1
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Carnes J, McDermott SM, Stuart K. RNA editing catalytic complexes edit multiple mRNA sites non-processively in Trypanosoma brucei. Mol Biochem Parasitol 2023; 256:111596. [PMID: 37742784 DOI: 10.1016/j.molbiopara.2023.111596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 08/25/2023] [Accepted: 09/20/2023] [Indexed: 09/26/2023]
Abstract
RNA editing generates mature mitochondrial mRNAs in T. brucei by extensive uridine insertion and deletion at numerous editing sites (ESs) as specified by guide RNAs (gRNAs). The editing is performed by three RNA Editing Catalytic Complexes (RECCs) which each have a different endonuclease in addition to 12 proteins in common resulting in RECC1 that is specific for deletion ESs and RECC2 and RECC3 that are specific for insertion ESs. Thus, different RECCs are required for editing of mRNA sequence regions where single gRNAs specify a combination of insertion and deletion ESs. We investigated how the three different RECCs might edit combinations of insertion and deletion ESs that are specified by single gRNAs by testing whether their endonuclease compositions are stable or dynamic during editing. We analyzed in vivo BirA* proximity labeling and found that the endonucleases remain associated with their set of common RECC proteins during editing when expressed at normal physiological levels. We also found that overexpression of endonuclease components resulted in minor effects on RECCs but did not affect growth. Thus, the protein stoichiometries that exist within each RECC can be altered by perturbations of RECC expression levels. These results indicate that editing of consecutive insertion and deletion ESs occurs by successive engagement and disengagement of RECCs, i.e., is non-processive, which is likely the case for consecutive pairs of insertion or deletion ESs. This clarifies the nature of the complex patterns of partially edited mRNAs that occur in vivo.
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Affiliation(s)
- Jason Carnes
- Seattle Children's Research Institute, Seattle, WA 98109, USA
| | - Suzanne M McDermott
- Seattle Children's Research Institute, Seattle, WA 98109, USA; Departments of Pediatrics and Global Health, University of Washington, Seattle, WA 98195, USA
| | - Kenneth Stuart
- Seattle Children's Research Institute, Seattle, WA 98109, USA; Departments of Pediatrics and Global Health, University of Washington, Seattle, WA 98195, USA.
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2
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Kumar V, Ivens A, Goodall Z, Meehan J, Doharey PK, Hillhouse A, Hurtado DO, Cai JJ, Zhang X, Schnaufer A, Cruz-Reyes J. Site-specific and substrate-specific control of accurate mRNA editing by a helicase complex in trypanosomes. RNA (NEW YORK, N.Y.) 2020; 26:1862-1881. [PMID: 32873716 PMCID: PMC7668249 DOI: 10.1261/rna.076513.120] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 08/22/2020] [Indexed: 05/21/2023]
Abstract
Trypanosome U-insertion/deletion RNA editing in mitochondrial mRNAs involves guide RNAs (gRNAs) and the auxiliary RNA editing substrate binding complex (RESC) and RNA editing helicase 2 complex (REH2C). RESC and REH2C stably copurify with editing mRNAs but the functional interplay between these complexes remains unclear. Most steady-state mRNAs are partially edited and include misedited "junction" regions that match neither pre-mRNA nor fully edited transcripts. Editing specificity is central to mitochondrial RNA maturation and function, but its basic control mechanisms remain unclear. Here we applied a novel nucleotide-resolution RNA-seq approach to examine ribosomal protein subunit 12 (RPS12) and ATPase subunit 6 (A6) mRNA transcripts. We directly compared transcripts associated with RESC and REH2C to those found in total mitochondrial RNA. RESC-associated transcripts exhibited site-preferential enrichments in total and accurate edits. REH2C loss-of-function induced similar substrate-specific and site-specific editing effects in total and RESC-associated RNA. It decreased total editing primarily at RPS12 5' positions but increased total editing at examined A6 3' positions. REH2C loss-of-function caused site-preferential loss of accurate editing in both transcripts. However, changes in total or accurate edits did not necessarily involve common sites. A few 5' nucleotides of the initiating gRNA (gRNA-1) directed accurate editing in both transcripts. However, in RPS12, two conserved 3'-terminal adenines in gRNA-1 could direct a noncanonical 2U-insertion that causes major pausing in 3'-5' progression. In A6, a noncanonical sequence element that depends on REH2C in a region normally targeted by the 3' half of gRNA-1 may hinder early editing progression. Overall, we defined transcript-specific effects of REH2C loss.
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Affiliation(s)
- Vikas Kumar
- Department of Biochemistry, Texas A&M University, College Station, Texas 77843, USA
| | - Alasdair Ivens
- Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh EH9 3FL, Scotland, United Kingdom
| | - Zachary Goodall
- Department of Biochemistry, Texas A&M University, College Station, Texas 77843, USA
| | - Joshua Meehan
- Department of Biochemistry, Texas A&M University, College Station, Texas 77843, USA
| | - Pawan Kumar Doharey
- Department of Biochemistry, Texas A&M University, College Station, Texas 77843, USA
| | - Andrew Hillhouse
- Texas A&M Institute for Genome Sciences and Society, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas 77843, USA
| | - Daniel Osorio Hurtado
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843, USA
| | - James J Cai
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843, USA
| | - Xiuren Zhang
- Department of Biochemistry, Texas A&M University, College Station, Texas 77843, USA
| | - Achim Schnaufer
- Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh EH9 3FL, Scotland, United Kingdom
| | - Jorge Cruz-Reyes
- Department of Biochemistry, Texas A&M University, College Station, Texas 77843, USA
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3
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Sarcar SN, Miller DL. A specific, promoter-independent activity of T7 RNA polymerase suggests a general model for DNA/RNA editing in single subunit RNA Polymerases. Sci Rep 2018; 8:13885. [PMID: 30224735 PMCID: PMC6141538 DOI: 10.1038/s41598-018-32231-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 08/31/2018] [Indexed: 01/23/2023] Open
Abstract
Insertional RNA editing has been observed and characterized in mitochondria of myxomycetes. The single subunit mitochondrial RNA polymerase adds nontemplated nucleotides co-transcriptionally to produce functional tRNA, rRNA and mRNAs with full genetic information. Addition of nontemplated nucleotides to the 3′ ends of RNAs have been observed in polymerases related to the mitochondrial RNA polymerase. This activity has been observed with T7 RNA polymerase (T7 RNAP), the well characterized prototype of the single subunit polymerases, as a nonspecific addition of nucleotides to the 3′ end of T7 RNAP transcripts in vitro. Here we show that this novel activity is an editing activity that can add specific ribonucleotides to 3′ ends of RNA or DNA when oligonucleotides, able to form intramolecular or intermolecular hairpin loops with recessed 3′ ends, are added to T7 RNA polymerase in the presence of at least one ribonucleotide triphosphate. Specific ribonucleotides are added to the recessed 3′ ends through Watson-Crick base pairing with the non-base paired nucleotide adjacent to the 3′ end. Optimization of this activity is obtained through alteration of the lengths of the 5′-extension, hairpin loop, and hairpin duplex. These properties define a T7 RNAP activity different from either transcriptional elongation or initiation.
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Affiliation(s)
- Subha Narayan Sarcar
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, 75083-0688, USA
| | - Dennis L Miller
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, 75083-0688, USA.
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4
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Abstract
Codon usage depends on mutation bias, tRNA-mediated selection, and the need for high efficiency and accuracy in translation. One codon in a synonymous codon family is often strongly over-used, especially in highly expressed genes, which often leads to a high dN/dS ratio because dS is very small. Many different codon usage indices have been proposed to measure codon usage and codon adaptation. Sense codon could be misread by release factors and stop codons misread by tRNAs, which also contribute to codon usage in rare cases. This chapter outlines the conceptual framework on codon evolution, illustrates codon-specific and gene-specific codon usage indices, and presents their applications. A new index for codon adaptation that accounts for background mutation bias (Index of Translation Elongation) is presented and contrasted with codon adaptation index (CAI) which does not consider background mutation bias. They are used to re-analyze data from a recent paper claiming that translation elongation efficiency matters little in protein production. The reanalysis disproves the claim.
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5
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ARSDA: A New Approach for Storing, Transmitting and Analyzing Transcriptomic Data. G3-GENES GENOMES GENETICS 2017; 7:3839-3848. [PMID: 29079682 PMCID: PMC5714481 DOI: 10.1534/g3.117.300271] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Two major stumbling blocks exist in high-throughput sequencing (HTS) data analysis. The first is the sheer file size, typically in gigabytes when uncompressed, causing problems in storage, transmission, and analysis. However, these files do not need to be so large, and can be reduced without loss of information. Each HTS file, either in compressed .SRA or plain text .fastq format, contains numerous identical reads stored as separate entries. For example, among 44,603,541 forward reads in the SRR4011234.sra file (from a Bacillus subtilis transcriptomic study) deposited at NCBI’s SRA database, one read has 497,027 identical copies. Instead of storing them as separate entries, one can and should store them as a single entry with the SeqID_NumCopy format (which I dub as FASTA+ format). The second is the proper allocation of reads that map equally well to paralogous genes. I illustrate in detail a new method for such allocation. I have developed ARSDA software that implement these new approaches. A number of HTS files for model species are in the process of being processed and deposited at http://coevol.rdc.uottawa.ca to demonstrate that this approach not only saves a huge amount of storage space and transmission bandwidth, but also dramatically reduces time in downstream data analysis. Instead of matching the 497,027 identical reads separately against the B. subtilis genome, one only needs to match it once. ARSDA includes functions to take advantage of HTS data in the new sequence format for downstream data analysis such as gene expression characterization. I contrasted gene expression results between ARSDA and Cufflinks so readers can better appreciate the strength of ARSDA. ARSDA is freely available for Windows, Linux. and Macintosh computers at http://dambe.bio.uottawa.ca/ARSDA/ARSDA.aspx.
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6
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Simpson RM, Bruno AE, Chen R, Lott K, Tylec BL, Bard JE, Sun Y, Buck MJ, Read LK. Trypanosome RNA Editing Mediator Complex proteins have distinct functions in gRNA utilization. Nucleic Acids Res 2017; 45:7965-7983. [PMID: 28535252 PMCID: PMC5737529 DOI: 10.1093/nar/gkx458] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 05/01/2017] [Accepted: 05/10/2017] [Indexed: 11/13/2022] Open
Abstract
Uridine insertion/deletion RNA editing is an essential process in kinetoplastid parasites whereby mitochondrial mRNAs are modified through the specific insertion and deletion of uridines to generate functional open reading frames, many of which encode components of the mitochondrial respiratory chain. The roles of numerous non-enzymatic editing factors have remained opaque given the limitations of conventional methods to interrogate the order and mechanism by which editing progresses and thus roles of individual proteins. Here, we examined whole populations of partially edited sequences using high throughput sequencing and a novel bioinformatic platform, the Trypanosome RNA Editing Alignment Tool (TREAT), to elucidate the roles of three proteins in the RNA Editing Mediator Complex (REMC). We determined that the factors examined function in the progression of editing through a gRNA; however, they have distinct roles and REMC is likely heterogeneous in composition. We provide the first evidence that editing can proceed through numerous paths within a single gRNA and that non-linear modifications are essential, generating commonly observed junction regions. Our data support a model in which RNA editing is executed via multiple paths that necessitate successive re-modification of junction regions facilitated, in part, by the REMC variant containing TbRGG2 and MRB8180.
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Affiliation(s)
- Rachel M. Simpson
- Department of Microbiology and Immunology, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, 3435 Main Street, Buffalo, NY 14214, USA
| | - Andrew E. Bruno
- Center for Computational Research, University at Buffalo, 701 Ellicott St., Buffalo, NY 14203, USA
| | - Runpu Chen
- Department of Computer Science and Engineering, New York State Center of Excellence in Bioinformatics and Life Sciences, 701 Ellicott St., Buffalo, NY 14203, USA
| | - Kaylen Lott
- Department of Microbiology and Immunology, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, 3435 Main Street, Buffalo, NY 14214, USA
| | - Brianna L. Tylec
- Department of Microbiology and Immunology, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, 3435 Main Street, Buffalo, NY 14214, USA
| | - Jonathan E. Bard
- Genomics and Bioinformatics Core, University at Buffalo, 701 Ellicott St., Buffalo, NY 14203, USA
| | - Yijun Sun
- Department of Microbiology and Immunology, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, 3435 Main Street, Buffalo, NY 14214, USA
- Center for Computational Research, University at Buffalo, 701 Ellicott St., Buffalo, NY 14203, USA
| | - Michael J. Buck
- Department of Biochemistry, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, 701 Ellicott St., Buffalo, NY 14203, USA
| | - Laurie K. Read
- Department of Microbiology and Immunology, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, 3435 Main Street, Buffalo, NY 14214, USA
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7
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Carnes J, McDermott S, Anupama A, Oliver BG, Sather DN, Stuart K. In vivo cleavage specificity of Trypanosoma brucei editosome endonucleases. Nucleic Acids Res 2017; 45:4667-4686. [PMID: 28334821 PMCID: PMC5416837 DOI: 10.1093/nar/gkx116] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 01/09/2017] [Accepted: 02/15/2017] [Indexed: 11/13/2022] Open
Abstract
RNA editing is an essential post-transcriptional process that creates functional mitochondrial mRNAs in Kinetoplastids. Multiprotein editosomes catalyze pre-mRNA cleavage, uridine (U) insertion or deletion, and ligation as specified by guide RNAs. Three functionally and compositionally distinct editosomes differ by the mutually exclusive presence of the KREN1, KREN2 or KREN3 endonuclease and their associated partner proteins. Because endonuclease cleavage is a likely point of regulation for RNA editing, we elucidated endonuclease specificity in vivo. We used a mutant gamma ATP synthase allele (MGA) to circumvent the normal essentiality of the editing endonucleases, and created cell lines in which both alleles of one, two or all three of the endonucleases were deleted. Cells lacking multiple endonucleases had altered editosome sedimentation on glycerol gradients and substantial defects in overall editing. Deep sequencing analysis of RNAs from such cells revealed clear discrimination by editosomes between sites of deletion versus insertion editing and preferential but overlapping specificity for sites of insertion editing. Thus, endonuclease specificities in vivo are distinct but with some functional overlap. The overlapping specificities likely accommodate the more numerous sites of insertion versus deletion editing as editosomes collaborate to accurately edit thousands of distinct editing sites in vivo.
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Affiliation(s)
- Jason Carnes
- Center for Infectious Disease Research (formerly Seattle BioMed), Seattle, WA 98109, USA
| | - Suzanne McDermott
- Center for Infectious Disease Research (formerly Seattle BioMed), Seattle, WA 98109, USA
| | - Atashi Anupama
- Center for Infectious Disease Research (formerly Seattle BioMed), Seattle, WA 98109, USA
| | - Brian G. Oliver
- Center for Infectious Disease Research (formerly Seattle BioMed), Seattle, WA 98109, USA
| | - D. Noah Sather
- Center for Infectious Disease Research (formerly Seattle BioMed), Seattle, WA 98109, USA
| | - Kenneth Stuart
- Center for Infectious Disease Research (formerly Seattle BioMed), Seattle, WA 98109, USA
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8
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Simpson RM, Bruno AE, Bard JE, Buck MJ, Read LK. High-throughput sequencing of partially edited trypanosome mRNAs reveals barriers to editing progression and evidence for alternative editing. RNA (NEW YORK, N.Y.) 2016; 22:677-95. [PMID: 26908922 PMCID: PMC4836643 DOI: 10.1261/rna.055160.115] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 01/28/2016] [Indexed: 05/20/2023]
Abstract
Uridine insertion/deletion RNA editing in kinetoplastids entails the addition and deletion of uridine residues throughout the length of mitochondrial transcripts to generate translatable mRNAs. This complex process requires the coordinated use of several multiprotein complexes as well as the sequential use of noncoding template RNAs called guide RNAs. The majority of steady-state mitochondrial mRNAs are partially edited and often contain regions of mis-editing, termed junctions, whose role is unclear. Here, we report a novel method for sequencing entire populations of pre-edited partially edited, and fully edited RNAs and analyzing editing characteristics across populations using a new bioinformatics tool, the Trypanosome RNA Editing Alignment Tool (TREAT). Using TREAT, we examined populations of two transcripts, RPS12 and ND7-5', in wild-typeTrypanosoma brucei We provide evidence that the majority of partially edited sequences contain junctions, that intrinsic pause sites arise during the progression of editing, and that the mechanisms that mediate pausing in the generation of canonical fully edited sequences are distinct from those that mediate the ends of junction regions. Furthermore, we identify alternatively edited sequences that constitute plausible alternative open reading frames and identify substantial variability in the 5' UTRs of both canonical and alternatively edited sequences. This work is the first to use high-throughput sequencing to examine full-length sequences of whole populations of partially edited transcripts. Our method is highly applicable to current questions in the RNA editing field, including defining mechanisms of action for editing factors and identifying potential alternatively edited sequences.
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Affiliation(s)
- Rachel M Simpson
- Department of Microbiology and Immunology, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, New York 14214, USA
| | - Andrew E Bruno
- Center for Computational Research, University at Buffalo, Buffalo, New York 14203, USA
| | - Jonathan E Bard
- University at Buffalo Genomics and Bioinformatics Core, Buffalo, New York 14222, USA
| | - Michael J Buck
- Deparment of Biochemistry, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, New York 14214, USA
| | - Laurie K Read
- Department of Microbiology and Immunology, University at Buffalo, Jacobs School of Medicine and Biomedical Sciences, Buffalo, New York 14214, USA
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9
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Read LK, Lukeš J, Hashimi H. Trypanosome RNA editing: the complexity of getting U in and taking U out. WILEY INTERDISCIPLINARY REVIEWS-RNA 2015; 7:33-51. [PMID: 26522170 DOI: 10.1002/wrna.1313] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 09/21/2015] [Accepted: 09/22/2015] [Indexed: 12/27/2022]
Abstract
RNA editing, which adds sequence information to RNAs post-transcriptionally, is a widespread phenomenon throughout eukaryotes. The most complex form of this process is the uridine (U) insertion/deletion editing that occurs in the mitochondria of kinetoplastid protists. RNA editing in these flagellates is specified by trans-acting guide RNAs and entails the insertion of hundreds and deletion of dozens of U residues from mitochondrial RNAs to produce mature, translatable mRNAs. An emerging model indicates that the machinery required for trypanosome RNA editing is much more complicated than previously appreciated. A family of RNA editing core complexes (RECCs), which contain the required enzymes and several structural proteins, catalyze cycles of U insertion and deletion. A second, dynamic multiprotein complex, the Mitochondrial RNA Binding 1 (MRB1) complex, has recently come to light as another essential component of the trypanosome RNA editing machinery. MRB1 likely serves as the platform for kinetoplastid RNA editing, and plays critical roles in RNA utilization and editing processivity. MRB1 also appears to act as a hub for coordination of RNA editing with additional mitochondrial RNA processing events. This review highlights the current knowledge regarding the complex molecular machinery involved in trypanosome RNA editing. WIREs RNA 2016, 7:33-51. doi: 10.1002/wrna.1313 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Laurie K Read
- University at Buffalo School of Medicine, Buffalo, NY, USA
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic.,Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic.,Canadian Institute for Advanced Research, Toronto, ON, Canada
| | - Hassan Hashimi
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic.,Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
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10
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Madina BR, Kumar V, Mooers BHM, Cruz-Reyes J. Native Variants of the MRB1 Complex Exhibit Specialized Functions in Kinetoplastid RNA Editing. PLoS One 2015; 10:e0123441. [PMID: 25928631 PMCID: PMC4415780 DOI: 10.1371/journal.pone.0123441] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 03/04/2015] [Indexed: 12/20/2022] Open
Abstract
Adaptation and survival of Trypanosoma brucei requires editing of mitochondrial mRNA by uridylate (U) insertion and deletion. Hundreds of small guide RNAs (gRNAs) direct the mRNA editing at over 3,000 sites. RNA editing is controlled during the life cycle but the regulation of substrate and stage specificity remains unknown. Editing progresses in the 3' to 5' direction along the pre-mRNA in blocks, each targeted by a unique gRNA. A critical editing factor is the mitochondrial RNA binding complex 1 (MRB1) that binds gRNA and transiently interacts with the catalytic RNA editing core complex (RECC). MRB1 is a large and dynamic complex that appears to be comprised of distinct but related subcomplexes (termed here MRBs). MRBs seem to share a 'core' complex of proteins but differ in the composition of the 'variable' proteins. Since some proteins associate transiently the MRBs remain imprecisely defined. MRB1 controls editing by unknown mechanisms, and the functional relevance of the different MRBs is unclear. We previously identified two distinct MRBs, and showed that they carry mRNAs that undergo editing. We proposed that editing takes place in the MRBs because MRBs stably associate with mRNA and gRNA but only transiently interact with RECC, which is RNA free. Here, we identify the first specialized functions in MRBs: 1) 3010-MRB is a major scaffold for RNA editing, and 2) REH2-MRB contains a critical trans-acting RNA helicase (REH2) that affects multiple steps of editing function in 3010-MRB. These trans effects of the REH2 include loading of unedited mRNA and editing in the first block and in subsequent blocks as editing progresses. REH2 binds its own MRB via RNA, and conserved domains in REH2 were critical for REH2 to associate with the RNA and protein components of its MRB. Importantly, REH2 associates with a ~30 kDa RNA-binding protein in a novel ~15S subcomplex in RNA-depleted mitochondria. We use these new results to update our model of MRB function and organization.
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Affiliation(s)
- Bhaskara R. Madina
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, United States of America
| | - Vikas Kumar
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, United States of America
| | - Blaine H. M. Mooers
- Department of Biochemistry & Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, United States of America
| | - Jorge Cruz-Reyes
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, United States of America
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11
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Madina BR, Kumar V, Metz R, Mooers BH, Bundschuh R, Cruz-Reyes J. Native mitochondrial RNA-binding complexes in kinetoplastid RNA editing differ in guide RNA composition. RNA (NEW YORK, N.Y.) 2014; 20:1142-52. [PMID: 24865612 PMCID: PMC4114691 DOI: 10.1261/rna.044495.114] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2014] [Accepted: 04/25/2014] [Indexed: 05/20/2023]
Abstract
Mitochondrial mRNAs in kinetoplastids require extensive U-insertion/deletion editing that progresses 3'-to-5' in small blocks, each directed by a guide RNA (gRNA), and exhibits substrate and developmental stage-specificity by unsolved mechanisms. Here, we address compositionally related factors, collectively known as the mitochondrial RNA-binding complex 1 (MRB1) or gRNA-binding complex (GRBC), that contain gRNA, have a dynamic protein composition, and transiently associate with several mitochondrial factors including RNA editing core complexes (RECC) and ribosomes. MRB1 controls editing by still unknown mechanisms. We performed the first next-generation sequencing study of native subcomplexes of MRB1, immunoselected via either RNA helicase 2 (REH2), that binds RNA and associates with unwinding activity, or MRB3010, that affects an early editing step. The particles contain either REH2 or MRB3010 but share the core GAP1 and other proteins detected by RNA photo-crosslinking. Analyses of the first editing blocks indicate an enrichment of several initiating gRNAs in the MRB3010-purified complex. Our data also indicate fast evolution of mRNA 3' ends and strain-specific alternative 3' editing within 3' UTR or C-terminal protein-coding sequence that could impact mitochondrial physiology. Moreover, we found robust specific copurification of edited and pre-edited mRNAs, suggesting that these particles may bind both mRNA and gRNA editing substrates. We propose that multiple subcomplexes of MRB1 with different RNA/protein composition serve as a scaffold for specific assembly of editing substrates and RECC, thereby forming the editing holoenzyme. The MRB3010-subcomplex may promote early editing through its preferential recruitment of initiating gRNAs.
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MESH Headings
- Amino Acid Sequence
- Base Composition
- Base Sequence
- Cells, Cultured
- Kinetoplastida/genetics
- Kinetoplastida/metabolism
- Molecular Sequence Data
- Protozoan Proteins/genetics
- Protozoan Proteins/metabolism
- RNA/chemistry
- RNA/metabolism
- RNA Editing
- RNA, Guide, Kinetoplastida/chemistry
- RNA, Guide, Kinetoplastida/genetics
- RNA, Guide, Kinetoplastida/metabolism
- RNA, Messenger/chemistry
- RNA, Messenger/metabolism
- RNA, Mitochondrial
- RNA, Protozoan/chemistry
- RNA, Protozoan/metabolism
- Trypanosoma brucei brucei/genetics
- Trypanosoma brucei brucei/metabolism
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Affiliation(s)
- Bhaskara R. Madina
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA
| | - Vikas Kumar
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA
| | - Richard Metz
- Texas AgriLife Genomics and Bioinformatics Service, Texas A&M University, College Station, Texas 77845, USA
| | - Blaine H.M. Mooers
- Department of Biochemistry & Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
| | - Ralf Bundschuh
- Department of Physics, Department of Chemistry & Biochemistry, Division of Hematology, Center of RNA Biology, The Ohio State University, Columbus, Ohio 43210-1117, USA
| | - Jorge Cruz-Reyes
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA
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12
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Editosome accessory factors KREPB9 and KREPB10 in Trypanosoma brucei. EUKARYOTIC CELL 2012; 11:832-43. [PMID: 22562468 DOI: 10.1128/ec.00046-12] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Multiprotein complexes, called editosomes, catalyze the uridine insertion and deletion RNA editing that forms translatable mitochondrial mRNAs in kinetoplastid parasites. We have identified here two new U1-like zinc finger proteins that associate with editosomes and have shown that they are related to KREPB6, KREPB7, and KREPB8, and thus we have named them Kinetoplastid RNA Editing Proteins, KREPB9 and KREPB10. They are conserved and syntenic in trypanosomatids although KREPB10 is absent in Trypanosoma vivax and both are absent in Leishmania. Tandem affinity purification (TAP)-tagged KREPB9 and KREPB10 incorporate into ~20S editosomes and/or subcomplexes thereof and preferentially associate with deletion subcomplexes, as do KREPB6, KREPB7, and KREPB8. KREPB10 also associates with editosomes that are isolated via a chimeric endonuclease, KREN1 in KREPB8 RNA interference (RNAi) cells, or MEAT1. The purified complexes have precleaved editing activities and endonuclease cleavage activity that appears to leave a 5' OH on the 3' product. RNAi knockdowns did not affect growth but resulted in relative reductions of both edited and unedited mitochondrial mRNAs. The similarity of KREPB9 and KREPB10 to KREPB6, KREPB7, and KREPB8 suggests they may be accessory factors that affect editing endonuclease activity and as a consequence may affect mitochondrial mRNA stability. KREPB9 and KREPB10, along with KREPB6, KREPB7, and KREPB8, may enable the endonucleases to discriminate among and accurately cleave hundreds of different editing sites and may be involved in the control of differential editing during the life cycle of T. brucei.
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Aphasizhev R, Aphasizheva I. Uridine insertion/deletion editing in trypanosomes: a playground for RNA-guided information transfer. WILEY INTERDISCIPLINARY REVIEWS. RNA 2011; 2:669-85. [PMID: 21823228 PMCID: PMC3154072 DOI: 10.1002/wrna.82] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
RNA editing is a collective term referring to enzymatic processes that change RNA sequence apart from splicing, 5' capping or 3' extension. In this article, we focus on uridine insertion/deletion mRNA editing found exclusively in mitochondria of kinetoplastid protists. This type of editing corrects frameshifts, introduces start and stops codons, and often adds much of the coding sequence to create an open reading frame. The mitochondrial genome of trypanosomatids, the most extensively studied clade within the order Kinetoplastida, is composed of ∼50 maxicircles with limited coding capacity and thousands of minicircles. To produce functional mRNAs, a multitude of nuclear-encoded factors mediate interactions of maxicircle-encoded pre-mRNAs with a vast repertoire of minicircle-encoded guide RNAs. Editing reactions of mRNA cleavage, U-insertions or U-deletions, and ligation are catalyzed by the RNA editing core complex (RECC, the 20S editosome) while each step of this enzymatic cascade is directed by guide RNAs. These 50-60 nucleotide (nt) molecules are 3' uridylated by RET1 TUTase and stabilized via association with the gRNA binding complex (GRBC). Remarkably, the information transfer between maxicircle and minicircle transcriptomes does not rely on template-dependent polymerization of nucleic acids. Instead, intrinsic substrate specificities of key enzymes are largely responsible for the fidelity of editing. Conversely, the efficiency of editing is enhanced by assembling enzymes and RNA binding proteins into stable multiprotein complexes. WIREs RNA 2011 2 669-685 DOI: 10.1002/wrna.82 For further resources related to this article, please visit the WIREs website.
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MESH Headings
- Endonucleases/chemistry
- Endonucleases/genetics
- Endonucleases/metabolism
- Models, Biological
- Models, Molecular
- Protozoan Proteins/chemistry
- Protozoan Proteins/genetics
- Protozoan Proteins/metabolism
- RNA Editing/genetics
- RNA Editing/physiology
- RNA Helicases/chemistry
- RNA Helicases/genetics
- RNA Helicases/metabolism
- RNA, Guide, Kinetoplastida/genetics
- RNA, Guide, Kinetoplastida/metabolism
- RNA, Messenger/chemistry
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Protozoan/chemistry
- RNA, Protozoan/genetics
- RNA, Protozoan/metabolism
- RNA-Binding Proteins/chemistry
- RNA-Binding Proteins/genetics
- RNA-Binding Proteins/metabolism
- Trypanosoma/genetics
- Trypanosoma/metabolism
- Uridine/chemistry
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Affiliation(s)
- Ruslan Aphasizhev
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, USA.
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Knoop V. When you can't trust the DNA: RNA editing changes transcript sequences. Cell Mol Life Sci 2011; 68:567-86. [PMID: 20938709 PMCID: PMC11114842 DOI: 10.1007/s00018-010-0538-9] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 09/13/2010] [Accepted: 09/23/2010] [Indexed: 12/25/2022]
Abstract
RNA editing describes targeted sequence alterations in RNAs so that the transcript sequences differ from their DNA template. Since the original discovery of RNA editing in trypanosomes nearly 25 years ago more than a dozen such processes of nucleotide insertions, deletions, and exchanges have been identified in evolutionarily widely separated groups of the living world including plants, animals, fungi, protists, bacteria, and viruses. In many cases gene expression in mitochondria is affected, but RNA editing also takes place in chloroplasts and in nucleocytosolic genetic environments. While some RNA editing systems largely seem to repair defect genes (cryptogenes), others have obvious functions in modulating gene activities. The present review aims for an overview on the current states of research in the different systems of RNA editing by following a historic timeline along the respective original discoveries.
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Affiliation(s)
- Volker Knoop
- Abteilung Molekulare Evolution, Institut für Zelluläre und Molekulare Botanik (IZMB), Bonn, Germany.
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Hinrichsen I, Bolle N, Paun L, Kempken F. RNA processing in plant mitochondria is independent of transcription. PLANT MOLECULAR BIOLOGY 2009; 70:663-668. [PMID: 19412686 DOI: 10.1007/s11103-009-9498-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Accepted: 04/18/2009] [Indexed: 05/27/2023]
Abstract
We analyzed the ability of plant mitochondria to process introduced RNA. Arabidopsis thaliana cox2 transcripts were synthesized in vitro. The in vitro transcribed mRNA was electroporated into maize and cauliflower mitochondria and incubated in organello. RNA was isolated and RT-PCR was carried out to analyze RNA processing. Our data indicate that cox2 transcripts introduced into isolated plant mitochondria are processed completely. This is the first report of in organello editing of introduced transcripts. We also found that none of the transcription, translation, or respiration inhibitors we used influenced RNA splicing or RNA editing of the cox2 transcript. Thus, our data also demonstrate that plant mitochondrial RNA processing may be independent of both transcription and respiratory regulation.
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Affiliation(s)
- Inga Hinrichsen
- Abteilung Botanische Genetik und Molekularbiologie, Botanisches Institut und Botanischer Garten, Christian-Albrechts-Universität zu Kiel, Olshausenstrasse 40, 24098 Kiel, Germany
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16
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Osato D, Rogers K, Guo Q, Li F, Richmond G, Klug F, Simpson L. Uridine insertion/deletion RNA editing in trypanosomatid mitochondria: In search of the editosome. RNA (NEW YORK, N.Y.) 2009; 15:1338-44. [PMID: 19447916 PMCID: PMC2704074 DOI: 10.1261/rna.1642809] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The RNA ligase-containing or L-complex is the core complex involved in uridine insertion/deletion RNA editing in trypanosome mitochondria. Blue native gels of glycerol gradient-separated fractions of mitochondrial lysate from cells transfected with the TAP-tagged editing protein, LC-8 (TbMP44/KREPB5), show a approximately 1 MDa L-complex band and, in addition, two minor higher molecular weight REL1-containing complexes: one (L*a) co-sedimenting with the L-complex and running in the gel at around 1.2 MDa; the other (L*b) showing a continuous increase in molecular weight from 1 MDa to particles sedimenting over 70S. The L*b-complexes appear to be mainly composed of L-complex components, since polypeptide profiles of L- and L*b-complex gradient fractions were similar in composition and L*b-complex bands often degraded to L-complex bands after manipulation or freeze-thaw cycles. The L*a-complex may be artifactual since this gel shift can be produced by various experimental manipulations. However, the nature of the change and any cellular role remain to be determined. The L*b-complexes from both lysate and TAP pull-down were sensitive to RNase A digestion, suggesting that RNA is involved with the stability of the L*b-complexes. The MRP1/2 RNA binding complex is localized mainly in the L*b-complexes in substoichiometric amounts and this association is RNase sensitive. We suggest that the L*b-complexes may provide a scaffold for dynamic interaction with other editing factors during the editing process to form the active holoenzyme or "editosome."
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Affiliation(s)
- Daren Osato
- Department of Microbiology, Immunology and Molecular Genetics, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California 90095, USA
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Niemann M, Brecht M, Schlüter E, Weitzel K, Zacharias M, Göringer HU. TbMP42 is a structure-sensitive ribonuclease that likely follows a metal ion catalysis mechanism. Nucleic Acids Res 2008; 36:4465-73. [PMID: 18603593 PMCID: PMC2490751 DOI: 10.1093/nar/gkn410] [Citation(s) in RCA: 16] [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: 05/06/2008] [Revised: 06/10/2008] [Accepted: 06/10/2008] [Indexed: 12/22/2022] Open
Abstract
RNA editing in African trypanosomes is characterized by a uridylate-specific insertion and/or deletion reaction that generates functional mitochondrial transcripts. The process is catalyzed by a multi-enzyme complex, the editosome, which consists of approximately 20 proteins. While for some of the polypeptides a contribution to the editing reaction can be deduced from their domain structure, the involvement of other proteins remains elusive. TbMP42, is a component of the editosome that is characterized by two C(2)H(2)-type zinc-finger domains and a putative oligosaccharide/oligonucleotide-binding fold. Recombinant TbMP42 has been shown to possess endo/exoribonuclease activity in vitro; however, the protein lacks canonical nuclease motifs. Using a set of synthetic gRNA/pre-mRNA substrate RNAs, we demonstrate that TbMP42 acts as a topology-dependent ribonuclease that is sensitive to base stacking. We further show that the chelation of Zn(2+) cations is inhibitory to the enzyme activity and that the chemical modification of amino acids known to coordinate Zn(2+) inactivates rTbMP42. Together, the data are suggestive of a Zn(2+)-dependent metal ion catalysis mechanism for the ribonucleolytic activity of rTbMP42.
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Affiliation(s)
- Moritz Niemann
- Genetics, Darmstadt University of Technology, Schnittspahnstraße 10, 64287 Darmstadt and Computational Biology, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
| | - Michael Brecht
- Genetics, Darmstadt University of Technology, Schnittspahnstraße 10, 64287 Darmstadt and Computational Biology, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
| | - Elke Schlüter
- Genetics, Darmstadt University of Technology, Schnittspahnstraße 10, 64287 Darmstadt and Computational Biology, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
| | - Kerstin Weitzel
- Genetics, Darmstadt University of Technology, Schnittspahnstraße 10, 64287 Darmstadt and Computational Biology, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
| | - Martin Zacharias
- Genetics, Darmstadt University of Technology, Schnittspahnstraße 10, 64287 Darmstadt and Computational Biology, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
| | - H. Ulrich Göringer
- Genetics, Darmstadt University of Technology, Schnittspahnstraße 10, 64287 Darmstadt and Computational Biology, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany
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