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Su A, Ge S, Zhou B, Wang Z, Zhou L, Zhang Z, Yan X, Wang Y, Li D, Zhang H, Xu X, Zhao T. Analysis of the Tomato mTERF Gene Family and Study of the Stress Resistance Function of SLmTERF-13. PLANTS (BASEL, SWITZERLAND) 2023; 12:2862. [PMID: 37571015 PMCID: PMC10421145 DOI: 10.3390/plants12152862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 07/26/2023] [Accepted: 08/02/2023] [Indexed: 08/13/2023]
Abstract
Mitochondrial transcription termination factor (mTERF) is a DNA-binding protein that is encoded by nuclear genes, ultimately functions in mitochondria and can affect gene expression. By combining with mitochondrial nucleic acids, mTERF regulates the replication, transcription and translation of mitochondrial genes and plays an important role in the response of plants to abiotic stress. However, there are few studies on mTERF genes in tomato, which limits the in-depth study and utilization of mTERF family genes in tomato stress resistance regulation. In this study, a total of 28 mTERF gene family members were obtained through genome-wide mining and identification of the tomato mTERF gene family. Bioinformatics analysis showed that all members of the family contained environmental stress or hormone response elements. Gene expression pattern analysis showed that the selected genes had different responses to drought, high salt and low temperature stress. Most of the genes played key roles under drought and salt stress, and the response patterns were more similar. The VIGS method was used to silence the SLmTERF13 gene, which was significantly upregulated under drought and salt stress, and it was found that the resistance ability of silenced plants was decreased under both kinds of stress, indicating that the SLmTERF13 gene was involved in the regulation of the tomato abiotic stress response. These results provide important insights for further evolutionary studies and contribute to a better understanding of the role of the mTERF genes in tomato growth and development and abiotic stress response, which will ultimately play a role in future studies of tomato gene function.
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Affiliation(s)
- Ao Su
- Tomato Research Institute, College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin 150030, China; (A.S.); (S.G.)
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture and Rural Affairs, Northeast Agricultural University, Harbin 150030, China
| | - Siyu Ge
- Tomato Research Institute, College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin 150030, China; (A.S.); (S.G.)
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture and Rural Affairs, Northeast Agricultural University, Harbin 150030, China
| | - Boyan Zhou
- Tomato Research Institute, College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin 150030, China; (A.S.); (S.G.)
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture and Rural Affairs, Northeast Agricultural University, Harbin 150030, China
| | - Ziyu Wang
- Tomato Research Institute, College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin 150030, China; (A.S.); (S.G.)
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture and Rural Affairs, Northeast Agricultural University, Harbin 150030, China
| | - Liping Zhou
- Tomato Research Institute, College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin 150030, China; (A.S.); (S.G.)
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture and Rural Affairs, Northeast Agricultural University, Harbin 150030, China
| | - Ziwei Zhang
- Tomato Research Institute, College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin 150030, China; (A.S.); (S.G.)
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture and Rural Affairs, Northeast Agricultural University, Harbin 150030, China
| | - Xiaoyu Yan
- Tomato Research Institute, College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin 150030, China; (A.S.); (S.G.)
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture and Rural Affairs, Northeast Agricultural University, Harbin 150030, China
| | - Yu Wang
- Tomato Research Institute, College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin 150030, China; (A.S.); (S.G.)
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture and Rural Affairs, Northeast Agricultural University, Harbin 150030, China
| | - Dalong Li
- Tomato Research Institute, College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin 150030, China; (A.S.); (S.G.)
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture and Rural Affairs, Northeast Agricultural University, Harbin 150030, China
| | - He Zhang
- Tomato Research Institute, College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin 150030, China; (A.S.); (S.G.)
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture and Rural Affairs, Northeast Agricultural University, Harbin 150030, China
| | - Xiangyang Xu
- Tomato Research Institute, College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin 150030, China; (A.S.); (S.G.)
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture and Rural Affairs, Northeast Agricultural University, Harbin 150030, China
| | - Tingting Zhao
- Tomato Research Institute, College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin 150030, China; (A.S.); (S.G.)
- Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (Northeast Region), Ministry of Agriculture and Rural Affairs, Northeast Agricultural University, Harbin 150030, China
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Nakai H, Tsuchiya Y, Koike N, Asano T, Ueno M, Umemura Y, Sasawaki Y, Ono R, Hamuro J, Sotozono C, Yagita K. Comprehensive Analysis Identified the Circadian Clock and Global Circadian Gene Expression in Human Corneal Endothelial Cells. Invest Ophthalmol Vis Sci 2022; 63:16. [PMID: 35579906 PMCID: PMC9123520 DOI: 10.1167/iovs.63.5.16] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To investigate circadian clock oscillation and circadian global gene expression in cultured human corneal endothelial cells (cHCECs) to elucidate and assess the potential function of circadian regulation in HCECs. Methods In this study, we introduced a circadian bioluminescence reporter, Bmal1:luciferase (Bmal1:luc), into cHCECs and subsequently monitored real-time bioluminescence rhythms. RNA-sequencing data analysis was then performed using sequential time-course samples of the cHCECs to obtain a comprehensive understanding of the circadian gene expression rhythms. The potential relevance of rhythmically expressed genes was then assessed by systematic approaches using functional clustering and individual gene annotations. Results Bmal1:luc bioluminescence exhibited clear circadian oscillation in the cHCECs. The core clock genes and clock-related genes showed high-amplitude robust circadian messenger RNA (mRNA) expression rhythms in cHCECs after treatment with dexamethasone, and 329 genes that exhibited circadian mRNA expression rhythms were identified (i.e., genes involved in various physiological processes including glycolysis, mitochondrial function, antioxidative systems, hypoxic responses, apoptosis, and extracellular matrix regulation, which represent the physiological functions of HCECs). Conclusions Our findings revealed that cHCECs have a robust and functional circadian clock, and our discovery that a large number of genes exhibit circadian mRNA expression rhythms in cHCECs suggests a potential contribution of circadian regulation to fine-tune HCEC functions for daily changes in the environment.
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Affiliation(s)
- Hiroko Nakai
- Department of Physiology and Systems Bioscience, Kyoto Prefectural University of Medicine, Kyoto, Japan.,Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Yoshiki Tsuchiya
- Department of Physiology and Systems Bioscience, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Nobuya Koike
- Department of Physiology and Systems Bioscience, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Taiki Asano
- Department of Physiology and Systems Bioscience, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Morio Ueno
- Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Yasuhiro Umemura
- Department of Physiology and Systems Bioscience, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Yuh Sasawaki
- Department of Physiology and Systems Bioscience, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Ryutaro Ono
- Department of Physiology and Systems Bioscience, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Junji Hamuro
- Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Chie Sotozono
- Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Kazuhiro Yagita
- Department of Physiology and Systems Bioscience, Kyoto Prefectural University of Medicine, Kyoto, Japan
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Melonek J, Small I. Triticeae genome sequences reveal huge expansions of gene families implicated in fertility restoration. CURRENT OPINION IN PLANT BIOLOGY 2022; 66:102166. [PMID: 35021148 DOI: 10.1016/j.pbi.2021.102166] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 11/23/2021] [Accepted: 12/02/2021] [Indexed: 06/14/2023]
Abstract
Breakthroughs in assembly of whole-genome sequencing and targeted sequence capture data have accelerated comparative genomics analyses in cereals with big and complex genomes such as wheat. This newly acquired information has revealed unexpected expansions in two large gene families linked to restoration of fertility in species that exhibit cytoplasmic male sterility. Extreme levels of copy-number and structural variation detected within and between species illustrate the genetic diversity among the family members and reveal the evolutionary mechanisms at work. This new knowledge will greatly facilitate the development of hybrid production strategies in wheat and related species.
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Affiliation(s)
- Joanna Melonek
- ARC Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, Crawley, WA, Australia.
| | - Ian Small
- ARC Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, Crawley, WA, Australia
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Miranda M, Bonekamp NA, Kühl I. Starting the engine of the powerhouse: mitochondrial transcription and beyond. Biol Chem 2022; 403:779-805. [PMID: 35355496 DOI: 10.1515/hsz-2021-0416] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 03/09/2022] [Indexed: 12/25/2022]
Abstract
Mitochondria are central hubs for cellular metabolism, coordinating a variety of metabolic reactions crucial for human health. Mitochondria provide most of the cellular energy via their oxidative phosphorylation (OXPHOS) system, which requires the coordinated expression of genes encoded by both the nuclear (nDNA) and mitochondrial genomes (mtDNA). Transcription of mtDNA is not only essential for the biogenesis of the OXPHOS system, but also generates RNA primers necessary to initiate mtDNA replication. Like the prokaryotic system, mitochondria have no membrane-based compartmentalization to separate the different steps of mtDNA maintenance and expression and depend entirely on nDNA-encoded factors imported into the organelle. Our understanding of mitochondrial transcription in mammalian cells has largely progressed, but the mechanisms regulating mtDNA gene expression are still poorly understood despite their profound importance for human disease. Here, we review mechanisms of mitochondrial gene expression with a focus on the recent findings in the field of mammalian mtDNA transcription and disease phenotypes caused by defects in proteins involved in this process.
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Affiliation(s)
- Maria Miranda
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, D-50931, Germany
| | - Nina A Bonekamp
- Department of Neuroanatomy, Mannheim Center for Translational Neurosciences (MCTN), Medical Faculty Mannheim, Heidelberg University, Mannheim, D-68167, Germany
| | - Inge Kühl
- Department of Cell Biology, Institute of Integrative Biology of the Cell (I2BC), UMR9198, CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, F-91190, France
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Wang M, Zhou F, Wang HM, Xue DX, Liu YG, Zhang QY. A rice mTERF protein V14 sustains photosynthesis establishment and temperature acclimation in early seedling leaves. BMC PLANT BIOLOGY 2021; 21:406. [PMID: 34488627 PMCID: PMC8420055 DOI: 10.1186/s12870-021-03192-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 08/28/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Plant mitochondrial transcription termination factor (mTERF) family members play important roles in development and stress tolerance through regulation of organellar gene expression. However, their molecular functions have yet to be clearly defined. RESULTS Here an mTERF gene V14 was identified by fine mapping using a conditional albino mutant v14 that displayed albinism only in the first two true leaves, which was confirmed by transgenic complementation tests. Subcellular localization and real-time PCR analyses indicated that V14 encodes a chloroplastic protein ubiquitously expressed in leaves while spiking in the second true leaf. Chloroplastic gene expression profiling in the pale leaves of v14 through real-time PCR and Northern blotting analyses showed abnormal accumulation of the unprocessed transcripts covering the rpoB-rpoC1 and/or rpoC1-rpoC2 intercistronic regions accompanied by reduced abundance of the mature rpoC1 and rpoC2 transcripts, which encode two core subunits of the plastid-encoded plastid RNA polymerase (PEP). Subsequent immunoblotting analyses confirmed the reduced accumulation of RpoC1 and RpoC2. A light-inducible photosynthetic gene psbD was also found down-regulated at both the mRNA and protein levels. Interestingly, such stage-specific aberrant posttranscriptional regulation and psbD expression can be reversed by high temperatures (30 ~ 35 °C), although V14 expression lacks thermo-sensitivity. Meanwhile, three V14 homologous genes were found heat-inducible with similar temporal expression patterns, implicating their possible functional redundancy to V14. CONCLUSIONS These data revealed a critical role of V14 in chloroplast development, which impacts, in a stage-specific and thermo-sensitive way, the appropriate processing of rpoB-rpoC1-rpoC2 precursors and the expression of certain photosynthetic proteins. Our findings thus expand the knowledge of the molecular functions of rice mTERFs and suggest the contributions of plant mTERFs to photosynthesis establishment and temperature acclimation.
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Affiliation(s)
- Man Wang
- Present Address: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Sciences, South China Agricultural University, Guangzhou, 510642 China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642 China
| | - Feng Zhou
- Present Address: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Sciences, South China Agricultural University, Guangzhou, 510642 China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642 China
| | - Hong Mei Wang
- Present Address: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Sciences, South China Agricultural University, Guangzhou, 510642 China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642 China
| | - De Xing Xue
- Present Address: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Sciences, South China Agricultural University, Guangzhou, 510642 China
| | - Yao-Guang Liu
- Present Address: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Sciences, South China Agricultural University, Guangzhou, 510642 China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642 China
- SCAU Main Campus Teaching & Research Base, Guangzhou, China
| | - Qun Yu Zhang
- Present Address: State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Sciences, South China Agricultural University, Guangzhou, 510642 China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642 China
- SCAU Main Campus Teaching & Research Base, Guangzhou, China
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Łabędzka-Dmoch K, Kolondra A, Karpińska MA, Dębek S, Grochowska J, Grochowski M, Piątkowski J, Hoang Diu Bui T, Golik P. Pervasive transcription of the mitochondrial genome in Candida albicans is revealed in mutants lacking the mtEXO RNase complex. RNA Biol 2021; 18:303-317. [PMID: 34229573 PMCID: PMC8677008 DOI: 10.1080/15476286.2021.1943929] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The mitochondrial genome of the pathogenic yeast Candida albicans displays a typical organization of several (eight) primary transcription units separated by noncoding regions. Presence of genes encoding Complex I subunits and the stability of its mtDNA sequence make it an attractive model to study organellar genome expression using transcriptomic approaches. The main activity responsible for RNA degradation in mitochondria is a two-component complex (mtEXO) consisting of a 3ʹ-5ʹ exoribonuclease, in yeasts encoded by the DSS1 gene, and a conserved Suv3p helicase. In C. albicans, deletion of either DSS1 or SUV3 gene results in multiple defects in mitochondrial genome expression leading to the loss of respiratory competence. Transcriptomic analysis reveals pervasive transcription in mutants lacking the mtEXO activity, with evidence of the entire genome being transcribed, whereas in wild-type strains no RNAs corresponding to a significant fraction of the noncoding genome can be detected. Antisense (‘mirror’) transcripts, absent from normal mitochondria are also prominent in the mutants. The expression of multiple mature transcripts, particularly those translated from bicistronic mRNAs, as well as those that contain introns is affected in the mutants, resulting in a decreased level of proteins and reduced respiratory complex activity. The phenotype is most severe in the case of Complex IV, where a decrease of mature COX1 mRNA level to ~5% results in a complete loss of activity. These results show that RNA degradation by mtEXO is essential for shaping the mitochondrial transcriptome and is required to maintain the functional demarcation between transcription units and non-coding genome segments.
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Affiliation(s)
- Karolina Łabędzka-Dmoch
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Adam Kolondra
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Magdalena A Karpińska
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Sonia Dębek
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Joanna Grochowska
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland.,Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
| | - Maciej Grochowski
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Jakub Piątkowski
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Thi Hoang Diu Bui
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Paweł Golik
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw, Poland.,Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, Poland
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Yin X, Gao Y, Song S, Hassani D, Lu J. Identification, characterization and functional analysis of grape (Vitis vinifera L.) mitochondrial transcription termination factor (mTERF) genes in responding to biotic stress and exogenous phytohormone. BMC Genomics 2021; 22:136. [PMID: 33637035 PMCID: PMC7913399 DOI: 10.1186/s12864-021-07446-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 02/15/2021] [Indexed: 11/29/2022] Open
Abstract
Background Mitochondrial transcription termination factor (mTERF) is a large gene family which plays a significant role during plant growth under various environmental stresses. However, knowledge of mTERF genes in grapevine (Vitis L.) is limited. Results In this research, a comprehensive analysis of grape mTERF (VvmTERF) genes, including chromosome locations, phylogeny, protein motifs, gene structures, gene duplications, synteny analysis and expression profiles, was conducted. As a result, a total of 25 mTERF genes were identified from the grape genome, which are distributed on 13 chromosomes with diverse densities and segmental duplication events. The grape mTERF gene family is classified into nine clades based on phylogenetic analysis and structural characteristics. These VvmTERF genes showed differential expression patterns in response to multiple phytohormone treatments and biotic stresses, including treatments with abscisic acid and methyl jasmonate, and inoculation of Plasmopara viticola and Erysiphe necator. Conclusions These research findings, as the first of its kind in grapevine, will provide useful information for future development of new stress tolerant grape cultivars through genetic manipulation of VvmTERF genes. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07446-z.
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Affiliation(s)
- Xiangjing Yin
- Center for Viticulture and Enology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Yu Gao
- Center for Viticulture and Enology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Shiren Song
- Center for Viticulture and Enology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Danial Hassani
- Joint International Research Laboratory of Metabolic and Developmental Sciences, Key Laboratory of Urban Agriculture (South) Ministry of Agriculture, Plant Biotechnology Research Center, Fudan-SJTU-Nottingham Plant Biotechnology R&D Center, School of Agriculture and Biology, Shanghai Jiao Tong University (SJTU), Shanghai, 200240, China
| | - Jiang Lu
- Center for Viticulture and Enology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, 200240, China.
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Wobbe L. The Molecular Function of Plant mTERFs as Key Regulators of Organellar Gene Expression. PLANT & CELL PHYSIOLOGY 2021; 61:2004-2017. [PMID: 33067620 DOI: 10.1093/pcp/pcaa132] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 09/25/2020] [Indexed: 05/27/2023]
Abstract
The protein family of mTERFs (mitochondrial transcription termination factors) was initially studied in mammalian and insect mitochondria before the first Arabidopsis mTERF mutant was characterized. More than 10 years of research on the function of plant mTERFs in the flowering plants Arabidopsis thaliana, Zea mays and the green microalga Chlamydomonas reinhardtii has since highlighted that mTERFs are key regulators of organellar gene expression (OGE) in mitochondria and in chloroplasts. Additional functions to be fulfilled by plant mTERFs (e.g. splicing) and the fact that the expression of two organellar genomes had to be facilitated have led to a massive expansion of the plant mTERF portfolio compared to that found in mammals. Plant mTERFs are implicated in all steps of OGE ranging from the modulation of transcription to the maturation of tRNAs and hence translation. Furthermore, being regulators of OGE, mTERFs are required for a successful long-term acclimation to abiotic stress, retrograde signaling and interorganellar communication. Here, I review the recent progress in the elucidation of molecular mTERF functions.
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Affiliation(s)
- Lutz Wobbe
- Algae Biotechnology & Bioenergy Group, Faculty of Biology, Center for Biotechnology (CeBiTec), Bielefeld University, Universit�tsstrasse 27, Bielefeld 33615, Germany
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Méteignier LV, Ghandour R, Zimmerman A, Kuhn L, Meurer J, Zoschke R, Hammani K. Arabidopsis mTERF9 protein promotes chloroplast ribosomal assembly and translation by establishing ribonucleoprotein interactions in vivo. Nucleic Acids Res 2021; 49:1114-1132. [PMID: 33398331 PMCID: PMC7826268 DOI: 10.1093/nar/gkaa1244] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Revised: 12/07/2020] [Accepted: 12/13/2020] [Indexed: 12/13/2022] Open
Abstract
The mitochondrial transcription termination factor proteins are nuclear-encoded nucleic acid binders defined by degenerate tandem helical-repeats of ∼30 amino acids. They are found in metazoans and plants where they localize in organelles. In higher plants, the mTERF family comprises ∼30 members and several of these have been linked to plant development and response to abiotic stress. However, knowledge of the molecular basis underlying these physiological effects is scarce. We show that the Arabidopsis mTERF9 protein promotes the accumulation of the 16S and 23S rRNAs in chloroplasts, and interacts predominantly with the 16S rRNA in vivo and in vitro. Furthermore, mTERF9 is found in large complexes containing ribosomes and polysomes in chloroplasts. The comprehensive analysis of mTERF9 in vivo protein interactome identified many subunits of the 70S ribosome whose assembly is compromised in the null mterf9 mutant, putative ribosome biogenesis factors and CPN60 chaperonins. Protein interaction assays in yeast revealed that mTERF9 directly interact with these proteins. Our data demonstrate that mTERF9 integrates protein-protein and protein-RNA interactions to promote chloroplast ribosomal assembly and translation. Besides extending our knowledge of mTERF functional repertoire in plants, these findings provide an important insight into the chloroplast ribosome biogenesis.
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Affiliation(s)
- Louis-Valentin Méteignier
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France
| | - Rabea Ghandour
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
| | - Aude Zimmerman
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France
| | - Lauriane Kuhn
- Plateforme protéomique Strasbourg Esplanade FRC1589 du CNRS, Université de Strasbourg, 15 rue René Descartes, 67084 Strasbourg, France
| | - Jörg Meurer
- Plant Sciences, Faculty of Biology, Ludwig-Maximilians-University Munich, Großhaderner Street 2-4, 82152 Planegg-Martinsried, Germany
| | - Reimo Zoschke
- Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
| | - Kamel Hammani
- Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France
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10
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Arabidopsis Mitochondrial Transcription Termination Factor mTERF2 Promotes Splicing of Group IIB Introns. Cells 2021; 10:cells10020315. [PMID: 33546419 PMCID: PMC7913559 DOI: 10.3390/cells10020315] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/29/2021] [Accepted: 01/30/2021] [Indexed: 12/21/2022] Open
Abstract
Plastid gene expression (PGE) is essential for chloroplast biogenesis and function and, hence, for plant development. However, many aspects of PGE remain obscure due to the complexity of the process. A hallmark of nuclear-organellar coordination of gene expression is the emergence of nucleus-encoded protein families, including nucleic-acid binding proteins, during the evolution of the green plant lineage. One of these is the mitochondrial transcription termination factor (mTERF) family, the members of which regulate various steps in gene expression in chloroplasts and/or mitochondria. Here, we describe the molecular function of the chloroplast-localized mTERF2 in Arabidopsis thaliana. The complete loss of mTERF2 function results in embryo lethality, whereas directed, microRNA (amiR)-mediated knockdown of MTERF2 is associated with perturbed plant development and reduced chlorophyll content. Moreover, photosynthesis is impaired in amiR-mterf2 plants, as indicated by reduced levels of photosystem subunits, although the levels of the corresponding messenger RNAs are not affected. RNA immunoprecipitation followed by RNA sequencing (RIP-Seq) experiments, combined with whole-genome RNA-Seq, RNA gel-blot, and quantitative RT-PCR analyses, revealed that mTERF2 is required for the splicing of the group IIB introns of ycf3 (intron 1) and rps12.
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11
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Jiang D, Chen J, Zhang Z, Hou X. Mitochondrial Transcription Termination Factor 27 Is Required for Salt Tolerance in Arabidopsis thaliana. Int J Mol Sci 2021; 22:ijms22031466. [PMID: 33540552 PMCID: PMC7867191 DOI: 10.3390/ijms22031466] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 01/22/2021] [Accepted: 01/26/2021] [Indexed: 01/15/2023] Open
Abstract
In plants, mTERF proteins are primarily found in mitochondria and chloroplasts. Studies have identified several mTERF proteins that affect plant development, respond to abiotic stresses, and regulate organellar gene expression, but the functions and underlying mechanisms of plant mTERF proteins remain largely unknown. Here, we investigated the function of Arabidopsis mTERF27 using molecular genetic, cytological, and biochemical approaches. Arabidopsis mTERF27 had four mTERF motifs and was evolutionarily conserved from moss to higher plants. The phenotype of the mTERF27-knockout mutant mterf27 did not differ obviously from that of the wild-type under normal growth conditions but was hypersensitive to salt stress. mTERF27 was localized to the mitochondria, and the transcript levels of some mitochondrion-encoded genes were reduced in the mterf27 mutant. Importantly, loss of mTERF27 function led to developmental defects in the mitochondria under salt stress. Furthermore, mTERF27 formed homomers and directly interacted with multiple organellar RNA editing factor 8 (MORF8). Thus, our results indicated that mTERF27 is likely crucial for mitochondrial development under salt stress, and that this protein may be a member of the protein interaction network regulating mitochondrial gene expression.
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Research Progress in the Molecular Functions of Plant mTERF Proteins. Cells 2021; 10:cells10020205. [PMID: 33494215 PMCID: PMC7909791 DOI: 10.3390/cells10020205] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Revised: 01/16/2021] [Accepted: 01/18/2021] [Indexed: 12/16/2022] Open
Abstract
Present-day chloroplast and mitochondrial genomes contain only a few dozen genes involved in ATP synthesis, photosynthesis, and gene expression. The proteins encoded by these genes are only a small fraction of the many hundreds of proteins that act in chloroplasts and mitochondria. Hence, the vast majority, including components of organellar gene expression (OGE) machineries, are encoded by nuclear genes, translated into the cytosol and imported to these organelles. Consequently, the expression of nuclear and organellar genomes has to be very precisely coordinated. Furthermore, OGE regulation is crucial to chloroplast and mitochondria biogenesis, and hence, to plant growth and development. Notwithstanding, the molecular mechanisms governing OGE are still poorly understood. Recent results have revealed the increasing importance of nuclear-encoded modular proteins capable of binding nucleic acids and regulating OGE. Mitochondrial transcription termination factor (mTERF) proteins are a good example of this category of OGE regulators. Plant mTERFs are located in chloroplasts and/or mitochondria, and have been characterized mainly from the isolation and analyses of Arabidopsis and maize mutants. These studies have revealed their fundamental roles in different plant development aspects and responses to abiotic stress. Fourteen mTERFs have been hitherto characterized in land plants, albeit to a different extent. These numbers are limited if we consider that 31 and 35 mTERFs have been, respectively, identified in maize and Arabidopsis. Notwithstanding, remarkable progress has been made in recent years to elucidate the molecular mechanisms by which mTERFs regulate OGE. Consequently, it has been experimentally demonstrated that plant mTERFs are required for the transcription termination of chloroplast genes (mTERF6 and mTERF8), transcriptional pausing and the stabilization of chloroplast transcripts (MDA1/mTERF5), intron splicing in chloroplasts (BSM/RUG2/mTERF4 and Zm-mTERF4) and mitochondria (mTERF15 and ZmSMK3) and very recently, also in the assembly of chloroplast ribosomes and translation (mTERF9). This review aims to provide a detailed update of current knowledge about the molecular functions of plant mTERF proteins. It principally focuses on new research that has made an outstanding contribution to unravel the molecular mechanisms by which plant mTERFs regulate the expression of chloroplast and mitochondrial genomes.
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Li T, Pan W, Yuan Y, Liu Y, Li Y, Wu X, Wang F, Cui L. Identification, Characterization, and Expression Profile Analysis of the mTERF Gene Family and Its Role in the Response to Abiotic Stress in Barley ( Hordeum vulgare L.). FRONTIERS IN PLANT SCIENCE 2021; 12:684619. [PMID: 34335653 PMCID: PMC8319850 DOI: 10.3389/fpls.2021.684619] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 06/23/2021] [Indexed: 05/17/2023]
Abstract
Plant mitochondrial transcription termination factor (mTERF) family regulates organellar gene expression (OGE) and is functionally characterized in diverse species. However, limited data are available about its functions in the agriculturally important cereal barley (Hordeum vulgare L.). In this study, we identified 60 mTERFs in the barley genome (HvmTERFs) through a comprehensive search against the most updated barley reference genome, Morex V2. Then, phylogenetic analysis categorized these genes into nine subfamilies, with approximately half of the HvmTERFs belonging to subfamily IX. Members within the same subfamily generally possessed conserved motif composition and exon-intron structure. Both segmental and tandem duplication contributed to the expansion of HvmTERFs, and the duplicated gene pairs were subjected to strong purifying selection. Expression analysis suggested that many HvmTERFs may play important roles in barley development (e.g., seedlings, leaves, and developing inflorescences) and abiotic stresses (e.g., cold, salt, and metal ion), and HvmTERF21 and HvmTERF23 were significant induced by various abiotic stresses and/or phytohormone treatment. Finally, the nucleotide diversity was decreased by only 4.5% for HvmTERFs during the process of barley domestication. Collectively, this is the first report to characterize HvmTERFs, which will not only provide important insights into further evolutionary studies but also contribute to a better understanding of the potential functions of HvmTERFs and ultimately will be useful in future gene functional studies.
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Affiliation(s)
- Tingting Li
- College of Bioscience and Engineering, Jiangxi Agricultural University, Nanchang, China
| | - Wenqiu Pan
- State Key Laboratory of Crop Stress Biology in Arid Areas and College of Agronomy, Northwest A&F University, Yangling, China
| | - Yiyuan Yuan
- College of Bioscience and Engineering, Jiangxi Agricultural University, Nanchang, China
| | - Ying Liu
- College of Bioscience and Engineering, Jiangxi Agricultural University, Nanchang, China
| | - Yihan Li
- College of Bioscience and Engineering, Jiangxi Agricultural University, Nanchang, China
| | - Xiaoyu Wu
- College of Bioscience and Engineering, Jiangxi Agricultural University, Nanchang, China
| | - Fei Wang
- College of Bioscience and Engineering, Jiangxi Agricultural University, Nanchang, China
| | - Licao Cui
- College of Bioscience and Engineering, Jiangxi Agricultural University, Nanchang, China
- *Correspondence: Licao Cui
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Smoczynska A, Pacak AM, Nuc P, Swida-Barteczka A, Kruszka K, Karlowski WM, Jarmolowski A, Szweykowska-Kulinska Z. A Functional Network of Novel Barley MicroRNAs and Their Targets in Response to Drought. Genes (Basel) 2020; 11:genes11050488. [PMID: 32365647 PMCID: PMC7290300 DOI: 10.3390/genes11050488] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 04/17/2020] [Accepted: 04/21/2020] [Indexed: 12/27/2022] Open
Abstract
The regulation of mRNA (messenger RNA) levels by microRNA-mediated activity is especially important in plant responses to environmental stresses. In this work, we report six novel barley microRNAs, including two processed from the same precursor that are severely downregulated under drought conditions. For all analyzed microRNAs, we found target genes that were upregulated under drought conditions and that were known to be involved in a plethora of processes from disease resistance to chromatin–protein complex formation and the regulation of transcription in mitochondria. Targets for novel barley microRNAs were confirmed through degradome data analysis and RT-qPCR using primers flanking microRNA-recognition site. Our results show a broad transcriptional response of barley to water deficiency conditions through microRNA-mediated gene regulation and facilitate further research on drought tolerance in crops.
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Affiliation(s)
- Aleksandra Smoczynska
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, 61-614 Poznan, Poland; (A.S.); (A.M.P.); (P.N.); (A.S.-B.); (K.K.); (A.J.)
| | - Andrzej M. Pacak
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, 61-614 Poznan, Poland; (A.S.); (A.M.P.); (P.N.); (A.S.-B.); (K.K.); (A.J.)
| | - Przemysław Nuc
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, 61-614 Poznan, Poland; (A.S.); (A.M.P.); (P.N.); (A.S.-B.); (K.K.); (A.J.)
| | - Aleksandra Swida-Barteczka
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, 61-614 Poznan, Poland; (A.S.); (A.M.P.); (P.N.); (A.S.-B.); (K.K.); (A.J.)
| | - Katarzyna Kruszka
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, 61-614 Poznan, Poland; (A.S.); (A.M.P.); (P.N.); (A.S.-B.); (K.K.); (A.J.)
| | - Wojciech M. Karlowski
- Department of Computational Biology, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, 61-712 Poznan, Poland;
| | - Artur Jarmolowski
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, 61-614 Poznan, Poland; (A.S.); (A.M.P.); (P.N.); (A.S.-B.); (K.K.); (A.J.)
| | - Zofia Szweykowska-Kulinska
- Department of Gene Expression, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, 61-614 Poznan, Poland; (A.S.); (A.M.P.); (P.N.); (A.S.-B.); (K.K.); (A.J.)
- Correspondence: ; Tel.: +48-61-829-5950
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What Does the Molecular Genetics of Different Types of Restorer-of-Fertility Genes Imply? PLANTS 2020; 9:plants9030361. [PMID: 32182978 PMCID: PMC7154926 DOI: 10.3390/plants9030361] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 03/11/2020] [Accepted: 03/11/2020] [Indexed: 12/13/2022]
Abstract
Cytoplasmic male sterility (CMS) is a widely used trait for hybrid seed production. Although male sterility is caused by S cytoplasm (male-sterility inducing mitochondria), the action of S cytoplasm is suppressed by restorer-of-fertility (Rf), a nuclear gene. Hence, the genetics of Rf has attained particular interest among plant breeders. The genetic model posits Rf diversity in which an Rf specifically suppresses the cognate S cytoplasm. Molecular analysis of Rf loci in plants has identified various genes; however, pentatricopeptide repeat (PPR) protein (a specific type of RNA-binding protein) is so prominent as the Rf-gene product that Rfs have been categorized into two classes, PPR and non-PPR. In contrast, several shared features between PPR- and some non-PPR Rfs are apparent, suggesting the possibility of another grouping. Our present focus is to group Rfs by molecular genetic classes other than the presence of PPRs. We propose three categories that define partially overlapping groups of Rfs: association with post-transcriptional regulation of mitochondrial gene expression, resistance gene-like copy number variation at the locus, and lack of a direct link to S-orf (a mitochondrial ORF associated with CMS). These groups appear to reflect their own evolutionary background and their mechanism of conferring S cytoplasm specificity.
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Jiang D, Tang R, Shi Y, Ke X, Wang Y, Che Y, Luan S, Hou X. Arabidopsis Seedling Lethal 1 Interacting With Plastid-Encoded RNA Polymerase Complex Proteins Is Essential for Chloroplast Development. FRONTIERS IN PLANT SCIENCE 2020; 11:602782. [PMID: 33391315 PMCID: PMC7772139 DOI: 10.3389/fpls.2020.602782] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 11/27/2020] [Indexed: 05/16/2023]
Abstract
Mitochondrial transcription termination factors (mTERFs) are highly conserved proteins in metazoans. Plants have many more mTERF proteins than animals. The functions and the underlying mechanisms of plants' mTERFs remain largely unknown. In plants, mTERF family proteins are present in both mitochondria and plastids and are involved in gene expression in these organelles through different mechanisms. In this study, we screened Arabidopsis mutants with pigment-defective phenotypes and isolated a T-DNA insertion mutant exhibiting seedling-lethal and albino phenotypes [seedling lethal 1 (sl1)]. The SL1 gene encodes an mTERF protein localized in the chloroplast stroma. The sl1 mutant showed severe defects in chloroplast development, photosystem assembly, and the accumulation of photosynthetic proteins. Furthermore, the transcript levels of some plastid-encoded proteins were significantly reduced in the mutant, suggesting that SL1/mTERF3 may function in the chloroplast gene expression. Indeed, SL1/mTERF3 interacted with PAP12/PTAC7, PAP5/PTAC12, and PAP7/PTAC14 in the subgroup of DNA/RNA metabolism in the plastid-encoded RNA polymerase (PEP) complex. Taken together, the characterization of the plant chloroplast mTERF protein, SL1/mTERF3, that associated with PEP complex proteins provided new insights into RNA transcription in the chloroplast.
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Affiliation(s)
- Deyuan Jiang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Renjie Tang
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States
| | - Yafei Shi
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Xiangsheng Ke
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Yetao Wang
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
| | - Yufen Che
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States
| | - Sheng Luan
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States
- Sheng Luan,
| | - Xin Hou
- State Key Laboratory of Hybrid Rice, College of Life Sciences, Wuhan University, Wuhan, China
- *Correspondence: Xin Hou,
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17
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Genome-Wide Identification and Characterization of the Mitochondrial Transcription Termination Factors (mTERFs) in Capsicum annuum L. Int J Mol Sci 2019; 21:ijms21010269. [PMID: 31906076 PMCID: PMC6982079 DOI: 10.3390/ijms21010269] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 12/26/2019] [Accepted: 12/28/2019] [Indexed: 12/16/2022] Open
Abstract
Mitochondrial transcription termination factors (mTERFs) regulate the expression of mitochondrial genes and are closely related to the function of the mitochondrion and chloroplast. In this study, the mTERF gene family in capsicum (Capsicum annuum L.) was identified and characterized through genomic and bioinformatic analyses. Capsicum was found to possess at least 35 mTERF genes (CamTERFs), which were divided into eight major groups following phylogenetic analysis. Analysis of CamTERF promoters revealed the presence of many cis-elements related to the regulation of cellular respiration and photosynthesis. In addition, CamTERF promoters contained cis-elements related to phytohormone regulation and stress responses. Differentially expressed genes in different tissues and developmental phases were identified using RNA-seq data, which revealed that CamTERFs exhibit various expression and co-expression patterns. Gene ontology (GO) annotations associated CamTERFs primarily with mitochondrion and chloroplast function and composition. These results contribute towards understanding the role of mTERFs in capsicum growth, development, and stress responses. Moreover, our data assist in the identification of CamTERFs with important functions, which opens avenues for future studies.
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18
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Kotrys AV, Szczesny RJ. Mitochondrial Gene Expression and Beyond-Novel Aspects of Cellular Physiology. Cells 2019; 9:cells9010017. [PMID: 31861673 PMCID: PMC7017415 DOI: 10.3390/cells9010017] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 12/15/2019] [Accepted: 12/17/2019] [Indexed: 02/06/2023] Open
Abstract
Mitochondria are peculiar organelles whose proper function depends on the crosstalk between two genomes, mitochondrial and nuclear. The human mitochondrial genome (mtDNA) encodes only 13 proteins; nevertheless, its proper expression is essential for cellular homeostasis, as mtDNA-encoded proteins are constituents of mitochondrial respiratory complexes. In addition, mtDNA expression results in the production of RNA molecules, which influence cell physiology once released from the mitochondria into the cytoplasm. As a result, dysfunctions of mtDNA expression may lead to pathologies in humans. Here, we review the mechanisms of mitochondrial gene expression with a focus on recent findings in the field. We summarize the complex turnover of mitochondrial transcripts and present an increasing body of evidence indicating new functions of mitochondrial transcripts. We discuss mitochondrial gene regulation in different cellular contexts, focusing on stress conditions. Finally, we highlight the importance of emerging aspects of mitochondrial gene regulation in human health and disease.
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19
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Holt IJ. The mitochondrial R-loop. Nucleic Acids Res 2019; 47:5480-5489. [PMID: 31045202 PMCID: PMC6582354 DOI: 10.1093/nar/gkz277] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 03/11/2019] [Accepted: 04/29/2019] [Indexed: 12/18/2022] Open
Abstract
The DNA in mitochondria contributes essential components of the organelle’s energy producing machinery that is essential for life. In 1971, many mitochondrial DNA molecules were found to have a third strand of DNA that maps to a region containing critical regulatory elements for transcription and replication. Forty-five years later, a third strand of RNA in the same region has been reported. This mitochondrial R-loop is present on thousands of copies of mitochondrial DNA per cell making it potentially the most abundant R-loop in nature. Here, I assess the discovery of the mitochondrial R-loop, discuss why it remained unrecognized for almost half a century and propose for it central roles in the replication, organization and expression of mitochondrial DNA, which if compromised can lead to disease states.
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Affiliation(s)
- Ian J Holt
- Biodonostia Health Research Institute, 20014 San Sebastián, Spain & IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain.,Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, Royal Free Campus, London, NW3 2PF, UK.,CIBERNED (Center for Networked Biomedical Research on Neurodegenerative Diseases, Ministry of Economy and Competitiveness, Institute Carlos III), Madrid, Spain
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20
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Bouda E, Stapon A, Garcia-Diaz M. Mechanisms of mammalian mitochondrial transcription. Protein Sci 2019; 28:1594-1605. [PMID: 31309618 DOI: 10.1002/pro.3688] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 07/10/2019] [Accepted: 07/11/2019] [Indexed: 01/06/2023]
Abstract
Numerous age-related human diseases have been associated with deficiencies in cellular energy production. Moreover, genetic alterations resulting in mitochondrial dysfunction are the cause of inheritable disorders commonly known as mitochondrial diseases. Many of these deficiencies have been directly or indirectly linked to deficits in mitochondrial gene expression. Transcription is an essential step in gene expression and elucidating the molecular mechanisms involved in this process is critical for understanding defects in energy production. For the past five decades, substantial efforts have been invested in the field of mitochondrial transcription. These efforts have led to the discovery of the main protein factors responsible for transcription as well as to a basic mechanistic understanding of the transcription process. They have also revealed various mechanisms of transcriptional regulation as well as the links that exist between the transcription process and downstream processes of RNA maturation. Here, we review the knowledge gathered in early mitochondrial transcription studies and focus on recent findings that shape our current understanding of mitochondrial transcription, posttranscriptional processing, as well as transcriptional regulation in mammalian systems.
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Affiliation(s)
- Emilie Bouda
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York
| | - Anthony Stapon
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York
| | - Miguel Garcia-Diaz
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York
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21
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Bernhard T, Koch M, Snowdon RJ, Friedt W, Wittkop B. Undesired fertility restoration in msm1 barley associates with two mTERF genes. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2019; 132:1335-1350. [PMID: 30659305 DOI: 10.1007/s00122-019-03281-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 01/07/2019] [Indexed: 05/02/2023]
Abstract
The novel Rfm3 locus causing undesired fertility restoration in the msm1 cytoplasm of winter barley is located on the short arm of chromosome 6H. Undesired fertility restoration of cytoplasmic male sterile (CMS) mother lines in absence of the functional Rfm1 restorer gene is a significant problem for hybrid breeding in winter barley. Here, we describe that a novel restorer locus on the short arm of chromosome 6H, designated Rfm3, is closely linked to two mitochondrial transcription termination factor family (mTERF) protein coding genes. Genome-wide association studies in a multiparental mapping population revealed that two of the most significantly associated markers are located very close to these genes, with one marker lying directly within one mTERF gene sequence. Sequences of the candidate genes in the parental lines, segregating individuals and an independent set of breeding lines clearly revealed haplotypes discriminating completely sterile, partially fertile and Rfm1-restorer lines. The haplotypes segregate for several single nucleotide polymorphisms, a 6 bp insertion-deletion (InDel) polymorphism and another 2 bp InDel. CMS-unstable genotypes carrying haplotypes associated with undesired fertility restoration showed significantly higher grain setting on bagged spikes when plants were subjected to elevated temperatures during anthesis, indicating a temperature influence on pollen fertility. SNPs associated with desirable Rfm3 haplotypes can be implemented in marker-assisted selection of stable CMS mother lines.
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Affiliation(s)
- Timm Bernhard
- Department of Plant Breeding, IFZ Research Centre for Biosystems, Land Use and Nutrition, Justus Liebig University, Heinrich-Buff-Ring 26-32, 35392, Giessen, Germany.
| | - Michael Koch
- Deutsche Saatveredelung AG, Thueler Str. 30, 33154, Salzkotten, Germany
| | - Rod J Snowdon
- Department of Plant Breeding, IFZ Research Centre for Biosystems, Land Use and Nutrition, Justus Liebig University, Heinrich-Buff-Ring 26-32, 35392, Giessen, Germany
| | - Wolfgang Friedt
- Department of Plant Breeding, IFZ Research Centre for Biosystems, Land Use and Nutrition, Justus Liebig University, Heinrich-Buff-Ring 26-32, 35392, Giessen, Germany
| | - Benjamin Wittkop
- Department of Plant Breeding, IFZ Research Centre for Biosystems, Land Use and Nutrition, Justus Liebig University, Heinrich-Buff-Ring 26-32, 35392, Giessen, Germany
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22
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Ji D, Manavski N, Meurer J, Zhang L, Chi W. Regulated chloroplast transcription termination. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1860:69-77. [PMID: 30414934 DOI: 10.1016/j.bbabio.2018.11.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 10/15/2018] [Accepted: 11/07/2018] [Indexed: 11/16/2022]
Abstract
Transcription termination by the RNA polymerase (RNAP) is a fundamental step of gene expression that involves the release of the nascent transcript and dissociation of the RNAP from the DNA template. However, the functional importance of termination extends beyond the mere definition of the gene borders. Chloroplasts originate from cyanobacteria and possess their own gene expression system. Plastids have a unique hybrid transcription system consisting of two different types of RNAPs of dissimilar phylogenetic origin together with several additional nuclear encoded components. Although the basic components involved in chloroplast transcription have been identified, little attention has been paid to the chloroplast transcription termination. Recent identification and functional characterization of novel factors in regulating transcription termination in Arabidopsis chloroplasts via genetic and biochemical approaches have provided insights into the mechanisms and significance of transcription termination in chloroplast gene expression. This review provides an overview of the current knowledge of the transcription termination in chloroplasts.
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Affiliation(s)
- Daili Ji
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Nikolay Manavski
- Centre National de la Recherche Scientifique (CNRS), Institut de Biologie Moleculaire des Plantes, 12 rue du General Zimmer, 67084 Strasbourg, France
| | - Jörg Meurer
- Plant Molecular Biology, Faculty of Biology, Ludwig-Maximilians-University Munich, D-82152 Planegg-Martinsried, Germany
| | - Lixin Zhang
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Wei Chi
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
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23
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Structural basis of mitochondrial transcription. Nat Struct Mol Biol 2018; 25:754-765. [PMID: 30190598 DOI: 10.1038/s41594-018-0122-9] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 07/29/2018] [Indexed: 01/17/2023]
Abstract
The mitochondrial genome is transcribed by a single-subunit DNA-dependent RNA polymerase (mtRNAP) and its auxiliary factors. Structural studies have elucidated how mtRNAP cooperates with its dedicated transcription factors to direct RNA synthesis: initiation factors TFAM and TFB2M assist in promoter-DNA binding and opening by mtRNAP while the elongation factor TEFM increases polymerase processivity to the levels required for synthesis of long polycistronic mtRNA transcripts. Here, we review the emerging body of structural and functional studies of human mitochondrial transcription, provide a molecular movie that can be used for teaching purposes and discuss the open questions to guide future directions of investigation.
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The Characterization of Arabidopsis mterf6 Mutants Reveals a New Role for mTERF6 in Tolerance to Abiotic Stress. Int J Mol Sci 2018; 19:ijms19082388. [PMID: 30110886 PMCID: PMC6121570 DOI: 10.3390/ijms19082388] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 08/06/2018] [Accepted: 08/11/2018] [Indexed: 12/29/2022] Open
Abstract
Exposure of plants to abiotic stresses, such as salinity, cold, heat, or drought, affects their growth and development, and can significantly reduce their productivity. Plants have developed adaptive strategies to deal with situations of abiotic stresses with guarantees of success, which have favoured the expansion and functional diversification of different gene families. The family of mitochondrial transcription termination factors (mTERFs), first identified in animals and more recently in plants, is likely a good example of this. In plants, mTERFs are located in chloroplasts and/or mitochondria, participate in the control of organellar gene expression (OGE), and, compared with animals, the mTERF family is expanded. Furthermore, the mutations in some of the hitherto characterised plant mTERFs result in altered responses to salt, high light, heat, or osmotic stress, which suggests a role for these genes in plant adaptation and tolerance to adverse environmental conditions. In this work, we investigated the effect of impaired mTERF6 function on the tolerance of Arabidopsis to salt, osmotic and moderate heat stresses, and on the response to the abscisic acid (ABA) hormone, required for plants to adapt to abiotic stresses. We found that the strong loss-of-function mterf6-2 and mterf6-5 mutants, mainly the former, were hypersensitive to NaCl, mannitol, and ABA during germination and seedling establishment. Additionally, mterf6-5 exhibited a higher sensitivity to moderate heat stress and a lower response to NaCl and ABA later in development. Our computational analysis revealed considerable changes in the mTERF6 transcript levels in plants exposed to different abiotic stresses. Together, our results pinpoint a function for Arabidopsis mTERF6 in the tolerance to adverse environmental conditions, and highlight the importance of plant mTERFs, and hence of OGE homeostasis, for proper acclimation to abiotic stress.
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Hussain M, Iqbal MA, Till BJ, Rahman MU. Identification of induced mutations in hexaploid wheat genome using exome capture assay. PLoS One 2018; 13:e0201918. [PMID: 30102729 PMCID: PMC6089429 DOI: 10.1371/journal.pone.0201918] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 07/24/2018] [Indexed: 12/02/2022] Open
Abstract
Wheat is a staple food crop of many countries. Improving resilience to biotic and abiotic stresses remain key breeding targets. Among these, rust diseases are the most detrimental in terms of depressing wheat production. In the present study, chemical mutagenesis was used to induce mutations in the wheat variety NN-Gandum-1. This cultivar is moderately resistant to leaf and yellow rust. The aim of mutagenesis was to improve resistance to the disease as well as to study function of genes conferring resistance to the disease. In the present investigation, a 0.8% EMS dose was found optimum for supporting 45-55% germination of NN-Gandum-1. A total of 3,634 M2 fertile plants were produced from each of the M1 plant. Out of these, 33 (0.91%) and 20 plants (0.55%) showed absolute resistance to leaf and yellow rust, respectively. While 126 (3.46%) and 127 plants (3.49%) exhibited high susceptibility to the leaf and yellow rust, respectively. In the M4 generation, a total of 11 M4 lines (nine absolute resistant and two highly susceptible) and one wild type were selected for NGS-based exome capture assay. A total of 104,779 SNPs were identified that were randomly distributed throughout the wheat sub genomes (A, B and D). Induced mutations in intronic sequences predominated. The highest total number of SNPs detected in this assay were mapped to chr.2B (14,273 SNPs), which contains the highest number of targeted base pairs in the assay. The average mutation density across all regions interrogated was estimated to be one mutation per 20.91 Mb. The highest mutation frequency was found in chr.2D (1/11.7 kb) and the lowest in chr.7D (1/353.4 kb). Out of the detected mutations, 101 SNPs were filtered using analysis criteria aimed to enrich for mutations that may affect gene function. Out of these, one putative SNP detected in Lr21 were selected for further analysis. The SNP identified in chimeric allele (Lr21) of a resistant mutant (N1-252) was located in a NBS domain of chr.1BS at 3.4 Mb position. Through computational analysis, it was demonstrated that this identified SNP causes a substitution of glutamic acid with alanine, resulting in a predicted altered protein structure. This mutation, therefore, is a candidate for contributing to the resistance phenotype in the mutant line. Based on this work, we conclude that the wheat mutant resource developed is useful as a source of novel genetic variation for forward-genetic screens and also as a useful tool for gaining insights into the important biological circuits of different traits of complex genomes like wheat.
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Affiliation(s)
- Momina Hussain
- Plant Genomics & Mol. Breeding Lab, National Institute for Biotechnology & Genetic Engineering (NIBGE), Faisalabad, Pakistan
- Department of Biotechnology, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad, Pakistan
| | - Muhammad Atif Iqbal
- Plant Genomics & Mol. Breeding Lab, National Institute for Biotechnology & Genetic Engineering (NIBGE), Faisalabad, Pakistan
- Department of Biotechnology, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad, Pakistan
| | - Bradley J. Till
- University of Vienna, Department fürChromosomenbiologie, Vienna, Austria
| | - Mehboob-ur- Rahman
- Plant Genomics & Mol. Breeding Lab, National Institute for Biotechnology & Genetic Engineering (NIBGE), Faisalabad, Pakistan
- Department of Biotechnology, Pakistan Institute of Engineering and Applied Sciences (PIEAS), Nilore, Islamabad, Pakistan
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Zhang Y, Cui YL, Zhang XL, Yu QB, Wang X, Yuan XB, Qin XM, He XF, Huang C, Yang ZN. A nuclear-encoded protein, mTERF6, mediates transcription termination of rpoA polycistron for plastid-encoded RNA polymerase-dependent chloroplast gene expression and chloroplast development. Sci Rep 2018; 8:11929. [PMID: 30093718 PMCID: PMC6085346 DOI: 10.1038/s41598-018-30166-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 04/20/2018] [Indexed: 12/13/2022] Open
Abstract
The expression of plastid genes is regulated by two types of DNA-dependent RNA polymerases, plastid-encoded RNA polymerase (PEP) and nuclear-encoded RNA polymerase (NEP). The plastid rpoA polycistron encodes a series of essential chloroplast ribosome subunits and a core subunit of PEP. Despite the functional importance, little is known about the regulation of rpoA polycistron. In this work, we show that mTERF6 directly associates with a 3′-end sequence of rpoA polycistron in vitro and in vivo, and that absence of mTERF6 promotes read-through transcription at this site, indicating that mTERF6 acts as a factor required for termination of plastid genes’ transcription in vivo. In addition, the transcriptions of some essential ribosome subunits encoded by rpoA polycistron and PEP-dependent plastid genes are reduced in the mterf6 knockout mutant. RpoA, a PEP core subunit, accumulates to about 50% that of the wild type in the mutant, where early chloroplast development is impaired. Overall, our functional analyses of mTERF6 provide evidence that it is more likely a factor required for transcription termination of rpoA polycistron, which is essential for chloroplast gene expression and chloroplast development.
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Affiliation(s)
- Yi Zhang
- College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China.,Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences, Shanghai, 201602, China
| | - Yong-Lan Cui
- College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Xiao-Lei Zhang
- College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Qing-Bo Yu
- College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Xi Wang
- College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Xin-Bo Yuan
- College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Xue-Mei Qin
- College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Xiao-Fang He
- College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Chao Huang
- College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Zhong-Nan Yang
- College of Life and Environmental Sciences, Shanghai Normal University, Shanghai, 200234, China.
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27
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Shoguchi E, Beedessee G, Tada I, Hisata K, Kawashima T, Takeuchi T, Arakaki N, Fujie M, Koyanagi R, Roy MC, Kawachi M, Hidaka M, Satoh N, Shinzato C. Two divergent Symbiodinium genomes reveal conservation of a gene cluster for sunscreen biosynthesis and recently lost genes. BMC Genomics 2018; 19:458. [PMID: 29898658 PMCID: PMC6001144 DOI: 10.1186/s12864-018-4857-9] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 06/06/2018] [Indexed: 11/10/2022] Open
Abstract
Background The marine dinoflagellate, Symbiodinium, is a well-known photosynthetic partner for coral and other diverse, non-photosynthetic hosts in subtropical and tropical shallows, where it comprises an essential component of marine ecosystems. Using molecular phylogenetics, the genus Symbiodinium has been classified into nine major clades, A-I, and one of the reported differences among phenotypes is their capacity to synthesize mycosporine-like amino acids (MAAs), which absorb UV radiation. However, the genetic basis for this difference in synthetic capacity is unknown. To understand genetics underlying Symbiodinium diversity, we report two draft genomes, one from clade A, presumed to have been the earliest branching clade, and the other from clade C, in the terminal branch. Results The nuclear genome of Symbiodinium clade A (SymA) has more gene families than that of clade C, with larger numbers of organelle-related genes, including mitochondrial transcription terminal factor (mTERF) and Rubisco. While clade C (SymC) has fewer gene families, it displays specific expansions of repeat domain-containing genes, such as leucine-rich repeats (LRRs) and retrovirus-related dUTPases. Interestingly, the SymA genome encodes a gene cluster for MAA biosynthesis, potentially transferred from an endosymbiotic red alga (probably of bacterial origin), while SymC has completely lost these genes. Conclusions Our analysis demonstrates that SymC appears to have evolved by losing gene families, such as the MAA biosynthesis gene cluster. In contrast to the conservation of genes related to photosynthetic ability, the terminal clade has suffered more gene family losses than other clades, suggesting a possible adaptation to symbiosis. Overall, this study implies that Symbiodinium ecology drives acquisition and loss of gene families. Electronic supplementary material The online version of this article (10.1186/s12864-018-4857-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Eiichi Shoguchi
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, 904-0495, Japan.
| | - Girish Beedessee
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, 904-0495, Japan
| | - Ipputa Tada
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, 904-0495, Japan.,Present address: Department of Genetics, School of Life Science, The Graduate University for Advanced Studies, 1111, Yata, Mishima-shi, Shizuoka, 411-8540, Japan
| | - Kanako Hisata
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, 904-0495, Japan
| | - Takeshi Kawashima
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, 904-0495, Japan.,Present address: Center for Information Biology, National Institute of Genetics, Mishima, 411-8540, Japan
| | - Takeshi Takeuchi
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, 904-0495, Japan
| | - Nana Arakaki
- DNA Sequencing Section, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, 904-0495, Japan
| | - Manabu Fujie
- DNA Sequencing Section, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, 904-0495, Japan
| | - Ryo Koyanagi
- DNA Sequencing Section, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, 904-0495, Japan
| | - Michael C Roy
- Instrumental Analysis Section, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, 904-0495, Japan
| | - Masanobu Kawachi
- Center for Environmental Biology and Ecosystem Studies, National Institute for Environmental Studies, Tsukuba, 305-8506, Japan
| | - Michio Hidaka
- Department of Chemistry, Biology and Marine Science, University of the Ryukyus, Nishihara, Okinawa, 903-0213, Japan
| | - Noriyuki Satoh
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, 904-0495, Japan
| | - Chuya Shinzato
- Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, 904-0495, Japan. .,Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwanoha, Kashiwa, 277-8564, Japan.
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28
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Shokolenko IN, Alexeyev MF. Mitochondrial transcription in mammalian cells. Front Biosci (Landmark Ed) 2017; 22:835-853. [PMID: 27814650 DOI: 10.2741/4520] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
As a consequence of recent discoveries of intimate involvement of mitochondria with key cellular processes, there has been a resurgence of interest in all aspects of mitochondrial biology, including the intricate mechanisms of mitochondrial DNA maintenance and expression. Despite four decades of research, there remains a lot to be learned about the processes that enable transcription of genetic information from mitochondrial DNA to RNA, as well as their regulation. These processes are vitally important, as evidenced by the lethality of inactivating the central components of mitochondrial transcription machinery. Here, we review the current understanding of mitochondrial transcription and its regulation in mammalian cells. We also discuss key theories in the field and highlight controversial subjects and future directions as we see them.
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Affiliation(s)
- Inna N Shokolenko
- University of South Alabama, Patt Capps Covey College of Allied Health Professions, Biomedical Sciences Department, 5721 USA Drive N, HAHN 4021, Mobile, AL 36688-0002, USA
| | - Mikhail F Alexeyev
- Department of Physiology and Cell Biology, University of South Alabama, 5851 USA Dr. North, MSB3074, Mobile, AL 36688, USA,
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29
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Xu D, Leister D, Kleine T. Arabidopsis thaliana mTERF10 and mTERF11, but Not mTERF12, Are Involved in the Response to Salt Stress. FRONTIERS IN PLANT SCIENCE 2017; 8:1213. [PMID: 28769941 PMCID: PMC5509804 DOI: 10.3389/fpls.2017.01213] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 06/27/2017] [Indexed: 05/10/2023]
Abstract
Plastid gene expression (PGE) is crucial for plant development and acclimation to various environmental stress conditions. Members of the "mitochondrial transcription termination factor" (mTERF) family, which are present in both metazoans and plants, are involved in organellar gene expression. Arabidopsis thaliana contains 35 mTERF proteins, of which mTERF10, mTERF11, and mTERF12 were previously assigned to the "chloroplast-associated" group. Here, we show that all three are localized to chloroplast nucleoids, which are associated with PGE. Knock-down of MTERF10, MTERF11, or MTERF12 has no overt phenotypic effect under normal growth conditions. However, in silico analysis of MTERF10, -11, and -12 expression levels points to a possible involvement of mTERF10 and mTERF11 in responses to abiotic stress. Exposing mutant lines for 7 days to moderate heat (30°C) or light stress (400 μmol photons m-2 s-1) fails to induce a phenotype in mterf mutant lines. However, growth on MS medium supplemented with NaCl reveals that overexpression of MTERF11 results in higher salt tolerance. Conversely, mterf10 mutants are hypersensitive to salt stress, while plants that modestly overexpress MTERF10 are markedly less susceptible. Furthermore, MTERF10 overexpression leads to enhanced germination and growth on MS medium supplemented with ABA. These findings point to an involvement of mTERF10 in salt tolerance, possibly through an ABA-mediated mechanism. Thus, characterization of an increasing number of plant mTERF proteins reveals their roles in the response, tolerance and acclimation to different abiotic stresses.
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30
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Quesada V. The roles of mitochondrial transcription termination factors (MTERFs) in plants. PHYSIOLOGIA PLANTARUM 2016; 157:389-99. [PMID: 26781919 DOI: 10.1111/ppl.12416] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 11/16/2015] [Accepted: 11/24/2015] [Indexed: 05/25/2023]
Abstract
Stress such as salinity, cold, heat or drought affect plant growth and development, and frequently result in diminished productivity. Unlike animals, plants are sedentary organisms that must withstand and cope with environmental stresses. During evolution, plants have developed strategies to successfully adapt to or tolerate such stresses, which might have led to the expansion and functional diversification of gene families. Some new genes may have acquired functions that could differ from those of their animal homologues, e.g. in response to abiotic stress. The mitochondrial transcription termination factor (MTERF) family could be a good example of this. Originally identified and characterized in metazoans, MTERFs regulate transcription, translation and DNA replication in vertebrate mitochondria. Plant genomes harbor a considerably larger number of MTERFs than animals. Nonetheless, only eight plant MTERFs have been characterized, which encode chloroplast or mitochondrial proteins. Mutations in MTERFs alter the expression of organelle genes and impair chloroplast or mitochondria development. This information is transmitted to the nucleus, probably through retrograde signaling, because mterf plants often exhibit changes in nuclear gene expression. This study summarizes the recent findings, mainly from the analysis of mterf mutants, which support an emerging role for plant MTERFs in response to abiotic stress.
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Affiliation(s)
- Víctor Quesada
- Instituto de Bioingeniería, Universidad Miguel Hernández, Campus de Elche, 03202, Elche, Spain
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31
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Byrnes J, Hauser K, Norona L, Mejia E, Simmerling C, Garcia-Diaz M. Base Flipping by MTERF1 Can Accommodate Multiple Conformations and Occurs in a Stepwise Fashion. J Mol Biol 2016; 428:2542-2556. [PMID: 26523681 PMCID: PMC4851923 DOI: 10.1016/j.jmb.2015.10.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Revised: 10/14/2015] [Accepted: 10/20/2015] [Indexed: 11/28/2022]
Abstract
Human mitochondrial transcription termination occurs within the leu-tRNA gene and is mediated by the DNA binding protein MTERF1. The crystal structure of MTERF1 bound to the canonical termination sequence reveals a rare base flipping event that involves the eversion of three nucleotides. These nucleotides are stabilized by stacking interactions with three MTERF1 residues, which are essential not only for base flipping but also for termination activity. To further understand the mechanism of base flipping, we examined each of the individual stacking interactions in structural, energetic and functional detail. Individual substitutions of Arg162, Tyr288 and Phe243 have revealed unequal contributions to overall termination activity. Furthermore, our work identifies an important role for Phe322 in the base flipping mechanism and we demonstrate how Phe322 and Phe243 are important for coupling base flipping between the heavy and light strand DNA chains. We propose a stepwise model for the base flipping process that recapitulates our observations. Finally, we show that MTERF1 has the ability to accommodate alternate active conformations. The adaptability of base flipping has implications for MTERF1 function and for the putative function of MTERF1 at alternative binding sites in human mitochondria.
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Affiliation(s)
- James Byrnes
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794, USA
| | - Kevin Hauser
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794, USA
| | - Leah Norona
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794, USA
| | - Edison Mejia
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794, USA
| | - Carlos Simmerling
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794, USA; Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Miguel Garcia-Diaz
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794, USA.
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32
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Shi Y, Posse V, Zhu X, Hyvärinen AK, Jacobs HT, Falkenberg M, Gustafsson CM. Mitochondrial transcription termination factor 1 directs polar replication fork pausing. Nucleic Acids Res 2016; 44:5732-42. [PMID: 27112570 PMCID: PMC4937320 DOI: 10.1093/nar/gkw302] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 04/12/2016] [Indexed: 12/01/2022] Open
Abstract
During replication of nuclear ribosomal DNA (rDNA), clashes with the transcription apparatus can cause replication fork collapse and genomic instability. To avoid this problem, a replication fork barrier protein is situated downstream of rDNA, there preventing replication in the direction opposite rDNA transcription. A potential candidate for a similar function in mitochondria is the mitochondrial transcription termination factor 1 (MTERF1, also denoted mTERF), which binds to a sequence just downstream of the ribosomal transcription unit. Previous studies have shown that MTERF1 prevents antisense transcription over the ribosomal RNA genes, a process which we here show to be independent of the transcription elongation factor TEFM. Importantly, we now demonstrate that MTERF1 arrests mitochondrial DNA (mtDNA) replication with distinct polarity. The effect is explained by the ability of MTERF1 to act as a directional contrahelicase, blocking mtDNA unwinding by the mitochondrial helicase TWINKLE. This conclusion is also supported by in vivo evidence that MTERF1 stimulates TWINKLE pausing. We conclude that MTERF1 can direct polar replication fork arrest in mammalian mitochondria.
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Affiliation(s)
- Yonghong Shi
- Institute of Biomedicine, University of Gothenburg, P.O. Box 440, SE-405 30 Gothenburg, Sweden Center for Molecular Medicine, National Heart Lung and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Viktor Posse
- Institute of Biomedicine, University of Gothenburg, P.O. Box 440, SE-405 30 Gothenburg, Sweden
| | - Xuefeng Zhu
- Institute of Biomedicine, University of Gothenburg, P.O. Box 440, SE-405 30 Gothenburg, Sweden Center for Molecular Medicine, National Heart Lung and Blood Institute, NIH, Bethesda, MD 20892, USA
| | - Anne K Hyvärinen
- BioMediTech and Tampere University Hospital, FI-33014, University of Tampere, Finland
| | - Howard T Jacobs
- BioMediTech and Tampere University Hospital, FI-33014, University of Tampere, Finland Institute of Biotechnology, FI-00014, University of Helsinki, Finland
| | - Maria Falkenberg
- Institute of Biomedicine, University of Gothenburg, P.O. Box 440, SE-405 30 Gothenburg, Sweden
| | - Claes M Gustafsson
- Institute of Biomedicine, University of Gothenburg, P.O. Box 440, SE-405 30 Gothenburg, Sweden
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Abstract
Mammalian mitochondrial DNA (mtDNA) encodes 13 proteins that are essential for the function of the oxidative phosphorylation system, which is composed of four respiratory-chain complexes and adenosine triphosphate (ATP) synthase. Remarkably, the maintenance and expression of mtDNA depend on the mitochondrial import of hundreds of nuclear-encoded proteins that control genome maintenance, replication, transcription, RNA maturation, and mitochondrial translation. The importance of this complex regulatory system is underscored by the identification of numerous mutations of nuclear genes that impair mtDNA maintenance and expression at different levels, causing human mitochondrial diseases with pleiotropic clinical manifestations. The basic scientific understanding of the mechanisms controlling mtDNA function has progressed considerably during the past few years, thanks to advances in biochemistry, genetics, and structural biology. The challenges for the future will be to understand how mtDNA maintenance and expression are regulated and to what extent direct intramitochondrial cross talk between different processes, such as transcription and translation, is important.
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Affiliation(s)
- Claes M Gustafsson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, 405 30 Gothenburg, Sweden; ,
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, 405 30 Gothenburg, Sweden; ,
| | - Nils-Göran Larsson
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany; .,Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden
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34
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Robles P, Micol JL, Quesada V. Mutations in the plant-conserved MTERF9 alter chloroplast gene expression, development and tolerance to abiotic stress in Arabidopsis thaliana. PHYSIOLOGIA PLANTARUM 2015; 154:297-313. [PMID: 25393651 DOI: 10.1111/ppl.12307] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 10/27/2014] [Accepted: 11/04/2014] [Indexed: 05/07/2023]
Abstract
The control of organelle gene expression in plants is far from fully understood. The characterization of mutants in Arabidopsis thaliana is assigning an increasingly prominent role to the mitochondrial transcription termination factors (mTERFs) in this process. To gain insight into the function of mTERF genes in plants, we took a reverse genetics approach to identify and characterize A. thaliana mTERF-defective mutants. Here we report the characterization of the mterf9 mutant, affected in an mTERF protein functionally conserved in plants and targeted to chloroplasts. Loss of MTERF9 results in defective chloroplast development, which is likely to cause paleness, stunted growth and reduced mesophyll cell numbers. Expression analysis of different plastid genes revealed reduced levels of plastid-encoded polymerase (PEP)-dependent transcripts and increased levels of transcripts dependent of nucleus-encoded polymerase. mterf9 plants exhibited altered responses to sugars, abscisic acid (ABA), salt and osmotic stresses, and the microarray data analysis showed modifications in MTERF9 expression after salt or mannitol treatments. Our genetic interactions results indicate a functional relationship between MTERF9 and the previously characterized MDA1 gene, and between MDA1 and some plastid ribosomal genes. MDA1 and MTERF9 were upregulated in the mterf9 and mda1 mutants, respectively. Moreover, 21 of 50 genes were commonly co-expressed with MDA1 and MTERF9. The analysis of the MDA1 and MTERF9 promoters showed that both were rich in stress-related cis-regulatory elements. Our results highlight the role of the MTERF9 gene in plant biology and deepens the understanding of the functional relationship of plant mTERF genes.
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Affiliation(s)
- Pedro Robles
- Instituto de Bioingeniería, Universidad Miguel Hernández, Elche 03202, Spain
| | - José Luis Micol
- Instituto de Bioingeniería, Universidad Miguel Hernández, Elche 03202, Spain
| | - Víctor Quesada
- Instituto de Bioingeniería, Universidad Miguel Hernández, Elche 03202, Spain
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35
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Roberti M, Polosa PL, Bruni F, Deceglie S, Gadaleta MN, Cantatore P. MTERF factors: a multifunction protein family. Biomol Concepts 2015; 1:215-24. [PMID: 25961998 DOI: 10.1515/bmc.2010.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The MTERF family is a large protein family, identified in metazoans and plants, which consists of four subfamilies, MTERF1, 2, 3 and 4. Mitochondrial localisation was predicted for the vast majority of MTERF family members and demonstrated for the characterised MTERF proteins. The main structural feature of MTERF proteins is the presence of a modular architecture, based on repetitions of a 30-residue module, the mTERF motif, containing leucine zipper-like heptads. The MTERF family includes transcription termination factors: human mTERF, sea urchin mtDBP and Drosophila DmTTF. In addition to terminating transcription, they are involved in transcription initiation and in the control of mtDNA replication. This multiplicity of functions seems to flank differences in the gene organisation of mitochondrial genomes. MTERF2 and MTERF3 play antithetical roles in controlling mitochondrial transcription: that is, mammalian and Drosophila MTERF3 act as negative regulators, whereas mammalian MTERF2 functions as a positive regulator. Both proteins contact mtDNA in the promoter region, perhaps establishing interactions, either mutual or with other factors. Regulation of MTERF gene expression in human and Drosophila depends on nuclear transcription factors NRF-2 and DREF, respectively, and proceeds through pathways which appear to discriminate between factors positively or negatively acting in mitochondrial transcription. In this emerging scenario, it appears that MTERF proteins act to coordinate mitochondrial transcription.
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36
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Kaniak-Golik A, Skoneczna A. Mitochondria-nucleus network for genome stability. Free Radic Biol Med 2015; 82:73-104. [PMID: 25640729 DOI: 10.1016/j.freeradbiomed.2015.01.013] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 11/25/2014] [Accepted: 01/13/2015] [Indexed: 12/21/2022]
Abstract
The proper functioning of the cell depends on preserving the cellular genome. In yeast cells, a limited number of genes are located on mitochondrial DNA. Although the mechanisms underlying nuclear genome maintenance are well understood, much less is known about the mechanisms that ensure mitochondrial genome stability. Mitochondria influence the stability of the nuclear genome and vice versa. Little is known about the two-way communication and mutual influence of the nuclear and mitochondrial genomes. Although the mitochondrial genome replicates independent of the nuclear genome and is organized by a distinct set of mitochondrial nucleoid proteins, nearly all genome stability mechanisms responsible for maintaining the nuclear genome, such as mismatch repair, base excision repair, and double-strand break repair via homologous recombination or the nonhomologous end-joining pathway, also act to protect mitochondrial DNA. In addition to mitochondria-specific DNA polymerase γ, the polymerases α, η, ζ, and Rev1 have been found in this organelle. A nuclear genome instability phenotype results from a failure of various mitochondrial functions, such as an electron transport chain activity breakdown leading to a decrease in ATP production, a reduction in the mitochondrial membrane potential (ΔΨ), and a block in nucleotide and amino acid biosynthesis. The loss of ΔΨ inhibits the production of iron-sulfur prosthetic groups, which impairs the assembly of Fe-S proteins, including those that mediate DNA transactions; disturbs iron homeostasis; leads to oxidative stress; and perturbs wobble tRNA modification and ribosome assembly, thereby affecting translation and leading to proteotoxic stress. In this review, we present the current knowledge of the mechanisms that govern mitochondrial genome maintenance and demonstrate ways in which the impairment of mitochondrial function can affect nuclear genome stability.
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Affiliation(s)
- Aneta Kaniak-Golik
- Laboratory of Mutagenesis and DNA Repair, Institute of Biochemistry and Biophysics, Polish Academy of Science, 02-106 Warsaw, Poland
| | - Adrianna Skoneczna
- Laboratory of Mutagenesis and DNA Repair, Institute of Biochemistry and Biophysics, Polish Academy of Science, 02-106 Warsaw, Poland.
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Iommarini L, Peralta S, Torraco A, Diaz F. Mitochondrial Diseases Part II: Mouse models of OXPHOS deficiencies caused by defects in regulatory factors and other components required for mitochondrial function. Mitochondrion 2015; 22:96-118. [PMID: 25640959 DOI: 10.1016/j.mito.2015.01.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 01/22/2015] [Indexed: 01/21/2023]
Abstract
Mitochondrial disorders are defined as defects that affect the oxidative phosphorylation system (OXPHOS). They are characterized by a heterogeneous array of clinical presentations due in part to a wide variety of factors required for proper function of the components of the OXPHOS system. There is no cure for these disorders owing to our poor knowledge of the pathogenic mechanisms of disease. To understand the mechanisms of human disease numerous mouse models have been developed in recent years. Here we summarize the features of several mouse models of mitochondrial diseases directly related to those factors affecting mtDNA maintenance, replication, transcription, translation as well as other proteins that are involved in mitochondrial dynamics and quality control which affect mitochondrial OXPHOS function without being intrinsic components of the system. We discuss how these models have contributed to our understanding of mitochondrial diseases and their pathogenic mechanisms.
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Affiliation(s)
- Luisa Iommarini
- Department of Pharmacy and Biotechnology (FABIT), University of Bologna, Via Irnerio 42, 40128 Bologna, Italy.
| | - Susana Peralta
- Department of Neurology, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
| | - Alessandra Torraco
- Unit for Neuromuscular and Neurodegenerative Disorders, Laboratory of Molecular Medicine, Bambino Gesù Children's Hospital, IRCCS, Viale di San Paolo, 15 - 00146, Rome, Italy.
| | - Francisca Diaz
- Department of Neurology, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
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Emerging functions of mammalian and plant mTERFs. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:786-97. [PMID: 25582570 DOI: 10.1016/j.bbabio.2014.12.009] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 12/21/2014] [Indexed: 11/24/2022]
Abstract
Organellar gene expression (OGE) is crucial for plant development, respiration and photosynthesis, but the mechanisms that control it are still largely unclear. Thus, OGE requires various nucleus-encoded proteins that promote transcription, splicing, trimming and editing of organellar RNAs, and regulate their translation. In mammals, members of the mitochondrial transcription termination factor (mTERF) family play important roles in OGE. Intriguingly, three of the four mammalian mTERFs do not actually terminate transcription, as their designation suggests, but appear to function in antisense transcription termination and ribosome biogenesis. During the evolution of land plants, the mTERF family has expanded to approximately 30 members, but knowledge of their function in photosynthetic organisms remains sparse. Here, we review recent advances in the characterization of mterf mutants in mammals and photosynthetic organisms, focusing particularly on the progress made in elucidating their molecular functions in the last two years. This article is part of a Special Issue entitled: Chloroplast biogenesis.
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Hsu YW, Wang HJ, Hsieh MH, Hsieh HL, Jauh GY. Arabidopsis mTERF15 is required for mitochondrial nad2 intron 3 splicing and functional complex I activity. PLoS One 2014; 9:e112360. [PMID: 25402171 PMCID: PMC4234379 DOI: 10.1371/journal.pone.0112360] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 10/03/2014] [Indexed: 01/08/2023] Open
Abstract
Mitochondria play a pivotal role in most eukaryotic cells, as they are responsible for the generation of energy and diverse metabolic intermediates for many cellular events. During endosymbiosis, approximately 99% of the genes encoded by the mitochondrial genome were transferred into the host nucleus, and mitochondria import more than 1000 nuclear-encoded proteins from the cytosol to maintain structural integrity and fundamental functions, including DNA replication, mRNA transcription and RNA metabolism of dozens of mitochondrial genes. In metazoans, a family of nuclear-encoded proteins called the mitochondrial transcription termination factors (mTERFs) regulates mitochondrial transcription, including transcriptional termination and initiation, via their DNA-binding activities, and the dysfunction of individual mTERF members causes severe developmental defects. Arabidopsis thaliana and Oryza sativa contain 35 and 48 mTERFs, respectively, but the biological functions of only a few of these proteins have been explored. Here, we investigated the biological role and molecular mechanism of Arabidopsis mTERF15 in plant organelle metabolism using molecular genetics, cytological and biochemical approaches. The null homozygous T-DNA mutant of mTERF15, mterf15, was found to result in substantial retardation of both vegetative and reproductive development, which was fully complemented by the wild-type genomic sequence. Surprisingly, mitochondria-localized mTERF15 lacks obvious DNA-binding activity but processes mitochondrial nad2 intron 3 splicing through its RNA-binding ability. Impairment of this splicing event not only disrupted mitochondrial structure but also abolished the activity of mitochondrial respiratory chain complex I. These effects are in agreement with the severe phenotype of the mterf15 homozygous mutant. Our study suggests that Arabidopsis mTERF15 functions as a splicing factor for nad2 intron 3 splicing in mitochondria, which is essential for normal plant growth and development.
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Affiliation(s)
- Ya-Wen Hsu
- Institute of Plant Biology, National Taiwan University, Taipei, 116, Taiwan, ROC
- Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei, 11529, Taiwan, ROC
| | - Huei-Jing Wang
- Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei, 11529, Taiwan, ROC
| | - Ming-Hsiun Hsieh
- Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei, 11529, Taiwan, ROC
| | - Hsu-Liang Hsieh
- Institute of Plant Biology, National Taiwan University, Taipei, 116, Taiwan, ROC
| | - Guang-Yuh Jauh
- Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei, 11529, Taiwan, ROC
- Biotechnology Center, National Chung-Hsing University, Taichung, 402, Taiwan, ROC
- * E-mail:
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Chen G, Dai J, Tan S, Meng S, Liu Z, Li M, Cui Q, Yu M. MTERF1 regulates the oxidative phosphorylation activity and cell proliferation in HeLa cells. Acta Biochim Biophys Sin (Shanghai) 2014; 46:512-21. [PMID: 24777141 DOI: 10.1093/abbs/gmu029] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The mitochondrial transcription termination factor (MTERF) family is a group of highly conserved DNA-binding proteins composed of four key members, MTERF1-4. To date, several studies have investigated the binding sites of MTERF1 on mitochondrial genome and the regulation of mitochondrial gene transcription, but the more intricate connection between mitochondrial genes transcription regulation, mitochondrial oxidative phosphorylation (OXPHOS), and cell proliferation is still poorly understood. In this study, we constructed over-expression and knockdown vectors of MTERF1 that were transfected into HeLa cells to investigate the functions of MTERF1. Results showed that although MTERF1 is a positive regulatory factor of mitochondrial genes transcription, it had no significant effect on the replication of mitochondrial DNA. Over-expression of MTERF1 increased mitochondrial oxidative phosphorylation activity and promoted ATP synthesis, cyclin D1 expression, and cell proliferation, while its knockdown inhibited ATP synthesis, decreased cyclin D1 expression, and slowed the cell growth. These results suggested that MTERF1 may promote cell proliferation by regulating oxidative phosphorylation activity in HeLa cells. Ultimately, these findings create a foundation for further and more conclusive studies on the physiological functions of MTERF family by providing novel insights into the potential mechanisms underlying cell proliferation regulation.
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Affiliation(s)
- Guiyuan Chen
- Laboratory of Biochemistry and Molecular Biology, School of Life Sciences, Yunnan University, Kunming 650091, China Department of Biochemistry and Molecular Biology, School of Basic Medicine, Dali University, Dali 671000, China
| | - Jie Dai
- Yunnan Province Disease Prevention Control Center, Kunming 650031, China
| | - Shirui Tan
- Laboratory of Biochemistry and Molecular Biology, School of Life Sciences, Yunnan University, Kunming 650091, China
| | - Shengke Meng
- Laboratory of Biochemistry and Molecular Biology, School of Life Sciences, Yunnan University, Kunming 650091, China
| | - Zhongjian Liu
- Laboratory of Biochemistry and Molecular Biology, School of Life Sciences, Yunnan University, Kunming 650091, China
| | - Meizhang Li
- Laboratory of Biochemistry and Molecular Biology, School of Life Sciences, Yunnan University, Kunming 650091, China
| | - Qinghua Cui
- Laboratory of Biochemistry and Molecular Biology, School of Life Sciences, Yunnan University, Kunming 650091, China
| | - Min Yu
- Laboratory of Biochemistry and Molecular Biology, School of Life Sciences, Yunnan University, Kunming 650091, China
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Hammani K, Giegé P. RNA metabolism in plant mitochondria. TRENDS IN PLANT SCIENCE 2014; 19:380-9. [PMID: 24462302 DOI: 10.1016/j.tplants.2013.12.008] [Citation(s) in RCA: 142] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 12/11/2013] [Accepted: 12/19/2013] [Indexed: 05/02/2023]
Abstract
Mitochondria are essential for the eukaryotic cell and are derived from the endosymbiosis of an α-proteobacterial ancestor. Compared to other eukaryotes, RNA metabolism in plant mitochondria is complex and combines bacterial-like traits with novel features that evolved in the host cell. These complex RNA processes are regulated by families of nucleus-encoded RNA-binding proteins. Transcription is particularly relaxed and is initiated from multiple promoters covering the entire genome. The variety of RNA precursors accumulating in mitochondria highlights the importance of post-transcriptional processes to determine the size and abundance of transcripts. Here we review RNA metabolism in plant mitochondria, from RNA transcription to translation, with a special focus on their unique features that are controlled by trans-factors.
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Affiliation(s)
- Kamel Hammani
- Centre National de la Recherche Scientifique (CNRS), Institut de Biologie Moléculaire des Plantes, Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France.
| | - Philippe Giegé
- Centre National de la Recherche Scientifique (CNRS), Institut de Biologie Moléculaire des Plantes, Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France
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Hensen F, Cansiz S, Gerhold JM, Spelbrink JN. To be or not to be a nucleoid protein: A comparison of mass-spectrometry based approaches in the identification of potential mtDNA-nucleoid associated proteins. Biochimie 2014; 100:219-26. [DOI: 10.1016/j.biochi.2013.09.017] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 09/17/2013] [Indexed: 01/09/2023]
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Zhao Y, Cai M, Zhang X, Li Y, Zhang J, Zhao H, Kong F, Zheng Y, Qiu F. Genome-wide identification, evolution and expression analysis of mTERF gene family in maize. PLoS One 2014; 9:e94126. [PMID: 24718683 PMCID: PMC3981765 DOI: 10.1371/journal.pone.0094126] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 03/12/2014] [Indexed: 11/19/2022] Open
Abstract
Plant mitochondrial transcription termination factor (mTERF) genes comprise a large family with important roles in regulating organelle gene expression. In this study, a comprehensive database search yielded 31 potential mTERF genes in maize (Zea mays L.) and most of them were targeted to mitochondria or chloroplasts. Maize mTERF were divided into nine main groups based on phylogenetic analysis, and group IX represented the mitochondria and species-specific clade that diverged from other groups. Tandem and segmental duplication both contributed to the expansion of the mTERF gene family in the maize genome. Comprehensive expression analysis of these genes, using microarray data and RNA-seq data, revealed that these genes exhibit a variety of expression patterns. Environmental stimulus experiments revealed differential up or down-regulation expression of maize mTERF genes in seedlings exposed to light/dark, salts and plant hormones, respectively, suggesting various important roles of maize mTERF genes in light acclimation and stress-related responses. These results will be useful for elucidating the roles of mTERF genes in the growth, development and stress response of maize.
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Affiliation(s)
- Yanxin Zhao
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Manjun Cai
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Xiaobo Zhang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Yurong Li
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Jianhua Zhang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Hailiang Zhao
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Fei Kong
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Yonglian Zheng
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Fazhan Qiu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- * E-mail:
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44
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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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45
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Jõers P, Lewis SC, Fukuoh A, Parhiala M, Ellilä S, Holt IJ, Jacobs HT. Mitochondrial transcription terminator family members mTTF and mTerf5 have opposing roles in coordination of mtDNA synthesis. PLoS Genet 2013; 9:e1003800. [PMID: 24068965 PMCID: PMC3778013 DOI: 10.1371/journal.pgen.1003800] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Accepted: 07/30/2013] [Indexed: 12/19/2022] Open
Abstract
All genomes require a system for avoidance or handling of collisions between the machineries of DNA replication and transcription. We have investigated the roles in this process of the mTERF (mitochondrial transcription termination factor) family members mTTF and mTerf5 in Drosophila melanogaster. The two mTTF binding sites in Drosophila mtDNA, which also bind mTerf5, were found to coincide with major sites of replication pausing. RNAi-mediated knockdown of either factor resulted in mtDNA depletion and developmental arrest. mTTF knockdown decreased site-specific replication pausing, but led to an increase in replication stalling and fork regression in broad zones around each mTTF binding site. Lagging-strand DNA synthesis was impaired, with extended RNA/DNA hybrid segments seen in replication intermediates. This was accompanied by the accumulation of recombination intermediates and nicked/broken mtDNA species. Conversely, mTerf5 knockdown led to enhanced replication pausing at mTTF binding sites, a decrease in fragile replication intermediates containing single-stranded segments, and the disappearance of species containing segments of RNA/DNA hybrid. These findings indicate an essential and previously undescribed role for proteins of the mTERF family in the integration of transcription and DNA replication, preventing unregulated collisions and facilitating productive interactions between the two machineries that are inferred to be essential for completion of lagging-strand DNA synthesis.
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Affiliation(s)
- Priit Jõers
- Institute of Biomedical Technology and Tampere University Hospital, Tampere, Finland
- Estonian Biocentre, Tartu, Estonia
| | - Samantha C. Lewis
- Institute of Biomedical Technology and Tampere University Hospital, Tampere, Finland
- Department of Biology, University of California, Riverside, California, United States of America
| | - Atsushi Fukuoh
- Institute of Biomedical Technology and Tampere University Hospital, Tampere, Finland
- Department of Clinical Chemistry and Laboratory Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan
- Department of Medical Laboratory Science, Junshin Gakuen University, Fukuoka, Japan
| | - Mikael Parhiala
- Institute of Biomedical Technology and Tampere University Hospital, Tampere, Finland
| | - Simo Ellilä
- Institute of Biomedical Technology and Tampere University Hospital, Tampere, Finland
| | - Ian J. Holt
- MRC National Institute of Medical Research, London, United Kingdom
| | - Howard T. Jacobs
- Institute of Biomedical Technology and Tampere University Hospital, Tampere, Finland
- Molecular Neurology Research Program, University of Helsinki, Helsinki, Finland
- * E-mail:
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Hammani K, Bonnard G, Bouchoucha A, Gobert A, Pinker F, Salinas T, Giegé P. Helical repeats modular proteins are major players for organelle gene expression. Biochimie 2013; 100:141-50. [PMID: 24021622 DOI: 10.1016/j.biochi.2013.08.031] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 08/30/2013] [Indexed: 11/18/2022]
Abstract
Mitochondria and chloroplasts are often described as semi-autonomous organelles because they have retained a genome. They thus require fully functional gene expression machineries. Many of the required processes going all the way from transcription to translation have specificities in organelles and arose during eukaryote history. Most factors involved in these RNA maturation steps have remained elusive for a long time. The recent identification of a number of novel protein families including pentatricopeptide repeat proteins, half-a-tetratricopeptide proteins, octotricopeptide repeat proteins and mitochondrial transcription termination factors has helped to settle long-standing questions regarding organelle gene expression. In particular, their functions have been related to replication, transcription, RNA processing, RNA editing, splicing, the control of RNA turnover and translation throughout eukaryotes. These families of proteins, although evolutionary independent, seem to share a common overall architecture. For all of them, proteins contain tandem arrays of repeated motifs. Each module is composed of two to three α-helices and their succession forms a super-helix. Here, we review the features characterising these protein families, in particular, their distribution, the identified functions and mode of action and propose that they might share similar substrate recognition mechanisms.
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Wobbe L, Nixon PJ. The mTERF protein MOC1 terminates mitochondrial DNA transcription in the unicellular green alga Chlamydomonas reinhardtii. Nucleic Acids Res 2013; 41:6553-67. [PMID: 23649833 PMCID: PMC3711419 DOI: 10.1093/nar/gkt313] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The molecular function of mTERFs (mitochondrial transcription termination factors) has so far only been described for metazoan members of the protein family and in animals they control mitochondrial replication, transcription and translation. Cells of photosynthetic eukaryotes harbour chloroplasts and mitochondria, which are in an intense cross-talk that is vital for photosynthesis. Chlamydomonas reinhardtii is a unicellular green alga widely used as a model organism for photosynthesis research and green biotechnology. Among the six nuclear C. reinhardtii mTERF genes is mTERF-like gene of Chlamydomonas (MOC1), whose inactivation alters mitorespiration and interestingly also light-acclimation processes in the chloroplast that favour the enhanced production of biohydrogen. We show here from in vitro studies that MOC1 binds specifically to a sequence within the mitochondrial rRNA-coding module S3, and that a knockout of MOC1 in the mutant stm6 increases read-through transcription at this site, indicating that MOC1 acts as a transcription terminator in vivo. Whereas the level of certain antisense RNA species is higher in stm6, the amount of unprocessed mitochondrial sense transcripts is strongly reduced, demonstrating that a loss of MOC1 causes perturbed mitochondrial DNA (mtDNA) expression. Overall, we provide evidence for the existence of mitochondrial antisense RNAs in C. reinhardtii and show that mTERF-mediated transcription termination is an evolutionary-conserved mechanism occurring in phototrophic protists and metazoans.
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Affiliation(s)
- Lutz Wobbe
- Department of Biology, Algae Biotechnology and Bioenergy-Center for Biotechnology (CeBiTec), Bielefeld University, 33615 Bielefeld, Germany.
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48
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Terzioglu M, Ruzzenente B, Harmel J, Mourier A, Jemt E, López MD, Kukat C, Stewart JB, Wibom R, Meharg C, Habermann B, Falkenberg M, Gustafsson CM, Park CB, Larsson NG. MTERF1 binds mtDNA to prevent transcriptional interference at the light-strand promoter but is dispensable for rRNA gene transcription regulation. Cell Metab 2013; 17:618-26. [PMID: 23562081 DOI: 10.1016/j.cmet.2013.03.006] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 01/22/2013] [Accepted: 03/12/2013] [Indexed: 11/30/2022]
Abstract
Mitochondrial transcription termination factor 1, MTERF1, has been reported to couple rRNA gene transcription initiation with termination and is therefore thought to be a key regulator of mammalian mitochondrial ribosome biogenesis. The prevailing model is based on a series of observations published over the last two decades, but no in vivo evidence exists to show that MTERF1 regulates transcription of the heavy-strand region of mtDNA containing the rRNA genes. Here, we demonstrate that knockout of Mterf1 in mice has no effect on mitochondrial rRNA levels or mitochondrial translation. Instead, loss of Mterf1 influences transcription initiation at the light-strand promoter, resulting in a decrease of de novo transcription manifested as reduced 7S RNA levels. Based on these observations, we suggest that MTERF1 does not regulate heavy-strand transcription, but rather acts to block transcription on the opposite strand of mtDNA to prevent transcription interference at the light-strand promoter.
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Affiliation(s)
- Mügen Terzioglu
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
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49
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Wredenberg A, Lagouge M, Bratic A, Metodiev MD, Spåhr H, Mourier A, Freyer C, Ruzzenente B, Tain L, Grönke S, Baggio F, Kukat C, Kremmer E, Wibom R, Polosa PL, Habermann B, Partridge L, Park CB, Larsson NG. MTERF3 regulates mitochondrial ribosome biogenesis in invertebrates and mammals. PLoS Genet 2013; 9:e1003178. [PMID: 23300484 PMCID: PMC3536695 DOI: 10.1371/journal.pgen.1003178] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 10/31/2012] [Indexed: 11/18/2022] Open
Abstract
Regulation of mitochondrial DNA (mtDNA) expression is critical for the control of oxidative phosphorylation in response to physiological demand, and this regulation is often impaired in disease and aging. We have previously shown that mitochondrial transcription termination factor 3 (MTERF3) is a key regulator that represses mtDNA transcription in the mouse, but its molecular mode of action has remained elusive. Based on the hypothesis that key regulatory mechanisms for mtDNA expression are conserved in metazoans, we analyzed Mterf3 knockout and knockdown flies. We demonstrate here that decreased expression of MTERF3 not only leads to activation of mtDNA transcription, but also impairs assembly of the large mitochondrial ribosomal subunit. This novel function of MTERF3 in mitochondrial ribosomal biogenesis is conserved in the mouse, thus we identify a novel and unexpected role for MTERF3 in coordinating the crosstalk between transcription and translation for the regulation of mammalian mtDNA gene expression.
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Affiliation(s)
- Anna Wredenberg
- Max-Planck Institute for Biology of Ageing, Köln, Germany
- Department Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Marie Lagouge
- Max-Planck Institute for Biology of Ageing, Köln, Germany
| | - Ana Bratic
- Max-Planck Institute for Biology of Ageing, Köln, Germany
- Department Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | | | - Henrik Spåhr
- Max-Planck Institute for Biology of Ageing, Köln, Germany
| | - Arnaud Mourier
- Max-Planck Institute for Biology of Ageing, Köln, Germany
| | - Christoph Freyer
- Max-Planck Institute for Biology of Ageing, Köln, Germany
- Department Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | | | - Luke Tain
- Max-Planck Institute for Biology of Ageing, Köln, Germany
| | | | | | | | - Elisabeth Kremmer
- Helmholtz Center, Institute for Molecular Immunology, Munich, Germany
| | - Rolf Wibom
- Department Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Paola Loguercio Polosa
- Department of Biosciences, Biotechnologies, and Pharmacological Sciences, University of Bari Aldo Moro, Bari, Italy
| | | | | | - Chan Bae Park
- Institute for Medical Sciences, Ajou University School of Medicine, Suwon, Korea
- Mitochondria Hub Regulation Center, Dong-A University College of Medicine, Busan, Republic of Korea
- * E-mail: (CBP); (N-GL)
| | - Nils-Göran Larsson
- Max-Planck Institute for Biology of Ageing, Köln, Germany
- Department Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
- * E-mail: (CBP); (N-GL)
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50
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Montagna M, Sassera D, Griggio F, Epis S, Bandi C, Gissi C. Tick-box for 3'-end formation of mitochondrial transcripts in Ixodida, basal chelicerates and Drosophila. PLoS One 2012; 7:e47538. [PMID: 23077630 PMCID: PMC3471875 DOI: 10.1371/journal.pone.0047538] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 09/12/2012] [Indexed: 01/01/2023] Open
Abstract
According to the tRNA punctuation model, the mitochondrial genome (mtDNA) of mammals and arthropods is transcribed as large polycistronic precursors that are maturated by endonucleolytic cleavage at tRNA borders and RNA polyadenylation. Starting from the newly sequenced mtDNA of Ixodes ricinus and using a combination of mitogenomics and transcriptional analyses, we found that in all currently-sequenced tick lineages (Prostriata, Metastriata and Argasidae) the 3'-end of the polyadenylated nad1 and rrnL transcripts does not follow the tRNA punctuation model and is located upstream of a degenerate 17-bp DNA motif. A slightly different motif is also present downstream the 3'-end of nad1 transcripts in the primitive chelicerate Limulus polyphemus and in Drosophila species, indicating the ancient origin and the evolutionary conservation of this motif in arthropods. The transcriptional analyses suggest that this motif directs the 3'-end formation of the nad1/rrnL mature RNAs, likely working as a transcription termination signal or a processing signal of precursor transcripts. Moreover, as most regulatory elements, this motif is characterized by a taxon-specific evolution. Although this signal is not exclusive of ticks, making a play on words it has been named "Tick-Box", since it is a check mark that has to be verified for the 3'-end formation of some mt transcripts, and its consensus sequence has been here carefully characterized in ticks. Indeed, in the whole mtDNA of all ticks, the Tick-Box is always present downstream of nad1 and rrnL, mainly in non-coding regions (NCRs) and occasionally within trnL(CUN). However, some metastriates present a third Tick-Box at an intriguing site--inside the small NCR located at one end of a 3.4 kb translocated region, the other end of which exhibits the nad1 Tick-Box--hinting that this motif could have been involved in metastriate gene order rearrangements.
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Affiliation(s)
- Matteo Montagna
- Dipartimento di Scienze Veterinarie e Sanità Pubblica, Università degli Studi di Milano, Milano, Italy
| | - Davide Sassera
- Dipartimento di Scienze Veterinarie e Sanità Pubblica, Università degli Studi di Milano, Milano, Italy
| | - Francesca Griggio
- Dipartimento di Bioscienze, Università degli Studi di Milano, Milano, Italy
| | - Sara Epis
- Dipartimento di Scienze Veterinarie e Sanità Pubblica, Università degli Studi di Milano, Milano, Italy
| | - Claudio Bandi
- Dipartimento di Scienze Veterinarie e Sanità Pubblica, Università degli Studi di Milano, Milano, Italy
| | - Carmela Gissi
- Dipartimento di Bioscienze, Università degli Studi di Milano, Milano, Italy
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