101
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Doyle JJ. Defining coalescent genes: Theory meets practice in organelle phylogenomics. Syst Biol 2021; 71:476-489. [PMID: 34191012 DOI: 10.1093/sysbio/syab053] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 06/24/2021] [Accepted: 06/28/2021] [Indexed: 11/13/2022] Open
Abstract
The species tree paradigm that dominates current molecular systematic practice infers species trees from collections of sequences under assumptions of the multispecies coalescent (MSC), i.e., that there is free recombination between the sequences and no (or very low) recombination within them. These coalescent genes (c-genes) are thus defined in an historical rather than molecular sense, and can in theory be as large as an entire genome or as small as a single nucleotide. A debate about how to define c-genes centers on the contention that nuclear gene sequences used in many coalescent analyses undergo too much recombination, such that their introns comprise multiple c-genes, violating a key assumption of the MSC. Recently a similar argument has been made for the genes of plastid (e.g., chloroplast) and mitochondrial genomes, which for the last 30 or more years have been considered to represent a single c-gene for the purposes of phylogeny reconstruction because they are non-recombining in a historical sense. Consequently, it has been suggested that these genomes should be analyzed using coalescent methods that treat their genes-over 70 protein-coding genes in the case of most plastid genomes (plastomes)-as independent estimates of species phylogeny, in contrast to the usual practice of concatenation, which is appropriate for generating gene trees. However, although recombination certainly occurs in the plastome, as has been recognized since the 1970's, it is unlikely to be phylogenetically relevant. This is because such historically effective recombination can only occur when plastomes with incongruent histories are brought together in the same plastid. However, plastids sort rapidly into different cell lineages and rarely fuse. Thus, because of plastid biology, the plastome is a more canonical c-gene than is the average multi-intron mammalian nuclear gene. The plastome should thus continue to be treated as a single estimate of the underlying species phylogeny, as should the mitochondrial genome. The implications of this long-held insight of molecular systematics for studies in the phylogenomic era are explored.
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Affiliation(s)
- Jeff J Doyle
- Plant Biology Section, Plant Breeding & Genetics Section, and L. H. Bailey Hortorium, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853 USA
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102
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Ultra-deep sequencing reveals dramatic alteration of organellar genomes in Physcomitrella patens due to biased asymmetric recombination. Commun Biol 2021; 4:633. [PMID: 34045660 PMCID: PMC8159992 DOI: 10.1038/s42003-021-02141-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 04/22/2021] [Indexed: 12/21/2022] Open
Abstract
Destabilization of organelle genomes causes organelle dysfunction that appears as abnormal growth in plants and diseases in human. In plants, loss of the bacterial-type homologous recombination repair (HRR) factors RECA and RECG induces organelle genome instability. In this study, we show the landscape of organelle genome instability in Physcomitrella patens HRR knockout mutants by deep sequencing in combination with informatics approaches. Genome-wide maps of rearrangement positions in the organelle genomes, which exhibited prominent mutant-specific patterns, were highly biased in terms of direction and location and often associated with dramatic variation in read depth. The rearrangements were location-dependent and mostly derived from the asymmetric products of microhomology-mediated recombination. Our results provide an overall picture of organelle-specific gross genomic rearrangements in the HRR mutants, and suggest that chloroplasts and mitochondria share common mechanisms for replication-related rearrangements. Masaki Odahara and Kensuke Nakamura et al. use deep paired-end sequencing to examine organellar genome recombination when homologous recombination repair genes are individually knocked out in the moss, Physcomitrella patens. Their results suggest that chloroplasts and mitochondria share a common mechanism for replication-related rearrangements.
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103
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Záhonová K, Lax G, Sinha SD, Leonard G, Richards TA, Lukeš J, Wideman JG. Single-cell genomics unveils a canonical origin of the diverse mitochondrial genomes of euglenozoans. BMC Biol 2021; 19:103. [PMID: 34001130 PMCID: PMC8130358 DOI: 10.1186/s12915-021-01035-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 04/22/2021] [Indexed: 12/28/2022] Open
Abstract
Background The supergroup Euglenozoa unites heterotrophic flagellates from three major clades, kinetoplastids, diplonemids, and euglenids, each of which exhibits extremely divergent mitochondrial characteristics. Mitochondrial genomes (mtDNAs) of euglenids comprise multiple linear chromosomes carrying single genes, whereas mitochondrial chromosomes are circular non-catenated in diplonemids, but circular and catenated in kinetoplastids. In diplonemids and kinetoplastids, mitochondrial mRNAs require extensive and diverse editing and/or trans-splicing to produce mature transcripts. All known euglenozoan mtDNAs exhibit extremely short mitochondrial small (rns) and large (rnl) subunit rRNA genes, and absence of tRNA genes. How these features evolved from an ancestral bacteria-like circular mitochondrial genome remains unanswered. Results We sequenced and assembled 20 euglenozoan single-cell amplified genomes (SAGs). In our phylogenetic and phylogenomic analyses, three SAGs were placed within kinetoplastids, 14 within diplonemids, one (EU2) within euglenids, and two SAGs with nearly identical small subunit rRNA gene (18S) sequences (EU17/18) branched as either a basal lineage of euglenids, or as a sister to all euglenozoans. Near-complete mitochondrial genomes were identified in EU2 and EU17/18. Surprisingly, both EU2 and EU17/18 mitochondrial contigs contained multiple genes and one tRNA gene. Furthermore, EU17/18 mtDNA possessed several features unique among euglenozoans including full-length rns and rnl genes, six mitoribosomal genes, and nad11, all likely on a single chromosome. Conclusions Our data strongly suggest that EU17/18 is an early-branching euglenozoan with numerous ancestral mitochondrial features. Collectively these data contribute to untangling the early evolution of euglenozoan mitochondria. Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01035-y.
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Affiliation(s)
- Kristína Záhonová
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic.,Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Gordon Lax
- Department of Botany, University of British Columbia, Vancouver, Canada
| | - Savar D Sinha
- Center for Mechanisms of Evolution, Biodesign Institute, School of Life Sciences, Arizona State University, Tempe, USA
| | - Guy Leonard
- Department of Zoology, University of Oxford, Oxford, UK
| | | | - Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic. .,Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic.
| | - Jeremy G Wideman
- Center for Mechanisms of Evolution, Biodesign Institute, School of Life Sciences, Arizona State University, Tempe, USA.
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104
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Broz AK, Waneka G, Wu Z, Fernandes Gyorfy M, Sloan DB. Detecting de novo mitochondrial mutations in angiosperms with highly divergent evolutionary rates. Genetics 2021; 218:iyab039. [PMID: 33704433 PMCID: PMC8128415 DOI: 10.1093/genetics/iyab039] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 03/04/2021] [Indexed: 02/06/2023] Open
Abstract
Although plant mitochondrial genomes typically show low rates of sequence evolution, levels of divergence in certain angiosperm lineages suggest anomalously high mitochondrial mutation rates. However, de novo mutations have never been directly analyzed in such lineages. Recent advances in high-fidelity DNA sequencing technologies have enabled detection of mitochondrial mutations when still present at low heteroplasmic frequencies. To date, these approaches have only been performed on a single plant species (Arabidopsis thaliana). Here, we apply a high-fidelity technique (Duplex Sequencing) to multiple angiosperms from the genus Silene, which exhibits extreme heterogeneity in rates of mitochondrial sequence evolution among close relatives. Consistent with phylogenetic evidence, we found that Silene latifolia maintains low mitochondrial variant frequencies that are comparable with previous measurements in Arabidopsis. Silene noctiflora also exhibited low variant frequencies despite high levels of historical sequence divergence, which supports other lines of evidence that this species has reverted to lower mitochondrial mutation rates after a past episode of acceleration. In contrast, S. conica showed much higher variant frequencies in mitochondrial (but not in plastid) DNA, consistent with an ongoing bout of elevated mitochondrial mutation rates. Moreover, we found an altered mutational spectrum in S. conica heavily biased towards AT→GC transitions. We also observed an unusually low number of mitochondrial genome copies per cell in S. conica, potentially pointing to reduced opportunities for homologous recombination to accurately repair mismatches in this species. Overall, these results suggest that historical fluctuations in mutation rates are driving extreme variation in rates of plant mitochondrial sequence evolution.
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Affiliation(s)
- Amanda K Broz
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Gus Waneka
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Zhiqiang Wu
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, 518120 Shenzhen, China
| | | | - Daniel B Sloan
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
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105
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Zhou J, Zhang S, Wang J, Shen H, Ai B, Gao W, Zhang C, Fei Q, Yuan D, Wu Z, Tembrock LR, Li S, Gu C, Liao X. Chloroplast genomes in Populus (Salicaceae): comparisons from an intensively sampled genus reveal dynamic patterns of evolution. Sci Rep 2021; 11:9471. [PMID: 33947883 PMCID: PMC8096831 DOI: 10.1038/s41598-021-88160-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 04/06/2021] [Indexed: 02/02/2023] Open
Abstract
The chloroplast is one of two organelles containing a separate genome that codes for essential and distinct cellular functions such as photosynthesis. Given the importance of chloroplasts in plant metabolism, the genomic architecture and gene content have been strongly conserved through long periods of time and as such are useful molecular tools for evolutionary inferences. At present, complete chloroplast genomes from over 4000 species have been deposited into publicly accessible databases. Despite the large number of complete chloroplast genomes, comprehensive analyses regarding genome architecture and gene content have not been conducted for many lineages with complete species sampling. In this study, we employed the genus Populus to assess how more comprehensively sampled chloroplast genome analyses can be used in understanding chloroplast evolution in a broadly studied lineage of angiosperms. We conducted comparative analyses across Populus in order to elucidate variation in key genome features such as genome size, gene number, gene content, repeat type and number, SSR (Simple Sequence Repeat) abundance, and boundary positioning between the four main units of the genome. We found that some genome annotations were variable across the genus owing in part from errors in assembly or data checking and from this provided corrected annotations. We also employed complete chloroplast genomes for phylogenetic analyses including the dating of divergence times throughout the genus. Lastly, we utilized re-sequencing data to describe the variations of pan-chloroplast genomes at the population level for P. euphratica. The analyses used in this paper provide a blueprint for the types of analyses that can be conducted with publicly available chloroplast genomes as well as methods for building upon existing datasets to improve evolutionary inference.
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Affiliation(s)
- Jiawei Zhou
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Shuo Zhang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Jie Wang
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
- School of Landscape and Architecture, Zhejiang Provincial Key Laboratory of Germplasm Innovation and Utilization for Garden Plants, Key Laboratory of National Forestry and Grassland Administration on Germplasm Innovation and Utilization for Southern Garden Plants, Zhejiang A & F University, Hangzhou, 311300, China
| | - Hongmei Shen
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
- The Second Peoples's Hospital of Nantong, Nantong, 226000, Jiangsu, China
| | - Bin Ai
- Foshan Green Development Innovation Research Institute, Foshan, 528000, Guangdong, China
| | - Wei Gao
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Cuijun Zhang
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Qili Fei
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Daojun Yuan
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
| | - Zhiqiang Wu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, Hubei, China
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
- The College of Horticulture, Shanxi Agricultural University, Taigu, 030801, Shanxi, China
| | - Luke R Tembrock
- Department of Agricultural Biology, Colorado State University, Fort Collins, CO, 80523, USA.
| | - Sen Li
- The College of Horticulture, Shanxi Agricultural University, Taigu, 030801, Shanxi, China.
| | - Cuihua Gu
- School of Landscape and Architecture, Zhejiang Provincial Key Laboratory of Germplasm Innovation and Utilization for Garden Plants, Key Laboratory of National Forestry and Grassland Administration on Germplasm Innovation and Utilization for Southern Garden Plants, Zhejiang A & F University, Hangzhou, 311300, China.
| | - Xuezhu Liao
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China.
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106
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Salinas-Giegé T, Ubrig E, Drouard L. Cyanophora paradoxa mitochondrial tRNAs play a double game. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 106:1105-1115. [PMID: 33666295 DOI: 10.1111/tpj.15222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 02/26/2021] [Accepted: 03/01/2021] [Indexed: 06/12/2023]
Abstract
Present-day mitochondria derive from a single endosymbiosis of an α-proteobacterium into a proto-eukaryotic cell. Since this monophyletic event, mitochondria have evolved considerably, and unique traits have been independently acquired in the different eukaryotic kingdoms. Mitochondrial genome expression and RNA metabolism have diverged greatly. Here, Cyanophora paradoxa, a freshwater alga considered as a living fossil among photosynthetic organisms, represents an exciting model for studying the evolution of mitochondrial gene expression. As expected, fully mature tRNAs are released from primary transcripts to function in mitochondrial translation. We also show that these tRNAs take part in an mRNA processing punctuation mechanism in a non-conventional manner, leading to mRNA-tRNA hybrids with a CCA triplet at their 3'-extremities. In this case, tRNAs are probably used as stabilizing structures impeding the degradation of mRNA by exonucleases. From our data we propose that the present-day tRNA-like elements (t-elements) found at the 3'-terminals of mitochondrial mRNAs in land plants originate from true tRNAs like those observed in the mitochondria of this basal photosynthetic glaucophyte.
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Affiliation(s)
- Thalia Salinas-Giegé
- Institut de Biologie Moléculaire des Plantes-CNRS, Université de Strasbourg, Strasbourg, France
| | - Elodie Ubrig
- Institut de Biologie Moléculaire des Plantes-CNRS, Université de Strasbourg, Strasbourg, France
| | - Laurence Drouard
- Institut de Biologie Moléculaire des Plantes-CNRS, Université de Strasbourg, Strasbourg, France
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107
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Edwards DM, Røyrvik EC, Chustecki JM, Giannakis K, Glastad RC, Radzvilavicius AL, Johnston IG. Avoiding organelle mutational meltdown across eukaryotes with or without a germline bottleneck. PLoS Biol 2021; 19:e3001153. [PMID: 33891583 PMCID: PMC8064548 DOI: 10.1371/journal.pbio.3001153] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 02/23/2021] [Indexed: 11/25/2022] Open
Abstract
Mitochondrial DNA (mtDNA) and plastid DNA (ptDNA) encode vital bioenergetic apparatus, and mutations in these organelle DNA (oDNA) molecules can be devastating. In the germline of several animals, a genetic “bottleneck” increases cell-to-cell variance in mtDNA heteroplasmy, allowing purifying selection to act to maintain low proportions of mutant mtDNA. However, most eukaryotes do not sequester a germline early in development, and even the animal bottleneck remains poorly understood. How then do eukaryotic organelles avoid Muller’s ratchet—the gradual buildup of deleterious oDNA mutations? Here, we construct a comprehensive and predictive genetic model, quantitatively describing how different mechanisms segregate and decrease oDNA damage across eukaryotes. We apply this comprehensive theory to characterise the animal bottleneck with recent single-cell observations in diverse mouse models. Further, we show that gene conversion is a particularly powerful mechanism to increase beneficial cell-to-cell variance without depleting oDNA copy number, explaining the benefit of observed oDNA recombination in diverse organisms which do not sequester animal-like germlines (for example, sponges, corals, fungi, and plants). Genomic, transcriptomic, and structural datasets across eukaryotes support this mechanism for generating beneficial variance without a germline bottleneck. This framework explains puzzling oDNA differences across taxa, suggesting how Muller’s ratchet is avoided in different eukaryotes. A comprehensive model for mitochondrial and plasmid DNA segregation, supported by with genomic, transcriptomic, and single-cell data, shows how the attritional effects of Muller’s ratchet can be avoided in the organelles of diverse eukaryotes.
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Affiliation(s)
| | | | | | | | | | | | - Iain G. Johnston
- Department of Mathematics, University of Bergen, Norway
- Computational Biology Unit, University of Bergen, Norway
- * E-mail:
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108
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Pyrih J, Pánek T, Durante IM, Rašková V, Cimrhanzlová K, Kriegová E, Tsaousis AD, Eliáš M, Lukeš J. Vestiges of the Bacterial Signal Recognition Particle-Based Protein Targeting in Mitochondria. Mol Biol Evol 2021; 38:3170-3187. [PMID: 33837778 PMCID: PMC8321541 DOI: 10.1093/molbev/msab090] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 02/23/2021] [Indexed: 12/22/2022] Open
Abstract
The main bacterial pathway for inserting proteins into the plasma membrane relies on the signal recognition particle (SRP), composed of the Ffh protein and an associated RNA component, and the SRP-docking protein FtsY. Eukaryotes use an equivalent system of archaeal origin to deliver proteins into the endoplasmic reticulum, whereas a bacteria-derived SRP and FtsY function in the plastid. Here we report on the presence of homologs of the bacterial Ffh and FtsY proteins in various unrelated plastid-lacking unicellular eukaryotes, namely Heterolobosea, Alveida, Goniomonas, and Hemimastigophora. The monophyly of novel eukaryotic Ffh and FtsY groups, predicted mitochondrial localization experimentally confirmed for Naegleria gruberi, and a strong alphaproteobacterial affinity of the Ffh group, collectively suggest that they constitute parts of an ancestral mitochondrial signal peptide-based protein-targeting system inherited from the last eukaryotic common ancestor, but lost from the majority of extant eukaryotes. The ability of putative signal peptides, predicted in a subset of mitochondrial-encoded N. gruberi proteins, to target a reporter fluorescent protein into the endoplasmic reticulum of Trypanosoma brucei, likely through their interaction with the cytosolic SRP, provided further support for this notion. We also illustrate that known mitochondrial ribosome-interacting proteins implicated in membrane protein targeting in opisthokonts (Mba1, Mdm38, and Mrx15) are broadly conserved in eukaryotes and nonredundant with the mitochondrial SRP system. Finally, we identified a novel mitochondrial protein (MAP67) present in diverse eukaryotes and related to the signal peptide-binding domain of Ffh, which may well be a hitherto unrecognized component of the mitochondrial membrane protein-targeting machinery.
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Affiliation(s)
- Jan Pyrih
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic.,Laboratory of Molecular and Evolutionary Parasitology, RAPID Group, School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Tomáš Pánek
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czech Republic.,Department of Zoology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Ignacio Miguel Durante
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
| | - Vendula Rašková
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic.,Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Kristýna Cimrhanzlová
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic.,Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Eva Kriegová
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
| | - Anastasios D Tsaousis
- Laboratory of Molecular and Evolutionary Parasitology, RAPID Group, School of Biosciences, University of Kent, Canterbury, United Kingdom
| | - Marek Eliáš
- Department of Biology and Ecology, Faculty of Science, University of Ostrava, Ostrava, Czech Republic
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic.,Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic
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109
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Guo W, Zhu A, Fan W, Adams RP, Mower JP. Extensive Shifts from Cis- to Trans-splicing of Gymnosperm Mitochondrial Introns. Mol Biol Evol 2021; 37:1615-1620. [PMID: 32027368 DOI: 10.1093/molbev/msaa029] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Hundreds of plant mitogenomes have been sequenced from angiosperms, but relatively few mitogenomes are available from its sister lineage, gymnosperms. To examine mitogenomic diversity among extant gymnosperms, we generated draft mitogenomes from 11 diverse species and compared them with four previously published mitogenomes. Examined mitogenomes from Pinaceae and cycads retained all 41 protein genes and 26 introns present in the common ancestor of seed plants, whereas gnetophyte and cupressophyte mitogenomes experienced extensive gene and intron loss. In Pinaceae and cupressophyte mitogenomes, an unprecedented number of exons are distantly dispersed, requiring trans-splicing of 50-70% of mitochondrial introns to generate mature transcripts. RNAseq data confirm trans-splicing of these dispersed exons in Pinus. The prevalence of trans-splicing in vascular plant lineages with recombinogenic mitogenomes suggests that genomic rearrangement is the primary cause of shifts from cis- to trans-splicing in plant mitochondria.
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Affiliation(s)
- Wenhu Guo
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE.,School of Biological Sciences, University of Nebraska, Lincoln, NE
| | - Andan Zhu
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE.,Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE.,Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
| | - Weishu Fan
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE.,Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE.,Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
| | | | - Jeffrey P Mower
- Center for Plant Science Innovation, University of Nebraska, Lincoln, NE.,Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE
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110
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Farhat S, Le P, Kayal E, Noel B, Bigeard E, Corre E, Maumus F, Florent I, Alberti A, Aury JM, Barbeyron T, Cai R, Da Silva C, Istace B, Labadie K, Marie D, Mercier J, Rukwavu T, Szymczak J, Tonon T, Alves-de-Souza C, Rouzé P, Van de Peer Y, Wincker P, Rombauts S, Porcel BM, Guillou L. Rapid protein evolution, organellar reductions, and invasive intronic elements in the marine aerobic parasite dinoflagellate Amoebophrya spp. BMC Biol 2021; 19:1. [PMID: 33407428 PMCID: PMC7789003 DOI: 10.1186/s12915-020-00927-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Accepted: 11/12/2020] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Dinoflagellates are aquatic protists particularly widespread in the oceans worldwide. Some are responsible for toxic blooms while others live in symbiotic relationships, either as mutualistic symbionts in corals or as parasites infecting other protists and animals. Dinoflagellates harbor atypically large genomes (~ 3 to 250 Gb), with gene organization and gene expression patterns very different from closely related apicomplexan parasites. Here we sequenced and analyzed the genomes of two early-diverging and co-occurring parasitic dinoflagellate Amoebophrya strains, to shed light on the emergence of such atypical genomic features, dinoflagellate evolution, and host specialization. RESULTS We sequenced, assembled, and annotated high-quality genomes for two Amoebophrya strains (A25 and A120), using a combination of Illumina paired-end short-read and Oxford Nanopore Technology (ONT) MinION long-read sequencing approaches. We found a small number of transposable elements, along with short introns and intergenic regions, and a limited number of gene families, together contribute to the compactness of the Amoebophrya genomes, a feature potentially linked with parasitism. While the majority of Amoebophrya proteins (63.7% of A25 and 59.3% of A120) had no functional assignment, we found many orthologs shared with Dinophyceae. Our analyses revealed a strong tendency for genes encoded by unidirectional clusters and high levels of synteny conservation between the two genomes despite low interspecific protein sequence similarity, suggesting rapid protein evolution. Most strikingly, we identified a large portion of non-canonical introns, including repeated introns, displaying a broad variability of associated splicing motifs never observed among eukaryotes. Those introner elements appear to have the capacity to spread over their respective genomes in a manner similar to transposable elements. Finally, we confirmed the reduction of organelles observed in Amoebophrya spp., i.e., loss of the plastid, potential loss of a mitochondrial genome and functions. CONCLUSION These results expand the range of atypical genome features found in basal dinoflagellates and raise questions regarding speciation and the evolutionary mechanisms at play while parastitism was selected for in this particular unicellular lineage.
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Affiliation(s)
- Sarah Farhat
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ. Evry, Université Paris-Saclay, 91057, Evry, France
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York, 11794, USA
| | - Phuong Le
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Ehsan Kayal
- Sorbonne Université, CNRS, FR2424, Station Biologique de Roscoff, Place Georges Teissier, 29680, Roscoff, France
| | - Benjamin Noel
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ. Evry, Université Paris-Saclay, 91057, Evry, France
| | - Estelle Bigeard
- Sorbonne Université, CNRS, UMR7144 Adaptation et Diversité en Milieu Marin, Ecology of Marine Plankton (ECOMAP), Station Biologique de Roscoff SBR, 29680, Roscoff, France
| | - Erwan Corre
- Sorbonne Université, CNRS, FR2424, Station Biologique de Roscoff, Place Georges Teissier, 29680, Roscoff, France
| | - Florian Maumus
- URGI, INRA, Université Paris-Saclay, 78026, Versailles, France
| | - Isabelle Florent
- Unité Molécules de Communication et Adaptation des Microorganismes (MCAM, UMR7245), Muséum national d'Histoire naturelle, CNRS, CP 52, 57 rue Cuvier, 75005, Paris, France
| | - Adriana Alberti
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ. Evry, Université Paris-Saclay, 91057, Evry, France
| | - Jean-Marc Aury
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ. Evry, Université Paris-Saclay, 91057, Evry, France
| | - Tristan Barbeyron
- Sorbonne Université, CNRS, UMR 8227, Station Biologique de Roscoff, Place Georges Teissier, 29680, Roscoff, France
| | - Ruibo Cai
- Sorbonne Université, CNRS, UMR7144 Adaptation et Diversité en Milieu Marin, Ecology of Marine Plankton (ECOMAP), Station Biologique de Roscoff SBR, 29680, Roscoff, France
| | - Corinne Da Silva
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ. Evry, Université Paris-Saclay, 91057, Evry, France
| | - Benjamin Istace
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ. Evry, Université Paris-Saclay, 91057, Evry, France
| | - Karine Labadie
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ. Evry, Université Paris-Saclay, 91057, Evry, France
| | - Dominique Marie
- Sorbonne Université, CNRS, UMR7144 Adaptation et Diversité en Milieu Marin, Ecology of Marine Plankton (ECOMAP), Station Biologique de Roscoff SBR, 29680, Roscoff, France
| | - Jonathan Mercier
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ. Evry, Université Paris-Saclay, 91057, Evry, France
| | - Tsinda Rukwavu
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ. Evry, Université Paris-Saclay, 91057, Evry, France
| | - Jeremy Szymczak
- Sorbonne Université, CNRS, FR2424, Station Biologique de Roscoff, Place Georges Teissier, 29680, Roscoff, France
- Sorbonne Université, CNRS, UMR7144 Adaptation et Diversité en Milieu Marin, Ecology of Marine Plankton (ECOMAP), Station Biologique de Roscoff SBR, 29680, Roscoff, France
| | - Thierry Tonon
- Centre for Novel Agricultural Products, Department of Biology, University of York, Heslington, York, YO10 5DD, UK
| | - Catharina Alves-de-Souza
- Algal Resources Collection, MARBIONC, Center for Marine Sciences, University of North Carolina Wilmington, 5600 Marvin K. Moss Lane, Wilmington, NC, 28409, USA
| | - Pierre Rouzé
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Yves Van de Peer
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - Patrick Wincker
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ. Evry, Université Paris-Saclay, 91057, Evry, France
| | - Stephane Rombauts
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium
- VIB Center for Plant Systems Biology, Ghent, Belgium
| | - Betina M Porcel
- Génomique Métabolique, Genoscope, Institut François Jacob, CEA, CNRS, Univ. Evry, Université Paris-Saclay, 91057, Evry, France.
| | - Laure Guillou
- Sorbonne Université, CNRS, UMR7144 Adaptation et Diversité en Milieu Marin, Ecology of Marine Plankton (ECOMAP), Station Biologique de Roscoff SBR, 29680, Roscoff, France.
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Abstract
The ATAC-seq assay has emerged as the most useful, versatile, and widely adaptable method for profiling accessible chromatin regions and tracking the activity of cis-regulatory elements (cREs) in eukaryotes. Thanks to its great utility, it is now being applied to map active chromatin in the context of a very wide diversity of biological systems and questions. In the course of these studies, considerable experience working with ATAC-seq data has accumulated and a standard set of computational tasks that need to be carried for most ATAC-seq analyses has emerged. Here, we review and provide examples of common such analytical procedures (including data processing, quality control, peak calling, identifying differentially accessible open chromatin regions, and variable transcription factor (TF) motif accessibility) and discuss recommended optimal practices.
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Kayal E, Alves-de-Souza C, Farhat S, Velo-Suarez L, Monjol J, Szymczak J, Bigeard E, Marie D, Noel B, Porcel BM, Corre E, Six C, Guillou L. Dinoflagellate Host Chloroplasts and Mitochondria Remain Functional During Amoebophrya Infection. Front Microbiol 2020; 11:600823. [PMID: 33424803 PMCID: PMC7793755 DOI: 10.3389/fmicb.2020.600823] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/19/2020] [Indexed: 11/13/2022] Open
Abstract
Dinoflagellates are major components of phytoplankton that play critical roles in many microbial food webs, many of them being hosts of countless intracellular parasites. The phototrophic dinoflagellate Scrippsiella acuminata (Dinophyceae) can be infected by the microeukaryotic parasitoids Amoebophrya spp. (Syndiniales), some of which primarily target and digest the host nucleus. Early digestion of the nucleus at the beginning of the infection is expected to greatly impact the host metabolism, inducing the knockout of the organellar machineries that highly depend upon nuclear gene expression, such as the mitochondrial OXPHOS pathway and the plastid photosynthetic carbon fixation. However, previous studies have reported that chloroplasts remain functional in swimming host cells infected by Amoebophrya. We report here a multi-approach monitoring study of S. acuminata organelles over a complete infection cycle by nucleus-targeting Amoebophrya sp. strain A120. Our results show sustained and efficient photosystem II activity as a hallmark of functional chloroplast throughout the infection period despite the complete digestion of the host nucleus. We also report the importance played by light on parasite production, i.e., the amount of host biomass converted to parasite infective propagules. Using a differential gene expression analysis, we observed an apparent increase of all 3 mitochondrial and 9 out of the 11 plastidial genes involved in the electron transport chains (ETC) of the respiration pathways during the first stages of the infection. The longer resilience of organellar genes compared to those encoded by the nucleus suggests that both mitochondria and chloroplasts remain functional throughout most of the infection. This extended organelle functionality, along with higher parasite production under light conditions, suggests that host bioenergetic organelles likely benefit the parasite Amoebophrya sp. A120 and improve its fitness during the intracellular infective stage.
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Affiliation(s)
- Ehsan Kayal
- Fédération de Recherche 2424 Sorbonne Université & Centre National pour la Recherche Scientifique, Station Biologique de Roscoff, Roscoff, France
| | - Catharina Alves-de-Souza
- Algal Resources Collection, Center for Marine Sciences, University of North Carolina Wilmington, Wilmington, NC, United States
| | - Sarah Farhat
- Génomique Métabolique, Génoscope, Institut François Jacob, CEA, CNRS, Université d'Evry, Université Paris-Saclay, Evry, France
| | - Lourdes Velo-Suarez
- UMR 1078, Genetics, Functional Genomics and Biotechnology, INSERM. UFR Médecine, Brest, France
| | - Joanne Monjol
- UMR 7144 Sorbonne Université & Centre National pour la Recherche Scientifique, «Adaptation and Diversity in Marine Environment», Team «Ecology of Marine Plankton, ECOMAP», Station Biologique de Roscoff, Roscoff, France
| | - Jeremy Szymczak
- UMR 7144 Sorbonne Université & Centre National pour la Recherche Scientifique, «Adaptation and Diversity in Marine Environment», Team «Ecology of Marine Plankton, ECOMAP», Station Biologique de Roscoff, Roscoff, France
| | - Estelle Bigeard
- UMR 7144 Sorbonne Université & Centre National pour la Recherche Scientifique, «Adaptation and Diversity in Marine Environment», Team «Ecology of Marine Plankton, ECOMAP», Station Biologique de Roscoff, Roscoff, France
| | - Dominique Marie
- UMR 7144 Sorbonne Université & Centre National pour la Recherche Scientifique, «Adaptation and Diversity in Marine Environment», Team «Ecology of Marine Plankton, ECOMAP», Station Biologique de Roscoff, Roscoff, France
| | - Benjamin Noel
- Génomique Métabolique, Génoscope, Institut François Jacob, CEA, CNRS, Université d'Evry, Université Paris-Saclay, Evry, France
| | - Betina M Porcel
- Génomique Métabolique, Génoscope, Institut François Jacob, CEA, CNRS, Université d'Evry, Université Paris-Saclay, Evry, France
| | - Erwan Corre
- Fédération de Recherche 2424 Sorbonne Université & Centre National pour la Recherche Scientifique, Station Biologique de Roscoff, Roscoff, France
| | - Christophe Six
- UMR 7144 Sorbonne Université & Centre National pour la Recherche Scientifique, «Adaptation and Diversity in Marine Environment», Team «Ecology of Marine Plankton, ECOMAP», Station Biologique de Roscoff, Roscoff, France
| | - Laure Guillou
- UMR 7144 Sorbonne Université & Centre National pour la Recherche Scientifique, «Adaptation and Diversity in Marine Environment», Team «Ecology of Marine Plankton, ECOMAP», Station Biologique de Roscoff, Roscoff, France
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Russell S, Jackson C, Reyes-Prieto A. High Sequence Divergence but Limited Architectural Rearrangements in Organelle Genomes of Cyanophora (Glaucophyta) Species. J Eukaryot Microbiol 2020; 68:e12831. [PMID: 33142007 DOI: 10.1111/jeu.12831] [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: 07/15/2020] [Revised: 09/16/2020] [Accepted: 10/27/2020] [Indexed: 11/29/2022]
Abstract
Cyanophora is the glaucophyte model taxon. Following the sequencing of the nuclear genome of C. paradoxa, studies based on single organelle and nuclear molecular markers revealed previously unrecognized species diversity within this glaucophyte genus. Here, we present the complete plastid (ptDNA) and mitochondrial (mtDNA) genomes of C. kugrensii, C. sudae, and C. biloba. The respective sizes and coding capacities of both ptDNAs and mtDNAs are conserved among Cyanophora species with only minor differences due to specific gene duplications. Organelle phylogenomic analyses consistently recover the species C. kugrensii and C. paradoxa as a clade and C. sudae and C. biloba as a separate group. The phylogenetic affiliations of the four Cyanophora species are consistent with architectural similarities shared at the organelle genomic level. Genetic distance estimations from both organelle sequences are also consistent with phylogenetic and architecture evidence. Comparative analyses confirm that the Cyanophora mitochondrial genes accumulate substitutions at 3-fold higher rates than plastid counterparts, suggesting that mtDNA markers are more appropriate to investigate glaucophyte diversity and evolutionary events that occur at a population level. The study of complete organelle genomes is becoming the standard for species delimitation and is particularly relevant to study cryptic diversity in microbial groups.
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Affiliation(s)
- Sarah Russell
- Department of Biology, University of New Brunswick, 10 Bailey Drive, Fredericton, NB, E3B 5A3, Canada.,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Christopher Jackson
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.,Royal Botanic Gardens Victoria, Melbourne, Vic., Australia
| | - Adrian Reyes-Prieto
- Department of Biology, University of New Brunswick, 10 Bailey Drive, Fredericton, NB, E3B 5A3, Canada
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114
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Kang JS, Zhang HR, Wang YR, Liang SQ, Mao ZY, Zhang XC, Xiang QP. Distinctive evolutionary pattern of organelle genomes linked to the nuclear genome in Selaginellaceae. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 104:1657-1672. [PMID: 33073395 DOI: 10.1111/tpj.15028] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 08/21/2020] [Accepted: 10/02/2020] [Indexed: 06/11/2023]
Abstract
Plastids and mitochondria are endosymbiotic organelles that store genetic information. The genomes of these organelles generally exhibit contrasting patterns regarding genome architecture and genetic content. However, they have similar genetic features in Selaginellaceae, and little is known about what causes parallel evolution. Here, we document the multipartite plastid genomes (plastomes) and the highly divergent mitochondrial genomes (mitogenomes) from spikemoss obtained by combining short- and long-reads. The 188-kb multipartite plastome has three ribosomal operon copies in the master genomic conformation, creating the alternative subgenomic conformation composed of 110- and 78-kb subgenomes. The long-read data indicated that the two different genomic conformations were present in almost equal proportions in the plastomes of Selaginella nipponica. The mitogenome of S. nipponica was assembled into 27 contigs with a total size of 110 kb. All contigs contained directly arranged repeats at both ends, which introduced multiple conformations. Our results showed that plastomes and mitogenomes share high tRNA losses, GC-biased nucleotides, elevated substitution rates and complicated organization. The exploration of nuclear-encoded organelle DNA replication, recombination and repair proteins indicated that, several single-targeted proteins, particularly plastid-targeted recombinase A1, have been lost in Selaginellaceae; conversely, the dual-targeted proteins remain intact. According to the reported function of recombinase A1, we propose that the plastomes of spikemoss often fail to pair homologous sequences during recombination, and the dual-targeted proteins play a key role in the convergent genetic features of plastomes and mitogenomes. Our results provide a distinctive evolutionary pattern of the organelle genomes in Selaginellaceae and evidence of their convergent evolution.
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Affiliation(s)
- Jong-Soo Kang
- 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
| | - Hong-Rui Zhang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Ya-Rong Wang
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Si-Qi Liang
- 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
| | - Zhi-Yuan Mao
- University of Chinese Academy of Sciences, Beijing, 100049, China
- Photosynthesis Research Center, Key Laboratory of Photobiology, 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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115
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Lukeš J, Kaur B, Speijer D. RNA Editing in Mitochondria and Plastids: Weird and Widespread. Trends Genet 2020; 37:99-102. [PMID: 33203574 DOI: 10.1016/j.tig.2020.10.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 10/05/2020] [Accepted: 10/06/2020] [Indexed: 12/31/2022]
Abstract
Though widespread, RNA editing is rare, except in endosymbiotic organelles. A combination of higher mutation rates, relaxation of energetic constraints, and high genetic drift is found within plastids and mitochondria and is conducive for evolution and expansion of editing processes, possibly starting as repair mechanisms. To illustrate this, we present an exhaustive phylogenetic overview of editing types.
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Affiliation(s)
- Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic.
| | - Binnypreet Kaur
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
| | - Dave Speijer
- Medical Biochemistry, University of Amsterdam, AMC, Amsterdam, The Netherlands.
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116
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Butenko A, Hammond M, Field MC, Ginger ML, Yurchenko V, Lukeš J. Reductionist Pathways for Parasitism in Euglenozoans? Expanded Datasets Provide New Insights. Trends Parasitol 2020; 37:100-116. [PMID: 33127331 DOI: 10.1016/j.pt.2020.10.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 09/30/2020] [Accepted: 10/01/2020] [Indexed: 12/21/2022]
Abstract
The unicellular trypanosomatids belong to the phylum Euglenozoa and all known species are obligate parasites. Distinct lineages infect plants, invertebrates, and vertebrates, including humans. Genome data for marine diplonemids, together with freshwater euglenids and free-living kinetoplastids, the closest known nonparasitic relatives to trypanosomatids, recently became available. Robust phylogenetic reconstructions across Euglenozoa are now possible and place the results of parasite-focused studies into an evolutionary context. Here we discuss recent advances in identifying the factors shaping the evolution of Euglenozoa, focusing on ancestral features generally considered parasite-specific. Remarkably, most of these predate the transition(s) to parasitism, suggesting that the presence of certain preconditions makes a significant lifestyle change more likely.
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Affiliation(s)
- Anzhelika Butenko
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic; Faculty of Science, University of Ostrava, Ostrava, Czech Republic.
| | - Michael Hammond
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
| | - Mark C Field
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic; School of Life Sciences, University of Dundee, Dundee, UK
| | - Michael L Ginger
- School of Applied Sciences, University of Huddersfield, Huddersfield, UK
| | - Vyacheslav Yurchenko
- Faculty of Science, University of Ostrava, Ostrava, Czech Republic; Martsinovsky Institute of Medical Parasitology, Sechenov University, Moscow, Russia
| | - Julius Lukeš
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic; Faculty of Sciences, University of South Bohemia, České Budějovice (Budweis), Czech Republic.
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117
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Nguyen DT, Wu B, Xiao S, Hao W. Evolution of a Record-Setting AT-Rich Genome: Indel Mutation, Recombination, and Substitution Bias. Genome Biol Evol 2020; 12:2344-2354. [PMID: 32986811 PMCID: PMC7846184 DOI: 10.1093/gbe/evaa202] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/19/2020] [Indexed: 12/16/2022] Open
Abstract
Genome-wide nucleotide composition varies widely among species. Despite extensive research, the source of genome-wide nucleotide composition diversity remains elusive. Yeast mitochondrial genomes (mitogenomes) are highly A + T rich, and they provide a unique opportunity to study the evolution of AT-biased landscape. In this study, we sequenced ten complete mitogenomes of the Saccharomycodes ludwigii yeast with 8% G + C content, the lowest genome-wide %(G + C) in all published genomes to date. The S. ludwigii mitogenomes have high densities of short tandem repeats but severely underrepresented mononucleotide repeats. Comparative population genomics of these record-setting A + T-rich genomes shows dynamic indel mutations and strong mutation bias toward A/T. Indel mutations play a greater role in genomic variation among very closely related strains than nucleotide substitutions. Indels have resulted in presence–absence polymorphism of tRNAArg (ACG) among S. ludwigii mitogenomes. Interestingly, these mitogenomes have undergone recombination, a genetic process that can increase G + C content by GC-biased gene conversion. Finally, the expected equilibrium G + C content under mutation pressure alone is higher than observed G + C content, suggesting existence of mechanisms other than AT-biased mutation operating to increase A/T. Together, our findings shed new lights on mechanisms driving extremely AT-rich genomes.
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Affiliation(s)
- Duong T Nguyen
- Department of Biological Sciences, Wayne State University
| | - Baojun Wu
- Department of Biological Sciences, Wayne State University
| | - Shujie Xiao
- Department of Biological Sciences, Wayne State University
| | - Weilong Hao
- Department of Biological Sciences, Wayne State University
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118
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Putintseva YA, Bondar EI, Simonov EP, Sharov VV, Oreshkova NV, Kuzmin DA, Konstantinov YM, Shmakov VN, Belkov VI, Sadovsky MG, Keech O, Krutovsky KV. Siberian larch (Larix sibirica Ledeb.) mitochondrial genome assembled using both short and long nucleotide sequence reads is currently the largest known mitogenome. BMC Genomics 2020; 21:654. [PMID: 32972367 PMCID: PMC7517811 DOI: 10.1186/s12864-020-07061-4] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 09/10/2020] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Plant mitochondrial genomes (mitogenomes) can be structurally complex while their size can vary from ~ 222 Kbp in Brassica napus to 11.3 Mbp in Silene conica. To date, in comparison with the number of plant species, only a few plant mitogenomes have been sequenced and released, particularly for conifers (the Pinaceae family). Conifers cover an ancient group of land plants that includes about 600 species, and which are of great ecological and economical value. Among them, Siberian larch (Larix sibirica Ledeb.) represents one of the keystone species in Siberian boreal forests. Yet, despite its importance for evolutionary and population studies, the mitogenome of Siberian larch has not yet been assembled and studied. RESULTS Two sources of DNA sequences were used to search for mitochondrial DNA (mtDNA) sequences: mtDNA enriched samples and nucleotide reads generated in the de novo whole genome sequencing project, respectively. The assembly of the Siberian larch mitogenome contained nine contigs, with the shortest and the largest contigs being 24,767 bp and 4,008,762 bp, respectively. The total size of the genome was estimated at 11.7 Mbp. In total, 40 protein-coding, 34 tRNA, and 3 rRNA genes and numerous repetitive elements (REs) were annotated in this mitogenome. In total, 864 C-to-U RNA editing sites were found for 38 out of 40 protein-coding genes. The immense size of this genome, currently the largest reported, can be partly explained by variable numbers of mobile genetic elements, and introns, but unlikely by plasmid-related sequences. We found few plasmid-like insertions representing only 0.11% of the entire Siberian larch mitogenome. CONCLUSIONS Our study showed that the size of the Siberian larch mitogenome is much larger than in other so far studied Gymnosperms, and in the same range as for the annual flowering plant Silene conica (11.3 Mbp). Similar to other species, the Siberian larch mitogenome contains relatively few genes, and despite its huge size, the repeated and low complexity regions cover only 14.46% of the mitogenome sequence.
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Affiliation(s)
- Yuliya A Putintseva
- Laboratory of Forest Genomics, Genome Research and Education Center, Institute of Fundamental Biology and Biotechnology, Siberian Federal University, Krasnoyarsk, 660036, Russia
| | - Eugeniya I Bondar
- Laboratory of Forest Genomics, Genome Research and Education Center, Institute of Fundamental Biology and Biotechnology, Siberian Federal University, Krasnoyarsk, 660036, Russia
- Laboratory of Genomic Research and Biotechnology, Federal Research Center "Krasnoyarsk Science Center", Siberian Branch, Russian Academy of Sciences, Krasnoyarsk, 660036, Russia
| | - Evgeniy P Simonov
- Institute of Environmental and Agricultural Biology (X-BIO), University of Tyumen, Tyumen, 625003, Russia
| | - Vadim V Sharov
- Laboratory of Forest Genomics, Genome Research and Education Center, Institute of Fundamental Biology and Biotechnology, Siberian Federal University, Krasnoyarsk, 660036, Russia
- Laboratory of Genomic Research and Biotechnology, Federal Research Center "Krasnoyarsk Science Center", Siberian Branch, Russian Academy of Sciences, Krasnoyarsk, 660036, Russia
- Department of High Performance Computing, Institute of Space and Information Technologies, Siberian Federal University, Krasnoyarsk, 660074, Russia
| | - Natalya V Oreshkova
- Laboratory of Forest Genomics, Genome Research and Education Center, Institute of Fundamental Biology and Biotechnology, Siberian Federal University, Krasnoyarsk, 660036, Russia
- Laboratory of Genomic Research and Biotechnology, Federal Research Center "Krasnoyarsk Science Center", Siberian Branch, Russian Academy of Sciences, Krasnoyarsk, 660036, Russia
- Laboratory of Forest Genetics and Selection, V. N. Sukachev Institute of Forest, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk, 660036, Russia
| | - Dmitry A Kuzmin
- Laboratory of Forest Genomics, Genome Research and Education Center, Institute of Fundamental Biology and Biotechnology, Siberian Federal University, Krasnoyarsk, 660036, Russia
- Department of High Performance Computing, Institute of Space and Information Technologies, Siberian Federal University, Krasnoyarsk, 660074, Russia
| | - Yuri M Konstantinov
- Laboratory of Plant Genetic Engineering, Siberian Institute of Plant Physiology and Biochemistry, Siberian Branch, Russian Academy of Sciences, Irkutsk, 664033, Russia
| | - Vladimir N Shmakov
- Laboratory of Plant Genetic Engineering, Siberian Institute of Plant Physiology and Biochemistry, Siberian Branch, Russian Academy of Sciences, Irkutsk, 664033, Russia
| | - Vadim I Belkov
- Laboratory of Plant Genetic Engineering, Siberian Institute of Plant Physiology and Biochemistry, Siberian Branch, Russian Academy of Sciences, Irkutsk, 664033, Russia
| | - Michael G Sadovsky
- Institute of Computational Modeling, Siberian Branch, Russian Academy of Sciences, Krasnoyarsk, 660036, Russia
| | - Olivier Keech
- Department of Plant Physiology, UPSC, Umeå University, S-90187, Umeå, Sweden
| | - Konstantin V Krutovsky
- Laboratory of Forest Genomics, Genome Research and Education Center, Institute of Fundamental Biology and Biotechnology, Siberian Federal University, Krasnoyarsk, 660036, Russia.
- Department of Forest Genetics and Forest Tree Breeding, Georg-August University of Göttingen, 37077, Göttingen, Germany.
- Center for Integrated Breeding Research, George-August University of Göttingen, 37075, Göttingen, Germany.
- Laboratory of Population Genetics, N.I. Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow, 119333, Russia.
- Department of Ecosystem Science and Management, Texas A&M University, College Station, TX, 77843-2138, USA.
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Lee J, Park J, Xi H, Park J. Comprehensive Analyses of the Complete Mitochondrial Genome of Figulus binodulus (Coleoptera: Lucanidae). JOURNAL OF INSECT SCIENCE (ONLINE) 2020; 20:10. [PMID: 32976575 PMCID: PMC7583265 DOI: 10.1093/jisesa/ieaa090] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Indexed: 05/06/2023]
Abstract
Figulus binodulus Waterhouse is a small stag beetle distributed in East Asia. We determined the first mitochondrial genome of F. binodulus of which is 16,261-bp long including 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNAs, and a single large noncoding region of 1,717 bp. Gene order of F. binodulus is identical to the ancestral insect mitochondrial gene order as in most other stag beetle species. All of 22 tRNAs could be shaped into typical clover-leaf structure except trnSer1. Comparative analyses of 21 Lucanidae mitochondrial genomes was conducted in aspect of their length and AT-GC ratio. Nucleotide diversities analyses provide that cox1 and cox2 in Lucanidae are less diverse than those of Scarabaeoidea. Fifty simple sequence repeats (SSRs) were identified on F. binodulus mitochondrial genome. Comparative analysis of SSRs among five mitochondrial genomes displayed similar trend along with SSR types. Figulus binodulus was sister to all other available family Lucanidae species in the phylogenetic tree.
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Affiliation(s)
- Jungmo Lee
- InfoBoss Inc., Ltd., Seolleung-ro, Gangnam-gu, Seoul, Republic of Korea
- InfoBoss Research Center, Seolleung-ro, Gangnam-gu, Seoul, Republic of Korea
| | - Jonghyun Park
- InfoBoss Inc., Ltd., Seolleung-ro, Gangnam-gu, Seoul, Republic of Korea
- InfoBoss Research Center, Seolleung-ro, Gangnam-gu, Seoul, Republic of Korea
| | - Hong Xi
- InfoBoss Inc., Ltd., Seolleung-ro, Gangnam-gu, Seoul, Republic of Korea
- InfoBoss Research Center, Seolleung-ro, Gangnam-gu, Seoul, Republic of Korea
| | - Jongsun Park
- InfoBoss Inc., Ltd., Seolleung-ro, Gangnam-gu, Seoul, Republic of Korea
- InfoBoss Research Center, Seolleung-ro, Gangnam-gu, Seoul, Republic of Korea
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120
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The Investigation of Perennial Sunflower Species ( Helianthus L.) Mitochondrial Genomes. Genes (Basel) 2020; 11:genes11090982. [PMID: 32846894 PMCID: PMC7565312 DOI: 10.3390/genes11090982] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 08/18/2020] [Accepted: 08/20/2020] [Indexed: 12/23/2022] Open
Abstract
The genus Helianthus is a diverse taxonomic group with approximately 50 species. Most sunflower genomic investigations are devoted to economically valuable species, e.g., H. annuus, while other Helianthus species, especially perennial, are predominantly a blind spot. In the current study, we have assembled the complete mitogenomes of two perennial species: H. grosseserratus (273,543 bp) and H. strumosus (281,055 bp). We analyzed their sequences and gene profiles in comparison to the available complete mitogenomes of H. annuus. Except for sdh4 and trnA-UGC, both perennial sunflower species had the same gene content and almost identical protein-coding sequences when compared with each other and with annual sunflowers (H. annuus). Common mitochondrial open reading frames (ORFs) (orf117, orf139, and orf334) in sunflowers and unique ORFs for H. grosseserratus (orf633) and H. strumosus (orf126, orf184, orf207) were identified. The maintenance of plastid-derived coding sequences in the mitogenomes of both annual and perennial sunflowers and the low frequency of nonsynonymous mutations point at an extremely low variability of mitochondrial DNA (mtDNA) coding sequences in the Helianthus genus.
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121
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Smith DR. Revisiting Ceriantharian (Anthozoa) Mitochondrial Genomes: Casting Doubts about Their Structure and Size. Genome Biol Evol 2020; 12:1440-1443. [PMID: 32589745 PMCID: PMC7487158 DOI: 10.1093/gbe/evaa130] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/19/2020] [Indexed: 01/22/2023] Open
Abstract
Recently, Stampar et al. (2019. Linear mitochondrial genome in Anthozoa (Cnidaria): a case study in. Sci Rep. 9(1):6094.) uncovered highly atypical mitochondrial genome structures in the cnidarian species Pachycerianthus magnus and Isarachnanthus nocturnus (Anthozoa, Ceriantharia). These two mitochondrial DNAs assembled as linear fragmented genomes, comprising eight and five chromosomes, respectively—architectures unlike any other anthozoan mitogenome described to date. What’s more, they have cumulative lengths of 77.8 (P. magnus) and 80.9 kb (I. nocturnus), making them the largest animal mitochondrial DNAs on record, a finding which garnered significant attention by various news media. Here, I take a closer look at the work of Stampar et al. and question their key results. I provide evidence that the currently available mitogenome sequences for I. nocturnus and P. magnus, including their structures, sizes, and chromosome numbers, should be treated with caution. More work must be done on these genomes before one can say with any certainty that they are linear, fragmented, or the largest animal mitogenomes observed to date.
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Affiliation(s)
- David Roy Smith
- Department of Biology, University of Western Ontario, London, Ontario, Canada
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122
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Hall ND, Zhang H, Mower JP, McElroy JS, Goertzen LR. The Mitochondrial Genome of Eleusine indica and Characterization of Gene Content within Poaceae. Genome Biol Evol 2020; 12:3684-3697. [PMID: 31665327 PMCID: PMC7145533 DOI: 10.1093/gbe/evz229] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2019] [Indexed: 12/12/2022] Open
Abstract
Plant mitochondrial (mt) genome assembly provides baseline data on size, structure, and gene content, but resolving the sequence of these large and complex organelle genomes remains challenging due to fragmentation, frequent recombination, and transfers of DNA from neighboring plastids. The mt genome for Eleusine indica (Poaceae: goosegrass) is comprehensibly analyzed here, providing key reference data for an economically significant invasive species that is also the maternal parent of the allotetraploid crop Finger millet (Eleusine coracana). The assembled E. indica genome contains 33 protein coding genes, 6 rRNA subunits, 24 tRNA, 8 large repetitive regions 15 kb of transposable elements across a total of 520,691 bp. Evidence of RNA editing and loss of rpl2, rpl5, rps14, rps11, sdh4, and sdh3 genes is evaluated in the context of an updated survey of mt genomic gene content across the grasses through an analysis of publicly available data. Hypothesized patterns of Poaceae mt gene loss are examined in a phylogenetic context to clarify timing, showing that rpl2 was transferred to the nucleus from the mitochondrion prior to the origin of the PACMAD clade.
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Affiliation(s)
- Nathan D Hall
- Department of Biological Sciences, Auburn University
| | - Hui Zhang
- Department of Crop, Soil and Environmental Sciences, Auburn University
| | - Jeffrey P Mower
- Department of Agronomy and Horticulture, University of Nebraska-Lincoln
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123
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Pyrih J, Rašková V, Škodová-Sveráková I, Pánek T, Lukeš J. ZapE/Afg1 interacts with Oxa1 and its depletion causes a multifaceted phenotype. PLoS One 2020; 15:e0234918. [PMID: 32579605 PMCID: PMC7314023 DOI: 10.1371/journal.pone.0234918] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 06/04/2020] [Indexed: 11/19/2022] Open
Abstract
ZapE/Afg1 is a component of the inner cell membrane of some eubacteria and the inner mitochondrial membrane of eukaryotes. This protein is involved in FtsZ-dependent division of eubacteria. In the yeast and human mitochondrion, ZapE/Afg1 likely interacts with Oxa1 and facilitates the degradation of mitochondrion-encoded subunits of respiratory complexes. Furthermore, the depletion of ZapE increases resistance to apoptosis, decreases oxidative stress tolerance, and impacts mitochondrial protein homeostasis. It remains unclear whether ZapE is a multifunctional protein, or whether some of the described effects are just secondary phenotypes. Here, we have analyzed the functions of ZapE in Trypanosoma brucei, a parasitic protist, and an important model organism. Using a newly developed proximity-dependent biotinylation approach (BioID2), we have identified the inner mitochondrial membrane insertase Oxa1 among three putative interacting partners of ZapE, which is present in two paralogs. RNAi-mediated depletion of both ZapE paralogs likely affected the function of respiratory complexes I and IV. Consistently, we show that the distribution of mitochondrial ZapE is restricted only to organisms with Oxa1, respiratory complexes, and a mitochondrial genome. We propose that the evolutionarily conserved interaction of ZapE with Oxa1, which is required for proper insertion of many inner mitochondrial membrane proteins, is behind the multifaceted phenotype caused by the ablation of ZapE.
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Affiliation(s)
- Jan Pyrih
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
- * E-mail: (JL); (JP)
| | - Vendula Rašková
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice (Budweis), Czech Republic
| | - Ingrid Škodová-Sveráková
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
- Faculty of Sciences, Comenius University, Bratislava, Slovakia
| | - Tomáš Pánek
- Faculty of Sciences, University of Ostrava, Ostrava, Czech Republic
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice (Budweis), Czech Republic
- * E-mail: (JL); (JP)
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124
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Abstract
Host-beneficial endosymbioses, which are formed when a microorganism takes up residence inside another cell and provides a fitness advantage to the host, have had a dramatic influence on the evolution of life. These intimate relationships have yielded the mitochondrion and the plastid (chloroplast) - the ancient organelles that in part define eukaryotic life - along with many more recent associations involving a wide variety of hosts and microbial partners. These relationships are often envisioned as stable associations that appear cooperative and persist for extremely long periods of time. But recent evidence suggests that this stable state is often born from turbulent and conflicting origins, and that the apparent stability of many beneficial endosymbiotic relationships - although certainly real in many cases - is not an inevitable outcome of these associations. Here we review how stable endosymbioses form, how they are maintained, and how they sometimes break down and are reborn. We focus on relationships formed by insects and their resident microorganisms because these symbioses have been the focus of significant empirical work over the last two decades. We review these relationships over five life stages: origin, birth, middle age, old age, and death.
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125
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Mower JP. Variation in protein gene and intron content among land plant mitogenomes. Mitochondrion 2020; 53:203-213. [PMID: 32535166 DOI: 10.1016/j.mito.2020.06.002] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Revised: 05/24/2020] [Accepted: 06/08/2020] [Indexed: 12/20/2022]
Abstract
The functional content of the mitochondrial genome (mitogenome) is highly diverse across eukaryotes. Among land plants, our understanding of the variation in mitochondrial gene and intron content is improving from concerted efforts to densely sample mitogenomes from diverse land plants. Here I review the current state of knowledge regarding the diversity in content of protein genes and introns in the mitogenomes of all major land plant lineages. Mitochondrial protein gene content is largely conserved among mosses and liverworts, but it varies substantially among and within other land plant lineages due to convergent losses of genes encoding ribosomal proteins and, to a lesser extent, genes for proteins involved in cytochrome c maturation and oxidative phosphorylation. Mitochondrial intron content is fairly stable within each major land plant lineage, but highly variable among lineages, resulting from occasional gains and many convergent losses over time. Trans-splicing has evolved dozens of times in various vascular plant lineages, particularly those with relatively higher rates of mitogenomic rearrangement. Across eukaryotes, mitochondrial protein gene and intron content has been shaped massive convergent evolution.
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Affiliation(s)
- Jeffrey P Mower
- Center for Plant Science Innovation and Department of Agronomy and Horticulture, University of Nebraska, Lincoln, NE.
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126
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Sugimoto H, Hirano M, Tanaka H, Tanaka T, Kitagawa-Yogo R, Muramoto N, Mitsukawa N. Plastid-targeted forms of restriction endonucleases enhance the plastid genome rearrangement rate and trigger the reorganization of its genomic architecture. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 102:1042-1057. [PMID: 31925982 DOI: 10.1111/tpj.14687] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 12/25/2019] [Accepted: 01/02/2020] [Indexed: 06/10/2023]
Abstract
Plant cells have acquired chloroplasts (plastids) with a unique genome (ptDNA), which developed during the evolution of endosymbiosis. The gene content and genome structure of ptDNAs in land plants are considerably stable, although those of algal ptDNAs are highly varied. Plant cells seem, therefore, to be intolerant of any structural or organizational changes in the ptDNA. Genome rearrangement functions as a driver of genomic evolutionary divergence. Here, we aimed to create various types of rearrangements in the ptDNA of Arabidopsis genomes using plastid-targeted forms of restriction endonucleases (pREs). Arabidopsis plants expressing each of the three specific pREs, i.e., pTaqI, pHinP1I, and pMseI, were generated; they showed the leaf variegation phenotypes associated with impaired chloroplast development. We confirmed that these pREs caused double-stranded breaks (DSB) at their recognition sites in ptDNAs. Genome-wide analysis of ptDNAs revealed that the transgenic lines exhibited a large number of rearrangements such as inversions and deletions/duplications, which were dominantly repaired by microhomology-mediated recombination and microhomology-mediated end-joining, and less by non-homologous end-joining. Notably, pHinP1I, which recognized a small number of sites in ptDNA, induced drastic structural changes, including regional copy number variations throughout ptDNAs. In contrast, the transient expression of either pTaqI or pMseI, whose recognition site numbers were relatively larger, resulted in small-scale changes at the whole genome level. These results indicated that DSB frequencies and their distribution are major determinants in shaping ptDNAs.
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Affiliation(s)
- Hiroki Sugimoto
- Genome Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
| | - Minoru Hirano
- Bio System Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
| | - Hidenori Tanaka
- Genome Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
| | - Tomoko Tanaka
- Genome Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
| | - Ritsuko Kitagawa-Yogo
- Genome Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
| | - Nobuhiko Muramoto
- Genome Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
| | - Norihiro Mitsukawa
- Genome Engineering Program, Strategic Research Division, Toyota Central R&D Laboratories, Inc., Nagakute, Aichi, 480-1192, Japan
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127
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Łukasik P, Chong RA, Nazario K, Matsuura Y, Bublitz DAC, Campbell MA, Meyer MC, Van Leuven JT, Pessacq P, Veloso C, Simon C, McCutcheon JP. One Hundred Mitochondrial Genomes of Cicadas. J Hered 2020; 110:247-256. [PMID: 30590568 DOI: 10.1093/jhered/esy068] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Accepted: 12/21/2018] [Indexed: 01/10/2023] Open
Abstract
Mitochondrial genomes can provide valuable information on the biology and evolutionary histories of their host organisms. Here, we present and characterize the complete coding regions of 107 mitochondrial genomes (mitogenomes) of cicadas (Insecta: Hemiptera: Auchenorrhyncha: Cicadoidea), representing 31 genera, 61 species, and 83 populations. We show that all cicada mitogenomes retain the organization and gene contents thought to be ancestral in insects, with some variability among cicada clades in the length of a region between the genes nad2 and cox1, which encodes 3 tRNAs. Phylogenetic analyses using these mitogenomes recapitulate a recent 5-gene classification of cicadas into families and subfamilies, but also identify a species that falls outside of the established taxonomic framework. While protein-coding genes are under strong purifying selection, tests of relative evolutionary rates reveal significant variation in evolutionary rates across taxa, highlighting the dynamic nature of mitochondrial genome evolution in cicadas. These data will serve as a useful reference for future research into the systematics, ecology, and evolution of the superfamily Cicadoidea.
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Affiliation(s)
- Piotr Łukasik
- Division of Biological Sciences, University of Montana, Missoula, MT
| | - Rebecca A Chong
- Department of Biology, University of Hawai'i at Mānoa, Honolulu, HI
| | - Katherine Nazario
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT
| | - Yu Matsuura
- Tropical Biosphere Research Center, University of the Ryukyus, Japan
| | - De Anna C Bublitz
- Division of Biological Sciences, University of Montana, Missoula, MT
| | | | - Mariah C Meyer
- Division of Biological Sciences, University of Montana, Missoula, MT
| | | | - Pablo Pessacq
- Centro de Investigaciones Esquel de Montaña y Estepa Patagónicas (CIEMEP), Esquel, Chubut, Argentina
| | - Claudio Veloso
- Department of Ecological Sciences, Science Faculty, University of Chile, Santiago, Chile
| | - Chris Simon
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT
| | - John P McCutcheon
- Division of Biological Sciences, University of Montana, Missoula, MT
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128
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Abstract
Ever since its discovery, the double-stranded DNA contained in the mitochondria of eukaryotes has fascinated researchers because of its bacterial endosymbiotic origin, crucial role in encoding subunits of the respiratory complexes, compact nature, and specific inheritance mechanisms. In the last few years, high-throughput sequencing techniques have accelerated the sequencing of mitochondrial genomes (mitogenomes) and uncovered the great diversity of organizations, gene contents, and modes of replication and transcription found in living eukaryotes. Some early divergent lineages of unicellular eukaryotes retain certain synteny and gene content resembling those observed in the genomes of alphaproteobacteria (the inferred closest living group of mitochondria), whereas others adapted to anaerobic environments have drastically reduced or even lost the mitogenome. In the three main multicellular lineages of eukaryotes, mitogenomes have pursued diverse evolutionary trajectories in which different types of molecules (circular versus linear and single versus multipartite), gene structures (with or without self-splicing introns), gene contents, gene orders, genetic codes, and transfer RNA editing mechanisms have been selected. Whereas animals have evolved a rather compact mitochondrial genome between 11 and 50 Kb in length with a highly conserved gene content in bilaterians, plants exhibit large mitochondrial genomes of 66 Kb to 11.3 Mb with large intergenic repetitions prone to recombination, and fungal mitogenomes have intermediate sizes of 12 to 236 Kb.
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Affiliation(s)
- Rafael Zardoya
- Departamento de Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias Naturales (MNCN-CSIC), Madrid, Spain
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129
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Hill GE. Mitonuclear Compensatory Coevolution. Trends Genet 2020; 36:403-414. [PMID: 32396834 DOI: 10.1016/j.tig.2020.03.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 02/27/2020] [Accepted: 03/08/2020] [Indexed: 01/03/2023]
Abstract
In bilaterian animals, the mitochondrial genome is small, haploid, does not typically recombine, and is subject to accumulation of deleterious alleles via Muller's ratchet. These basic features of the genomic architecture present a paradox: mutational erosion of these genomes should lead to decline in mitochondrial function over time, yet no such decline is observed. Compensatory coevolution, whereby the nuclear genome evolves to compensate for the deleterious alleles in the mitochondrial genome, presents a potential solution to the paradox of Muller's ratchet without loss of function. Here, I review different proposed forms of mitonuclear compensatory coevolution. Empirical evidence from diverse eukaryotic taxa supports the mitonuclear compensatory coevolution hypothesis, but the ubiquity and importance of such compensatory coevolution remains a topic of debate.
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Affiliation(s)
- Geoffrey E Hill
- Department of Biological Science, 331 Funchess Hall, Auburn University, Auburn, AL 36849-5414, USA.
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130
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Klucnika A, Ma H. A battle for transmission: the cooperative and selfish animal mitochondrial genomes. Open Biol 2020; 9:180267. [PMID: 30890027 PMCID: PMC6451365 DOI: 10.1098/rsob.180267] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The mitochondrial genome is an evolutionarily persistent and cooperative component of metazoan cells that contributes to energy production and many other cellular processes. Despite sharing the same host as the nuclear genome, the multi-copy mitochondrial DNA (mtDNA) follows very different rules of replication and transmission, which translate into differences in the patterns of selection. On one hand, mtDNA is dependent on the host for its transmission, so selections would favour genomes that boost organismal fitness. On the other hand, genetic heterogeneity within an individual allows different mitochondrial genomes to compete for transmission. This intra-organismal competition could select for the best replicator, which does not necessarily give the fittest organisms, resulting in mito-nuclear conflict. In this review, we discuss the recent advances in our understanding of the mechanisms and opposing forces governing mtDNA transmission and selection in bilaterians, and what the implications of these are for mtDNA evolution and mitochondrial replacement therapy.
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Affiliation(s)
- Anna Klucnika
- 1 Wellcome Trust/Cancer Research UK Gurdon Institute , Tennis Court Road, Cambridge CB2 1QN , UK.,2 Department of Genetics, University of Cambridge , Downing Street, Cambridge CB2 3EH , UK
| | - Hansong Ma
- 1 Wellcome Trust/Cancer Research UK Gurdon Institute , Tennis Court Road, Cambridge CB2 1QN , UK.,2 Department of Genetics, University of Cambridge , Downing Street, Cambridge CB2 3EH , UK
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131
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Sweet AD, Johnson KP, Cameron SL. Mitochondrial genomes of Columbicola feather lice are highly fragmented, indicating repeated evolution of minicircle-type genomes in parasitic lice. PeerJ 2020; 8:e8759. [PMID: 32231878 PMCID: PMC7098387 DOI: 10.7717/peerj.8759] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 02/16/2020] [Indexed: 01/21/2023] Open
Abstract
Most animals have a conserved mitochondrial genome structure composed of a single chromosome. However, some organisms have their mitochondrial genes separated on several smaller circular or linear chromosomes. Highly fragmented circular chromosomes (“minicircles”) are especially prevalent in parasitic lice (Insecta: Phthiraptera), with 16 species known to have between nine and 20 mitochondrial minicircles per genome. All of these species belong to the same clade (mammalian lice), suggesting a single origin of drastic fragmentation. Nevertheless, other work indicates a lesser degree of fragmentation (2–3 chromosomes/genome) is present in some avian feather lice (Ischnocera: Philopteridae). In this study, we tested for minicircles in four species of the feather louse genus Columbicola (Philopteridae). Using whole genome shotgun sequence data, we applied three different bioinformatic approaches for assembling the Columbicola mitochondrial genome. We further confirmed these approaches by assembling the mitochondrial genome of Pediculus humanus from shotgun sequencing reads, a species known to have minicircles. Columbicola spp. genomes are highly fragmented into 15–17 minicircles between ∼1,100 and ∼3,100 bp in length, with 1–4 genes per minicircle. Subsequent annotation of the minicircles indicated that tRNA arrangements of minicircles varied substantially between species. These mitochondrial minicircles for species of Columbicola represent the first feather lice (Philopteridae) for which minicircles have been found in a full mitochondrial genome assembly. Combined with recent phylogenetic studies of parasitic lice, our results provide strong evidence that highly fragmented mitochondrial genomes, which are otherwise rare across the Tree of Life, evolved multiple times within parasitic lice.
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Affiliation(s)
- Andrew D Sweet
- Department of Entomology, Purdue University, West Lafayette, IN, United States of America
| | - Kevin P Johnson
- Illinois Natural History Survey, Prairie Research Institute, University of Illinois, Champaign, IL, United States of America
| | - Stephen L Cameron
- Department of Entomology, Purdue University, West Lafayette, IN, United States of America
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132
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Pedrola-Monfort J, Lázaro-Gimeno D, Boluda CG, Pedrola L, Garmendia A, Soler C, Soriano JM. Evolutionary Trends in the Mitochondrial Genome of Archaeplastida: How Does the GC Bias Affect the Transition from Water to Land? PLANTS 2020; 9:plants9030358. [PMID: 32178249 PMCID: PMC7154891 DOI: 10.3390/plants9030358] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 03/09/2020] [Accepted: 03/11/2020] [Indexed: 12/22/2022]
Abstract
Among the most intriguing mysteries in the evolutionary biology of photosynthetic organisms are the genesis and consequences of the dramatic increase in the mitochondrial and nuclear genome sizes, together with the concomitant evolution of the three genetic compartments, particularly during the transition from water to land. To clarify the evolutionary trends in the mitochondrial genome of Archaeplastida, we analyzed the sequences from 37 complete genomes. Therefore, we utilized mitochondrial, plastidial and nuclear ribosomal DNA molecular markers on 100 species of Streptophyta for each subunit. Hierarchical models of sequence evolution were fitted to test the heterogeneity in the base composition. The best resulting phylogenies were used for reconstructing the ancestral Guanine-Cytosine (GC) content and equilibrium GC frequency (GC*) using non-homogeneous and non-stationary models fitted with a maximum likelihood approach. The mitochondrial genome length was strongly related to repetitive sequences across Archaeplastida evolution; however, the length seemed not to be linked to the other studied variables, as different lineages showed diverse evolutionary patterns. In contrast, Streptophyta exhibited a powerful positive relationship between the GC content, non-coding DNA, and repetitive sequences, while the evolution of Chlorophyta reflected a strong positive linear relationship between the genome length and the number of genes.
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Affiliation(s)
- Joan Pedrola-Monfort
- Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, 46980 Paterna, Spain; (J.P.-M.); (D.L.-G.); (C.G.B.); (L.P.)
| | - David Lázaro-Gimeno
- Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, 46980 Paterna, Spain; (J.P.-M.); (D.L.-G.); (C.G.B.); (L.P.)
| | - Carlos G. Boluda
- Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, 46980 Paterna, Spain; (J.P.-M.); (D.L.-G.); (C.G.B.); (L.P.)
- Unité de Phylogénie et Génetique Moléculaires, Conservatoire et Jardin Botaniques, Chambésy, 1292 Geneva, Switzerland
| | - Laia Pedrola
- Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, 46980 Paterna, Spain; (J.P.-M.); (D.L.-G.); (C.G.B.); (L.P.)
| | - Alfonso Garmendia
- Mediterranean Agroforestry Institute, Department of Agroforest Ecosystems, Polytechnic University of Valencia, 46022 Valencia, Spain;
| | - Carla Soler
- Biomaterials, Institute of Materials Science, University of Valencia, 46980 Paterna, Spain;
| | - Jose M. Soriano
- Biomaterials, Institute of Materials Science, University of Valencia, 46980 Paterna, Spain;
- Correspondence: ; Tel.: +34-963-543-056
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133
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Tomáška Ľ, Nosek J. Co-evolution in the Jungle: From Leafcutter Ant Colonies to Chromosomal Ends. J Mol Evol 2020; 88:293-318. [PMID: 32157325 DOI: 10.1007/s00239-020-09935-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 02/25/2020] [Indexed: 02/06/2023]
Abstract
Biological entities are multicomponent systems where each part is directly or indirectly dependent on the others. In effect, a change in a single component might have a consequence on the functioning of its partners, thus affecting the fitness of the entire system. In this article, we provide a few examples of such complex biological systems, ranging from ant colonies to a population of amino acids within a single-polypeptide chain. Based on these examples, we discuss one of the central and still challenging questions in biology: how do such multicomponent consortia co-evolve? More specifically, we ask how telomeres, nucleo-protein complexes protecting the integrity of linear DNA chromosomes, originated from the ancestral organisms having circular genomes and thus not dealing with end-replication and end-protection problems. Using the examples of rapidly evolving topologies of mitochondrial genomes in eukaryotic microorganisms, we show what means of co-evolution were employed to accommodate various types of telomere-maintenance mechanisms in mitochondria. We also describe an unprecedented runaway evolution of telomeric repeats in nuclei of ascomycetous yeasts accompanied by co-evolution of telomere-associated proteins. We propose several scenarios derived from research on telomeres and supported by other studies from various fields of biology, while emphasizing that the relevant answers are still not in sight. It is this uncertainty and a lack of a detailed roadmap that makes the journey through the jungle of biological systems still exciting and worth undertaking.
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Affiliation(s)
- Ľubomír Tomáška
- Department of Genetics, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, 842 15, Bratislava, Slovakia.
| | - Jozef Nosek
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, 842 15, Bratislava, Slovakia
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134
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Evolving mtDNA populations within cells. Biochem Soc Trans 2020; 47:1367-1382. [PMID: 31484687 PMCID: PMC6824680 DOI: 10.1042/bst20190238] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 08/06/2019] [Accepted: 08/08/2019] [Indexed: 12/14/2022]
Abstract
Mitochondrial DNA (mtDNA) encodes vital respiratory machinery. Populations of mtDNA molecules exist in most eukaryotic cells, subject to replication, degradation, mutation, and other population processes. These processes affect the genetic makeup of cellular mtDNA populations, changing cell-to-cell distributions, means, and variances of mutant mtDNA load over time. As mtDNA mutant load has nonlinear effects on cell functionality, and cell functionality has nonlinear effects on tissue performance, these statistics of cellular mtDNA populations play vital roles in health, disease, and inheritance. This mini review will describe some of the better-known ways in which these populations change over time in different organisms, highlighting the importance of quantitatively understanding both mutant load mean and variance. Due to length constraints, we cannot attempt to be comprehensive but hope to provide useful links to some of the many excellent studies on these topics.
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135
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Zou H, Jakovlić I, Zhang D, Hua CJ, Chen R, Li WX, Li M, Wang GT. Architectural instability, inverted skews and mitochondrial phylogenomics of Isopoda: outgroup choice affects the long-branch attraction artefacts. ROYAL SOCIETY OPEN SCIENCE 2020; 7:191887. [PMID: 32257344 PMCID: PMC7062073 DOI: 10.1098/rsos.191887] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 01/14/2020] [Indexed: 05/13/2023]
Abstract
The majority strand of mitochondrial genomes of crustaceans usually exhibits negative GC skews. Most isopods exhibit an inversed strand asymmetry, believed to be a consequence of an inversion of the replication origin (ROI). Recently, we proposed that an additional ROI event in the common ancestor of Cymothoidae and Corallanidae families resulted in a double-inverted skew (negative GC), and that taxa with homoplastic skews cluster together in phylogenetic analyses (long-branch attraction, LBA). Herein, we further explore these hypotheses, for which we sequenced the mitogenome of Asotana magnifica (Cymothoidae), and tested whether our conclusions were biased by poor taxon sampling and inclusion of outgroups. (1) The new mitogenome also exhibits a double-inverted skew, which supports the hypothesis of an additional ROI event in the common ancestor of Cymothoidae and Corallanidae families. (2) It exhibits a unique gene order, which corroborates that isopods possess exceptionally destabilized mitogenomic architecture. (3) Improved taxonomic sampling failed to resolve skew-driven phylogenetic artefacts. (4) The use of a single outgroup exacerbated the LBA, whereas both the use of a large number of outgroups and complete exclusion of outgroups ameliorated it.
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Affiliation(s)
- Hong Zou
- Key Laboratory of Aquaculture Disease Control, Ministry of Agriculture, and State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China
| | - Ivan Jakovlić
- Bio-Transduction Lab, Wuhan 430075, People's Republic of China
| | - Dong Zhang
- Key Laboratory of Aquaculture Disease Control, Ministry of Agriculture, and State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Cong-Jie Hua
- Key Laboratory of Aquaculture Disease Control, Ministry of Agriculture, and State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China
- Department of Pathogenic Biology, School of Medicine, Jianghan University, Wuhan 430056, People's Republic of China
| | - Rong Chen
- Bio-Transduction Lab, Wuhan 430075, People's Republic of China
| | - Wen-Xiang Li
- Key Laboratory of Aquaculture Disease Control, Ministry of Agriculture, and State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Ming Li
- Key Laboratory of Aquaculture Disease Control, Ministry of Agriculture, and State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Gui-Tang Wang
- Key Laboratory of Aquaculture Disease Control, Ministry of Agriculture, and State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, People's Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
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136
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Krasovec M, Sanchez-Brosseau S, Piganeau G. First Estimation of the Spontaneous Mutation Rate in Diatoms. Genome Biol Evol 2020; 11:1829-1837. [PMID: 31218358 PMCID: PMC6604790 DOI: 10.1093/gbe/evz130] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/17/2019] [Indexed: 12/25/2022] Open
Abstract
Mutations are the origin of genetic diversity, and the mutation rate is a fundamental parameter to understand all aspects of molecular evolution. The combination of mutation-accumulation experiments and high-throughput sequencing enabled the estimation of mutation rates in most model organisms, but several major eukaryotic lineages remain unexplored. Here, we report the first estimation of the spontaneous mutation rate in a model unicellular eukaryote from the Stramenopile kingdom, the diatom Phaeodactylum tricornutum (strain RCC2967). We sequenced 36 mutation accumulation lines for an average of 181 generations per line and identified 156 de novo mutations. The base substitution mutation rate per site per generation is μbs = 4.77 × 10-10 and the insertion-deletion mutation rate is μid = 1.58 × 10-11. The mutation rate varies as a function of the nucleotide context and is biased toward an excess of mutations from GC to AT, consistent with previous observations in other species. Interestingly, the mutation rates between the genomes of organelles and the nucleus differ, with a significantly higher mutation rate in the mitochondria. This confirms previous claims based on indirect estimations of the mutation rate in mitochondria of photosynthetic eukaryotes that acquired their plastid through a secondary endosymbiosis. This novel estimate enables us to infer the effective population size of P. tricornutum to be Ne∼8.72 × 106.
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Affiliation(s)
- Marc Krasovec
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, Banyuls/Mer, France
| | - Sophie Sanchez-Brosseau
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, Banyuls/Mer, France
| | - Gwenael Piganeau
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, Banyuls/Mer, France.,Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
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137
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Dujon B. Mitochondrial genetics revisited. Yeast 2020; 37:191-205. [DOI: 10.1002/yea.3445] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 10/05/2019] [Accepted: 10/08/2019] [Indexed: 12/17/2022] Open
Affiliation(s)
- Bernard Dujon
- Department Genomes and GeneticsInstitut Pasteur Paris France
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138
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Shatskaya NV, Bogdanova VS, Kosterin OE, Vasiliev GV, Kimeklis AK, Andronov EE, Provorov NA. The plastid and mitochondrial genomes of Vavilovia Formosa (Stev.) Fed. and the phylogeny of related legume genera. Vavilovskii Zhurnal Genet Selektsii 2020. [DOI: 10.18699/vj19.574] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The plastid and mitochondrial genomes of Vavilovia formosa (Stev.) Fed. were assembled on the base of the data of high-throughput sequencing of DNA isolated from a sample from North Osetia, Russia, using Illumina and PacBio platforms. The long PacBio reads were sufficient for reliable assembling organellar genomes while the short Illumina reads obtained from total DNA were unacceptable for this purpose because of substantial contamination by nuclear sequences. The organellar genomes were circular DNA molecules; the genome of mitochondria was represented by two circular chromosomes. A phylogenetic analysis on the basis of plastid genomes available in public databases was performed for some representatives of the tribes Fabeae, Trifolieae and Cicereae. As was expected, the V. formosa branch proved to be sister to the Pisum branch, and the tribe Fabeae was monophyletic. The position of Trifolium L. appeared sensitive to the phylogeny reconstruction method, either clustering with Fabeae or with the genera Medicago L., Trigonella L. and Melilotus Mill., but the internodes between successive divergences were short in all cases, suggesting that the radiation of Trifolium, other Trifolieae and Fabeae was fast, occurring within a small time interval as compared to further evolution of these lineages. The data on the relatedness of the plastid genomes of Trifolium and Fabeae correlate with the similarity of N2-fixing symbionts in these legumes represented by Rhizobium leguminosarum biovars trifolii and viciae, while the symbionts of Medicago, Melilotus and Trigonella belong to the Sinorhizobium meliloti and S. medicae species, which are distant from Rhizobium.
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Affiliation(s)
| | | | - O. E. Kosterin
- Institute of Cytology and Genetics, SB RAS; Novosibirsk State University
| | | | - A. K. Kimeklis
- All-Russia Research Institute for Agricultural Microbiology
| | - E. E. Andronov
- All-Russia Research Institute for Agricultural Microbiology
| | - N. A. Provorov
- All-Russia Research Institute for Agricultural Microbiology
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139
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Repetti SI, Jackson CJ, Judd LM, Wick RR, Holt KE, Verbruggen H. The inflated mitochondrial genomes of siphonous green algae reflect processes driving expansion of noncoding DNA and proliferation of introns. PeerJ 2020; 8:e8273. [PMID: 31915577 PMCID: PMC6944098 DOI: 10.7717/peerj.8273] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 11/22/2019] [Indexed: 02/06/2023] Open
Abstract
Within the siphonous green algal order Bryopsidales, the size and gene arrangement of chloroplast genomes has been examined extensively, while mitochondrial genomes have been mostly overlooked. The recently published mitochondrial genome of Caulerpa lentillifera is large with expanded noncoding DNA, but it remains unclear if this is characteristic of the entire order. Our study aims to evaluate the evolutionary forces shaping organelle genome dynamics in the Bryopsidales based on the C. lentillifera and Ostreobium quekettii mitochondrial genomes. In this study, the mitochondrial genome of O. quekettii was characterised using a combination of long and short read sequencing, and bioinformatic tools for annotation and sequence analyses. We compared the mitochondrial and chloroplast genomes of O. quekettii and C. lentillifera to examine hypotheses related to genome evolution. The O. quekettii mitochondrial genome is the largest green algal mitochondrial genome sequenced (241,739 bp), considerably larger than its chloroplast genome. As with the mtDNA of C. lentillifera, most of this excess size is from the expansion of intergenic DNA and proliferation of introns. Inflated mitochondrial genomes in the Bryopsidales suggest effective population size, recombination and/or mutation rate, influenced by nuclear-encoded proteins, differ between the genomes of mitochondria and chloroplasts, reducing the strength of selection to influence evolution of their mitochondrial genomes.
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Affiliation(s)
- Sonja I Repetti
- School of BioSciences, University of Melbourne, Melbourne, VIC, Australia
| | | | - Louise M Judd
- Department of Infectious Diseases, Monash University, Melbourne, VIC, Australia
| | - Ryan R Wick
- Department of Infectious Diseases, Monash University, Melbourne, VIC, Australia
| | - Kathryn E Holt
- Department of Infectious Diseases, Monash University, Melbourne, VIC, Australia
| | - Heroen Verbruggen
- School of BioSciences, University of Melbourne, Melbourne, VIC, Australia
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140
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van den Ameele J, Li AY, Ma H, Chinnery PF. Mitochondrial heteroplasmy beyond the oocyte bottleneck. Semin Cell Dev Biol 2020; 97:156-166. [DOI: 10.1016/j.semcdb.2019.10.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 09/17/2019] [Accepted: 10/01/2019] [Indexed: 12/31/2022]
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141
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Dong Q, Xing X, Han Y, Wei X, Zhang S. De Novo Organelle Biogenesis in the Cyanobacterium TDX16 Released from the Green Alga <i>Haematococcus pluvialis</i>. Cell 2020. [DOI: 10.4236/cellbio.2020.91003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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142
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Thairu MW, Hansen AK. It's a small, small world: unravelling the role and evolution of small RNAs in organelle and endosymbiont genomes. FEMS Microbiol Lett 2019; 366:5371121. [PMID: 30844054 DOI: 10.1093/femsle/fnz049] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 03/05/2019] [Indexed: 12/19/2022] Open
Abstract
Organelles and host-restricted bacterial symbionts are characterized by having highly reduced genomes that lack many key regulatory genes and elements. Thus, it has been hypothesized that the eukaryotic nuclear genome is primarily responsible for regulating these symbioses. However, with the discovery of organelle- and symbiont-expressed small RNAs (sRNAs) there is emerging evidence that these sRNAs may play a role in gene regulation as well. Here, we compare the diversity of organelle and bacterial symbiont sRNAs recently identified using genome-enabled '-omic' technologies and discuss their potential role in gene regulation. We also discuss how the genome architecture of small genomes may influence the evolution of these sRNAs and their potential function. Additionally, these new studies suggest that some sRNAs are conserved within organelle and symbiont taxa and respond to changes in the environment and/or their hosts. In summary, these results suggest that organelle and symbiont sRNAs may play a role in gene regulation in addition to nuclear-encoded host mechanisms.
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Affiliation(s)
- Margaret W Thairu
- Department of Entomology, University of California, Riverside, Riverside, CA, USA
| | - Allison K Hansen
- Department of Entomology, University of California, Riverside, Riverside, CA, USA
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143
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Klucnika A, Ma H. Mapping and editing animal mitochondrial genomes: can we overcome the challenges? Philos Trans R Soc Lond B Biol Sci 2019; 375:20190187. [PMID: 31787046 DOI: 10.1098/rstb.2019.0187] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The animal mitochondrial genome, although small, can have a big impact on health and disease. Non-pathogenic sequence variation among mitochondrial DNA (mtDNA) haplotypes influences traits including fertility, healthspan and lifespan, whereas pathogenic mutations are linked to incurable mitochondrial diseases and other complex conditions like ageing, diabetes, cancer and neurodegeneration. However, we know very little about how mtDNA genetic variation contributes to phenotypic differences. Infrequent recombination, the multicopy nature and nucleic acid-impenetrable membranes present significant challenges that hamper our ability to precisely map mtDNA variants responsible for traits, and to genetically modify mtDNA so that we can isolate specific mutants and characterize their biochemical and physiological consequences. Here, we summarize the past struggles and efforts in developing systems to map and edit mtDNA. We also assess the future of performing forward and reverse genetic studies on animal mitochondrial genomes. This article is part of the theme issue 'Linking the mitochondrial genotype to phenotype: a complex endeavour'.
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Affiliation(s)
- Anna Klucnika
- Wellcome Trust/Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QN, UK.,Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK
| | - Hansong Ma
- Wellcome Trust/Cancer Research UK Gurdon Institute, Tennis Court Road, Cambridge CB2 1QN, UK.,Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK
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144
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Cui Y, Zhou J, Chen X, Xu Z, Wang Y, Sun W, Song J, Yao H. Complete chloroplast genome and comparative analysis of three Lycium (Solanaceae) species with medicinal and edible properties. GENE REPORTS 2019. [DOI: 10.1016/j.genrep.2019.100464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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145
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Brieba LG. Structure-Function Analysis Reveals the Singularity of Plant Mitochondrial DNA Replication Components: A Mosaic and Redundant System. PLANTS 2019; 8:plants8120533. [PMID: 31766564 PMCID: PMC6963530 DOI: 10.3390/plants8120533] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 11/18/2019] [Accepted: 11/19/2019] [Indexed: 02/06/2023]
Abstract
Plants are sessile organisms, and their DNA is particularly exposed to damaging agents. The integrity of plant mitochondrial and plastid genomes is necessary for cell survival. During evolution, plants have evolved mechanisms to replicate their mitochondrial genomes while minimizing the effects of DNA damaging agents. The recombinogenic character of plant mitochondrial DNA, absence of defined origins of replication, and its linear structure suggest that mitochondrial DNA replication is achieved by a recombination-dependent replication mechanism. Here, I review the mitochondrial proteins possibly involved in mitochondrial DNA replication from a structural point of view. A revision of these proteins supports the idea that mitochondrial DNA replication could be replicated by several processes. The analysis indicates that DNA replication in plant mitochondria could be achieved by a recombination-dependent replication mechanism, but also by a replisome in which primers are synthesized by three different enzymes: Mitochondrial RNA polymerase, Primase-Helicase, and Primase-Polymerase. The recombination-dependent replication model and primers synthesized by the Primase-Polymerase may be responsible for the presence of genomic rearrangements in plant mitochondria.
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Affiliation(s)
- Luis Gabriel Brieba
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato, Guanajuato C.P. 36821, Mexico
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146
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Aguirre-Dugua X, Castellanos-Morales G, Paredes-Torres LM, Hernández-Rosales HS, Barrera-Redondo J, Sánchez-de la Vega G, Tapia-Aguirre F, Ruiz-Mondragón KY, Scheinvar E, Hernández P, Aguirre-Planter E, Montes-Hernández S, Lira-Saade R, Eguiarte LE. Evolutionary Dynamics of Transferred Sequences Between Organellar Genomes in Cucurbita. J Mol Evol 2019; 87:327-342. [PMID: 31701178 DOI: 10.1007/s00239-019-09916-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 10/28/2019] [Indexed: 12/12/2022]
Abstract
Twenty-nine DNA regions of plastid origin have been previously identified in the mitochondrial genome of Cucurbita pepo (pumpkin; Cucurbitaceae). Four of these regions harbor homolog sequences of rbcL, matK, rpl20-rps12 and trnL-trnF, which are widely used as molecular markers for phylogenetic and phylogeographic studies. We extracted the mitochondrial copies of these regions based on the mitochondrial genome of C. pepo and, along with published sequences for these plastome markers from 13 Cucurbita taxa, we performed phylogenetic molecular analyses to identify inter-organellar transfer events in the Cucurbita phylogeny and changes in their nucleotide substitution rates. Phylogenetic reconstruction and tree selection tests suggest that rpl20 and rbcL mitochondrial paralogs arose before Cucurbita diversification whereas the mitochondrial matK and trnL-trnF paralogs emerged most probably later, in the mesophytic Cucurbita clade. Nucleotide substitution rates increased one order of magnitude in all the mitochondrial paralogs compared to their original plastid sequences. Additionally, mitochondrial trnL-trnF sequences obtained by PCR from nine Cucurbita taxa revealed higher nucleotide diversity in the mitochondrial than in the plastid copies, likely related to the higher nucleotide substitution rates in the mitochondrial region and loss of functional constraints in its tRNA genes.
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Affiliation(s)
- Xitlali Aguirre-Dugua
- Unidad de Biotecnología Y Prototipos, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Av. De Los Barrios 1, Col. Los Reyes Iztacala, 54090, Tlalnepantla, Estado de México, Mexico.
| | - Gabriela Castellanos-Morales
- Departamento de Conservación de La Biodiversidad, El Colegio de La Frontera Sur, Unidad Villahermosa, Carretera Villahermosa-Reforma km. 15.5, Ranchería El Guineo 2a Sección, 86280, Villahermosa, Tabasco, Mexico
| | - Leslie M Paredes-Torres
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Circuito Exterior S/N Anexo Al Jardín Botánico, 04510, Ciudad de México, Mexico
| | - Helena S Hernández-Rosales
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Circuito Exterior S/N Anexo Al Jardín Botánico, 04510, Ciudad de México, Mexico
| | - Josué Barrera-Redondo
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Circuito Exterior S/N Anexo Al Jardín Botánico, 04510, Ciudad de México, Mexico
| | - Guillermo Sánchez-de la Vega
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Circuito Exterior S/N Anexo Al Jardín Botánico, 04510, Ciudad de México, Mexico
| | - Fernando Tapia-Aguirre
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Circuito Exterior S/N Anexo Al Jardín Botánico, 04510, Ciudad de México, Mexico
| | - Karen Y Ruiz-Mondragón
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Circuito Exterior S/N Anexo Al Jardín Botánico, 04510, Ciudad de México, Mexico
| | - Enrique Scheinvar
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Circuito Exterior S/N Anexo Al Jardín Botánico, 04510, Ciudad de México, Mexico
| | - Paulina Hernández
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Circuito Exterior S/N Anexo Al Jardín Botánico, 04510, Ciudad de México, Mexico
| | - Erika Aguirre-Planter
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Circuito Exterior S/N Anexo Al Jardín Botánico, 04510, Ciudad de México, Mexico
| | - Salvador Montes-Hernández
- Campo Experimental Bajío, Instituto Nacional de Investigaciones Forestales, Agrícolas Y Pecuarias (INIFAP), Km 6.5 Carretera Celaya-San Miguel de Allende, 38110, Celaya, Gto., Mexico
| | - Rafael Lira-Saade
- Unidad de Biotecnología Y Prototipos, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Av. De Los Barrios 1, Col. Los Reyes Iztacala, 54090, Tlalnepantla, Estado de México, Mexico.
| | - Luis E Eguiarte
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Circuito Exterior S/N Anexo Al Jardín Botánico, 04510, Ciudad de México, Mexico.
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147
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Smith DR. Revisiting published genomes with fresh eyes and new data: Revising old sequencing data can yield unexpected insights and identify errors. EMBO Rep 2019; 20:e49482. [PMID: 31680386 DOI: 10.15252/embr.201949482] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Old data are like yesterday's leftovers: sapped of novelty and excitement. But revisiting old sequence data with a fresh mind and new techniques can yield new and unexpected results.
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Affiliation(s)
- David R Smith
- Department of Biology, University of Western Ontario, London, ON, Canada
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148
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Mammalian mitochondrial translation - revealing consequences of divergent evolution. Biochem Soc Trans 2019; 47:1429-1436. [PMID: 31551356 DOI: 10.1042/bst20190265] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 08/15/2019] [Accepted: 08/19/2019] [Indexed: 12/16/2022]
Abstract
Mitochondria are ubiquitous organelles present in the cytoplasm of all nucleated eukaryotic cells. These organelles are described as arising from a common ancestor but a comparison of numerous aspects of mitochondria between different organisms provides remarkable examples of divergent evolution. In humans, these organelles are of dual genetic origin, comprising ∼1500 nuclear-encoded proteins and thirteen that are encoded by the mitochondrial genome. Of the various functions that these organelles perform, it is only oxidative phosphorylation, which provides ATP as a source of chemical energy, that is dependent on synthesis of these thirteen mitochondrially encoded proteins. A prerequisite for this process of translation are the mitoribosomes. The recent revolution in cryo-electron microscopy has generated high-resolution mitoribosome structures and has undoubtedly revealed some of the most distinctive molecular aspects of the mitoribosomes from different organisms. However, we still lack a complete understanding of the mechanistic aspects of this process and many of the factors involved in post-transcriptional gene expression in mitochondria. This review reflects on the current knowledge and illustrates some of the striking differences that have been identified between mitochondria from a range of organisms.
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Husnik F, Keeling PJ. The fate of obligate endosymbionts: reduction, integration, or extinction. Curr Opin Genet Dev 2019; 58-59:1-8. [DOI: 10.1016/j.gde.2019.07.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 07/16/2019] [Accepted: 07/21/2019] [Indexed: 11/29/2022]
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Johri P, Marinov GK, Doak TG, Lynch M. Population Genetics of Paramecium Mitochondrial Genomes: Recombination, Mutation Spectrum, and Efficacy of Selection. Genome Biol Evol 2019; 11:1398-1416. [PMID: 30980669 PMCID: PMC6505448 DOI: 10.1093/gbe/evz081] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/09/2019] [Indexed: 12/11/2022] Open
Abstract
The evolution of mitochondrial genomes and their population-genetic environment among unicellular eukaryotes are understudied. Ciliate mitochondrial genomes exhibit a unique combination of characteristics, including a linear organization and the presence of multiple genes with no known function or detectable homologs in other eukaryotes. Here we study the variation of ciliate mitochondrial genomes both within and across 13 highly diverged Paramecium species, including multiple species from the P. aurelia species complex, with four outgroup species: P. caudatum, P. multimicronucleatum, and two strains that may represent novel related species. We observe extraordinary conservation of gene order and protein-coding content in Paramecium mitochondria across species. In contrast, significant differences are observed in tRNA content and copy number, which is highly conserved in species belonging to the P. aurelia complex but variable among and even within the other Paramecium species. There is an increase in GC content from ∼20% to ∼40% on the branch leading to the P. aurelia complex. Patterns of polymorphism in population-genomic data and mutation-accumulation experiments suggest that the increase in GC content is primarily due to changes in the mutation spectra in the P. aurelia species. Finally, we find no evidence of recombination in Paramecium mitochondria and find that the mitochondrial genome appears to experience either similar or stronger efficacy of purifying selection than the nucleus.
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Affiliation(s)
- Parul Johri
- Department of Biology, Indiana University, Bloomington
| | - Georgi K Marinov
- Department of Biology, Indiana University, Bloomington.,Department of Genetics, Stanford University School of Medicine, Stanford, CA
| | - Thomas G Doak
- Department of Biology, Indiana University, Bloomington.,National Center for Genome Analysis Support, Indiana University, Bloomington
| | - Michael Lynch
- Department of Biology, Indiana University, Bloomington.,Center for Mechanisms of Evolution, School of Life Sciences, Arizona State University, Tempe
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