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Huang KY, Kan SL, Shen TT, Gong P, Feng YY, Du H, Zhao YP, Wan T, Wang XQ, Ran JH. A Comprehensive Evolutionary Study of Chloroplast RNA Editing in Gymnosperms: A Novel Type of G-to-A RNA Editing Is Common in Gymnosperms. Int J Mol Sci 2022; 23:ijms231810844. [PMID: 36142757 PMCID: PMC9505161 DOI: 10.3390/ijms231810844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 09/09/2022] [Accepted: 09/13/2022] [Indexed: 12/05/2022] Open
Abstract
Although more than 9100 plant plastomes have been sequenced, RNA editing sites of the whole plastome have been experimentally verified in only approximately 21 species, which seriously hampers the comprehensive evolutionary study of chloroplast RNA editing. We investigated the evolutionary pattern of chloroplast RNA editing sites in 19 species from all 13 families of gymnosperms based on a combination of genomic and transcriptomic data. We found that the chloroplast C-to-U RNA editing sites of gymnosperms shared many common characteristics with those of other land plants, but also exhibited many unique characteristics. In contrast to that noted in angiosperms, the density of RNA editing sites in ndh genes was not the highest in the sampled gymnosperms, and both loss and gain events at editing sites occurred frequently during the evolution of gymnosperms. In addition, GC content and plastomic size were positively correlated with the number of chloroplast RNA editing sites in gymnosperms, suggesting that the increase in GC content could provide more materials for RNA editing and facilitate the evolution of RNA editing in land plants or vice versa. Interestingly, novel G-to-A RNA editing events were commonly found in all sampled gymnosperm species, and G-to-A RNA editing exhibits many different characteristics from C-to-U RNA editing in gymnosperms. This study revealed a comprehensive evolutionary scenario for chloroplast RNA editing sites in gymnosperms, and reported that a novel type of G-to-A RNA editing is prevalent in gymnosperms.
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Affiliation(s)
- Kai-Yuan Huang
- 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
| | - Sheng-Long Kan
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Ting-Ting Shen
- School of Earth Sciences, East China University of Technology, Nanchang 330013, China
| | - Pin Gong
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Yuan-Yuan Feng
- 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 Du
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Yun-Peng Zhao
- Laboratory of Systematic & Evolutionary Botany and Biodiversity, College of Life Sciences, Zhejiang University, Hangzhou 310058, China
| | - Tao Wan
- Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
| | - Xiao-Quan Wang
- 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
| | - Jin-Hua Ran
- 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
- Correspondence:
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OTP970 Is Required for RNA Editing of Chloroplast ndhB Transcripts in Arabidopsis thaliana. Genes (Basel) 2022; 13:genes13010139. [PMID: 35052479 PMCID: PMC8774829 DOI: 10.3390/genes13010139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 01/09/2022] [Accepted: 01/10/2022] [Indexed: 11/19/2022] Open
Abstract
RNA editing is essential for compensating for defects or mutations in haploid organelle genomes and is regulated by numerous trans-factors. Pentatricopeptide repeat (PPR) proteins are the prime factors that are involved in RNA editing; however, many have not yet been identified. Here, we screened the plastid-targeted PLS-DYW subfamily of PPR proteins belonging to Arabidopsis thaliana and identified ORGANELLE TRANSCRIPT PROCESSING 970 (OTP970) as a key player in RNA editing in plastids. A loss-of-function otp970 mutant was impaired in RNA editing of ndhB transcripts at site 149 (ndhB-C149). RNA-immunoprecipitation analysis indicated that OTP970 was associated with the ndhB-C149 site. The complementation of the otp970 mutant with OTP970 lacking the DYW domain (OTP970∆DYW) failed to restore the RNA editing of ndhB-C149. ndhB gene encodes the B subunit of the NADH dehydrogenase-like (NDH) complex; however, neither NDH activity and stability nor NDH-PSI supercomplex formation were affected in otp970 mutant compared to the wild type, indicating that alteration in amino acid sequence is not necessary for NdhB function. Together, these results suggest that OTP970 is involved in the RNA editing of ndhB-C149 and that the DYW domain is essential for its function.
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He ZS, Zhu A, Yang JB, Fan W, Li DZ. Organelle Genomes and Transcriptomes of Nymphaea Reveal the Interplay between Intron Splicing and RNA Editing. Int J Mol Sci 2021; 22:ijms22189842. [PMID: 34576004 PMCID: PMC8466565 DOI: 10.3390/ijms22189842] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 09/04/2021] [Accepted: 09/08/2021] [Indexed: 11/16/2022] Open
Abstract
Posttranscriptional modifications, including intron splicing and RNA editing, are common processes during regulation of gene expression in plant organelle genomes. However, the intermediate products of intron-splicing, and the interplay between intron-splicing and RNA-editing were not well studied. Most organelle transcriptome analyses were based on the Illumina short reads which were unable to capture the full spectrum of transcript intermediates within an organelle. To fully investigate the intermediates during intron splicing and the underlying relationships with RNA editing, we used PacBio DNA-seq and Iso-seq, together with Illumina short reads genome and transcriptome sequencing data to assemble the chloroplast and mitochondrial genomes of Nymphaea 'Joey Tomocik' and analyze their posttranscriptional features. With the direct evidence from Iso-seq, multiple intermediates partially or fully intron-spliced were observed, and we also found that both cis- and trans-splicing introns were spliced randomly. Moreover, by using rRNA-depleted and non-Oligo(dT)-enrichment strand-specific RNA-seq data and combining direct SNP-calling and transcript-mapping methods, we identified 98 and 865 RNA-editing sites in the plastome and mitogenome of N. 'Joey Tomocik', respectively. The target codon preference, the tendency of increasing protein hydrophobicity, and the bias distribution of editing sites are similar in both organelles, suggesting their common evolutionary origin and shared editing machinery. The distribution of RNA editing sites also implies that the RNA editing sites in the intron and exon regions may splice synchronously, except those exonic sites adjacent to intron which could only be edited after being intron-spliced. Our study provides solid evidence for the multiple intermediates co-existing during intron-splicing and their interplay with RNA editing in organelle genomes of a basal angiosperm.
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Affiliation(s)
- Zheng-Shan He
- Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (Z.-S.H.); (A.Z.); (J.-B.Y.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Andan Zhu
- Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (Z.-S.H.); (A.Z.); (J.-B.Y.)
| | - Jun-Bo Yang
- Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (Z.-S.H.); (A.Z.); (J.-B.Y.)
| | - Weishu Fan
- Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (Z.-S.H.); (A.Z.); (J.-B.Y.)
- Correspondence: (W.F.); (D.-Z.L.); Tel.: +86-871-6523-8370 (W.F.); +86-871-6522-3503 (D.-Z.L.)
| | - De-Zhu Li
- Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China; (Z.-S.H.); (A.Z.); (J.-B.Y.)
- Correspondence: (W.F.); (D.-Z.L.); Tel.: +86-871-6523-8370 (W.F.); +86-871-6522-3503 (D.-Z.L.)
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Fan K, Peng Y, Ren Z, Li D, Zhen S, Hey S, Cui Y, Fu J, Gu R, Wang J, Wang G, Li L. Maize Defective Kernel605 Encodes a Canonical DYW-Type PPR Protein that Edits a Conserved Site of nad1 and Is Essential for Seed Nutritional Quality. PLANT & CELL PHYSIOLOGY 2020; 61:1954-1966. [PMID: 32818255 DOI: 10.1093/pcp/pcaa110] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 08/13/2020] [Indexed: 06/11/2023]
Abstract
Pentatricopeptide repeat (PPR) proteins involved in mitochondrial RNA cytidine (C)-to-uridine (U) editing mostly result in stagnant embryo and endosperm development upon loss of function. However, less is known about PPRs that are involved in farinaceous endosperm formation and maize quality. Here, we cloned a maize DYW-type PPR Defective Kernel605 (Dek605). Mutation of Dek605 delayed seed and seedling development. Mitochondrial transcript analysis of dek605 revealed that loss of DEK605 impaired C-to-U editing at the nad1-608 site and fails to alter Ser203 to Phe203 in NAD1 (dehydrogenase complex I), disrupting complex I assembly and reducing NADH dehydrogenase activity. Meanwhile, complexes III and IV in the cytochrome pathway, as well as AOX2 in the alternative respiratory pathway, are dramatically increased. Interestingly, the dek605 mutation resulted in opaque endosperm and increased levels of the free amino acids alanine, aspartic acid and phenylalanine. The down- and upregulated genes mainly involved in stress response-related and seed dormancy-related pathways, respectively, were observed after transcriptome analysis of dek605 at 12 d after pollination. Collectively, these results indicate that Dek605 specifically affects the single nad1-608 site and is required for normal seed development and resulted in nutritional quality relevant amino acid accumulation.
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Affiliation(s)
- Kaijian Fan
- Seed Science and Technology Research Center, Beijing Innovation Center for Seed Technology (MOA), Beijing Key Laboratory for Crop Genetic Improvement, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China
| | - Yixuan Peng
- Institute of Crop Sciences, Chinese Academy of Agricultural iences, Beijing 100081, China
| | - Zhenjing Ren
- Seed Science and Technology Research Center, Beijing Innovation Center for Seed Technology (MOA), Beijing Key Laboratory for Crop Genetic Improvement, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China
- Institute of Crop Sciences, Chinese Academy of Agricultural iences, Beijing 100081, China
| | - Delin Li
- Institute of Crop Sciences, Chinese Academy of Agricultural iences, Beijing 100081, China
| | - Sihan Zhen
- Institute of Crop Sciences, Chinese Academy of Agricultural iences, Beijing 100081, China
| | - Stefan Hey
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Yu Cui
- Seed Science and Technology Research Center, Beijing Innovation Center for Seed Technology (MOA), Beijing Key Laboratory for Crop Genetic Improvement, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China
| | - Junjie Fu
- Seed Science and Technology Research Center, Beijing Innovation Center for Seed Technology (MOA), Beijing Key Laboratory for Crop Genetic Improvement, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China
| | - Riliang Gu
- Institute of Crop Sciences, Chinese Academy of Agricultural iences, Beijing 100081, China
| | - Jianhua Wang
- Institute of Crop Sciences, Chinese Academy of Agricultural iences, Beijing 100081, China
| | - Guoying Wang
- Seed Science and Technology Research Center, Beijing Innovation Center for Seed Technology (MOA), Beijing Key Laboratory for Crop Genetic Improvement, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China
| | - Li Li
- Institute of Crop Sciences, Chinese Academy of Agricultural iences, Beijing 100081, China
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Sun Y, Xie M, Xu Z, Chan KC, Zhong JY, Fan K, Wong-Bajracharya J, Lam HM, Lim BL. Differential RNA Editing and Intron Splicing in Soybean Mitochondria during Nodulation. Int J Mol Sci 2020; 21:E9378. [PMID: 33317061 PMCID: PMC7764374 DOI: 10.3390/ijms21249378] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Revised: 12/04/2020] [Accepted: 12/07/2020] [Indexed: 12/12/2022] Open
Abstract
Nitrogen fixation in soybean consumes a tremendous amount of energy, leading to substantial differences in energy metabolism and mitochondrial activities between nodules and uninoculated roots. While C-to-U RNA editing and intron splicing of mitochondrial transcripts are common in plant species, their roles in relation to nodule functions are still elusive. In this study, we performed RNA-seq to compare transcript profiles and RNA editing of mitochondrial genes in soybean nodules and roots. A total of 631 RNA editing sites were identified on mitochondrial transcripts, with 12% or 74 sites differentially edited among the transcripts isolated from nodules, stripped roots, and uninoculated roots. Eight out of these 74 differentially edited sites are located on the matR transcript, of which the degrees of RNA editing were the highest in the nodule sample. The degree of mitochondrial intron splicing was also examined. The splicing efficiencies of several introns in nodules and stripped roots were higher than in uninoculated roots. These include nad1 introns 2/3/4, nad4 intron 3, nad5 introns 2/3, cox2 intron 1, and ccmFc intron 1. A greater splicing efficiency of nad4 intron 1, a higher NAD4 protein abundance, and a reduction in supercomplex I + III2 were also observed in nodules, although the causal relationship between these observations requires further investigation.
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Affiliation(s)
- Yuzhe Sun
- School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong, China; (Y.S.); (Z.X.); (K.C.C.); (J.Y.Z.)
| | - Min Xie
- Center for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong, China; (M.X.); (K.F.); (J.W.-B.)
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Zhou Xu
- School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong, China; (Y.S.); (Z.X.); (K.C.C.); (J.Y.Z.)
| | - Koon Chuen Chan
- School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong, China; (Y.S.); (Z.X.); (K.C.C.); (J.Y.Z.)
| | - Jia Yi Zhong
- School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong, China; (Y.S.); (Z.X.); (K.C.C.); (J.Y.Z.)
| | - Kejing Fan
- Center for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong, China; (M.X.); (K.F.); (J.W.-B.)
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Johanna Wong-Bajracharya
- Center for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong, China; (M.X.); (K.F.); (J.W.-B.)
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Hon-Ming Lam
- Center for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong, China; (M.X.); (K.F.); (J.W.-B.)
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Boon Leong Lim
- School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong, China; (Y.S.); (Z.X.); (K.C.C.); (J.Y.Z.)
- Center for Soybean Research of the State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong, China; (M.X.); (K.F.); (J.W.-B.)
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6
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Chu D, Wei L. Systematic analysis reveals cis and trans determinants affecting C-to-U RNA editing in Arabidopsis thaliana. BMC Genet 2020; 21:98. [PMID: 32883207 PMCID: PMC7469343 DOI: 10.1186/s12863-020-00907-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Accepted: 08/26/2020] [Indexed: 02/06/2023] Open
Abstract
Background C-to-U RNA editing is prevalent in the mitochondrial and chloroplast genes in plants. The biological functions of a fraction of C-to-U editing sites are continuously discovered by case studies. However, at genome-wide level, the cis and trans determinants affecting the occurrence or editing levels of these C-to-U events are relatively less studied. What is known is that the PPR (pentatricopeptide repeat) proteins are the main trans-regulatory elements responsible for the C-to-U conversion, but other determinants especially the cis-regulatory elements remain largely uninvestigated. Results By analyzing the transcriptome and translatome data in Arabidopsis thaliana roots and shoots, combined with RNA-seq data from hybrids of Arabidopsis thaliana and Arabidopsis lyrata, we perform genome-wide investigation on the cis elements and trans-regulatory elements that potentially affect C-to-U editing events. An upstream guanosine or double-stranded RNA (dsRNA) regions are unfavorable for editing events. Meanwhile, many genes including the transcription factors may indirectly play regulatory roles in trans. Conclusions The 5-prime thymidine facilitates editing and dsRNA structures prevent editing in cis. Many transcription factors affect editing in trans. Although the detailed molecular mechanisms underlying the cis and trans regulation remain to be experimentally verified, our findings provide novel aspects in studying the botanical C-to-U RNA editing events.
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Affiliation(s)
- Duan Chu
- College of Life Sciences, Beijing Normal University, No. 19 Xinjiekouwai Street, Haidian District, Beijing, China
| | - Lai Wei
- College of Life Sciences, Beijing Normal University, No. 19 Xinjiekouwai Street, Haidian District, Beijing, China.
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Xu C, Song S, Yang YZ, Lu F, Zhang MD, Sun F, Jia R, Song R, Tan BC. DEK46 performs C-to-U editing of a specific site in mitochondrial nad7 introns that is critical for intron splicing and seed development in maize. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 103:1767-1782. [PMID: 32559332 DOI: 10.1111/tpj.14862] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 05/14/2020] [Accepted: 05/21/2020] [Indexed: 05/02/2023]
Abstract
The self-splicing of group II introns during RNA processing depends on their catalytic structure and is influenced by numerous factors that promote the formation of that structure through direct binding. Here we report that C-to-U editing at a specific position in two nad7 introns is essential to splicing, which also implies that the catalytic activity of non-functional group II introns could be restored by editing. We characterized a maize (Zea mays) mutant, dek46, with a defective kernel phenotype; Dek46 encodes a pentatricopeptide repeat DYW protein exclusively localized in mitochondria. Analyses of the coding regions of mitochondrial transcripts did not uncover differences in RNA editing between dek46 mutant and wild-type maize, but showed that splicing of nad7 introns 3 and 4 is severely reduced in the mutant. Furthermore, editing at nucleotide 22 of domain 5 (D5-C22) of both introns is abolished in dek46. We constructed chimeric introns by swapping D5 of P.li.LSUI2 with D5 of nad7 intron 3. In vitro splicing assays indicated that the chimeric intron containing D5-U22 can be self-spliced, but the one containing D5-C22 cannot. These results indicate that DEK46 functions in the C-to-U editing of D5-C22 of both introns, and the U base at this position is critical to intron splicing.
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Affiliation(s)
- Chunhui Xu
- Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Shu Song
- Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Yan-Zhuo Yang
- Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Fan Lu
- Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Meng-Di Zhang
- Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Feng Sun
- Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Ruxue Jia
- Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Ruolin Song
- Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
| | - Bao-Cai Tan
- Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China
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Small ID, Schallenberg-Rüdinger M, Takenaka M, Mireau H, Ostersetzer-Biran O. Plant organellar RNA editing: what 30 years of research has revealed. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 101:1040-1056. [PMID: 31630458 DOI: 10.1111/tpj.14578] [Citation(s) in RCA: 160] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 09/25/2019] [Accepted: 10/08/2019] [Indexed: 05/21/2023]
Abstract
The central dogma in biology defines the flow of genetic information from DNA to RNA to protein. Accordingly, RNA molecules generally accurately follow the sequences of the genes from which they are transcribed. This rule is transgressed by RNA editing, which creates RNA products that differ from their DNA templates. Analyses of the RNA landscapes of terrestrial plants have indicated that RNA editing (in the form of C-U base transitions) is highly prevalent within organelles (that is, mitochondria and chloroplasts). Numerous C→U conversions (and in some plants also U→C) alter the coding sequences of many of the organellar transcripts and can also produce translatable mRNAs by creating AUG start sites or eliminating premature stop codons, or affect the RNA structure, influence splicing and alter the stability of RNAs. RNA-binding proteins are at the heart of post-transcriptional RNA expression. The C-to-U RNA editing process in plant mitochondria involves numerous nuclear-encoded factors, many of which have been identified as pentatricopeptide repeat (PPR) proteins that target editing sites in a sequence-specific manner. In this review we report on major discoveries on RNA editing in plant organelles, since it was first documented 30 years ago.
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Affiliation(s)
- Ian D Small
- ARC Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, Perth, WA, 6009, Australia
| | - Mareike Schallenberg-Rüdinger
- IZMB - Institut für Zelluläre und Molekulare Botanik, Abt. Molekulare Evolution, University of Bonn, Kirschallee 1, 53115, Bonn, Germany
| | - Mizuki Takenaka
- Department of Botany, Graduate School of Science, Kyoto University, Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Hakim Mireau
- Institut Jean-Pierre Bourgin, INRA, AgroParisTech, CNRS, Université Paris-Saclay, RD10, 78026, Versailles Cedex, France
| | - Oren Ostersetzer-Biran
- Department of Plant and Environmental Sciences, Institute of Life Sciences, The Hebrew University of Jerusalem, Edmond J. Safra Campus - Givat Ram, Jerusalem, 9190401, Israel
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9
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Chu D, Wei L. Reduced C-to-U RNA editing rates might play a regulatory role in stress response of Arabidopsis. JOURNAL OF PLANT PHYSIOLOGY 2020; 244:153081. [PMID: 31783167 DOI: 10.1016/j.jplph.2019.153081] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 11/07/2019] [Accepted: 11/08/2019] [Indexed: 06/10/2023]
Abstract
C-to-U RNA editing is prevalent in the mitochondrial and chloroplast genes in plants. The C-to-U editing rates are constantly very high. During genome evolution, those edited cytidines are likely to be replaced with thymidines at the DNA level. C-to-U editing events are suggested to be designed for reversing the unfavorable T-to-C DNA mutations. Despite the existing theory showing the importance of editing mechanisms, few studies have investigated the genome-wide adaptive signals of the C-to-U editome or the potential function of C-to-U editing events in the stress response. By analyzing the transcriptome and translatome data of normal and heat-shocked Arabidopsis thaliana and the RNA-seq from cold-stressed plants, combined with genome-wide comparison of mitochondrial/chloroplast genes and nuclear genes from multiple aspects, we present the conservational and translational features of each gene and depict the dynamic mitochondrial/chloroplast C-to-U RNA editome. We found that the tAI (tRNA adaptation index) and basic translation levels are lower for mitochondrial/chloroplast genes than for nuclear genes. Interestingly, although we found adaptive signals for the global C-to-U RNA editome in mitochondrial/chloroplast genes, the C-to-U (T) alteration would usually cause a reduction in the codon tAI value. Moreover, the C-to-U editing rates are significantly reduced under heat or cold stress when compared to the normal condition. This reduction is irrelevant to the temperature-sensitive RNA structures. Several cases have illustrated that under heat stress, the reduced C-to-U editing rates alleviate ribosome stalling and consequently facilitate the local translation. Our study reveals that in Arabidopsis thaliana the mitochondrial/chloroplast C-to-U RNA editing rates are reduced under heat or cold stress. This reduction is associated with the alleviation of decreased tAI/translation rate of edited codons. The regulation of C-to-U editing rates could be the tradeoff between quantity and quality. We profile the dynamic change of C-to-U RNA editome under heat stress and propose a potential role of editing sites in the heat response. Our work should be appealing to the plant physiologists as well as the RNA editing community.
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Affiliation(s)
- Duan Chu
- College of Life Sciences, Beijing Normal University, No. 19 Xinjiekouwai Street, Haidian District, Beijing, China
| | - Lai Wei
- College of Life Sciences, Beijing Normal University, No. 19 Xinjiekouwai Street, Haidian District, Beijing, China.
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10
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Ding S, Liu XY, Wang HC, Wang Y, Tang JJ, Yang YZ, Tan BC. SMK6 mediates the C-to-U editing at multiple sites in maize mitochondria. JOURNAL OF PLANT PHYSIOLOGY 2019; 240:152992. [PMID: 31234031 DOI: 10.1016/j.jplph.2019.152992] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 06/01/2019] [Accepted: 06/03/2019] [Indexed: 06/09/2023]
Abstract
The recently identified PPR-E+/NVWA/DYW2 RNA editing complex provides insights into the mechanism of RNA editing in higher plant organelles. However, whether the complex works together with the previously identified editing factors RIPs/MORFs is unclear. In this paper, we identified a maize Smk6 gene, which encodes a mitochondrion-targeted PPR-E+protein with E1 and E2 domains at the C terminus. Loss of Smk6 function affects the C-to-U editing at nad1-740, nad4L-110, nad7-739, and mttB-138,139 sites, impairs mitochondrial activity and blocks embryogenesis and endosperm development. Genetic and molecular analysis indicated that SMK6 is the maize ortholog of the Arabidopsis SLO2, which is a component of the PPR-E+/NVWA/DYW2 editing complex. However, yeast two-hybrid analyses did not detect any interaction between SMK6 and any of the mitochondrion-targeted RIPs/MORFs, suggesting that RIPs/MORFs may not be a component of PPR-E+/NVWA/DYW2 RNA editing complex. Further analyses are required to provide evidence that RIP/MORFs and SMK6 do not physically interact in vivo.
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Affiliation(s)
- Shuo Ding
- Key Lab of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Xin-Yuan Liu
- Key Lab of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Hong-Chun Wang
- Key Lab of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Yong Wang
- Key Lab of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Jiao-Jiao Tang
- Key Lab of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Yan-Zhuo Yang
- Key Lab of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China
| | - Bao-Cai Tan
- Key Lab of Plant Development and Environment Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao 266237, China.
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11
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Myszczyński K, Ślipiko M, Sawicki J. Potential of Transcript Editing Across Mitogenomes of Early Land Plants Shows Novel and Familiar Trends. Int J Mol Sci 2019; 20:E2963. [PMID: 31216623 PMCID: PMC6627324 DOI: 10.3390/ijms20122963] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2019] [Revised: 06/15/2019] [Accepted: 06/17/2019] [Indexed: 01/04/2023] Open
Abstract
RNA editing alters the identity of nucleotides in an RNA sequence so that the mature transcript differs from the template defined in the genome. This process has been observed in chloroplasts and mitochondria of both seed and early land plants. However, the frequency of RNA editing in plant mitochondria ranges from zero to thousands of editing sites. To date, analyses of RNA editing in mitochondria of early land plants have been conducted on a small number of genes or mitochondrial genomes of a single species. This study provides an overview of the mitogenomic RNA editing potential of the main lineages of these two groups of early land plants by predicting the RNA editing sites of 33 mitochondrial genes of 37 species of liverworts and mosses. For the purpose of the research, we newly assembled seven mitochondrial genomes of liverworts. The total number of liverwort genera with known complete mitogenome sequences has doubled and, as a result, the available complete mitogenome sequences now span almost all orders of liverworts. The RNA editing site predictions revealed that C-to-U RNA editing in liverworts and mosses is group-specific. This is especially evident in the case of liverwort lineages. The average level of C-to-U RNA editing appears to be over three times higher in liverworts than in mosses, while the C-to-U editing frequency of the majority of genes seems to be consistent for each gene across bryophytes.
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Affiliation(s)
- Kamil Myszczyński
- Department of Botany and Nature Protection, University of Warmia and Mazury in Olsztyn, Plac Łódzki 1, 10-727 Olsztyn, Poland.
| | - Monika Ślipiko
- Department of Botany and Nature Protection, University of Warmia and Mazury in Olsztyn, Plac Łódzki 1, 10-727 Olsztyn, Poland.
| | - Jakub Sawicki
- Department of Botany and Nature Protection, University of Warmia and Mazury in Olsztyn, Plac Łódzki 1, 10-727 Olsztyn, Poland.
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12
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Brenner WG, Mader M, Müller NA, Hoenicka H, Schroeder H, Zorn I, Fladung M, Kersten B. High Level of Conservation of Mitochondrial RNA Editing Sites Among Four Populus Species. G3 (BETHESDA, MD.) 2019; 9:709-717. [PMID: 30617214 PMCID: PMC6404595 DOI: 10.1534/g3.118.200763] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 12/01/2019] [Indexed: 01/29/2023]
Abstract
RNA editing occurs in the endosymbiont organelles of higher plants as C-to-U conversions of defined nucleotides. The availability of large quantities of RNA sequencing data makes it possible to identify RNA editing sites and to quantify their editing extent. We have investigated RNA editing in 34 protein-coding mitochondrial transcripts of four Populus species, a genus noteworthy for its remarkably small number of RNA editing sites compared to other angiosperms. 27 of these transcripts were subject to RNA editing in at least one species. In total, 355 RNA editing sites were identified with high confidence, their editing extents ranging from 10 to 100%. The most heavily edited transcripts were ccmB with the highest density of RNA editing sites (53.7 sites / kb) and ccmFn with the highest number of sites (39 sites). Most of the editing events are at position 1 or 2 of the codons, usually altering the encoded amino acid, and are highly conserved among the species, also with regard to their editing extent. However, one SNP was found in the newly sequenced and annotated mitochondrial genome of P. alba resulting in the loss of an RNA editing site compared to P. tremula and P. davidiana This SNP causes a C-to-T transition and an amino acid exchange from Ser to Phe, highlighting the widely discussed role of RNA editing in compensating mutations.
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Affiliation(s)
| | - Malte Mader
- Thünen Institute of Forest Genetics, 22927 Grosshansdorf, Germany
| | | | - Hans Hoenicka
- Thünen Institute of Forest Genetics, 22927 Grosshansdorf, Germany
| | - Hilke Schroeder
- Thünen Institute of Forest Genetics, 22927 Grosshansdorf, Germany
| | - Ingo Zorn
- Thünen Institute of Forest Genetics, 22927 Grosshansdorf, Germany
| | - Matthias Fladung
- Thünen Institute of Forest Genetics, 22927 Grosshansdorf, Germany
| | - Birgit Kersten
- Thünen Institute of Forest Genetics, 22927 Grosshansdorf, Germany
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13
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Mirzaei S, Mansouri M, Mohammadi-Nejad G, Sablok G. Comparative assessment of chloroplast transcriptional responses highlights conserved and unique patterns across Triticeae members under salt stress. PHOTOSYNTHESIS RESEARCH 2018; 136:357-369. [PMID: 29230609 DOI: 10.1007/s11120-017-0469-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 11/30/2017] [Indexed: 06/07/2023]
Abstract
Chloroplast functional genomics, in particular understanding the chloroplast transcriptional response is of immense importance mainly due to its role in oxygenic photosynthesis. As a photosynthetic unit, its efficiency and transcriptional activity is directly regulated by reactive oxygen species during abiotic and biotic stress and subsequently affects carbon assimilation, and plant biomass. In crops, understanding photosynthesis is crucial for crop domestication by identifying the traits that could be exploited for crop improvement. Transcriptionally and translationally active chloroplast plays a key role by regulating the PSI and PSII photo-reaction centres, which ubiquitously affects the light harvesting. Using a comparative transcriptomics mapping approach, we identified differential regulation of key chloroplast genes during salt stress across Triticeae members with potential genes involved in photosynthesis and electron transport system such as CytB6f. Apart from differentially regulated genes involved in PSI and PSII, we found widespread evidence of intron splicing events, specifically uniquely spliced petB and petD in Triticum aestivum and high proportion of RNA editing in ndh genes across the Triticeae members during salt stress. We also highlight the role and differential regulation of ATP synthase as member of CF0CF1 and also revealed the effect of salt stress on the water-splitting complex under salt stress. It is worthwhile to mention that the observed conserved down-regulation of psbJ across the Triticeae is limiting the assembly of water-splitting complexes and thus making the BEP clade Triticeae members more vulnerable to high light during the salt stress. Comparative understanding of the chloroplast transcriptional dynamics and photosynthetic regulation will improve the approaches for improved crop domestication.
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Affiliation(s)
- Saeid Mirzaei
- Department of Biotechnology, Institute of Science, High Technology and Environmental Sciences, Graduate University of Advanced Technology, Kerman, 7631818356, Iran.
| | - Mehdi Mansouri
- Department of Agricultural Biotechnology, Faculty of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran
| | - Ghasem Mohammadi-Nejad
- Research and Technology Institute of Plant Production, Shahid Bahonar University of Kerman, Kerman, Iran
| | - Gaurav Sablok
- Finnish Museum of Natural History (Botany), PO Box 7, 00014, Helsinki, Finland
- Department of Bioscience, Viikki Plant Science Center, PO Box 7, 00014, Helsinki, Finland
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14
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Chen TC, Liu YC, Wang X, Wu CH, Huang CH, Chang CC. Whole plastid transcriptomes reveal abundant RNA editing sites and differential editing status in Phalaenopsis aphrodite subsp. formosana. BOTANICAL STUDIES 2017; 58:38. [PMID: 28916985 PMCID: PMC5602750 DOI: 10.1186/s40529-017-0193-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2017] [Accepted: 09/08/2017] [Indexed: 05/08/2023]
Abstract
BACKGROUND RNA editing is a process of post-transcriptional level of gene regulation by nucleotide modification. Previously, the chloroplast DNA of Taiwan endemic moth orchid, P. aphrodite subsp. formosana was determined, and 44 RNA editing sites were identified from 24 plastid protein-coding transcripts of leaf tissue via RT-PCR and then conventional Sanger sequencing. However, the RNA editing status of whole-plastid transcripts in leaf and other distinct tissue types in moth orchids has not been addressed. To sensitively and extensively examine the plastid RNA editing status of moth orchid, RNA-Seq was used to investigate the editing status of whole-plastid transcripts from leaf and floral tissues by mapping the sequence reads to the corresponding cpDNA template. With the threshold of at least 5% C-to-U or U-to-C conversion events observed in sequence reads considered as RNA editing sites. RESULTS In total, 137 edits with 126 C-to-U and 11 U-to-C conversions, including 93 newly discovered edits, were identified in plastid transcripts, representing an average of 0.09% of the nucleotides examined in moth orchid. Overall, 110 and 106 edits were present in leaf and floral tissues, respectively, with 79 edits in common. As well, 79 edits were involved in protein-coding transcripts, and the 58 nucleotide conversions caused the non-synonymous substitution. At least 32 edits showed significant (≧20%) differential editing between leaf and floral tissues. Finally, RNA editing in trnM is required for the formation of a standard clover-leaf structure. CONCLUSIONS We identified 137 edits in plastid transcripts of moth orchid, the highest number reported so far in monocots. The consequence of RNA editing in protein-coding transcripts mainly cause the amino acid change and tend to increase the hydrophobicity as well as conservation among plant phylogeny. RNA editing occurred in non-protein-coding transcripts such as tRNA, introns and untranslated regulatory regions could affect the formation and stability of secondary structure, which might play an important role in the regulation of gene expression. Furthermore, some unidentified tissue-specific factors might be required for regulating RNA editing in moth orchid.
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Affiliation(s)
- Ting-Chieh Chen
- Institute of Biotechnology, National Cheng Kung University, Tainan, 701 Taiwan
- Department of Biotechnology and Bioindustry Sciences, National Cheng Kung University, Tainan, 701 Taiwan
| | - Yu-Chang Liu
- Institute of Biotechnology, National Cheng Kung University, Tainan, 701 Taiwan
- Department of Biotechnology and Bioindustry Sciences, National Cheng Kung University, Tainan, 701 Taiwan
| | - Xuewen Wang
- Department of Genetics, University of Georgia, Athens, GA 30602 USA
| | - Chi-Hsuan Wu
- Institute of Biotechnology, National Cheng Kung University, Tainan, 701 Taiwan
| | - Chih-Hao Huang
- Institute of Biotechnology, National Cheng Kung University, Tainan, 701 Taiwan
- Department of Biotechnology and Bioindustry Sciences, National Cheng Kung University, Tainan, 701 Taiwan
| | - Ching-Chun Chang
- Institute of Biotechnology, National Cheng Kung University, Tainan, 701 Taiwan
- Department of Biotechnology and Bioindustry Sciences, National Cheng Kung University, Tainan, 701 Taiwan
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15
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Shi X, Castandet B, Germain A, Hanson MR, Bentolila S. ORRM5, an RNA recognition motif-containing protein, has a unique effect on mitochondrial RNA editing. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:2833-2847. [PMID: 28549172 PMCID: PMC5853588 DOI: 10.1093/jxb/erx139] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 03/30/2017] [Indexed: 05/02/2023]
Abstract
Plants have an RNA editing mechanism that prevents deleterious organelle mutations from resulting in impaired proteins. A typical flowering plant modifies about 40 cytidines in chloroplast transcripts and many hundreds of cytidines in mitochondrial transcripts. The plant editosome, the molecular machinery responsible for this process, contains members of several protein families, including the organelle RNA recognition motif (ORRM)-containing family. ORRM1 and ORRM6 are chloroplast editing factors, while ORRM2, ORRM3, and ORRM4 are mitochondrial editing factors. Here we report the identification of organelle RRM protein 5 (ORRM5) as a mitochondrial editing factor with a unique mode of action. Unlike other ORRM editing factors, the absence of ORRM5 in orrm5 mutant plants results in an increase of the editing extent in 14% of the mitochondrial sites surveyed. The orrm5 mutant also exhibits a reduced splicing efficiency of the first nad5 intron and slower growth and delayed flowering time. ORRM5 contains an RNA recognition motif (RRM) and a glycine-rich domain at the C terminus. The RRM provides the editing activity of ORRM5 and is able to complement the splicing but not the morphological defects.
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Affiliation(s)
- Xiaowen Shi
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | | | - Arnaud Germain
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Maureen R Hanson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Stéphane Bentolila
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
- Correspondence:
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16
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Cahoon AB, Nauss JA, Stanley CD, Qureshi A. Deep Transcriptome Sequencing of Two Green Algae, Chara vulgaris and Chlamydomonas reinhardtii, Provides No Evidence of Organellar RNA Editing. Genes (Basel) 2017; 8:genes8020080. [PMID: 28230734 PMCID: PMC5333069 DOI: 10.3390/genes8020080] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 02/13/2017] [Indexed: 11/16/2022] Open
Abstract
Nearly all land plants post-transcriptionally modify specific nucleotides within RNAs, a process known as RNA editing. This adaptation allows the correction of deleterious mutations within the asexually reproducing and presumably non-recombinant chloroplast and mitochondrial genomes. There are no reports of RNA editing in any of the green algae so this phenomenon is presumed to have originated in embryophytes either after the invasion of land or in the now extinct algal ancestor of all land plants. This was challenged when a recent in silico screen for RNA edit sites based on genomic sequence homology predicted edit sites in the green alga Chara vulgaris, a multicellular alga found within the Streptophyta clade and one of the closest extant algal relatives of land plants. In this study, the organelle transcriptomes of C. vulgaris and Chlamydomonas reinhardtii were deep sequenced for a comprehensive assessment of RNA editing. Initial analyses based solely on sequence comparisons suggested potential edit sites in both species, but subsequent high-resolution melt analysis, RNase H-dependent PCR (rhPCR), and Sanger sequencing of DNA and complementary DNAs (cDNAs) from each of the putative edit sites revealed them to be either single-nucleotide polymorphisms (SNPs) or spurious deep sequencing results. The lack of RNA editing in these two lineages is consistent with the current hypothesis that RNA editing evolved after embryophytes split from its ancestral algal lineage.
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Affiliation(s)
- A Bruce Cahoon
- Department of Natural Sciences, University of Virginia's College at Wise, 1 College Ave., Wise, VA 24293, USA.
| | - John A Nauss
- Department of Natural Sciences, University of Virginia's College at Wise, 1 College Ave., Wise, VA 24293, USA.
| | - Conner D Stanley
- Department of Natural Sciences, University of Virginia's College at Wise, 1 College Ave., Wise, VA 24293, USA.
| | - Ali Qureshi
- Department of Natural Sciences, University of Virginia's College at Wise, 1 College Ave., Wise, VA 24293, USA.
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17
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Ichinose M, Sugita M. RNA Editing and Its Molecular Mechanism in Plant Organelles. Genes (Basel) 2016; 8:genes8010005. [PMID: 28025543 PMCID: PMC5295000 DOI: 10.3390/genes8010005] [Citation(s) in RCA: 131] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 11/23/2016] [Accepted: 12/20/2016] [Indexed: 12/03/2022] Open
Abstract
RNA editing by cytidine (C) to uridine (U) conversions is widespread in plant mitochondria and chloroplasts. In some plant taxa, “reverse” U-to-C editing also occurs. However, to date, no instance of RNA editing has yet been reported in green algae and the complex thalloid liverworts. RNA editing may have evolved in early land plants 450 million years ago. However, in some plant species, including the liverwort, Marchantia polymorpha, editing may have been lost during evolution. Most RNA editing events can restore the evolutionarily conserved amino acid residues in mRNAs or create translation start and stop codons. Therefore, RNA editing is an essential process to maintain genetic information at the RNA level. Individual RNA editing sites are recognized by plant-specific pentatricopeptide repeat (PPR) proteins that are encoded in the nuclear genome. These PPR proteins are characterized by repeat elements that bind specifically to RNA sequences upstream of target editing sites. In flowering plants, non-PPR proteins also participate in multiple RNA editing events as auxiliary factors. C-to-U editing can be explained by cytidine deamination. The proteins discovered to date are important factors for RNA editing but a bona fide RNA editing enzyme has yet to be identified.
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Affiliation(s)
- Mizuho Ichinose
- Center for Gene Research, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
- Institute of Transformative Bio-Molecules, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
| | - Mamoru Sugita
- Center for Gene Research, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
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18
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Xiu Z, Sun F, Shen Y, Zhang X, Jiang R, Bonnard G, Zhang J, Tan BC. EMPTY PERICARP16 is required for mitochondrial nad2 intron 4 cis-splicing, complex I assembly and seed development in maize. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2016; 85:507-19. [PMID: 26764126 DOI: 10.1111/tpj.13122] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Accepted: 01/05/2016] [Indexed: 05/02/2023]
Abstract
In higher plants, chloroplast and mitochondrial transcripts contain a number of group II introns that need to be precisely spliced before translation into functional proteins. However, the mechanism of splicing and the factors involved in this process are not well understood. By analysing a seed mutant in maize, we report here the identification of Empty pericarp16 (Emp16) that is required for splicing of nad2 intron 4 in mitochondria. Disruption of Emp16 function causes developmental arrest in the embryo and endosperm, giving rise to an empty pericarp phenotype in maize. Differentiation of the basal endosperm transfer layer cells is severely affected. Molecular cloning indicates that Emp16 encodes a P-type pentatricopeptide repeat (PPR) protein with 11 PPR motifs and is localized in the mitochondrion. Transcript analysis revealed that mitochondrial nad2 intron 4 splicing is abolished in the emp16 mutants, leading to severely reduced assembly and activity of complex I. In response, the mutant dramatically increases the accumulation of mitochondrial complex III and the expression of alternative oxidase AOX2. These results imply that EMP16 is specifically required for mitochondrial nad2 intron 4 cis-splicing and is essential for complex I assembly and embryogenesis and development endosperm in maize.
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Affiliation(s)
- Zhihui Xiu
- State Key Lab of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, NT, Hong Kong, China
| | - Feng Sun
- Key Lab of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Sciences, Shandong University, Jinan, 250100, China
| | - Yun Shen
- State Key Lab of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, NT, Hong Kong, China
| | - Xiaoyan Zhang
- Key Lab of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Sciences, Shandong University, Jinan, 250100, China
| | - Ruicheng Jiang
- Key Lab of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Sciences, Shandong University, Jinan, 250100, China
| | - Géraldine Bonnard
- Institut de Biologie Moléculaire des Plantes CNRS, Associé à l'Université de Strasbourg, 12 Rue du Général Zimmer, 67084, Strasbourg, France
| | - Jianhua Zhang
- State Key Lab of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, NT, Hong Kong, China
| | - Bao-Cai Tan
- Key Lab of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Sciences, Shandong University, Jinan, 250100, China
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19
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Shen XY, Li T, Chen S, Fan L, Gao J, Hou CL. Characterization and phylogenetic analysis of the mitochondrial genome of Shiraia bambusicola reveals special features in the order of pleosporales. PLoS One 2015; 10:e0116466. [PMID: 25790308 PMCID: PMC4366305 DOI: 10.1371/journal.pone.0116466] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Accepted: 12/08/2014] [Indexed: 12/20/2022] Open
Abstract
Shiraia bambusicola P. Henn. is a pathogenic fungus of bamboo, and its fruiting bodies are regarded as folk medicine. We determined and analyzed its complete mitochondrial DNA sequence (circular DNA molecule of 39,030 bp, G + C content of 25.19%). It contains the typical genes encoding proteins involved in electron transport and coupled oxidative phosphorylation (nad1-6 and nad4L, cob and cox1-3), one ATP synthase subunit (atp6), 4 hypothetical proteins, and two genes for large and small rRNAs (rnl and rns). There is a set of 32 tRNA genes comprising all 20 amino acids, and these genes are evenly distributed on the two strands. Phylogenetic analyses based on concatenated mitochondrial proteins indicated that S. bambusicola clustered with members of the order Pleosporales, which is in agreement with previous results. The gene arrangements of Dothideomycetes species contained three regions of gene orders partitioned in their mitochondrial genomes, including block 1 (nad6-atp6), block 2 (nad1-cox3) and block 3 (genes around rns). S. bambusicola displayed unique special features that differed from the other Pleosporales species, especially in the coding regions around rns (trnR-trnY). Moreover, a comparison of gene orders in mitochondrial genomes from Pezizomycotina revealed that although all encoded regions are located on the same strand in most Pezizomycotina mtDNAs, genes from Dothideomycetes species had different orientations, as well as diverse positions and colocalization of genes (such as cox3, cox1-cox2 and nad2-nad3); these distinctions were regarded as class-specific features. Interestingly, two incomplete copies of the atp6 gene were found on different strands of the mitogenomic DNA, a finding that has not been observed in the other analyzed fungal species. In our study, mitochondrial genomes from Dothideomycetes species were comprehensively analyzed for the first time, including many species that have not appeared in previous reports.
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Affiliation(s)
- Xiao-Ye Shen
- College of Life Science, Capital Normal University, Beijing, People’s Republic of China
| | - Tong Li
- College of Life Science, Capital Normal University, Beijing, People’s Republic of China
| | - Shuang Chen
- College of Life Science, Capital Normal University, Beijing, People’s Republic of China
| | - Li Fan
- College of Life Science, Capital Normal University, Beijing, People’s Republic of China
| | - Jian Gao
- Key Laboratory of Bamboo and Rattan Science and Technology of the SFA, International Centre for Bamboo and Rattan, Beijing, People’s Republic of China
| | - Cheng-Lin Hou
- College of Life Science, Capital Normal University, Beijing, People’s Republic of China
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20
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Yap A, Kindgren P, Colas des Francs-Small C, Kazama T, Tanz SK, Toriyama K, Small I. AEF1/MPR25 is implicated in RNA editing of plastid atpF and mitochondrial nad5, and also promotes atpF splicing in Arabidopsis and rice. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 81:661-9. [PMID: 25585673 DOI: 10.1111/tpj.12756] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 12/15/2014] [Accepted: 12/18/2014] [Indexed: 05/20/2023]
Abstract
RNA editing is an essential mechanism that modifies target cytidines to uridine in both mitochondrial and plastid mRNA. Target sites are recognized by pentatricopeptide repeat (PPR) proteins. Using bioinformatics predictions based on the code describing sequence recognition by PPR proteins, we have identified an Arabidopsis editing factor required for editing of atpF in plastids. A loss-of-function mutation in ATPF EDITING FACTOR 1 (AEF1, AT3G22150) results in severe variegation, presumably due to decreased plastid ATP synthase levels. Loss of editing at the atpF site is coupled with a large decrease in splicing of the atpF transcript, even though the editing site is within an exon and 53 nucleotides distant from the splice site. The rice orthologue of AEF1, MPR25, has been reported to be required for editing of a site in mitochondrial nad5 transcripts, and we confirm that editing of the same site is affected in the Arabidopsis aef1 mutant. We also show that splicing of chloroplast atpF transcripts is affected in the rice mpr25 mutant. AEF1 is thus highly unusual for an RNA editing specificity factor in that it has functions in both organelles.
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Affiliation(s)
- Aaron Yap
- Australian Research Council Centre of Excellence in Plant Energy Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
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21
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Guo W, Grewe F, Mower JP. Variable frequency of plastid RNA editing among ferns and repeated loss of uridine-to-cytidine editing from vascular plants. PLoS One 2015; 10:e0117075. [PMID: 25568947 PMCID: PMC4287625 DOI: 10.1371/journal.pone.0117075] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 12/19/2014] [Indexed: 12/22/2022] Open
Abstract
The distinct distribution and abundance of C-to-U and U-to-C RNA editing among land plants suggest that these two processes originated and evolve independently, but the paucity of information from several key lineages limits our understanding of their evolution. To examine the evolutionary diversity of RNA editing among ferns, we sequenced the plastid transcriptomes from two early diverging species, Ophioglossum californicum and Psilotum nudum. Using a relaxed automated approach to minimize false negatives combined with manual inspection to eliminate false positives, we identified 297 C-to-U and three U-to-C edit sites in the O. californicum plastid transcriptome but only 27 C-to-U and no U-to-C edit sites in the P. nudum plastid transcriptome. A broader comparison of editing content with the leptosporangiate fern Adiantum capillus-veneris and the hornwort Anthoceros formosae uncovered large variance in the abundance of plastid editing, indicating that the frequency and type of RNA editing is highly labile in ferns. Edit sites that increase protein conservation among species are more abundant and more efficiently edited than silent and non-conservative sites, suggesting that selection maintains functionally important editing. The absence of U-to-C editing from P. nudum plastid transcripts and other vascular plants demonstrates that U-to-C editing loss is a recurrent phenomenon in vascular plant evolution.
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Affiliation(s)
- Wenhu Guo
- Center for Plant Science Innovation, University of Nebraska, Lincoln, Nebraska, United States of America
- School of Biological Sciences, University of Nebraska, Lincoln, Nebraska, United States of America
- ACGT, Inc., Wheeling, Illinois, United States of America
| | - Felix Grewe
- Center for Plant Science Innovation, University of Nebraska, Lincoln, Nebraska, United States of America
- Department of Agronomy and Horticulture, University of Nebraska, Lincoln, Nebraska, United States of America
| | - Jeffrey P. Mower
- Center for Plant Science Innovation, University of Nebraska, Lincoln, Nebraska, United States of America
- Department of Agronomy and Horticulture, University of Nebraska, Lincoln, Nebraska, United States of America
- * E-mail:
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22
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Oldenkott B, Yamaguchi K, Tsuji-Tsukinoki S, Knie N, Knoop V. Chloroplast RNA editing going extreme: more than 3400 events of C-to-U editing in the chloroplast transcriptome of the lycophyte Selaginella uncinata. RNA (NEW YORK, N.Y.) 2014; 20:1499-506. [PMID: 25142065 PMCID: PMC4174432 DOI: 10.1261/rna.045575.114] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
RNA editing in chloroplasts and mitochondria of land plants differs significantly in abundance. For example, some 200-500 sites of cytidine-to-uridine RNA editing exist in flowering plant mitochondria as opposed to only 30-50 such C-to-U editing events in their chloroplasts. In contrast, we predicted significantly more chloroplast RNA editing for the protein-coding genes in the available complete plastome sequences of two species of the spike moss genus Selaginella (Lycopodiophyta). To evaluate these predictions we investigated the Selaginella uncinata chloroplast transcriptome. Our exhaustive cDNA studies identified the extraordinary number of 3415 RNA-editing events, exclusively of the C-to-U type, in the 74 mRNAs encoding intact reading frames in the S. uncinata chloroplast. We find the overwhelming majority (61%) of the 428 silent editing events leaving codon meanings unaltered directly neighboring other editing events, possibly suggesting a sterically more flexible RNA-editing deaminase activity in Selaginella. No evidence of RNA editing was found for tRNAs or rRNAs but we identified a total of 74 editing sites in cDNA sequences of four group II introns (petBi6g2, petDi8g2, ycf3i124g2, and ycf3i354g2) retained in partially matured transcripts, which strongly contribute to improved base-pairing in the intron secondary structures as a likely prerequisite for their splicing.
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Affiliation(s)
- Bastian Oldenkott
- IZMB-Institut für Zelluläre und Molekulare Botanik, Abteilung Molekulare Evolution, Universität Bonn, Kirschallee 1, 53115 Bonn, Germany
| | - Kazuo Yamaguchi
- Division of Functional Genomics, Advanced Science Research Center, Kanazawa University, Kanazawa 920-0934, Japan
| | - Sumika Tsuji-Tsukinoki
- Division of Functional Genomics, Advanced Science Research Center, Kanazawa University, Kanazawa 920-0934, Japan
| | - Nils Knie
- IZMB-Institut für Zelluläre und Molekulare Botanik, Abteilung Molekulare Evolution, Universität Bonn, Kirschallee 1, 53115 Bonn, Germany
| | - Volker Knoop
- IZMB-Institut für Zelluläre und Molekulare Botanik, Abteilung Molekulare Evolution, Universität Bonn, Kirschallee 1, 53115 Bonn, Germany
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Takenaka M, Zehrmann A, Verbitskiy D, Härtel B, Brennicke A. RNA editing in plants and its evolution. Annu Rev Genet 2014; 47:335-52. [PMID: 24274753 DOI: 10.1146/annurev-genet-111212-133519] [Citation(s) in RCA: 239] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
RNA editing alters the identity of nucleotides in RNA molecules such that the information for a protein in the mRNA differs from the prediction of the genomic DNA. In chloroplasts and mitochondria of flowering plants, RNA editing changes C nucleotides to U nucleotides; in ferns and mosses, it also changes U to C. The approximately 500 editing sites in mitochondria and 40 editing sites in plastids of flowering plants are individually addressed by specific proteins, genes for which are amplified in plant species with organellar RNA editing. These proteins contain repeat elements that bind to cognate RNA sequence motifs just 5' to the edited nucleotide. In flowering plants, the site-specific proteins interact selectively with individual members of a different, smaller family of proteins. These latter proteins may be connectors between the site-specific proteins and the as yet unknown deaminating enzymatic activity.
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Affiliation(s)
- Mizuki Takenaka
- Molekulare Botanik, Universität Ulm, 89069 Ulm, Germany; , , , ,
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24
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Takenaka M, Verbitskiy D, Zehrmann A, Härtel B, Bayer-Császár E, Glass F, Brennicke A. RNA editing in plant mitochondria—connecting RNA target sequences and acting proteins. Mitochondrion 2014; 19 Pt B:191-7. [PMID: 24732437 DOI: 10.1016/j.mito.2014.04.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 03/27/2014] [Accepted: 04/04/2014] [Indexed: 12/31/2022]
Abstract
RNA editing changes several hundred cytidines to uridines in the mRNAs of mitochondria in flowering plants. The target cytidines are identified by a subtype of PPR proteins characterized by tandem modules which each binds with a specific upstream nucleotide. Recent progress in correlating repeat structures with nucleotide identities allows to predict and identify target sites in mitochondrial RNAs. Additional proteins have been found to play a role in RNA editing; their precise function still needs to be elucidated. The enzymatic activity performing the C to U reaction may reside in the C-terminal DYW extensions of the PPR proteins; however, this still needs to be proven. Here we update recent progress in understanding RNA editing in flowering plant mitochondria.
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Affiliation(s)
| | | | - Anja Zehrmann
- Molekulare Botanik, Universität Ulm, 89069 Ulm, Germany
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25
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Braun HP, Binder S, Brennicke A, Eubel H, Fernie AR, Finkemeier I, Klodmann J, König AC, Kühn K, Meyer E, Obata T, Schwarzländer M, Takenaka M, Zehrmann A. The life of plant mitochondrial complex I. Mitochondrion 2014; 19 Pt B:295-313. [PMID: 24561573 DOI: 10.1016/j.mito.2014.02.006] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 01/28/2014] [Accepted: 02/12/2014] [Indexed: 12/29/2022]
Abstract
The mitochondrial NADH dehydrogenase complex (complex I) of the respiratory chain has several remarkable features in plants: (i) particularly many of its subunits are encoded by the mitochondrial genome, (ii) its mitochondrial transcripts undergo extensive maturation processes (e.g. RNA editing, trans-splicing), (iii) its assembly follows unique routes, (iv) it includes an additional functional domain which contains carbonic anhydrases and (v) it is, indirectly, involved in photosynthesis. Comprising about 50 distinct protein subunits, complex I of plants is very large. However, an even larger number of proteins are required to synthesize these subunits and assemble the enzyme complex. This review aims to follow the complete "life cycle" of plant complex I from various molecular perspectives. We provide arguments that complex I represents an ideal model system for studying the interplay of respiration and photosynthesis, the cooperation of mitochondria and the nucleus during organelle biogenesis and the evolution of the mitochondrial oxidative phosphorylation system.
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Affiliation(s)
- Hans-Peter Braun
- Institut für Pflanzengenetik, Leibniz Universität Hannover, Herrenhäuser Str. 2, 30419 Hannover, Germany.
| | - Stefan Binder
- Molekulare Botanik, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany
| | - Axel Brennicke
- Molekulare Botanik, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany
| | - Holger Eubel
- Institut für Pflanzengenetik, Leibniz Universität Hannover, Herrenhäuser Str. 2, 30419 Hannover, Germany
| | - Alisdair R Fernie
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Iris Finkemeier
- Plant Sciences, Ludwig Maximilians Universität München, Grosshadernerstr. 2-4, 82152 Planegg-Martinsried, Germany
| | - Jennifer Klodmann
- Institut für Pflanzengenetik, Leibniz Universität Hannover, Herrenhäuser Str. 2, 30419 Hannover, Germany
| | - Ann-Christine König
- Plant Sciences, Ludwig Maximilians Universität München, Grosshadernerstr. 2-4, 82152 Planegg-Martinsried, Germany
| | - Kristina Kühn
- Institut für Biologie/Molekulare Zellbiologie der Pflanzen, Humboldt Universität zu Berlin, Philippstraße 13, 10115 Berlin, Germany
| | - Etienne Meyer
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Toshihiro Obata
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Markus Schwarzländer
- INRES - Chemical Signalling, Rheinische Friedrich-Wilhelms-Universität Bonn, Friedrich-Ebert-Allee 144, D-53113 Bonn, Germany
| | - Mizuki Takenaka
- Molekulare Botanik, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany
| | - Anja Zehrmann
- Molekulare Botanik, Universität Ulm, Albert-Einstein-Allee 11, 89069 Ulm, Germany
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26
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Grimes BT, Sisay AK, Carroll HD, Cahoon AB. Deep sequencing of the tobacco mitochondrial transcriptome reveals expressed ORFs and numerous editing sites outside coding regions. BMC Genomics 2014; 15:31. [PMID: 24433288 PMCID: PMC3898247 DOI: 10.1186/1471-2164-15-31] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 01/13/2014] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND The purpose of this study was to sequence and assemble the tobacco mitochondrial transcriptome and obtain a genomic-level view of steady-state RNA abundance. Plant mitochondrial genomes have a small number of protein coding genes with large and variably sized intergenic spaces. In the tobacco mitogenome these intergenic spaces contain numerous open reading frames (ORFs) with no clear function. RESULTS The assembled transcriptome revealed distinct monocistronic and polycistronic transcripts along with large intergenic spaces with little to no detectable RNA. Eighteen of the 117 ORFs were found to have steady-state RNA amounts above background in both deep-sequencing and qRT-PCR experiments and ten of those were found to be polysome associated. In addition, the assembled transcriptome enabled a full mitogenome screen of RNA C→U editing sites. Six hundred and thirty five potential edits were found with 557 occurring within protein-coding genes, five in tRNA genes, and 73 in non-coding regions. These sites were found in every protein-coding transcript in the tobacco mitogenome. CONCLUSION These results suggest that a small number of the ORFs within the tobacco mitogenome may produce functional proteins and that RNA editing occurs in coding and non-coding regions of mitochondrial transcripts.
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Affiliation(s)
- Benjamin T Grimes
- Department of Biology, Box 60, Middle Tennessee State University, Murfreesboro, TN 37132, USA
| | - Awa K Sisay
- Computational Science Program, Middle Tennessee State University, Box 48, Murfreesboro, TN 37132, USA
| | - Hyrum D Carroll
- Computational Science Program, Middle Tennessee State University, Box 48, Murfreesboro, TN 37132, USA
| | - A Bruce Cahoon
- Department of Biology, Box 60, Middle Tennessee State University, Murfreesboro, TN 37132, USA
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27
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Grüttner S, Hopf C, Kumar A, Kempken F. Deletions in cox2 mRNA result in loss of splicing and RNA editing and gain of novel RNA editing sites. PLoS One 2013; 8:e82067. [PMID: 24324745 PMCID: PMC3852756 DOI: 10.1371/journal.pone.0082067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Accepted: 10/21/2013] [Indexed: 11/28/2022] Open
Abstract
As previously demonstrated, the maize cox2 RNA is fully edited in cauliflower mitochondria. Use of constructs with a deleted cox2 intron, however, led to a loss of RNA editing at almost all editing sites, with only a few sites still partially edited. Likewise, one deletion in exon 1 and three in exon 2 abolish RNA editing at all cox2 sites analyzed. Furthermore, intron splicing is abolished using these deletions. Mutation of a cytosine residue, which is normally edited and localized directly adjacent to the intron, to thymidine did not result in restoration of splicing, indicating that the loss of splicing was not due to loss of RNA editing. One deletion in exon 2 did not lead to loss of splicing. Instead, most editing sites were found to be edited, only three were not edited. Unexpectedly, we observed additional RNA editing events at new sites. Thus it appears that deletions in the cox2 RNA sequence can have a strong effect on RNA processing, leading to loss of splicing, loss of editing at all sites, or even to a gain of new editing sites. As these effects are not limited to the vicinity of the respective deletions, but appear to be widespread or even affect all editing sites, they may not be explained by the loss of PPR binding sites. Instead, it appears that several parts of the cox2 transcript are required for proper RNA processing. This indicates the roles of the RNA sequence and structural elements in the recognition of the editing sites.
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Affiliation(s)
- Stefanie Grüttner
- Abteilung für Botanische Genetik und Molekularbiologie, Botanisches Institut und Botanischer Garten, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
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28
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Liu YJ, Xiu ZH, Meeley R, Tan BC. Empty pericarp5 encodes a pentatricopeptide repeat protein that is required for mitochondrial RNA editing and seed development in maize. THE PLANT CELL 2013; 25:868-83. [PMID: 23463776 PMCID: PMC3634694 DOI: 10.1105/tpc.112.106781] [Citation(s) in RCA: 138] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2012] [Revised: 12/28/2012] [Accepted: 02/15/2013] [Indexed: 05/18/2023]
Abstract
In flowering plants, RNA editing is a posttranscriptional mechanism that converts specific cytidines to uridines in both mitochondrial and plastidial transcripts, altering the information encoded by these genes. Here, we report the molecular characterization of the empty pericarp5 (emp5) mutants in maize (Zea mays). Null mutation of Emp5 results in abortion of embryo and endosperm development at early stages. Emp5 encodes a mitochondrion-targeted DYW subgroup pentatricopeptide repeat (PPR) protein. Analysis of the mitochondrial transcripts revealed that loss of the EMP5 function abolishes the C-to-U editing of ribosomal protein L16 at the rpl16-458 site (100% edited in the wild type), decreases the editing at nine sites in NADH dehydrogenase9 (nad9), cytochrome c oxidase3 (cox3), and ribosomal protein S12 (rps12), and surprisingly increases the editing at five sites of ATP synthase F0 subunit a (atp6), apocytochrome b (cob), nad1, and rpl16. Mutant EMP5-4 lacking the E+ and DYW domains still retains the substrate specificity and editing function, only at reduced efficiency. This suggests that the E+ and DYW domains of EMP5 are not essential to the EMP5 editing function but are necessary for efficiency. Analysis of the ortholog in rice (Oryza sativa) indicates that rice EMP5 has a conserved function in C-to-U editing of the rice mitochondrial rpl16-458 site. EMP5 knockdown expression in transgenics resulted in slow growth and defective seeds. These results demonstrate that Emp5 encodes a PPR-DYW protein that is required for the editing of multiple transcripts in mitochondria, and the editing events, particularly the C-to-U editing at the rpl16-458 site, are critical to the mitochondrial functions and, hence, to seed development in maize.
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Affiliation(s)
- Yu-Jun Liu
- State Key Lab of Agrobiotechnology, Institute of Plant Molecular Biology and Agrobiotechnology, School of Life Science, Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
| | - Zhi-Hui Xiu
- State Key Lab of Agrobiotechnology, Institute of Plant Molecular Biology and Agrobiotechnology, School of Life Science, Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
| | | | - Bao-Cai Tan
- State Key Lab of Agrobiotechnology, Institute of Plant Molecular Biology and Agrobiotechnology, School of Life Science, Chinese University of Hong Kong, Shatin, N.T., Hong Kong, China
- Address correspondence to
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29
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Farré JC, Aknin C, Araya A, Castandet B. RNA editing in mitochondrial trans-introns is required for splicing. PLoS One 2012; 7:e52644. [PMID: 23285127 PMCID: PMC3527595 DOI: 10.1371/journal.pone.0052644] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 11/19/2012] [Indexed: 11/29/2022] Open
Abstract
In plant mitochondria, gene expression of translatable mRNAs is a complex process with two critical steps, RNA editing and splicing. We studied the role of RNA editing on non-coding regions of the mat-r-nad1e-nad5c transcript from wheat mitochondria. This RNA contains two trans-introns, 3'-nad1-I4 and 3'-nad5-I2, involved in different trans-splicing events, ensuring the association of nad1d-nad1e and nad5b-nad5c exons from nad1 and nad5 mRNAs respectively. The C-to-U editing changes studied here affect homologous positions on 3'-nad1-I4 and 3'-nad5-I2. It is proposed that these base changes are necessary to place an Adenosine residue in a bulging conformation characteristic of domain VI (D6) from group II introns. In this work, we investigated the role of RNA editing events on 3'-nad1-I4 and 3'-nad5-I2 in the trans-splicing process using in vivo and in organello approaches. When the branched intermediates formed during the splicing process were analyzed, the C residues from D6 intron domains from 3'-nad1-I4 and 3'-nad5-I2 were found changed to U, suggesting that RNA editing of these residues could be mandatory for splicing. This assumption was tested by expressing recombinant mat-r-nad1e transgenes introduced into mitochondria by electroporation. Mutation of the editing target residue dramatically affected trans-splicing. Interestingly, the exon joining efficiency was not recovered by compensatory mutations, suggesting that the role of RNA editing is not confined to the restoration of the secondary structure of domain D6 of the intron. Our results strongly support the hypothesis that RNA editing in trans-introns precedes maturation, and is required for the splicing reaction. In addition, this is the first report using an in organello approach to study the trans-splicing process, opening the way to future studies of this peculiar mechanism.
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Affiliation(s)
- Jean-Claude Farré
- UMR5234 Microbiologie Fondamentale et Pathologie, Centre National de la Recherche Scientifique and Université Bordeaux-Segalen, Bordeaux, France
| | - Cindy Aknin
- UMR5234 Microbiologie Fondamentale et Pathologie, Centre National de la Recherche Scientifique and Université Bordeaux-Segalen, Bordeaux, France
| | - Alejandro Araya
- UMR5234 Microbiologie Fondamentale et Pathologie, Centre National de la Recherche Scientifique and Université Bordeaux-Segalen, Bordeaux, France
- Institut de Biologie Végétale Moléculaire, UMR1332 Biologie du Fruit et Pathologie, Centre INRA de Bordeaux, Vilenave d'Ornon, France
- * E-mail:
| | - Benoît Castandet
- UMR5234 Microbiologie Fondamentale et Pathologie, Centre National de la Recherche Scientifique and Université Bordeaux-Segalen, Bordeaux, France
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30
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Castandet B, Araya A. RNA editing in plant organelles. Why make it easy? BIOCHEMISTRY (MOSCOW) 2011; 76:924-31. [DOI: 10.1134/s0006297911080086] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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31
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Bégu D, Castandet B, Araya A. RNA editing restores critical domains of a group I intron in fern mitochondria. Curr Genet 2011; 57:317-25. [DOI: 10.1007/s00294-011-0349-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 06/07/2011] [Accepted: 06/10/2011] [Indexed: 11/28/2022]
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32
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Increased accumulation of intron-containing transcripts in rice mitochondria caused by low temperature: is cold-sensitive RNA editing implicated? Curr Genet 2010; 56:529-41. [DOI: 10.1007/s00294-010-0320-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Revised: 09/01/2010] [Accepted: 09/07/2010] [Indexed: 12/20/2022]
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33
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Castandet B, Choury D, Bégu D, Jordana X, Araya A. Intron RNA editing is essential for splicing in plant mitochondria. Nucleic Acids Res 2010; 38:7112-21. [PMID: 20615898 PMCID: PMC2978366 DOI: 10.1093/nar/gkq591] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Most plant mitochondria messenger RNAs (mRNAs) undergo editing through C-to-U conversions located mainly in exon sequences. However, some RNA editing events are found in non-coding regions at critical positions in the predicted secondary and tertiary structures of introns, suggesting that RNA editing could be important for splicing. Here, we studied the relationships between editing and splicing of the mRNA encoding the ribosomal protein S10 (rps10), which has a group II intron and five editing sites. Two of them, C2 and C3, predicted to stabilize the folded structure of the intron necessary for splicing, were studied by using rps10 mutants introduced into isolated potato mitochondria by electroporation. While mutations of C2 involved in EBS2/IBS2 interactions did not affect splicing, probably by the presence of an alternative EBS2′ region in domain I of the intron, the edition of site C3 turned out to be critical for rps10 mRNA splicing; only the edited (U) form of the transcript was processed. Interestingly, RNA editing was strongly reduced in transcripts from two different intronless genes, rps10 from potato and cox2 from wheat, suggesting that efficient RNA processing may require a close interaction of factors engaged in different maturation processes. This is the first report linking editing and splicing in conditions close to the in vivo situation.
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Affiliation(s)
- Benoît Castandet
- Laboratoire de Microbiologie Cellulaire et Moléculaire et Pathogénicité (MCMP), UMR5234 CNRS- Université Victor Segalen Bordeaux2. 146 rue Léo Saignat 33076 Bordeaux Cedex, France
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34
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de Longevialle AF, Small ID, Lurin C. Nuclearly encoded splicing factors implicated in RNA splicing in higher plant organelles. MOLECULAR PLANT 2010; 3:691-705. [PMID: 20603383 DOI: 10.1093/mp/ssq025] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Plant organelles arose from two independent endosymbiosis events. Throughout evolutionary history, tight control of chloroplasts and mitochondria has been gained by the nucleus, which regulates most steps of organelle genome expression and metabolism. In particular, RNA maturation, including RNA splicing, is highly dependent on nuclearly encoded splicing factors. Most introns in organelles are group II introns, whose catalytic mechanism closely resembles that of the nuclear spliceosome. Plant group II introns have lost the ability to self-splice in vivo and require nuclearly encoded proteins as cofactors. Since the first splicing factor was identified in chloroplasts more than 10 years ago, many other proteins have been shown to be involved in splicing of one or more introns in chloroplasts or mitochondria. These new proteins belong to a variety of different families of RNA binding proteins and provide new insights into ribonucleo-protein complexes and RNA splicing machineries in organelles. In this review, we describe how splicing factors, encoded by the nucleus and targeted to the organelles, take part in post-transcriptional steps in higher plant organelle gene expression. We go on to discuss the potential for these factors to regulate organelle gene expression.
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Affiliation(s)
- Andéol Falcon de Longevialle
- Unité Mixte de Recherche en Génomique Végétale (Institut National de la Recherche Agronomique/Centre National de la Recherche Scientifique/Université d'Evry Val d'Essonne), 91057 Evry, France
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35
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Abstract
In eukaryotes, RNA trans-splicing is an important RNA-processing form for the end-to-end ligation of primary transcripts that are derived from separately transcribed exons. So far, three different categories of RNA trans-splicing have been found in organisms as diverse as algae to man. Here, we review one of these categories: the trans-splicing of discontinuous group II introns, which occurs in chloroplasts and mitochondria of lower eukaryotes and plants. Trans-spliced exons can be predicted from DNA sequences derived from a large number of sequenced organelle genomes. Further molecular genetic analysis of mutants has unravelled proteins, some of which being part of high-molecular-weight complexes that promote the splicing process. Based on data derived from the alga Chlamydomonas reinhardtii, a model is provided which defines the composition of an organelle spliceosome. This will have a general relevance for understanding the function of RNA-processing machineries in eukaryotic organelles.
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Affiliation(s)
- Stephanie Glanz
- Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum, Bochum, Germany
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36
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Bonen L. Cis- and trans-splicing of group II introns in plant mitochondria. Mitochondrion 2007; 8:26-34. [PMID: 18006386 DOI: 10.1016/j.mito.2007.09.005] [Citation(s) in RCA: 182] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2007] [Revised: 09/12/2007] [Accepted: 09/16/2007] [Indexed: 11/18/2022]
Abstract
Group II-type introns in the mitochondrial genes of flowering plants belong to the ribozymic, mobile retroelement family, but not all exhibit conventional structural features and some follow unusual splicing pathways. Moreover, several introns have been disrupted by DNA rearrangements, so that separately-transcribed precursors undergo splicing in trans. RNA processing in plant mitochondria has the added complexity of C-to-U RNA editing which also sometimes occurs within core intron structures or at exon sites very close to introns. It appears that mitochondrial introns in flowering plants have followed quite different evolutionary pathways than other group II introns.
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Affiliation(s)
- Linda Bonen
- Biology Department, University of Ottawa, 30 Marie Curie, Ottawa, Canada K1N 6N5.
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37
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Lang BF, Laforest MJ, Burger G. Mitochondrial introns: a critical view. Trends Genet 2007; 23:119-25. [PMID: 17280737 DOI: 10.1016/j.tig.2007.01.006] [Citation(s) in RCA: 234] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2006] [Revised: 12/14/2006] [Accepted: 01/18/2007] [Indexed: 11/17/2022]
Abstract
Although group I and group II introns were discovered more than 25 years ago, they are still difficult to identify. Modeling their RNA structure also remains particularly challenging for organelle sequences, owing to their great diversity. In fact, accelerated evolution in organelles often results in a reduced RNA structure and a loss of autocatalytic splicing and intron mobility. We set out to identify all mitochondrial group I and II introns in published sequences, and, to this end, we developed and applied a new search approach: RNAweasel. On the basis of the results, we focus here on building a comprehensive picture of mitochondrial group I introns, including a modified (reduced) consensus RNA secondary structure and a concise phylogeny-based subclassification.
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Affiliation(s)
- B Franz Lang
- Robert Cedergren Centre, Program in Evolutionary Biology, Canadian Institute for Advanced Research, Département de Biochimie, Université de Montréal, Montréal, Québec, Canada.
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Mower JP, Palmer JD. Patterns of partial RNA editing in mitochondrial genes of Beta vulgaris. Mol Genet Genomics 2006; 276:285-93. [PMID: 16862402 DOI: 10.1007/s00438-006-0139-3] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Accepted: 05/23/2006] [Indexed: 11/27/2022]
Abstract
RNA editing is a process that modifies the information in transcripts of almost all angiosperm mitochondrial protein-coding genes. In order to determine the frequency and distribution of mitochondrial RNA editing in Beta vulgaris, cDNAs were sequenced and compared to the published genome sequence. 357 C to U conversions were identified across the 31 known protein genes and pseudogenes in Beta, the fewest so far for a plant mitochondrial genome. Editing patterns in the putative gene orf518 indicate that it is most likely a functional ccmC homolog, indicating that patterns of editing can be a useful determinant of gene functionality. orf518 also contains a triplicated repeat region whose members are nearly identical yet differentially edited, most likely due to differences in the sequence context of the editing sites. In addition, we show that partial editing in Beta is common at silent editing sites but rare at nonsilent editing sites, extending previous observations to a complete plant mitochondrial genome. Finally, the degree of partial editing observed for certain genes was dependent on the choice of primers used, demonstrating that care must be taken when designing primers for use in editing studies.
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Affiliation(s)
- Jeffrey P Mower
- Department of Biology, Indiana University, Bloomington, IN 47405, USA. [corrected]
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Choury D, Farré JC, Jordana X, Araya A. Gene expression studies in isolated mitochondria: Solanum tuberosum rps10 is recognized by cognate potato but not by the transcription, splicing and editing machinery of wheat mitochondria. Nucleic Acids Res 2005; 33:7058-65. [PMID: 16352866 PMCID: PMC1312363 DOI: 10.1093/nar/gki1017] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The complex gene expression mechanisms that occur in plant mitochondria, such as RNA editing and splicing, are not yet well understood. RNA editing in higher plant mitochondria is a highly specific process which modifies mRNA sequences by C-to-U conversions. It has been suggested that in some cases this process is required for splicing. Here, we use an experimental model based on the introduction of DNA into isolated mitochondria by electroporation to study organellar gene expression events. Our aim was to compare processing and editing of potato small ribosomal protein 10 gene (rps10) transcripts in heterologous (wheat mitochondria) and homologous (potato mitochondria) contexts. rps10 is a suitable model because it contains a group II intron, is absent in wheat mitochondria but is actively expressed in potato mitochondria, where transcripts are spliced and undergo five C-to-U editing events. For this purpose, conditions for electroporating isolated potato mitochondria were established. rps10 was placed under the control of either potato or wheat cox2 promoters. We found that rps10 was only transcribed under the control of a cognate promoter. In wheat mitochondria, rps10 transcripts were neither spliced nor edited while they are correctly processed in potato mitochondria. Interestingly, a wheat editing site grafted into rps10 was not recognized by wheat mitochondria but was correctly edited in potato mitochondria. Taken together, these results suggest that editing might occur only when the transcripts are engaged in processing and that they would not be available to editing factors outside of a putative RNA maturation machinery complex.
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Affiliation(s)
| | | | - Xavier Jordana
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de ChileCasilla 114-D, Santiago, Chile
| | - Alejandro Araya
- To whom correspondence should be addressed. Tel: +33 5 57 57 17 46; Fax: +33 5 57 57 17 66;
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Fey J, Weil JH, Tomita K, Cosset A, Dietrich A, Small I, Maréchal-Drouard L. Role of editing in plant mitochondrial transfer RNAs. Gene 2002; 286:21-4. [PMID: 11943456 DOI: 10.1016/s0378-1119(01)00817-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Editing in plant mitochondria consists in C to U changes and mainly affects messenger RNAs, thus providing the correct genetic information for the biosynthesis of mitochondrial (mt) proteins. But editing can also affect some of the plant mt tRNAs encoded by the mt genome. In dicots, a C to U editing event corrects a C:A mismatch into a U:A base pair in the acceptor stem of mt tRNA(Phe) (GAA). In larch mitochondria, three C to U editing events restore U:A base pairs in the acceptor stem, D stem and anticodon stem, respectively, of mt tRNA(His) (GUG). For both these mt RNA(Phe) and tRNA(His), editing of the precursors is a prerequisite for their processing into mature tRNAs. In potato mt tRNA(Cys) (GCA), editing converts a C28:U42 mismatch in the anticodon stem into a U28:U42 non-canonical base pair, and reverse transcriptase minisequencing has shown that the mature mt tRNA(Cys) is fully edited. In the bryophyte Marchantia polymorpha this U residue is encoded in the mt genome and evolutionary studies suggest that restoration of a U28 residue is necessary when it is not encoded in the gene. However, in vitro studies have shown that neither processing of the precursor, nor aminoacylation of tRNA(Cys), requires C to U editing at this position. But sequencing of the purified mt tRNA(Cys) has shown that Psi is present at position 28, indicating that C to U editing is a prerequisite for the subsequent isomerization of U into Psi at position 28.
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MESH Headings
- Cytidine/genetics
- Cytidine/metabolism
- Mitochondria/genetics
- Plants/genetics
- Pseudouridine/genetics
- Pseudouridine/metabolism
- RNA Editing
- RNA, Plant/genetics
- RNA, Plant/metabolism
- RNA, Transfer/genetics
- RNA, Transfer/metabolism
- RNA, Transfer, Cys/genetics
- RNA, Transfer, Cys/metabolism
- RNA, Transfer, His/genetics
- RNA, Transfer, His/metabolism
- RNA, Transfer, Phe/genetics
- RNA, Transfer, Phe/metabolism
- Uridine/genetics
- Uridine/metabolism
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Affiliation(s)
- J Fey
- Institut de Biologie Moléculaire des Plantes, CNRS, 12 rue du Général Zimmer, 67084 Strasbourg, France
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42
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Abstract
The conversion of genetic information stored in DNA into a protein product proceeds through the obligatory intermediate of messenger RNA. The steady-state level of an mRNA is determined by its relative synthesis and degradation rates, i.e., an interplay between transcriptional regulation and control of RNA stability. When the biological status of an organism requires that a gene product's abundance varies as a function of developmental stage, environmental factors or intracellular signals, increased or decreased RNA stability can be the determining factor. RNA stability and processing have long been known as important regulatory points in chloroplast gene expression. Here we summarize current knowledge and prospects relevant to these processes, emphasizing biochemical data. The extensive literature on nuclear mutations affecting chloroplast RNA metabolism is reviewed in another article in this volume (Barkan and Goldschmidt-Clermont, this issue).
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Affiliation(s)
- R A Monde
- Boyce Thompson Institute for Plant Research, Tower Rd., Cornell University, Ithaca, NY 14853, USA
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Holländer V, Kück U. Group II intron splicing in Escherichia coli: phenotypes of cis-acting mutations resemble splicing defects observed in organelle RNA processing. Nucleic Acids Res 1999; 27:2339-44. [PMID: 10325423 PMCID: PMC148800 DOI: 10.1093/nar/27.11.2339] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The mitochondrial group IIB intron rI1, from the green algae Scenedesmus obliquus ' LSUrRNA gene, has been introduced into the lacZ gene encoding beta-galacto-sidase. After DNA-mediated transformation of the recombinant lacZ gene into Escherichia coli, we observed correct splicing of the chimeric precursor RNA in vivo. In contrast to autocatalytic in vitro self-splicing, intron processing in vivo is independent of the growth temperature, suggesting that in E.coli, trans -acting factors are involved in group II intron splicing. Such a system would seem suitable as a model for analyzing intron processing in a prokaryotic host. In order to study further the effect of cis -mutations on intron splicing, different rI1 mutants were analyzed (with respect to their splicing activity) in E.coli. Although the phenotypes of these E. coli intron splicing mutants were identical to those which can be observed during organellar splicing of rI1, they are different to those observed in in vitro self-splicing experiments. Therefore, in both organelles and prokaryotes, it is likely that either similar splicing factors or trans -acting factors exhibiting similar functions are involved in splicing. We speculate that ubiquitous trans -acting factors, via recent horizontal transfer, have contributed to the spread of group II introns.
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Affiliation(s)
- V Holländer
- Lehrstuhl für Allgemeine Botanik, Fakultät für Biologie, Ruhr-Universität Bochum, D-44780 Bochum, Germany
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Yoshinaga K, Kakehi T, Shima Y, Iinuma H, Masuzawa T, Ueno M. Extensive RNA editing and possible double-stranded structures determining editing sites in the atpB transcripts of hornwort chloroplasts. Nucleic Acids Res 1997; 25:4830-4. [PMID: 9365264 PMCID: PMC147111 DOI: 10.1093/nar/25.23.4830] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Three nonsense codons and an unusual initiation codon were located within the putative coding region of the atpB gene of chloroplast DNA of the hornwort Anthoceros formosae. Nucleotide sequencing of cDNA prepared from transcripts revealed extensive RNA editing. The unusual initiation codon ACG was changed to AUG and three nonsense codons were converted into sense codons. In total 15 C residues of the genomic DNA were replaced by U residues in the mRNA sequences, while 14 U residues were replaced by C residues. This is the highest number of editing events for a chloroplast mRNA reported so far. Partial editing was also shown in a cDNA clone where 23 sites were edited but six sites remained unedited, representing the existence of premature mRNA. The expected two-dimensional structure of the mRNA shows the existence of a sequence complementary to every editing site, which can produce continuous base pairing longer than 5 bp, suggesting that mispairing in the double strand is the site determinant for RNA editing in Anthoceros chloroplasts. Comparison of the cDNA sequence with other chloroplast genes suggests that the mechanism arose in the first land plants and has been reduced during evolution.
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Affiliation(s)
- K Yoshinaga
- Faculty of Science, Shizuoka University, Shizuoka 422, Japan.
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Vogel J, Hübschmann T, Börner T, Hess WR. Splicing and intron-internal RNA editing of trnK-matK transcripts in barley plastids: support for MatK as an essential splice factor. J Mol Biol 1997; 270:179-87. [PMID: 9236120 DOI: 10.1006/jmbi.1997.1115] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Group II introns frequently require assistance by specific factors, maturases, for folding and effective splicing in vivo. The only putative maturase of higher plant chloroplasts is encoded by matK, located in the intron of trnK. We show that in barley matK transcripts are modified at a first codon base by C-to-U RNA editing. The resulting H --> Y substitution restores a sequence motif that is present in maturases of yeast and plant mitochondria and of Lactococcus ltrA and that is positioned within the X domain. Processing of trnK-matK transcripts was further investigated in plastids lacking functional ribosomes due to a mutation. Absence of the intron-encoded matK gene product in these plastids is correlated with the accumulation of precursor transcripts for tRNALys(UUU)-matK, processed to different degrees, and by the lack of mature and spliced tRNA molecules. These results suggest an essential role of MatK for splicing of its own transcript in vivo. Processing of the 5' end of trnK exon 1 was found to proceed efficiently also in the mutant plastids although the two tRNA exons were separated by the 2481 nt intron. Consequently, presence of the intron does not interfere with the formation of mature 5' termini.
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Affiliation(s)
- J Vogel
- Humboldt-University, Department of Biology, Berlin, Germany
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Carrillo C, Bonen L. RNA editing status of nad7 intron domains in wheat mitochondria. Nucleic Acids Res 1997; 25:403-9. [PMID: 9016571 PMCID: PMC146442 DOI: 10.1093/nar/25.2.403] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The most highly conserved structures of group II introns are the helical domains V and VI near the 3'splice site. Within this region of each of the four introns in the wheat mitochondrial nad7 gene encoding NADH dehydrogenase subunit 7, there are A-C mispairs. To determine whether C-to-U type RNA editing restores conventional A-U pairing, we sequenced RT-PCR products from partially-spliced nad7 template RNA and gel-fractionated, excised intron RNA. We examined transcripts from germinating wheat embryos and seedlings because these two stages of development show pronounced differences in steady state levels of nad7 intronic RNAs. We observed editing at only two of the six predicted sites, and they were located at homologous positions within domain V of the third and fourth introns. A third site was found to be edited within the unmodelled domain VI loop of the fourth intron. Similar patterns of RNA editing were seen in wheat embryos and seedlings. These observations, and the presence of other non-conventional base pairs particularly within domain V of plant mitochondrial introns, indicate weaker helical core structure than in ribozymic group II introns. Moreover, the incompleteness or absence of editing in wheat nad7 excised intron RNA suggests that, although editing may contribute to splicing efficiency, it is not essential for splicing.
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Affiliation(s)
- C Carrillo
- Biology Department, University of Ottawa, 30 Marie Curie, Ottawa K1N 6N5, Canada
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47
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Binder S, Marchfelder A, Brennicke A. Regulation of gene expression in plant mitochondria. PLANT MOLECULAR BIOLOGY 1996; 32:303-314. [PMID: 8980484 DOI: 10.1007/bf00039387] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Many genes is plant mitochondria have been analyzed in the past 15 years and regulatory processes controlling gene expression can now be investigated. In vitro systems capable of initiating transcription faithfully at promoter sites have been developed for both monocot and dicot plants and will allow the identification of the interacting nucleic acid elements and proteins which specify and guide transcriptional activities. Mitochondrial activity, although required in all plant tissues, is capable of adapting to specific requirements by regulated gene expression. Investigation of the factors governing the quality and quantity of distinct RNAs will define the extent of interorganelle regulatory interference in mitochondrial gene expression.
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Affiliation(s)
- S Binder
- Allgemeine Botanik, Universität Ulm, Germany
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48
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Affiliation(s)
- M W Gray
- Canadian Institute for Advanced Research, Department of Biochemistry, Dalhousie University, Halifa NS, Canada.
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Marechal-Drouard L, Cosset A, Remacle C, Ramamonjisoa D, Dietrich A. A single editing event is a prerequisite for efficient processing of potato mitochondrial phenylalanine tRNA. Mol Cell Biol 1996; 16:3504-10. [PMID: 8668166 PMCID: PMC231345 DOI: 10.1128/mcb.16.7.3504] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
In bean, potato, and Oenothera plants, the C encoded at position 4 (C4) in the mitochondrial tRNA Phe GAA gene is converted into a U in the mature tRNA. This nucleotide change corrects a mismatched C4-A69 base pair which appears when the gene sequence is folded into the cloverleaf structure. C-to-U conversions constitute the most common editing events occurring in plant mitochondrial mRNAs. While most of these conversions introduce changes in the amino acids specified by the mRNA and appear to be essential for the synthesis of functional proteins in plant mitochondria, the putative role of mitochondrial tRNA editing has not yet been defined. Since the edited form of the tRNA has the correct secondary and tertiary structures compared with the nonedited form, the two main processes which might be affected by a nucleotide conversion are aminoacylation and maturation. To test these possibilities, we determined the aminoacylation properties of unedited and edited potato mitochondrial tRNAPhe in vitro transcripts, as well as the processing efficiency of in vitro-synthesized potato mitochondrial tRNAPhe precursors. Reverse transcription-PCR amplification of natural precursors followed by cDNA sequencing was also used to investigate the influence of editing on processing. Our results show that C-to-U conversion at position 4 in the potato mitochondrial tRNA Phe GAA is not required for aminoacylation with phenylalanine but is likely to he essential for efficient processing of this tRNA.
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Affiliation(s)
- L Marechal-Drouard
- Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, Université Louis Pasteur, Strasbourg, France
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50
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Marchfelder A, Brennicke A, Binder S. RNA editing is required for efficient excision of tRNA(Phe) from precursors in plant mitochondria. J Biol Chem 1996; 271:1898-903. [PMID: 8567636 DOI: 10.1074/jbc.271.4.1898] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
RNA editing corrects a 4C-A69 mismatch to a conventional 4T-A69 Watson-Crick base pair in the acceptor stem of the mitochondrially encoded tRNAPhe in plants. In vitro processing of edited and unedited Oenothera tRNA Phe precursor RNAs with pea mitochondrial protein extracts shows a significant effect of this RNA-editing event on the efficiency of 5' and 3' processing. While mature tRNA molecules are rapidly generated by in vitro processing from edited precursors, the formation of mature tRNAs from unedited pre-tRNAs is considerably reduced. Primer extension analyses of in vitro processing products show that processing at both 5' and 3' termini is governed by the RNA-editing event. Investigation of edited and unedited precursor RNAs by lead cleavage experiments reveals differences in the higher order structures of the pre-tRNAs. The differing conformations are most likely responsible for the altered processing efficiencies of edited and unedited precursor molecules. RNA editing of the tRNAPhe precursors is thus a prerequisite for efficient excision of the mature tRNAPhe in vitro. Hence RNA editing might be involved in regulating the amount of mature tRNAPhe in the steady state RNA pool of mitochondria in higher plants.
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Affiliation(s)
- A Marchfelder
- Institut für Genbiologische Forschung, Berlin, Germany
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