMCID: PMC6283605 DOI: 10.1371/journal.pntd.0006980] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 12/06/2018] [Accepted: 11/07/2018] [Indexed: 12/31/2022] Open
Abstract
Chemotherapy continues to have a major impact on reducing the burden of disease caused by trypanosomatids. Unfortunately though, the mode-of-action (MoA) of antitrypanosomal drugs typically remains unclear or only partially characterised. This is the case for four of five current drugs used to treat Human African Trypanosomiasis (HAT); eflornithine is a specific inhibitor of ornithine decarboxylase. Here, we used a panel of T. brucei cellular assays to probe the MoA of the current HAT drugs. The assays included DNA-staining followed by microscopy and quantitative image analysis, or flow cytometry; terminal dUTP nick end labelling to monitor mitochondrial (kinetoplast) DNA replication; antibody-based detection of sites of nuclear DNA damage; and fluorescent dye-staining of mitochondria or lysosomes. We found that melarsoprol inhibited mitosis; nifurtimox reduced mitochondrial protein abundance; pentamidine triggered progressive loss of kinetoplast DNA and disruption of mitochondrial membrane potential; and suramin inhibited cytokinesis. Thus, current antitrypanosomal drugs perturb distinct and specific cellular compartments, structures or cell cycle phases. Further exploiting the findings, we show that putative mitogen-activated protein-kinases contribute to the melarsoprol-induced mitotic defect, reminiscent of the mitotic arrest associated signalling cascade triggered by arsenicals in mammalian cells, used to treat leukaemia. Thus, cytology-based profiling can rapidly yield novel insight into antitrypanosomal drug MoA.
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Affiliation(s)
- James A. Thomas
- London School of Hygiene & Tropical Medicine, Keppel Street, London, United Kingdom
| | - Nicola Baker
- The Centre for Immunology and Infection, University of York, Heslington, York, United Kingdom
| | | | | | - Anna Trenaman
- Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
| | | | - Sam Alsford
- London School of Hygiene & Tropical Medicine, Keppel Street, London, United Kingdom
| | - David Horn
- Wellcome Trust Centre for Anti-Infectives Research, School of Life Sciences, University of Dundee, Dundee, United Kingdom
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7
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Verner Z, Basu S, Benz C, Dixit S, Dobáková E, Faktorová D, Hashimi H, Horáková E, Huang Z, Paris Z, Peña-Diaz P, Ridlon L, Týč J, Wildridge D, Zíková A, Lukeš J. Malleable mitochondrion of Trypanosoma brucei. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 315:73-151. [PMID: 25708462 DOI: 10.1016/bs.ircmb.2014.11.001] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The importance of mitochondria for a typical aerobic eukaryotic cell is undeniable, as the list of necessary mitochondrial processes is steadily growing. Here, we summarize the current knowledge of mitochondrial biology of an early-branching parasitic protist, Trypanosoma brucei, a causative agent of serious human and cattle diseases. We present a comprehensive survey of its mitochondrial pathways including kinetoplast DNA replication and maintenance, gene expression, protein and metabolite import, major metabolic pathways, Fe-S cluster synthesis, ion homeostasis, organellar dynamics, and other processes. As we describe in this chapter, the single mitochondrion of T. brucei is everything but simple and as such rivals mitochondria of multicellular organisms.
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Affiliation(s)
- Zdeněk Verner
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Present address: Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia; Present address: Faculty of Sciences, Charles University, Prague, Czech Republic
| | - Somsuvro Basu
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic; Present address: Institut für Zytobiologie und Zytopathologie, Philipps-Universität Marburg, Germany
| | - Corinna Benz
- Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Sameer Dixit
- Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Eva Dobáková
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Present address: Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
| | - Drahomíra Faktorová
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Hassan Hashimi
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Eva Horáková
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic
| | - Zhenqiu Huang
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Zdeněk Paris
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic
| | - Priscila Peña-Diaz
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic
| | - Lucie Ridlon
- Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic; Present address: Salk Institute, La Jolla, San Diego, USA
| | - Jiří Týč
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - David Wildridge
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic
| | - Alena Zíková
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
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8
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Aphasizheva I, Zhang L, Wang X, Kaake RM, Huang L, Monti S, Aphasizhev R. RNA binding and core complexes constitute the U-insertion/deletion editosome. Mol Cell Biol 2014; 34:4329-42. [PMID: 25225332 PMCID: PMC4248751 DOI: 10.1128/mcb.01075-14] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 09/02/2014] [Accepted: 09/11/2014] [Indexed: 12/19/2022] Open
Abstract
Enzymes embedded into the RNA editing core complex (RECC) catalyze the U-insertion/deletion editing cascade to generate open reading frames in trypanosomal mitochondrial mRNAs. The sequential reactions of mRNA cleavage, U-addition or removal, and ligation are directed by guide RNAs (gRNAs). We combined proteomic, genetic, and functional studies with sequencing of total and complex-bound RNAs to define a protein particle responsible for the recognition of gRNAs and pre-mRNA substrates, editing intermediates, and products. This approximately 23-polypeptide tripartite assembly, termed the RNA editing substrate binding complex (RESC), also functions as the interface between mRNA editing, polyadenylation, and translation. Furthermore, we found that gRNAs represent only a subset of small mitochondrial RNAs, and yet an inexplicably high fraction of them possess 3' U-tails, which correlates with gRNA's enrichment in the RESC. Although both gRNAs and mRNAs are associated with the RESC, their metabolic fates are distinct: gRNAs are degraded in an editing-dependent process, whereas edited mRNAs undergo 3' adenylation/uridylation prior to translation. Our results demonstrate that the well-characterized editing core complex (RECC) and the RNA binding particle defined in this study (RESC) typify enzymatic and substrate binding macromolecular constituents, respectively, of the ∼40S RNA editing holoenzyme, the editosome.
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MESH Headings
- Base Sequence
- Mitochondria/genetics
- Open Reading Frames/genetics
- Peptide Chain Elongation, Translational/genetics
- Polyadenylation/genetics
- Protozoan Proteins/metabolism
- RNA/genetics
- RNA Editing/genetics
- RNA Interference
- RNA, Catalytic/genetics
- RNA, Guide, Kinetoplastida/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Mitochondrial
- RNA, Protozoan/genetics
- RNA, Small Interfering
- RNA-Binding Proteins/genetics
- Sequence Analysis, RNA
- Trypanosoma brucei brucei/genetics
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Affiliation(s)
- Inna Aphasizheva
- Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Boston, Massachusetts, USA
| | - Liye Zhang
- Section of Computational Biomedicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Xiaorong Wang
- Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA
| | - Robyn M Kaake
- Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA
| | - Lan Huang
- Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA
| | - Stefano Monti
- Section of Computational Biomedicine, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Ruslan Aphasizhev
- Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Boston, Massachusetts, USA Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, USA
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9
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Ridlon L, Škodová I, Pan S, Lukeš J, Maslov DA. The importance of the 45 S ribosomal small subunit-related complex for mitochondrial translation in Trypanosoma brucei. J Biol Chem 2013; 288:32963-78. [PMID: 24089529 DOI: 10.1074/jbc.m113.501874] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The mitochondrial 45 S SSU* complex in Trypanosoma brucei contains the 9 S SSU ribosomal RNA, a set of SSU ribosomal proteins, several pentatricopeptide repeat (PPR) proteins, and proteins not typically found in ribosomes, including rhodanese domain protein (Rhod) and a 200-kDa coiled-coil protein. To investigate the function of this complex, PPR29, Rhod, 200-kDa protein, and mitochondrial ribosomal protein S17 were knocked down by RNAi in procyclic T. brucei. A growth retardation phenotype, a reduction in the amount of the 45 S SSU* complexes, and the preferential inhibition of synthesis of the cytochrome c oxidase subunit I over apocytochrome b were observed as early as day 2 postinduction of RNAi. On the contrary, the down-regulation of mitochondrial ribosomal protein L3 drastically reduced the amount of the large subunit and indiscriminately inhibited mitochondrial translation. The relative amounts of translation-competent, long poly(AU)-tailed cytochrome c oxidase subunit I and edited apocytochrome b mRNAs were selectively reduced by ablation of the 45 S SSU* complex. The formation of the 80 S translation complexes, identified by association of the long-tailed mRNAs with the mitoribosomes, was also disrupted. On the other hand, the relative amount of long-tailed edited RPS12 mRNA was not substantially affected, and there was no noticeable effect on the RPS12 translation complexes. In bloodstream trypanosomes, the amount of the 45 S complexes was drastically reduced compared with procyclics. We propose that the 45 S SSU* complex represents a factor required for normal mitochondrial translation that may have selective effects on different mRNAs.
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Affiliation(s)
- Lucie Ridlon
- From the Department of Biology, University of California, Riverside, California 92521
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10
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Identification of Pentatricopeptide Repeat Proteins in the Model Organism Dictyostelium discoideum. Int J Genomics 2013; 2013:586498. [PMID: 23998118 PMCID: PMC3753752 DOI: 10.1155/2013/586498] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 07/11/2013] [Indexed: 11/18/2022] Open
Abstract
Pentatricopeptide repeat (PPR) proteins are RNA binding proteins with functions in organelle RNA metabolism. They are found in all eukaryotes but have been most extensively studied in plants. We report on the identification of 12 PPR-encoding genes in the genome of the protist Dictyostelium discoideum, with potential homologs in other members of the same lineage and some predicted novel functions for the encoded gene products in protists. For one of the gene products, we show that it localizes to the mitochondria, and we also demonstrate that antisense inhibition of its expression leads to slower growth, a phenotype associated with mitochondrial dysfunction.
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11
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Wang Y, Zhang X, Lu S, Wang M, Wang L, Wang W, Cao F, Chen H, Wang J, Zhang J, Tu J. Inhibition of a basal transcription factor 3-like gene Osj10gBTF3 in rice results in significant plant miniaturization and typical pollen abortion. PLANT & CELL PHYSIOLOGY 2012; 53:2073-2089. [PMID: 23147221 DOI: 10.1093/pcp/pcs146] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
BTF3, which was originally recognized as a basal transcription factor, has been known to be involved in transcription initiation, translational regulation and protein localization in many eukaryotic organisms. However, its function remains largely unknown in plant species. In the present study, we analyzed a BTF3-related sequence in Oryza sativa L. subsp. japonica, which shares the conserved domain of a nascent polypeptide-associated complex with human BTF3, and was referred to as Osj10gBTF3. The expression of Osj10gBTF3 was primarily constitutive and generally modulated by salt, high temperature and exogenous phytohormone stress. The Osj10gBTF3::EGFP (enhanced green fluorescence protein) fusion protein was localized in both the nucleus and cytoplasmic membrane system. Inhibition of Osj10gBTF3 led to significant morphological changes in all detected tissues and organs, with a reduced size of between 25% and 52%. Furthermore, the pollen that developed was completely sterile, which was correlated with the altered expression of two Rf (fertility restorer)-like genes that encode pentatricopeptide repeat-containing proteins OsPPR676 and OsPPR920, translational initiation factors OseIF3e and OseIF3h, and the heat shock protein OsHSP82. These findings were verified through a yeast two-hybrid assay using a Nipponbare callus cDNA library as bait followed by the reverse transcription-PCR analysis of total leaf or anther RNAs. Our demonstration of the important role of Osj10gBTF3 in rice growth and development provides new insights showing that more complex regulatory functions are associated with BTF3 in plants.
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Affiliation(s)
- Ya Wang
- Institute of Crop Science, College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, PR China
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12
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Böhm C, Katari VS, Brecht M, Göringer HU. Trypanosoma brucei 20 S editosomes have one RNA substrate-binding site and execute RNA unwinding activity. J Biol Chem 2012; 287:26268-77. [PMID: 22661715 PMCID: PMC3406711 DOI: 10.1074/jbc.m112.365916] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 05/10/2012] [Indexed: 12/30/2022] Open
Abstract
Editing of mitochondrial pre-mRNAs in African trypanosomes generates full-length transcripts by the site-specific insertion and deletion of uridylate nucleotides. The reaction is catalyzed by a 0.8 MDa multienzyme complex, the editosome. Although the binding of substrate pre-edited mRNAs and cognate guide RNAs (gRNAs) represents the first step in the reaction cycle, the biochemical and biophysical details of the editosome/RNA interaction are not understood. Here we show that editosomes bind full-length substrate mRNAs with nanomolar affinity in a nonselective fashion. The complexes do not discriminate-neither kinetically nor thermodynamically-between different mitochondrial pre-mRNAs or between edited and unedited versions of the same transcript. They also bind gRNAs and gRNA/pre-mRNA hybrid RNAs with similar affinities and association rate constants. Gold labeling of editosome-bound RNA in combination with transmission electron microscopy identified a single RNA-binding site per editosome. However, atomic force microscopy of individual pre-mRNA-editosome complexes revealed that multiple editosomes can interact with one pre-mRNA. Lastly, we demonstrate a so far unknown activity of the editing machinery: editosome-bound RNA becomes unfolded by a chaperone-type RNA unwinding activity.
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MESH Headings
- Binding Sites
- Macromolecular Substances/chemistry
- Macromolecular Substances/ultrastructure
- Microscopy, Atomic Force
- Microscopy, Electron, Transmission
- Nucleic Acid Conformation
- Protein Binding
- Protozoan Proteins/chemistry
- Protozoan Proteins/ultrastructure
- RNA Processing, Post-Transcriptional
- RNA, Guide, Kinetoplastida/chemistry
- RNA, Guide, Kinetoplastida/ultrastructure
- RNA, Messenger/chemistry
- RNA, Messenger/ultrastructure
- RNA, Mitochondrial
- RNA, Protozoan/chemistry
- RNA-Binding Proteins/chemistry
- RNA-Binding Proteins/ultrastructure
- Surface Plasmon Resonance
- Trypanosoma brucei brucei/enzymology
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Affiliation(s)
- Cordula Böhm
- From the Department of Molecular Genetics, Darmstadt University of Technology, 64287 Darmstadt, Germany
| | - Venkata Subbaraju Katari
- From the Department of Molecular Genetics, Darmstadt University of Technology, 64287 Darmstadt, Germany
| | - Michael Brecht
- From the Department of Molecular Genetics, Darmstadt University of Technology, 64287 Darmstadt, Germany
| | - H. Ulrich Göringer
- From the Department of Molecular Genetics, Darmstadt University of Technology, 64287 Darmstadt, Germany
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Manavski N, Guyon V, Meurer J, Wienand U, Brettschneider R. An essential pentatricopeptide repeat protein facilitates 5' maturation and translation initiation of rps3 mRNA in maize mitochondria. THE PLANT CELL 2012; 24:3087-105. [PMID: 22773745 PMCID: PMC3426134 DOI: 10.1105/tpc.112.099051] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Pentatricopeptide repeat (PPR) proteins are members of one of the largest nucleus-encoded protein families in plants. Here, we describe the previously uncharacterized maize (Zea mays) PPR gene, MPPR6, which was isolated from a Mutator-induced collection of maize kernel mutants by a cDNA-based forward genetic approach. Identification of a second mutant allele and cosegregation analysis confirmed correlation with the mutant phenotype. Histological investigations revealed that the mutation coincides with abnormities in the transfer cell layer, retardation of embryo development, and a considerable reduction of starch level. The function of MPPR6 is conserved across a wide phylogenetic distance as revealed by heterologous complementation of the Arabidopsis thaliana mutant in the orthologous APPR6 gene. MPPR6 appeared to be exclusively present in mitochondria. RNA coimmunoprecipitation and in vitro binding studies revealed a specific physical interaction of MPPR6 with the 5' untranslated region of ribosomal protein S3 (rps3) mRNA. Mapping of transcript termini showed specifically extended rps3 5' ends in the mppr6 mutant. Considerable reduction of mitochondrial translation was observed, indicating loss of RPS3 function. This is consistent with the appearance of truncated RPS3 protein lacking the N terminus in mppr6. Our results suggest that MPPR6 is directly involved in 5' maturation and translation initiation of rps3 mRNA.
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Affiliation(s)
- Nikolay Manavski
- Biozentrum Klein Flottbek und Botanischer Garten, Universität Hamburg, 22609 Hamburg, Germany
- Biozentrum der Ludwig-Maximillians-Universität München, Plant Molecular Biology/Botany, 82152 Planegg-Martinsried, Germany
| | - Virginie Guyon
- Cereal Genetics and Genomics, Biogemma Société par Actions Simplifiées, 63720 Chappes, France
| | - Jörg Meurer
- Biozentrum der Ludwig-Maximillians-Universität München, Plant Molecular Biology/Botany, 82152 Planegg-Martinsried, Germany
| | - Udo Wienand
- Biozentrum Klein Flottbek und Botanischer Garten, Universität Hamburg, 22609 Hamburg, Germany
| | - Reinhold Brettschneider
- Biozentrum Klein Flottbek und Botanischer Garten, Universität Hamburg, 22609 Hamburg, Germany
- Address correspondence to
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