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Liu S, Wang H, Li X, Zhang F, Lee JKJ, Li Z, Yu C, Hu JJ, Zhao X, Suematsu T, Alvarez-Cabrera AL, Liu Q, Zhang L, Huang L, Aphasizheva I, Aphasizhev R, Zhou ZH. Structural basis of gRNA stabilization and mRNA recognition in trypanosomal RNA editing. Science 2023; 381:eadg4725. [PMID: 37410820 DOI: 10.1126/science.adg4725] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 05/17/2023] [Indexed: 07/08/2023]
Abstract
In Trypanosoma brucei, the editosome, composed of RNA-editing substrate-binding complex (RESC) and RNA-editing catalytic complex (RECC), orchestrates guide RNA (gRNA)-programmed editing to recode cryptic mitochondrial transcripts into messenger RNAs (mRNAs). The mechanism of information transfer from gRNA to mRNA is unclear owing to a lack of high-resolution structures for these complexes. With cryo-electron microscopy and functional studies, we have captured gRNA-stabilizing RESC-A and gRNA-mRNA-binding RESC-B and RESC-C particles. RESC-A sequesters gRNA termini, thus promoting hairpin formation and blocking mRNA access. The conversion of RESC-A into RESC-B or -C unfolds gRNA and allows mRNA selection. The ensuing gRNA-mRNA duplex protrudes from RESC-B, likely exposing editing sites to RECC-catalyzed cleavage, uridine insertion or deletion, and ligation. Our work reveals a remodeling event facilitating gRNA-mRNA hybridization and assembly of a macromolecular substrate for the editosome's catalytic modality.
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Affiliation(s)
- Shiheng Liu
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA, USA
- California NanoSystems Institute, University of California, Los Angeles, CA, USA
| | - Hong Wang
- Department of Molecular and Cell Biology, Boston University Medical Campus, Boston, MA, USA
| | - Xiaorun Li
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA, USA
- California NanoSystems Institute, University of California, Los Angeles, CA, USA
| | - Fan Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Jane K J Lee
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA, USA
- California NanoSystems Institute, University of California, Los Angeles, CA, USA
| | - Zihang Li
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA, USA
- California NanoSystems Institute, University of California, Los Angeles, CA, USA
| | - Clinton Yu
- Department of Physiology and Biophysics, University of California, Irvine, CA, USA
| | - Jason J Hu
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA, USA
- California NanoSystems Institute, University of California, Los Angeles, CA, USA
| | - Xiaojing Zhao
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Takuma Suematsu
- Department of Molecular and Cell Biology, Boston University Medical Campus, Boston, MA, USA
| | - Ana L Alvarez-Cabrera
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA, USA
- California NanoSystems Institute, University of California, Los Angeles, CA, USA
| | - Qiushi Liu
- Department of Molecular and Cell Biology, Boston University Medical Campus, Boston, MA, USA
| | - Liye Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- Shanghai Clinical Research and Trial Center, Shanghai 201210, China
| | - Lan Huang
- Department of Physiology and Biophysics, University of California, Irvine, CA, USA
| | - Inna Aphasizheva
- Department of Molecular and Cell Biology, Boston University Medical Campus, Boston, MA, USA
| | - Ruslan Aphasizhev
- Department of Molecular and Cell Biology, Boston University Medical Campus, Boston, MA, USA
- Department of Biochemistry, Boston University Medical Campus, Boston, MA, USA
| | - Z Hong Zhou
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA, USA
- California NanoSystems Institute, University of California, Los Angeles, CA, USA
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2
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How RNases Shape Mitochondrial Transcriptomes. Int J Mol Sci 2022; 23:ijms23116141. [PMID: 35682820 PMCID: PMC9181182 DOI: 10.3390/ijms23116141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 05/24/2022] [Accepted: 05/25/2022] [Indexed: 11/17/2022] Open
Abstract
Mitochondria are the power houses of eukaryote cells. These endosymbiotic organelles of prokaryote origin are considered as semi-autonomous since they have retained a genome and fully functional gene expression mechanisms. These pathways are particularly interesting because they combine features inherited from the bacterial ancestor of mitochondria with characteristics that appeared during eukaryote evolution. RNA biology is thus particularly diverse in mitochondria. It involves an unexpectedly vast array of factors, some of which being universal to all mitochondria and others being specific from specific eukaryote clades. Among them, ribonucleases are particularly prominent. They play pivotal functions such as the maturation of transcript ends, RNA degradation and surveillance functions that are required to attain the pool of mature RNAs required to synthesize essential mitochondrial proteins such as respiratory chain proteins. Beyond these functions, mitochondrial ribonucleases are also involved in the maintenance and replication of mitochondrial DNA, and even possibly in the biogenesis of mitochondrial ribosomes. The diversity of mitochondrial RNases is reviewed here, showing for instance how in some cases a bacterial-type enzyme was kept in some eukaryotes, while in other clades, eukaryote specific enzymes were recruited for the same function.
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3
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Gao Y, Liu H, Zhang C, Su S, Chen Y, Chen X, Li Y, Shao Z, Zhang Y, Shao Q, Li J, Huang Z, Ma J, Gan J. Structural basis for guide RNA trimming by RNase D ribonuclease in Trypanosoma brucei. Nucleic Acids Res 2021; 49:568-583. [PMID: 33332555 PMCID: PMC7797062 DOI: 10.1093/nar/gkaa1197] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 11/24/2020] [Indexed: 11/18/2022] Open
Abstract
Infection with kinetoplastid parasites, including Trypanosoma brucei (T. brucei), Trypanosoma cruzi (T. cruzi) and Leishmania can cause serious disease in humans. Like other kinetoplastid species, mRNAs of these disease-causing parasites must undergo posttranscriptional editing in order to be functional. mRNA editing is directed by gRNAs, a large group of small RNAs. Similar to mRNAs, gRNAs are also precisely regulated. In T. brucei, overexpression of RNase D ribonuclease (TbRND) leads to substantial reduction in the total gRNA population and subsequent inhibition of mRNA editing. However, the mechanisms regulating gRNA binding and cleavage by TbRND are not well defined. Here, we report a thorough structural study of TbRND. Besides Apo- and NMP-bound structures, we also solved one TbRND structure in complexed with single-stranded RNA. In combination with mutagenesis and in vitro cleavage assays, our structures indicated that TbRND follows the conserved two-cation-assisted mechanism in catalysis. TbRND is a unique RND member, as it contains a ZFD domain at its C-terminus. In addition to T. brucei, our studies also advanced our understanding on the potential gRNA degradation pathway in T. cruzi, Leishmania, as well for as other disease-associated parasites expressing ZFD-containing RNDs.
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Affiliation(s)
- Yanqing Gao
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Hehua Liu
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Biochemistry, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Chong Zhang
- College of Life Sciences, Sichuan University, Chengdu 610041, China
| | - Shichen Su
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Biochemistry, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Yiqing Chen
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Xi Chen
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Biochemistry, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Yangyang Li
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Zhiwei Shao
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Yixi Zhang
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Qiyuan Shao
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Jixi Li
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Zhen Huang
- College of Life Sciences, Sichuan University, Chengdu 610041, China
| | - Jinbiao Ma
- State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Biochemistry, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Jianhua Gan
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
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4
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Kumar R, Katwal S, Sharma B, Sharma A, Puri S, Kamboj N, Kanwar SS. Purification, characterization and cytotoxic properties of a bacterial RNase. Int J Biol Macromol 2020; 166:665-676. [PMID: 33137384 DOI: 10.1016/j.ijbiomac.2020.10.224] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 09/25/2020] [Accepted: 10/28/2020] [Indexed: 12/12/2022]
Abstract
An RNase produced by Bacillus safensis RB-5 was purified up to 22.32-fold by successive techniques of salting out, DEAE-anion exchange and gel permeation (Sephadex G-100) chromatography techniques with a yield of 2.27%. The purified RNase possessed a single band in SDS-PAGE (Mr ~ 60 kDa). The purified RNase showed optimal activity at temperature of 37 °C and pH 7.5 in the presence of substrate (Yeast RNA) and Mg2+ ions. The RNase activity was strongly inhibited by Hg2+ and mildly by Fe2+, Ba2+ and Zn2+ ions. Its half-life was found to be 8 h at 37 °C. The RNase kinetics study showed Km and Vmax value of 0.3 mM and 9.2 μmol/mg/min, respectively. The purified RNase also showed cytotoxic and antiproliferative activities towards a few transformed cell lines. The purified RNase (IC50 0.035 U/mL) effectively inhibited RD and Hep-2C cells proliferation & migration, while sparing HEK 293 cells. The purified RNase was cytotoxic as well as effective degrader of the RNA of transformed RD cells at low concentration. Moreover, the purified RNase of B. safensis RB-5 was found to possess a little hemolytic activity towards human RBCs.
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Affiliation(s)
- Rakesh Kumar
- Department of Biotechnology, Himachal Pradesh University, Summer Hill, Shimla 171 005, India
| | - Sunita Katwal
- Department of Biotechnology, Himachal Pradesh University, Summer Hill, Shimla 171 005, India
| | - Bhupender Sharma
- Department of Biotechnology, Himachal Pradesh University, Summer Hill, Shimla 171 005, India
| | - Abhishek Sharma
- Department of Biotechnology, Himachal Pradesh University, Summer Hill, Shimla 171 005, India
| | - Sanjeev Puri
- Stem Cells & Tissue Engineering Division, University Institute of Engineering & Technology, Punjab University, Chandigarh 160 014, India
| | - Nidhi Kamboj
- Stem Cells & Tissue Engineering Division, University Institute of Engineering & Technology, Punjab University, Chandigarh 160 014, India
| | - Shamsher Singh Kanwar
- Department of Biotechnology, Himachal Pradesh University, Summer Hill, Shimla 171 005, India.
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5
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Aphasizheva I, Alfonzo J, Carnes J, Cestari I, Cruz-Reyes J, Göringer HU, Hajduk S, Lukeš J, Madison-Antenucci S, Maslov DA, McDermott SM, Ochsenreiter T, Read LK, Salavati R, Schnaufer A, Schneider A, Simpson L, Stuart K, Yurchenko V, Zhou ZH, Zíková A, Zhang L, Zimmer S, Aphasizhev R. Lexis and Grammar of Mitochondrial RNA Processing in Trypanosomes. Trends Parasitol 2020; 36:337-355. [PMID: 32191849 PMCID: PMC7083771 DOI: 10.1016/j.pt.2020.01.006] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 01/19/2020] [Accepted: 01/22/2020] [Indexed: 12/15/2022]
Abstract
Trypanosoma brucei spp. cause African human and animal trypanosomiasis, a burden on health and economy in Africa. These hemoflagellates are distinguished by a kinetoplast nucleoid containing mitochondrial DNAs of two kinds: maxicircles encoding ribosomal RNAs (rRNAs) and proteins and minicircles bearing guide RNAs (gRNAs) for mRNA editing. All RNAs are produced by a phage-type RNA polymerase as 3' extended precursors, which undergo exonucleolytic trimming. Most pre-mRNAs proceed through 3' adenylation, uridine insertion/deletion editing, and 3' A/U-tailing. The rRNAs and gRNAs are 3' uridylated. Historically, RNA editing has attracted major research effort, and recently essential pre- and postediting processing events have been discovered. Here, we classify the key players that transform primary transcripts into mature molecules and regulate their function and turnover.
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Affiliation(s)
- Inna Aphasizheva
- Department of Molecular and Cell Biology, Boston University Medical Campus, Boston, MA 02118, USA.
| | - Juan Alfonzo
- Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA
| | - Jason Carnes
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA 98109, USA
| | - Igor Cestari
- Institute of Parasitology, McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, H9X3V9, Québec, Canada
| | - Jorge Cruz-Reyes
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
| | - H Ulrich Göringer
- Department of Molecular Genetics, Darmstadt University of Technology, 64287 Darmstadt, Germany
| | - Stephen Hajduk
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences and Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Susan Madison-Antenucci
- Parasitology Laboratory, Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA
| | - Dmitri A Maslov
- Department of Molecular, Cell, and Systems Biology, University of California - Riverside, Riverside, CA 92521, USA
| | - Suzanne M McDermott
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA 98109, USA
| | - Torsten Ochsenreiter
- Institute of Cell Biology, University of Bern, Baltzerstrasse 4, Bern CH-3012, Switzerland
| | - Laurie K Read
- Department of Microbiology and Immunology, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY 14203, USA
| | - Reza Salavati
- Institute of Parasitology, McGill University, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, H9X3V9, Québec, Canada
| | - Achim Schnaufer
- Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh EH9 3FL, UK
| | - André Schneider
- Department of Chemistry and Biochemistry, University of Bern, Bern CH-3012, Switzerland
| | - Larry Simpson
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA90095, USA
| | - Kenneth Stuart
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA 98109, USA
| | - Vyacheslav Yurchenko
- Life Science Research Centre, Faculty of Science, University of Ostrava, Ostrava, Czech Republic; Martsinovsky Institute of Medical Parasitology, Sechenov University, Moscow, Russia
| | - Z Hong Zhou
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA90095, USA
| | - Alena Zíková
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences and Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Liye Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China
| | - Sara Zimmer
- University of Minnesota Medical School, Duluth campus, Duluth, MN 55812, USA
| | - Ruslan Aphasizhev
- Department of Molecular and Cell Biology, Boston University Medical Campus, Boston, MA 02118, USA
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6
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Ramirez-Barrios R, Susa EK, Smoniewski CM, Faacks SP, Liggett CK, Zimmer SL. A link between mitochondrial gene expression and life stage morphologies in Trypanosoma cruzi. Mol Microbiol 2020; 113:1003-1021. [PMID: 31961979 DOI: 10.1111/mmi.14466] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 01/14/2020] [Accepted: 01/16/2020] [Indexed: 12/17/2022]
Abstract
The protozoan Trypanosoma cruzi has a complicated dual-host life cycle, and starvation can trigger transition from the replicating insect stage to the mammalian-infectious nonreplicating insect stage (epimastigote to trypomastigote differentiation). Abundance of some mature RNAs derived from its mitochondrial genome increase during culture starvation of T. cruzi for unknown reasons. Here, we examine T. cruzi mitochondrial gene expression in the mammalian intracellular replicating life stage (amastigote), and uncover implications of starvation-induced changes in gene expression. Mitochondrial RNA levels in general were found to be lowest in actively replicating amastigotes. We discovered that mitochondrial respiration decreases during starvation in insect stage cells, despite the previously observed increases in mitochondrial mRNAs encoding electron transport chain (ETC) components. Surprisingly, T. cruzi epimastigotes in replete medium grow at normal rates when we genetically compromised their ability to perform insertion/deletion editing and thereby generate mature forms of some mitochondrial mRNAs. However, these cells, when starved, were impeded in the epimastigote to trypomastigote transition. Further, they experience a short-flagella phenotype that may also be linked to differentiation. We hypothesize a scenario where levels of mature RNA species or editing in the single T. cruzi mitochondrion are linked to differentiation by a yet-unknown signaling mechanism.
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Affiliation(s)
- Roger Ramirez-Barrios
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN, USA
| | - Emily K Susa
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN, USA
| | - Clara M Smoniewski
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN, USA
| | - Sean P Faacks
- Department of Biology, University of Minnesota Duluth, Duluth, MN, USA
| | - Charles K Liggett
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN, USA
| | - Sara L Zimmer
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN, USA
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7
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Cruz-Reyes J, Mooers BHM, Doharey PK, Meehan J, Gulati S. Dynamic RNA holo-editosomes with subcomplex variants: Insights into the control of trypanosome editing. WILEY INTERDISCIPLINARY REVIEWS-RNA 2018; 9:e1502. [PMID: 30101566 DOI: 10.1002/wrna.1502] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 07/03/2018] [Accepted: 07/09/2018] [Indexed: 12/14/2022]
Abstract
RNA editing causes massive remodeling of the mitochondrial mRNA transcriptome in trypanosomes and related kinetoplastid protozoa. This type of editing involves the specific insertion or deletion of uridylates (U) directed by small noncoding guide RNAs (gRNAs). Because U-insertion exceeds U-deletion by a factor of 10, editing increases the nascent mRNA size by up to 55%. In Trypanosoma brucei, the editing apparatus uses ~40 proteins and >1,200 gRNAs to create the functional open reading frame in 12 mRNAs. Thousands of sites are specifically recognized in the pre-edited mRNAs and a myriad of partially edited transcript intermediates accumulates in mitochondria. The control of editing is poorly understood, but past work suggests that it occurs during substrate recognition, the initiation and progression of editing, and during the life-cycle in different hosts. The growing understanding of the editing proteins offers clues about editing control. Most editing proteins reside in the "RNA-free" RNA editing core complex (RECC) and in the accessory RNA editing substrate complex (RESC) that contains gRNA. Two accessory RNA helicases are known, including one in the RNA editing helicase 2 complex (REH2C). Both the RESC and the REH2C associate with mRNA, providing a rationale for the assembly of mRNA or its mRNPs, RESC, and the RECC enzyme. Identified variants of the canonical editing complexes further complicate the model of RNA editing. We examine specific examples of complex variants, differential effects of editing proteins on the mRNAs within and between T. brucei life stages, and possible control points in RNA holo-editosomes. This article is categorized under: RNA Processing > RNA Editing and Modification RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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Affiliation(s)
- Jorge Cruz-Reyes
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas
| | - Blaine H M Mooers
- Department of Biochemistry & Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Pawan K Doharey
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas
| | - Joshua Meehan
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas
| | - Shelly Gulati
- Department of Biochemistry & Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
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8
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Zhang L, Sement FM, Suematsu T, Yu T, Monti S, Huang L, Aphasizhev R, Aphasizheva I. PPR polyadenylation factor defines mitochondrial mRNA identity and stability in trypanosomes. EMBO J 2017; 36:2435-2454. [PMID: 28684539 DOI: 10.15252/embj.201796808] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 05/10/2017] [Accepted: 05/22/2017] [Indexed: 11/09/2022] Open
Abstract
In Trypanosoma brucei, most mitochondrial mRNAs undergo internal changes by RNA editing and 3' end modifications. The temporally separated and functionally distinct modifications are manifested by adenylation prior to editing, and by post-editing extension of a short A-tail into a long A/U-heteropolymer. The A-tail stabilizes partially and fully edited mRNAs, while the A/U-tail enables mRNA binding to the ribosome. Here, we identify an essential pentatricopeptide repeat-containing RNA binding protein, kinetoplast polyadenylation factor 3 (KPAF3), and demonstrate its role in protecting pre-mRNA against degradation by the processome. We show that KPAF3 recruits KPAP1 poly(A) polymerase to the 3' terminus, thus leading to pre-mRNA stabilization, or decay depending on the occurrence and extent of editing. In vitro, KPAF3 stimulates KPAP1 activity and inhibits mRNA uridylation by RET1 TUTase. Our findings indicate that KPAF3 selectively directs pre-mRNA toward adenylation rather than uridylation, which is a default post-trimming modification characteristic of ribosomal and guide RNAs. As a quality control mechanism, KPAF3 binding ensures that mRNAs entering the editing pathway are adenylated and, therefore, competent for post-editing A/U-tailing and translational activation.
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Affiliation(s)
- Liye Zhang
- Department of Molecular and Cell Biology, Boston University School of Dental Medicine, Boston, MA, USA.,Section of Computational Biomedicine, Boston University School of Medicine, Boston, MA, USA
| | - Francois M Sement
- Department of Molecular and Cell Biology, Boston University School of Dental Medicine, Boston, MA, USA
| | - Takuma Suematsu
- Department of Molecular and Cell Biology, Boston University School of Dental Medicine, Boston, MA, USA
| | - Tian Yu
- Department of Molecular and Cell Biology, Boston University School of Dental Medicine, Boston, MA, USA
| | - Stefano Monti
- Section of Computational Biomedicine, Boston University School of Medicine, Boston, MA, USA
| | - Lan Huang
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Ruslan Aphasizhev
- Department of Molecular and Cell Biology, Boston University School of Dental Medicine, Boston, MA, USA.,Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA
| | - Inna Aphasizheva
- Department of Molecular and Cell Biology, Boston University School of Dental Medicine, Boston, MA, USA
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9
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Mitochondrial Gene Expression Is Responsive to Starvation Stress and Developmental Transition in Trypanosoma cruzi. mSphere 2016; 1:mSphere.00051-16. [PMID: 27303725 PMCID: PMC4894683 DOI: 10.1128/msphere.00051-16] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 03/23/2016] [Indexed: 01/22/2023] Open
Abstract
Chagas disease is caused by insect-transmitted Trypanosoma cruzi. Halting T. cruzi’s life cycle in one of its various human and insect life stages would effectively stop the parasite’s infection cycle. T. cruzi is exposed to a variety of environmental conditions in its different life stages, and gene expression must be remodeled to survive these changes. In this work, we look at the impact that one of these changes, nutrient depletion, has on the expression of the 20 gene products encoded in the mitochondrial genome that is neglected by whole-genome studies. We show increases in mitochondrial RNA abundances in starved insect-stage cells, under two conditions in which transition to the infectious stage occurs or does not. This report is the first to show that T. cruzi mitochondrial gene expression is sensitive to environmental perturbations, consistent with mitochondrial gene expression regulatory pathways being potential antiparasitic targets. Trypanosoma cruzi parasites causing Chagas disease are passed between mammals by the triatomine bug vector. Within the insect, T. cruzi epimastigote-stage cells replicate and progress through the increasingly nutrient-restricted digestive tract, differentiating into infectious, nonreplicative metacyclic trypomastigotes. Thus, we evaluated how nutrient perturbations or metacyclogenesis affects mitochondrial gene expression in different insect life cycle stages. We compared mitochondrial RNA abundances in cultures containing fed, replicating epimastigotes, differentiating cultures containing both starved epimastigotes and metacyclic trypomastigotes and epimastigote starvation cultures. We observed increases in mitochondrial rRNAs and some mRNAs in differentiating cultures. These increases predominated only for the edited CYb mRNA in cultures enriched for metacyclic trypomastigotes. For the other transcripts, abundance increases were linked to starvation and were strongest in culture fractions with a high population of starved epimastigotes. We show that loss of both glucose and amino acids results in rapid increases in RNA abundances that are quickly reduced when these nutrients are returned. Furthermore, the individual RNAs exhibit distinct temporal abundance patterns, suggestive of multiple mechanisms regulating individual transcript abundance. Finally, increases in mitochondrial respiratory complex subunit mRNA abundances were not matched by increases in abundances of nucleus-encoded subunit mRNAs, nor were there statistically significant increases in protein levels of three nucleus-encoded subunits tested. These results show that, similarly to that in T. brucei, the mitochondrial genome in T. cruzi has the potential to alter gene expression in response to environmental or developmental stimuli but for an as-yet-unknown purpose. IMPORTANCE Chagas disease is caused by insect-transmitted Trypanosoma cruzi. Halting T. cruzi’s life cycle in one of its various human and insect life stages would effectively stop the parasite’s infection cycle. T. cruzi is exposed to a variety of environmental conditions in its different life stages, and gene expression must be remodeled to survive these changes. In this work, we look at the impact that one of these changes, nutrient depletion, has on the expression of the 20 gene products encoded in the mitochondrial genome that is neglected by whole-genome studies. We show increases in mitochondrial RNA abundances in starved insect-stage cells, under two conditions in which transition to the infectious stage occurs or does not. This report is the first to show that T. cruzi mitochondrial gene expression is sensitive to environmental perturbations, consistent with mitochondrial gene expression regulatory pathways being potential antiparasitic targets.
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Dietrich A, Wallet C, Iqbal RK, Gualberto JM, Lotfi F. Organellar non-coding RNAs: Emerging regulation mechanisms. Biochimie 2015; 117:48-62. [DOI: 10.1016/j.biochi.2015.06.027] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Accepted: 06/29/2015] [Indexed: 02/06/2023]
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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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Lott K, Li J, Fisk JC, Wang H, Aletta JM, Qu J, Read LK. Global proteomic analysis in trypanosomes reveals unique proteins and conserved cellular processes impacted by arginine methylation. J Proteomics 2013; 91:210-25. [PMID: 23872088 PMCID: PMC3935770 DOI: 10.1016/j.jprot.2013.07.010] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Revised: 06/26/2013] [Accepted: 07/07/2013] [Indexed: 12/14/2022]
Abstract
Arginine methylation is a common posttranslational modification with reported functions in transcription, RNA processing and translation, and DNA repair. Trypanosomes encode five protein arginine methyltransferases, suggesting that arginine methylation exerts widespread impacts on the biology of these organisms. Here, we performed a global proteomic analysis of Trypanosoma brucei to identify arginine methylated proteins and their sites of modification. Using an approach entailing two-dimensional chromatographic separation and alternating electron transfer dissociation and collision induced dissociation, we identified 1332 methylarginines in 676 proteins. The resulting data set represents the largest compilation of arginine methylated proteins in any organism to date. Functional classification revealed numerous arginine methylated proteins involved in flagellar function, RNA metabolism, DNA replication and repair, and intracellular protein trafficking. Thus, arginine methylation has the potential to impact aspects of T. brucei gene expression, cell biology, and pathogenesis. Interestingly, pathways with known methylated proteins in higher eukaryotes were identified in this study, but often different components of the pathway were methylated in trypanosomes. Methylarginines were often identified in glycine rich contexts, although exceptions to this rule were detected. Collectively, these data inform on a multitude of aspects of trypanosome biology and serve as a guide for the identification of homologous arginine methylated proteins in higher eukaryotes. BIOLOGICAL SIGNIFICANCE T. brucei is a protozoan parasite that causes lethal African sleeping sickness in humans and nagana in livestock, thereby imposing a significant medical and economic burden on sub-Saharan Africa. The parasite encounters very different environments as it cycles between mammalian and insect hosts, and must exert cellular responses to these varying milieus. One mechanism by which all cells respond to changing environments is through posttranslational modification of proteins. Arginine methylation is one such modification that can dramatically impact protein-protein and protein-nucleic acid interactions and subcellular localization of proteins. To define the breadth of arginine methylation in trypanosomes and identify target proteins, we performed a global proteomic analysis of arginine methylated proteins in insect stage T. brucei. We identified 1332 methylarginines in 676 proteins, generating the largest compilation of methylarginine containing proteins in any organism to date. Numerous arginine methylated proteins function in RNA and DNA related processes, suggesting this modification can impact T. brucei genome integrity and gene regulation at numerous points. Other processes that appear to be strongly influenced by arginine methylation are intracellular protein trafficking, signaling, protein folding and degradation, and flagellar function. The widespread nature of arginine methylation in trypanosomes highlights its potential to greatly affect parasite biology and pathogenesis.
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Affiliation(s)
- Kaylen Lott
- Department of Microbiology and Immunology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York, United States of America
| | - Jun Li
- Department of Pharmaceutical Sciences, University at Buffalo, Buffalo, NY, United States of America
| | - John C. Fisk
- Department of Microbiology and Immunology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York, United States of America
| | - Hao Wang
- Department of Pharmaceutical Sciences, University at Buffalo, Buffalo, NY, United States of America
| | - John M. Aletta
- CH3 BioSystems, New York State Center of Excellence in Bioinformatics and Life Sciences, Buffalo, NY, United States of America
| | - Jun Qu
- Department of Pharmaceutical Sciences, University at Buffalo, Buffalo, NY, United States of America
| | - Laurie K. Read
- Department of Microbiology and Immunology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York, United States of America
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Sakyiama J, Zimmer SL, Ciganda M, Williams N, Read LK. Ribosome biogenesis requires a highly diverged XRN family 5'->3' exoribonuclease for rRNA processing in Trypanosoma brucei. RNA (NEW YORK, N.Y.) 2013; 19:1419-1431. [PMID: 23974437 PMCID: PMC3854532 DOI: 10.1261/rna.038547.113] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 07/10/2013] [Indexed: 05/30/2023]
Abstract
Although biogenesis of ribosomes is a crucial process in all organisms and is thus well conserved, Trypanosoma brucei ribosome biogenesis, of which maturation of rRNAs is an early step, has multiple points of divergence. Our aim was to determine whether in the processing of the pre-rRNA precursor molecule, 5'→3' exoribonuclease activity in addition to endonucleolytic cleavage is necessary in T. brucei as in other organisms. Our approach initiated with the bioinformatic identification of a putative 5'→3' exoribonuclease, XRNE, which is highly diverged from the XRN2/Rat1 enzyme responsible for rRNA processing in other organisms. Tagging this protein in vivo allowed us to classify XRNE as nucleolar by indirect immunofluorescence and identify by copurification interacting proteins, many of which were ribosomal proteins, ribosome biogenesis proteins, and/or RNA processing proteins. To determine whether XRNE plays a role in ribosome biogenesis in procyclic form cells, we inducibly depleted the protein by RNA interference. This resulted in the generation of aberrant preprocessed 18S rRNA and 5' extended 5.8S rRNA, implicating XRNE in rRNA processing. Polysome profiles of XRNE-depleted cells demonstrated abnormal features including an increase in ribosome small subunit abundance, a decrease in large subunit abundance, and defects in polysome assembly. Furthermore, the 5' extended 5.8S rRNA in XRNE-depleted cells was observed in the large subunit, monosomes, and polysomes in this gradient. Therefore, the function of XRNE in rRNA processing, presumably due to exonucleolytic activity very early in ribosome biogenesis, has consequences that persist throughout all biogenesis stages.
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MESH Headings
- Amino Acid Sequence
- Blotting, Northern
- Blotting, Western
- Cell Nucleolus
- Cells, Cultured
- Exoribonucleases/genetics
- Exoribonucleases/metabolism
- Immunoprecipitation
- Molecular Sequence Data
- Organelle Biogenesis
- Polyribosomes/genetics
- Polyribosomes/metabolism
- RNA Processing, Post-Transcriptional
- RNA, Messenger/genetics
- RNA, Ribosomal, 18S/genetics
- RNA, Ribosomal, 18S/metabolism
- Real-Time Polymerase Chain Reaction
- Reverse Transcriptase Polymerase Chain Reaction
- Ribosomal Proteins/genetics
- Ribosomal Proteins/metabolism
- Ribosomes/metabolism
- Sequence Homology, Amino Acid
- Tandem Mass Spectrometry
- Trypanosoma brucei brucei/enzymology
- Trypanosoma brucei brucei/genetics
- Trypanosoma brucei brucei/growth & development
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Affiliation(s)
- Joseph Sakyiama
- Department of Microbiology and Immunology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York 14214, USA
| | - Sara L. Zimmer
- Department of Microbiology and Immunology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York 14214, USA
| | - Martin Ciganda
- Department of Microbiology and Immunology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York 14214, USA
| | - Noreen Williams
- Department of Microbiology and Immunology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York 14214, USA
| | - Laurie K. Read
- Department of Microbiology and Immunology, School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, New York 14214, USA
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Aphasizhev R, Aphasizheva I. Emerging roles of PPR proteins in trypanosomes: switches, blocks, and triggers. RNA Biol 2013; 10:1495-500. [PMID: 24055869 PMCID: PMC3858432 DOI: 10.4161/rna.26215] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 08/16/2013] [Accepted: 08/19/2013] [Indexed: 01/05/2023] Open
Abstract
Mitochondrial genomes of trypanosomes are composed of catenated maxicircles and mini-circles that are densely packed into a nucleoprotein structure called the kinetoplast. Maxicircle DNA (~25 kb long, 20-50 copies) resembles a typical mitochondrial genome bearing rRNA and respiratory complex subunits genes, and also contains 12 cryptogenes whose transcripts require U-insertion/deletion editing to assemble protein-coding sequences. Production of guide RNAs for the editing process remains the only established function of mini-circle DNA (~1 kb, ~10000 copies). Although editing remains the most studied step in mRNA biogenesis, recent investigations illuminated complex nucleolytic processing and pre- and post-editing 3' modification events that ultimately create translation-competent mRNAs. Key mRNA 3' processing enzymes, such as KPAP1 poly(A) polymerase and RET1 TUTase, have been identified but the mechanisms regulating their activities remain poorly understood. Discoveries of multiple pentatricopeptide repeat-containing (PPR) proteins populating polyadenylation complex and ribosomal subunits opened exciting experimental prospects that may ultimately lead to an integrated picture of mitochondrial gene expression.
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Affiliation(s)
- Ruslan Aphasizhev
- Department of Molecular and Cell Biology; Boston University Goldman School of Dental Medicine; Boston, MA USA
| | - Inna Aphasizheva
- Department of Molecular and Cell Biology; Boston University Goldman School of Dental Medicine; Boston, MA USA
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Fisk JC, Li J, Wang H, Aletta JM, Qu J, Read LK. Proteomic analysis reveals diverse classes of arginine methylproteins in mitochondria of trypanosomes. Mol Cell Proteomics 2012; 12:302-11. [PMID: 23152538 DOI: 10.1074/mcp.m112.022533] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Arginine (arg) methylation is a widespread posttranslational modification of proteins that impacts numerous cellular processes such as chromatin remodeling, RNA processing, DNA repair, and cell signaling. Known arg methylproteins arise mostly from yeast and mammals, and are almost exclusively nuclear and cytoplasmic. Trypanosoma brucei is an early branching eukaryote whose genome encodes five putative protein arg methyltransferases, and thus likely contains a plethora of arg methylproteins. Additionally, trypanosomes and related organisms possess a unique mitochondrion that undergoes dramatic developmental regulation and uses novel RNA editing and mitochondrial DNA replication mechanisms. Here, we performed a global mass spectrometric analysis of the T. brucei mitochondrion to identify new arg methylproteins in this medically relevant parasite. Enabling factors of this work are use of a combination digestion with two orthogonal enzymes, an efficient offline two dimensional chromatography separation, and high-resolution mass spectrometry analysis with two complementary activations. This approach led to the comprehensive, sensitive and confident identification and localization of methylarg at a proteome level. We identified 167 arg methylproteins with wide-ranging functions including metabolism, transport, chaperoning, RNA processing, translation, and DNA replication. Our data suggest that arg methylproteins in trypanosome mitochondria possess both trypanosome-specific and evolutionarily conserved modifications, depending on the protein targeted. This study is the first comprehensive analysis of mitochondrial arg methylation in any organism, and represents a significant advance in our knowledge of the range of arg methylproteins and their sites of modification. Moreover, these studies establish T. brucei as a model organism for the study of posttranslational modifications.
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Affiliation(s)
- John C Fisk
- Department of Microbiology and Immunology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, New York 14124, USA
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Kafková L, Ammerman ML, Faktorová D, Fisk JC, Zimmer SL, Sobotka R, Read LK, Lukeš J, Hashimi H. Functional characterization of two paralogs that are novel RNA binding proteins influencing mitochondrial transcripts of Trypanosoma brucei. RNA (NEW YORK, N.Y.) 2012; 18:1846-61. [PMID: 22898985 PMCID: PMC3446708 DOI: 10.1261/rna.033852.112] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Accepted: 07/11/2012] [Indexed: 05/20/2023]
Abstract
A majority of Trypanosoma brucei proteins have unknown functions, a consequence of its independent evolutionary history within the order Kinetoplastida that allowed for the emergence of several unique biological properties. Among these is RNA editing, needed for expression of mitochondrial-encoded genes. The recently discovered mitochondrial RNA binding complex 1 (MRB1) is composed of proteins with several functions in processing organellar RNA. We characterize two MRB1 subunits, referred to herein as MRB8170 and MRB4160, which are paralogs arisen from a large chromosome duplication occurring only in T. brucei. As with many other MRB1 proteins, both have no recognizable domains, motifs, or orthologs outside the order. We show that they are both novel RNA binding proteins, possibly representing a new class of these proteins. They associate with a similar subset of MRB1 subunits but not directly with each other. We generated cell lines that either individually or simultaneously target the mRNAs encoding both proteins using RNAi. Their dual silencing results in a differential effect on moderately and pan-edited RNAs, suggesting a possible functional separation of the two proteins. Cell growth persists upon RNAi silencing of each protein individually in contrast to the dual knockdown. Yet, their apparent redundancy in terms of cell viability is at odds with the finding that only one of these knockdowns results in the general degradation of pan-edited RNAs. While MRB8170 and MRB4160 share a considerable degree of conservation, our results suggest that their recent sequence divergence has led to them influencing mitochondrial mRNAs to differing degrees.
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Affiliation(s)
- Lucie Kafková
- Biology Center, Institute of Parasitology, Czech Academy of Sciences, University of South Bohemia, 370 05 České Budějovice (Budweis), Czech Republic
- Faculty of Sciences, University of South Bohemia, 370 05 České Budějovice (Budweis), Czech Republic
| | - Michelle L. Ammerman
- Department of Microbiology and Immunology, School of Medicine, State University of New York at Buffalo, Buffalo, New York 14214, USA
| | - Drahomíra Faktorová
- Faculty of Sciences, University of South Bohemia, 370 05 České Budějovice (Budweis), Czech Republic
| | - John C. Fisk
- Department of Microbiology and Immunology, School of Medicine, State University of New York at Buffalo, Buffalo, New York 14214, USA
| | - Sara L. Zimmer
- Department of Microbiology and Immunology, School of Medicine, State University of New York at Buffalo, Buffalo, New York 14214, USA
| | - Roman Sobotka
- Faculty of Sciences, University of South Bohemia, 370 05 České Budějovice (Budweis), Czech Republic
- Institute of Microbiology, Czech Academy of Sciences, 379 81 Třeboň, Czech Republic
| | - Laurie K. Read
- Department of Microbiology and Immunology, School of Medicine, State University of New York at Buffalo, Buffalo, New York 14214, USA
| | - Julius Lukeš
- Biology Center, Institute of Parasitology, Czech Academy of Sciences, University of South Bohemia, 370 05 České Budějovice (Budweis), Czech Republic
- Faculty of Sciences, University of South Bohemia, 370 05 České Budějovice (Budweis), Czech Republic
| | - Hassan Hashimi
- Biology Center, Institute of Parasitology, Czech Academy of Sciences, University of South Bohemia, 370 05 České Budějovice (Budweis), Czech Republic
- Faculty of Sciences, University of South Bohemia, 370 05 České Budějovice (Budweis), Czech Republic
- Corresponding authorE-mail
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Multifunctional G-rich and RRM-containing domains of TbRGG2 perform separate yet essential functions in trypanosome RNA editing. EUKARYOTIC CELL 2012; 11:1119-31. [PMID: 22798390 DOI: 10.1128/ec.00175-12] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Efficient editing of Trypanosoma brucei mitochondrial RNAs involves the actions of multiple accessory factors. T. brucei RGG2 (TbRGG2) is an essential protein crucial for initiation and 3'-to-5' progression of editing. TbRGG2 comprises an N-terminal G-rich region containing GWG and RG repeats and a C-terminal RNA recognition motif (RRM)-containing domain. Here, we perform in vitro and in vivo separation-of-function studies to interrogate the mechanism of TbRGG2 action in RNA editing. TbRGG2 preferentially binds preedited mRNA in vitro with high affinity attributable to its G-rich region. RNA-annealing and -melting activities are separable, carried out primarily by the G-rich and RRM domains, respectively. In vivo, the G-rich domain partially complements TbRGG2 knockdown, but the RRM domain is also required. Notably, TbRGG2's RNA-melting activity is dispensable for RNA editing in vivo. Interactions between TbRGG2 and MRB1 complex proteins are mediated by both G-rich and RRM-containing domains, depending on the binding partner. Overall, our results are consistent with a model in which the high-affinity RNA binding and RNA-annealing activities of the G-rich domain are essential for RNA editing in vivo. The RRM domain may have key functions involving interactions with the MRB1 complex and/or regulation of the activities of the G-rich domain.
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Additive and transcript-specific effects of KPAP1 and TbRND activities on 3' non-encoded tail characteristics and mRNA stability in Trypanosoma brucei. PLoS One 2012; 7:e37639. [PMID: 22629436 PMCID: PMC3357391 DOI: 10.1371/journal.pone.0037639] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Accepted: 04/26/2012] [Indexed: 01/09/2023] Open
Abstract
Short, non-encoded oligo(A), oligo(U), or A/U tails can impact mRNA stability in kinetoplastid mitochondria. However, a comprehensive picture of the relative effects of these modifications in RNA stability is lacking. Furthermore, while the U-preferring exoribonuclease TbRND acts on U-tailed gRNAs, its role in decay of uridylated mRNAs has only been cursorily investigated. Here, we analyzed the roles of mRNA 3′ tail composition and TbRND in RNA decay using cells harbouring single or double knockdown of TbRND and the KPAP1 poly(A) polymerase. Analysis of mRNA abundance and tail composition reveals dramatic and transcript-specific effects of adenylation and uridylation on mitochondrial RNAs. Oligo(A) and A-rich tails can stabilize a proportion of edited and never-edited RNAs. However, non-tailed RNAs are not inherently unstable, implicating additional stability determinants and/or spatial segregation of sub-populations of a given RNA in regulation of RNA decay. Oligo(U) tails, which have been shown to contribute to decay of some never-edited RNAs, are not universally destabilizing. We also show that RNAs display very different susceptibility to uridylation in the absence of KPAP1, a factor that may contribute to regulation of decay. Finally, 3′ tail composition apparently impacts the ability of an RNA to be edited.
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Madina BR, Kuppan G, Vashisht AA, Liang YH, Downey KM, Wohlschlegel JA, Ji X, Sze SH, Sacchettini JC, Read LK, Cruz-Reyes J. Guide RNA biogenesis involves a novel RNase III family endoribonuclease in Trypanosoma brucei. RNA (NEW YORK, N.Y.) 2011; 17:1821-30. [PMID: 21810935 PMCID: PMC3185915 DOI: 10.1261/rna.2815911] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 06/29/2011] [Indexed: 05/29/2023]
Abstract
The mitochondrial genome of kinetoplastids, including species of Trypanosoma and Leishmania, is an unprecedented DNA structure of catenated maxicircles and minicircles. Maxicircles represent the typical mitochondrial genome encoding components of the respiratory complexes and ribosomes. However, most mRNA sequences are cryptic, and their maturation requires a unique U insertion/deletion RNA editing. Minicircles encode hundreds of small guide RNAs (gRNAs) that partially anneal with unedited mRNAs and direct the extensive editing. Trypanosoma brucei gRNAs and mRNAs are transcribed as polycistronic precursors, which undergo processing preceding editing; however, the relevant nucleases are unknown. We report the identification and functional characterization of a close homolog of editing endonucleases, mRPN1 (mitochondrial RNA precursor-processing endonuclease 1), which is involved in gRNA biogenesis. Recombinant mRPN1 is a dimeric dsRNA-dependent endonuclease that requires Mg(2+), a critical catalytic carboxylate, and generates 2-nucleotide 3' overhangs. The cleavage specificity of mRPN1 is reminiscent of bacterial RNase III and thus is fundamentally distinct from editing endonucleases, which target a single scissile bond just 5' of short duplexes. An inducible knockdown of mRPN1 in T. brucei results in loss of gRNA and accumulation of precursor transcripts (pre-gRNAs), consistent with a role of mRPN1 in processing. mRPN1 stably associates with three proteins previously identified in relatively large complexes that do not contain mRPN1, and have been linked with multiple aspects of mitochondrial RNA metabolism. One protein, TbRGG2, directly binds mRPN1 and is thought to modulate gRNA utilization by editing complexes. The proposed participation of mRPN1 in processing of polycistronic RNA and its specific protein interactions in gRNA expression are discussed.
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Affiliation(s)
- Bhaskara Reddy Madina
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA
| | - Gokulan Kuppan
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA
| | - Ajay A. Vashisht
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095-1737, USA
| | - Yu-He Liang
- Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702, USA
| | - Kurtis M. Downey
- Department of Microbiology and Immunology, University at Buffalo, State University of New York, Buffalo, New York 14214, USA
| | - James A. Wohlschlegel
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095-1737, USA
| | - Xinhua Ji
- Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702, USA
| | - Sing-Hoi Sze
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA
- Department of Computer Science and Engineering, Texas A&M University, College Station, Texas 77843, USA
| | - James C. Sacchettini
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA
| | - Laurie K. Read
- Department of Microbiology and Immunology, University at Buffalo, State University of New York, Buffalo, New York 14214, USA
| | - Jorge Cruz-Reyes
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA
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