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Lang BF, Beck N, Prince S, Sarrasin M, Rioux P, Burger G. Mitochondrial genome annotation with MFannot: a critical analysis of gene identification and gene model prediction. FRONTIERS IN PLANT SCIENCE 2023; 14:1222186. [PMID: 37469769 PMCID: PMC10352661 DOI: 10.3389/fpls.2023.1222186] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Accepted: 06/15/2023] [Indexed: 07/21/2023]
Abstract
Compared to nuclear genomes, mitochondrial genomes (mitogenomes) are small and usually code for only a few dozen genes. Still, identifying genes and their structure can be challenging and time-consuming. Even automated tools for mitochondrial genome annotation often require manual analysis and curation by skilled experts. The most difficult steps are (i) the structural modelling of intron-containing genes; (ii) the identification and delineation of Group I and II introns; and (iii) the identification of moderately conserved, non-coding RNA (ncRNA) genes specifying 5S rRNAs, tmRNAs and RNase P RNAs. Additional challenges arise through genetic code evolution which can redefine the translational identity of both start and stop codons, thus obscuring protein-coding genes. Further, RNA editing can render gene identification difficult, if not impossible, without additional RNA sequence data. Current automated mito- and plastid-genome annotators are limited as they are typically tailored to specific eukaryotic groups. The MFannot annotator we developed is unique in its applicability to a broad taxonomic scope, its accuracy in gene model inference, and its capabilities in intron identification and classification. The pipeline leverages curated profile Hidden Markov Models (HMMs), covariance (CMs) and ERPIN models to better capture evolutionarily conserved signatures in the primary sequence (HMMs and CMs) as well as secondary structure (CMs and ERPIN). Here we formally describe MFannot, which has been available as a web-accessible service (https://megasun.bch.umontreal.ca/apps/mfannot/) to the research community for nearly 16 years. Further, we report its performance on particularly intron-rich mitogenomes and describe ongoing and future developments.
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Tang JY, Wei R, Zhang XC, Xiang QP. Mitogenome-based phylogenomics provides insights into the positions of the enigmatic sinensis group and the sanguinolenta group in Selaginellaceae (Lycophyte). Mol Phylogenet Evol 2023; 179:107673. [PMID: 36528332 DOI: 10.1016/j.ympev.2022.107673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 10/14/2022] [Accepted: 12/07/2022] [Indexed: 12/23/2022]
Abstract
Spikemoss (Selaginellaceae) is one of the basal lineages of vascular plants. This family has a single genus Selaginella which consists of about 750 extant species. The phylogeny of Selaginellaceae has been extensively studied mainly based on plastid DNA and a few nuclear sequences. However, the placement of the enigmatic sinensis group is a long-term controversy because of the long branch in the plastid DNA phylogeny. The sanguinolenta group is also a phylogenetically problematic clade owing to two alternative positions resulted from different datasets. Here, we newly sequenced 34 mitochondrial genomes (mitogenomes) of individuals representing all seven subgenera and major clades in Selaginellaceae. We assembled the draft mitogenomes and annotated the genes and performed phylogenetic analyses based on the shared 17 mitochondrial genes. Our major results include: (1) all the assembled mitogenomes have complicated structures, unparalleled high GC content and a small gene content set, and the positive correlations among GC content, substitution rates and the number of RNA editing sites hold; (2) the sinensis group was well supported as a member of subg. Stachygynandrum; (3) the sanguinolenta group was strongly resolved as sister to all other Selaginella species except for subg. Selaginella. This study demonstrates the potential of mitogenome data in providing novel insights into phylogenetically recalcitrant problems.
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Affiliation(s)
- Jun-Yong Tang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ran Wei
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Xian-Chun Zhang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
| | - Qiao-Ping Xiang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
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3
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Waltz F, Salinas-Giegé T, Englmeier R, Meichel H, Soufari H, Kuhn L, Pfeffer S, Förster F, Engel BD, Giegé P, Drouard L, Hashem Y. How to build a ribosome from RNA fragments in Chlamydomonas mitochondria. Nat Commun 2021; 12:7176. [PMID: 34887394 PMCID: PMC8660880 DOI: 10.1038/s41467-021-27200-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 11/08/2021] [Indexed: 01/12/2023] Open
Abstract
Mitochondria are the powerhouse of eukaryotic cells. They possess their own gene expression machineries where highly divergent and specialized ribosomes, named hereafter mitoribosomes, translate the few essential messenger RNAs still encoded by mitochondrial genomes. Here, we present a biochemical and structural characterization of the mitoribosome in the model green alga Chlamydomonas reinhardtii, as well as a functional study of some of its specific components. Single particle cryo-electron microscopy resolves how the Chlamydomonas mitoribosome is assembled from 13 rRNA fragments encoded by separate non-contiguous gene pieces. Additional proteins, mainly OPR, PPR and mTERF helical repeat proteins, are found in Chlamydomonas mitoribosome, revealing the structure of an OPR protein in complex with its RNA binding partner. Targeted amiRNA silencing indicates that these ribosomal proteins are required for mitoribosome integrity. Finally, we use cryo-electron tomography to show that Chlamydomonas mitoribosomes are attached to the inner mitochondrial membrane via two contact points mediated by Chlamydomonas-specific proteins. Our study expands our understanding of mitoribosome diversity and the various strategies these specialized molecular machines adopt for membrane tethering.
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Affiliation(s)
- Florent Waltz
- Institut Européen de Chimie et Biologie, U1212 Inserm, Université de Bordeaux, 2 rue R. Escarpit, 33600, Pessac, France
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, 12 rue du général Zimmer, 67084, Strasbourg, France
- Helmholtz Pioneer Campus, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany
| | - Thalia Salinas-Giegé
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, 12 rue du général Zimmer, 67084, Strasbourg, France
| | - Robert Englmeier
- Structural Biochemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands
| | - Herrade Meichel
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, 12 rue du général Zimmer, 67084, Strasbourg, France
| | - Heddy Soufari
- Institut Européen de Chimie et Biologie, U1212 Inserm, Université de Bordeaux, 2 rue R. Escarpit, 33600, Pessac, France
| | - Lauriane Kuhn
- Plateforme protéomique Strasbourg Esplanade FRC1589 du CNRS, Université de Strasbourg, 67084, Strasbourg, France
| | - Stefan Pfeffer
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, 69120, Heidelberg, Germany
| | - Friedrich Förster
- Structural Biochemistry, Bijvoet Centre for Biomolecular Research, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands
| | - Benjamin D Engel
- Helmholtz Pioneer Campus, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764, Neuherberg, Germany
- Department of Chemistry, Technical University of Munich, Lichtenbergstraße 4, 85748, Garching, Germany
| | - Philippe Giegé
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, 12 rue du général Zimmer, 67084, Strasbourg, France.
| | - Laurence Drouard
- Institut de biologie moléculaire des plantes, CNRS, Université de Strasbourg, 12 rue du général Zimmer, 67084, Strasbourg, France.
| | - Yaser Hashem
- Institut Européen de Chimie et Biologie, U1212 Inserm, Université de Bordeaux, 2 rue R. Escarpit, 33600, Pessac, France.
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Fučíková K, Lahr DJG. Uncovering Cryptic Diversity in Two Amoebozoan Species Using Complete Mitochondrial Genome Sequences. J Eukaryot Microbiol 2015. [PMID: 26211788 DOI: 10.1111/jeu.12253] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The Amoebozoa are a major eukaryotic lineage that encompasses a wide range of amoeboid organisms. The group is understudied from a systematic perspective: molecular tools have only been applied in the last 15 yr. Hence, there is an undersampling of both genes and taxa in the group especially compared to plants, animals, and fungi. Here, we present the complete mitochondrial genomes of two ubiquitous and abundant morpho-species (Acanthamoeba castellanii and Vermamoeba vermiformis). Both have mitochondrial genomes of close relatives previously available, enabling insights into recent divergences at a genomic scale, while simultaneously offering comparisons with divergence estimates obtained from traditionally used single genes, SSU rDNA and cox1. The newly sequenced mt genomes are significantly divergent from their previously sequenced conspecifics (A. castellannii 16.4% divergence at nucleotide level and 10.4% amino acid; V. vermiformis 21.6% and 13.1%, respectively), while divergence at the small subunit ribosomal DNA is below 1% within both species. Morphological analyses determined that these lineages are indistinguishable from their previously sequenced counterparts. Phylogenetic reconstructions using 26 mt genes also indicate a level of divergence that is comparable to divergence among species, while reconstructions using the small subunit ribosomal DNA (SSU rDNA) do not. In addition, we demonstrate that between closely related taxa, there are high levels of synteny, which can be explored for primer design to obtain larger fragments than the traditional barcoding genes. We conclude that, although most systematic work has relied on SSU, this gene alone can severely underestimate diversity. Thus, we suggest that the mt genome emerges as an alternative for unraveling the lower level phylogenetic relationships of Amoebozoa.
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Affiliation(s)
- Karolina Fučíková
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, USA
| | - Daniel J G Lahr
- Department of Zoology, Institute of Biosciences, University of São Paulo, São Paulo, 05508-090, Brazil
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5
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Valach M, Burger G, Gray MW, Lang BF. Widespread occurrence of organelle genome-encoded 5S rRNAs including permuted molecules. Nucleic Acids Res 2014; 42:13764-77. [PMID: 25429974 PMCID: PMC4267664 DOI: 10.1093/nar/gku1266] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 11/14/2014] [Accepted: 11/17/2014] [Indexed: 11/13/2022] Open
Abstract
5S Ribosomal RNA (5S rRNA) is a universal component of ribosomes, and the corresponding gene is easily identified in archaeal, bacterial and nuclear genome sequences. However, organelle gene homologs (rrn5) appear to be absent from most mitochondrial and several chloroplast genomes. Here, we re-examine the distribution of organelle rrn5 by building mitochondrion- and plastid-specific covariance models (CMs) with which we screened organelle genome sequences. We not only recover all organelle rrn5 genes annotated in GenBank records, but also identify more than 50 previously unrecognized homologs in mitochondrial genomes of various stramenopiles, red algae, cryptomonads, malawimonads and apusozoans, and surprisingly, in the apicoplast (highly derived plastid) genomes of the coccidian pathogens Toxoplasma gondii and Eimeria tenella. Comparative modeling of RNA secondary structure reveals that mitochondrial 5S rRNAs from brown algae adopt a permuted triskelion shape that has not been seen elsewhere. Expression of the newly predicted rrn5 genes is confirmed experimentally in 10 instances, based on our own and published RNA-Seq data. This study establishes that particularly mitochondrial 5S rRNA has a much broader taxonomic distribution and a much larger structural variability than previously thought. The newly developed CMs will be made available via the Rfam database and the MFannot organelle genome annotator.
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MESH Headings
- Coccidia/genetics
- Databases, Nucleic Acid
- Genes, Mitochondrial
- Genes, rRNA
- Genome, Mitochondrial
- Genome, Plastid
- Nucleic Acid Conformation
- Phaeophyceae/genetics
- RNA/chemistry
- RNA/genetics
- RNA, Mitochondrial
- RNA, Ribosomal, 5S/chemistry
- RNA, Ribosomal, 5S/classification
- RNA, Ribosomal, 5S/genetics
- Sequence Analysis, RNA
- Stramenopiles/genetics
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Affiliation(s)
- Matus Valach
- Department of Biochemistry and Robert-Cedergren Centre of Bioinformatics and Genomics, Université de Montréal, Montréal, QC, H3C 3J7, Canada
| | - Gertraud Burger
- Department of Biochemistry and Robert-Cedergren Centre of Bioinformatics and Genomics, Université de Montréal, Montréal, QC, H3C 3J7, Canada
| | - Michael W Gray
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS, B3H 4B2, Canada
| | - B Franz Lang
- Department of Biochemistry and Robert-Cedergren Centre of Bioinformatics and Genomics, Université de Montréal, Montréal, QC, H3C 3J7, Canada
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6
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Gawryluk RMR, Chisholm KA, Pinto DM, Gray MW. Compositional complexity of the mitochondrial proteome of a unicellular eukaryote (Acanthamoeba castellanii, supergroup Amoebozoa) rivals that of animals, fungi, and plants. J Proteomics 2014; 109:400-16. [PMID: 25026440 DOI: 10.1016/j.jprot.2014.07.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2014] [Revised: 06/09/2014] [Accepted: 07/04/2014] [Indexed: 12/22/2022]
Abstract
UNLABELLED We present a combined proteomic and bioinformatic investigation of mitochondrial proteins from the amoeboid protist Acanthamoeba castellanii, the first such comprehensive investigation in a free-living member of the supergroup Amoebozoa. This protist was chosen both for its phylogenetic position (as a sister to animals and fungi) and its ecological ubiquity and physiological flexibility. We report 1033 A. castellanii mitochondrial protein sequences, 709 supported by mass spectrometry data (676 nucleus-encoded and 33 mitochondrion-encoded), including two previously unannotated mtDNA-encoded proteins, which we identify as highly divergent mitochondrial ribosomal proteins. Other notable findings include duplicate proteins for all of the enzymes of the tricarboxylic acid (TCA) cycle-which, along with the identification of a mitochondrial malate synthase-isocitrate lyase fusion protein, suggests the interesting possibility that the glyoxylate cycle operates in A. castellanii mitochondria. Additionally, the A. castellanii genome encodes an unusually high number (at least 29) of mitochondrion-targeted pentatricopeptide repeat (PPR) proteins, organellar RNA metabolism factors in other organisms. We discuss several key mitochondrial pathways, including DNA replication, transcription and translation, protein degradation, protein import and Fe-S cluster biosynthesis, highlighting similarities and differences in these pathways in other eukaryotes. In compositional and functional complexity, the mitochondrial proteome of A. castellanii rivals that of multicellular eukaryotes. BIOLOGICAL SIGNIFICANCE Comprehensive proteomic surveys of mitochondria have been undertaken in a limited number of predominantly multicellular eukaryotes. This phylogenetically narrow perspective constrains and biases our insights into mitochondrial function and evolution, as it neglects protists, which account for most of the evolutionary and functional diversity within eukaryotes. We report here the first comprehensive investigation of the mitochondrial proteome in a member (A. castellanii) of the eukaryotic supergroup Amoebozoa. Through a combination of tandem mass spectrometry (MS/MS) and in silico data mining, we have retrieved 1033 candidate mitochondrial protein sequences, 709 having MS support. These data were used to reconstruct the metabolic pathways and protein complexes of A. castellanii mitochondria, and were integrated with data from other characterized mitochondrial proteomes to augment our understanding of mitochondrial proteome evolution. Our results demonstrate the power of combining direct proteomic and bioinformatic approaches in the discovery of novel mitochondrial proteins, both nucleus-encoded and mitochondrion-encoded, and highlight the compositional complexity of the A. castellanii mitochondrial proteome, which rivals that of animals, fungi and plants.
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Affiliation(s)
- Ryan M R Gawryluk
- Centre for Comparative Genomics and Evolutionary Bioinformatics, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Kenneth A Chisholm
- Mass Spectrometry and Proteomics Group, National Research Council of Canada, Halifax, Nova Scotia, Canada
| | - Devanand M Pinto
- Mass Spectrometry and Proteomics Group, National Research Council of Canada, Halifax, Nova Scotia, Canada
| | - Michael W Gray
- Centre for Comparative Genomics and Evolutionary Bioinformatics, Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada.
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7
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Yan M, Wang Y, Hu Y, Feng Y, Dai C, Wu J, Wu D, Zhang F, Zhai Q. A High-Throughput Quantitative Approach Reveals More Small RNA Modifications in Mouse Liver and Their Correlation with Diabetes. Anal Chem 2013; 85:12173-81. [DOI: 10.1021/ac4036026] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Menghong Yan
- Key Laboratory
of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai
Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Yuangao Wang
- Key Laboratory
of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai
Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Yanan Hu
- Key Laboratory
of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai
Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Yan Feng
- Key Laboratory
of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai
Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Changgui Dai
- Key Laboratory
of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai
Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Jingxia Wu
- Key Laboratory
of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai
Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Dongmei Wu
- Key Laboratory
of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai
Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Fang Zhang
- Key Laboratory
of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai
Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Qiwei Zhai
- Key Laboratory
of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai
Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China
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8
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Hecht J, Grewe F, Knoop V. Extreme RNA editing in coding islands and abundant microsatellites in repeat sequences of Selaginella moellendorffii mitochondria: the root of frequent plant mtDNA recombination in early tracheophytes. Genome Biol Evol 2011; 3:344-58. [PMID: 21436122 PMCID: PMC5654404 DOI: 10.1093/gbe/evr027] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Using an independent fosmid cloning approach and comprehensive transcriptome analysis to complement data from the Selaginella moellendorffii genome project, we determined the complete mitochondrial genome structure of this spikemoss. Numerous recombination events mediated mainly via long sequence repeats extending up to 7kbp result in a complex mtDNA network structure. Peculiar features associated with the repeat sequences are more than 80 different microsatellite sites (predominantly trinucleotide motifs). The S. moellendorffii mtDNA encodes a plant-typical core set of a twin-arginine translocase (tatC), 17 respiratory chain subunits, and 2 rRNAs but lacks atp4 and any tRNA genes. As a further novelty among plant chondromes, the nad4L gene is encoded within an intron of the nad1 gene. A total of 37 introns occupying the 20 mitochondrial genes (four of which are disrupted into trans-splicing arrangements including two novel instances of trans-splicing introns) make the S. moellendorffii chondrome the intron-richest and gene-poorest plant mtDNA known. Our parallel transcriptome analyses demonstrates functional splicing of all 37 introns and reveals a new record amount of plant organelle RNA editing with a total of 2,139 sites in mRNAs and 13 sites in the two rRNAs, all of which are exclusively of the C-to-U type.
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Affiliation(s)
- Julia Hecht
- Abteilung Molekulare Evolution, Institut für Zelluläre und Molekulare Botanik, Universität Bonn, D-53115 Bonn, Germany
| | - Felix Grewe
- Abteilung Molekulare Evolution, Institut für Zelluläre und Molekulare Botanik, Universität Bonn, D-53115 Bonn, Germany
| | - Volker Knoop
- Abteilung Molekulare Evolution, Institut für Zelluläre und Molekulare Botanik, Universität Bonn, D-53115 Bonn, Germany
- Corresponding author: E-mail:
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9
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Milbury CA, Lee JC, Cannone JJ, Gaffney PM, Gutell RR. Fragmentation of the large subunit ribosomal RNA gene in oyster mitochondrial genomes. BMC Genomics 2010; 11:485. [PMID: 20813041 PMCID: PMC2996981 DOI: 10.1186/1471-2164-11-485] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Accepted: 09/02/2010] [Indexed: 12/03/2022] Open
Abstract
Background Discontinuous genes have been observed in bacteria, archaea, and eukaryotic nuclei, mitochondria and chloroplasts. Gene discontinuity occurs in multiple forms: the two most frequent forms result from introns that are spliced out of the RNA and the resulting exons are spliced together to form a single transcript, and fragmented gene transcripts that are not covalently attached post-transcriptionally. Within the past few years, fragmented ribosomal RNA (rRNA) genes have been discovered in bilateral metazoan mitochondria, all within a group of related oysters. Results In this study, we have characterized this fragmentation with comparative analysis and experimentation. We present secondary structures, modeled using comparative sequence analysis of the discontinuous mitochondrial large subunit rRNA genes of the cupped oysters C. virginica, C. gigas, and C. hongkongensis. Comparative structure models for the large subunit rRNA in each of the three oyster species are generally similar to those for other bilateral metazoans. We also used RT-PCR and analyzed ESTs to determine if the two fragmented LSU rRNAs are spliced together. The two segments are transcribed separately, and not spliced together although they still form functional rRNAs and ribosomes. Conclusions Although many examples of discontinuous ribosomal genes have been documented in bacteria and archaea, as well as the nuclei, chloroplasts, and mitochondria of eukaryotes, oysters are some of the first characterized examples of fragmented bilateral animal mitochondrial rRNA genes. The secondary structures of the oyster LSU rRNA fragments have been predicted on the basis of previous comparative metazoan mitochondrial LSU rRNA structure models.
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Affiliation(s)
- Coren A Milbury
- College of Earth, Ocean, and Environment, University of Delaware, Lewes, DE, USA.
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10
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Bullerwell CE, Burger G, Gott JM, Kourennaia O, Schnare MN, Gray MW. Abundant 5S rRNA-like transcripts encoded by the mitochondrial genome in amoebozoa. EUKARYOTIC CELL 2010; 9:762-73. [PMID: 20304999 PMCID: PMC2863963 DOI: 10.1128/ec.00013-10] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Accepted: 03/14/2010] [Indexed: 11/20/2022]
Abstract
5S rRNAs are ubiquitous components of prokaryotic, chloroplast, and eukaryotic cytosolic ribosomes but are apparently absent from mitochondrial ribosomes (mitoribosomes) of many eukaryotic groups including animals and fungi. Nevertheless, a clearly identifiable, mitochondrion-encoded 5S rRNA is present in Acanthamoeba castellanii, a member of Amoebozoa. During a search for additional mitochondrial 5S rRNAs, we detected small abundant RNAs in other members of Amoebozoa, namely, in the lobose amoeba Hartmannella vermiformis and in the myxomycete slime mold Physarum polycephalum. These RNAs are encoded by mitochondrial DNA (mtDNA), cosediment with mitoribosomes in glycerol gradients, and can be folded into a secondary structure similar to that of bona fide 5S rRNAs. Further, in the mtDNA of another slime mold, Didymium nigripes, we identified a region that in sequence, potential secondary structure, and genomic location is similar to the corresponding region encoding the Physarum small RNA. A mtDNA-encoded small RNA previously identified in Dictyostelium discoideum is here shown to share several characteristics with known 5S rRNAs. Again, we detected genes encoding potential homologs of this RNA in the mtDNA of three other species of the genus Dictyostelium as well as in a related genus, Polysphondylium. Taken together, our results indicate a widespread occurrence of small, abundant, mtDNA-encoded RNAs with 5S rRNA-like structures that are associated with the mitoribosome in various amoebozoan taxa. Our working hypothesis is that these novel small abundant RNAs represent radically divergent mitochondrial 5S rRNA homologs. We posit that currently unrecognized 5S-like RNAs may exist in other mitochondrial systems in which a conventional 5S rRNA cannot be identified.
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MESH Headings
- Amoebozoa/cytology
- Amoebozoa/genetics
- Animals
- Base Sequence
- Cell Fractionation
- Computational Biology
- Conserved Sequence
- DNA, Mitochondrial/genetics
- Dictyostelium/genetics
- Genome, Mitochondrial/genetics
- Hartmannella/genetics
- Mitochondria/genetics
- Molecular Sequence Data
- Nucleic Acid Conformation
- Phylogeny
- Physarum polycephalum/genetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Ribosomal, 5S/chemistry
- RNA, Ribosomal, 5S/genetics
- Ribosome Subunits, Large, Eukaryotic/genetics
- Sequence Homology, Amino Acid
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Affiliation(s)
- Charles E. Bullerwell
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 1X5, Canada
| | - Gertraud Burger
- Robert Cedergren Center for Bioinformatics and Genomics, Département de Biochimie, Université de Montréal, Montréal, Quebec H3T 1J4, Canada; and
| | - Jonatha M. Gott
- Center for RNA Molecular Biology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106
| | - Olga Kourennaia
- Center for RNA Molecular Biology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, Ohio 44106
| | - Murray N. Schnare
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 1X5, Canada
| | - Michael W. Gray
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 1X5, Canada
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Smirnov AV, Entelis NS, Krasheninnikov IA, Martin R, Tarassov IA. Specific features of 5S rRNA structure - its interactions with macromolecules and possible functions. BIOCHEMISTRY (MOSCOW) 2009; 73:1418-37. [PMID: 19216709 DOI: 10.1134/s000629790813004x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Small non-coding RNAs are today a topic of great interest for molecular biologists because they can be regarded as relicts of a hypothetical "RNA world" which, apparently, preceded the modern stage of organic evolution on Earth. The small molecule of 5S rRNA (approximately 120 nucleotides) is a component of large ribosomal subunits of all living beings (5S rRNAs are not found only in mitoribosomes of fungi and metazoans). This molecule interacts with various protein factors and 23S (28S) rRNA. This review contains the accumulated data to date concerning 5S rRNA structure, interactions with other biological macromolecules, intracellular traffic, and functions in the cell.
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Affiliation(s)
- A V Smirnov
- Faculty of Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
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Oudot-Le Secq MP, Grimwood J, Shapiro H, Armbrust EV, Bowler C, Green BR. Chloroplast genomes of the diatoms Phaeodactylum tricornutum and Thalassiosira pseudonana: comparison with other plastid genomes of the red lineage. Mol Genet Genomics 2007; 277:427-39. [PMID: 17252281 DOI: 10.1007/s00438-006-0199-4] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2006] [Accepted: 11/30/2006] [Indexed: 11/28/2022]
Abstract
The chloroplast genomes of the pennate diatom Phaeodactylum tricornutum and the centric diatom Thalassiosira pseudonana have been completely sequenced and are compared with those of other secondary plastids of the red lineage: the centric diatom Odontella sinensis, the haptophyte Emiliania huxleyi, and the cryptophyte Guillardia theta. All five chromist genomes are compact, with small intergenic regions and no introns. The three diatom genomes are similar in gene content with 127-130 protein-coding genes, and genes for 27 tRNAs, three ribosomal RNAs and two small RNAs (tmRNA and signal recognition particle RNA). All three genomes have open-reading frames corresponding to ORFs148, 355 and 380 of O. sinensis, which have been assigned the names ycf88, ycf89 and ycf90. Gene order is not strictly conserved, but there are a number of conserved gene clusters showing remnants of red algal origin. The acpP, tsf and psb28 genes appear to be on the way from the plastid to the host nucleus, indicating that endosymbiotic gene transfer is a continuing process.
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Barth C, Le P, Fisher PR. Mitochondrial biology and disease in Dictyostelium. INTERNATIONAL REVIEW OF CYTOLOGY 2007; 263:207-52. [PMID: 17725968 DOI: 10.1016/s0074-7696(07)63005-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The cellular slime mold Dictyostelium discoideum has become an increasingly useful model for the study of mitochondrial biology and disease. Dictyostelium is an amoebazoan, a sister clade to the animal and fungal lineages. The mitochondrial biology of Dictyostelium exhibits some features which are unique, others which are common to all eukaryotes, and still others that are otherwise found only in the plant or the animal lineages. The AT-rich mitochondrial genome of Dictyostelium is larger than its mammalian counterpart and contains 56kb (compared to 17kb in mammals) encoding tRNAs, rRNAs, and 33 polypeptides (compared to 13 in mammals). It produces a single primary transcript that is cotranscriptionally processed into multiple monocistronic, dicistronic, and tricistronic mRNAs, tRNAs, and rRNAs. The mitochondrial fission mechanism employed by Dictyostelium involves both the extramitochondrial dynamin-based system used by plant, animal, and fungal mitochondria and the ancient FtsZ-based intramitochondrial fission process inherited from the bacterial ancestor. The mitochondrial protein-import apparatus is homologous to that of other eukaryote, and mitochondria in Dictyostelium play an important role in the programmed cell death pathways. Mitochondrial disease in Dictyostelium has been created both by targeted gene disruptions and by antisense RNA and RNAi inhibition of expression of essential nucleus-encoded mitochondrial proteins. This has revealed a regular pattern of aberrant mitochondrial disease phenotypes caused not by ATP insufficiency per se, but by chronic activation of the universal eukaryotic energy-sensing protein kinase AMPK. This novel insight into the cytopathological mechanisms of mitochondrial dysfunction suggests new possibilities for therapeutic intervention in mitochondrial and neurodegenerative diseases.
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Affiliation(s)
- Christian Barth
- Department of Microbiology, La Trobe University, Melbourne VIC 3086, Australia
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Gillespie JJ, Johnston JS, Cannone JJ, Gutell RR. Characteristics of the nuclear (18S, 5.8S, 28S and 5S) and mitochondrial (12S and 16S) rRNA genes of Apis mellifera (Insecta: Hymenoptera): structure, organization, and retrotransposable elements. INSECT MOLECULAR BIOLOGY 2006; 15:657-86. [PMID: 17069639 PMCID: PMC2048585 DOI: 10.1111/j.1365-2583.2006.00689.x] [Citation(s) in RCA: 189] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2006] [Accepted: 06/28/2006] [Indexed: 05/12/2023]
Abstract
As an accompanying manuscript to the release of the honey bee genome, we report the entire sequence of the nuclear (18S, 5.8S, 28S and 5S) and mitochondrial (12S and 16S) ribosomal RNA (rRNA)-encoding gene sequences (rDNA) and related internally and externally transcribed spacer regions of Apis mellifera (Insecta: Hymenoptera: Apocrita). Additionally, we predict secondary structures for the mature rRNA molecules based on comparative sequence analyses with other arthropod taxa and reference to recently published crystal structures of the ribosome. In general, the structures of honey bee rRNAs are in agreement with previously predicted rRNA models from other arthropods in core regions of the rRNA, with little additional expansion in non-conserved regions. Our multiple sequence alignments are made available on several public databases and provide a preliminary establishment of a global structural model of all rRNAs from the insects. Additionally, we provide conserved stretches of sequences flanking the rDNA cistrons that comprise the externally transcribed spacer regions (ETS) and part of the intergenic spacer region (IGS), including several repetitive motifs. Finally, we report the occurrence of retrotransposition in the nuclear large subunit rDNA, as R2 elements are present in the usual insertion points found in other arthropods. Interestingly, functional R1 elements usually present in the genomes of insects were not detected in the honey bee rRNA genes. The reverse transcriptase products of the R2 elements are deduced from their putative open reading frames and structurally aligned with those from another hymenopteran insect, the jewel wasp Nasonia (Pteromalidae). Stretches of conserved amino acids shared between Apis and Nasonia are illustrated and serve as potential sites for primer design, as target amplicons within these R2 elements may serve as novel phylogenetic markers for Hymenoptera. Given the impending completion of the sequencing of the Nasonia genome, we expect our report eventually to shed light on the evolution of the hymenopteran genome within higher insects, particularly regarding the relative maintenance of conserved rDNA genes, related variable spacer regions and retrotransposable elements.
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Affiliation(s)
- J J Gillespie
- Department of Entomology, Texas A & M University, College Station, TX, USA.
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Blake DP, Hesketh P, Archer A, Shirley MW, Smith AL. Eimeria maxima: The influence of host genotype on parasite reproduction as revealed by quantitative real-time PCR. Int J Parasitol 2006; 36:97-105. [PMID: 16300767 DOI: 10.1016/j.ijpara.2005.09.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2005] [Revised: 09/13/2005] [Accepted: 09/16/2005] [Indexed: 11/26/2022]
Abstract
The influence of host genotype on susceptibility to infection with Eimeria species has long been recognised, but beyond monitoring pathological severity or magnitude of oocyst excretion attempts to quantify fluctuations in parasite reproduction within the host have previously relied upon labour-intensive microscopic analysis. The development and application of a quantitative real-time PCR assay has opened this biological 'black box', permitting the sensitive and reproducible enumeration of parasite genomes throughout the course of infection. Generic and species-specific quantitative PCR methods are described, based upon the conserved 5S ribosomal RNA coding sequence of nine avian and murine Eimeria species and the Eimeria maxima MIC1 gene, respectively. These complementary assays have been applied to study the influence of host genotype on resistance to infection with E. maxima, revealing significant differences in parasite load between 'resistant' Line C and 'susceptible' Line 15I inbred chickens 5 days after infection. Parasite DNA remained detectable up to 20 days post-infection; 11 days after the last oocysts had been detected leaving the host.
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Affiliation(s)
- Damer P Blake
- Enteric Immunology Group, Institute for Animal Health, Compton, Nr. Newbury, Berkshire RG20 7NN, UK
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Abstract
Over the past several decades, our knowledge of the origin and evolution of mitochondria has been greatly advanced by determination of complete mitochondrial genome sequences. Among the most informative mitochondrial genomes have been those of protists (primarily unicellular eukaryotes), some of which harbor the most gene-rich and most eubacteria-like mitochondrial DNAs (mtDNAs) known. Comparison of mtDNA sequence data has provided insights into the radically diverse trends in mitochondrial genome evolution exhibited by different phylogenetically coherent groupings of eukaryotes, and has allowed us to pinpoint specific protist relatives of the multicellular eukaryotic lineages (animals, plants, and fungi). This comparative genomics approach has also revealed unique and fascinating aspects of mitochondrial gene expression, highlighting the mitochondrion as an evolutionary playground par excellence.
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Affiliation(s)
- Michael W Gray
- Robert Cedergren Center, Program in Evolutionary Biology, Canadian Institute for Advanced Research, Canada.
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