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Schmid LM, Manavski N, Chi W, Meurer J. Chloroplast Ribosome Biogenesis Factors. PLANT & CELL PHYSIOLOGY 2024; 65:516-536. [PMID: 37498958 DOI: 10.1093/pcp/pcad082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 07/13/2023] [Accepted: 07/25/2023] [Indexed: 07/29/2023]
Abstract
The formation of chloroplasts can be traced back to an ancient event in which a eukaryotic host cell containing mitochondria ingested a cyanobacterium. Since then, chloroplasts have retained many characteristics of their bacterial ancestor, including their transcription and translation machinery. In this review, recent research on the maturation of rRNA and ribosome assembly in chloroplasts is explored, along with their crucial role in plant survival and their implications for plant acclimation to changing environments. A comparison is made between the ribosome composition and auxiliary factors of ancient and modern chloroplasts, providing insights into the evolution of ribosome assembly factors. Although the chloroplast contains ancient proteins with conserved functions in ribosome assembly, newly evolved factors have also emerged to help plants acclimate to changes in their environment and internal signals. Overall, this review offers a comprehensive analysis of the molecular mechanisms underlying chloroplast ribosome assembly and highlights the importance of this process in plant survival, acclimation and adaptation.
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Affiliation(s)
- Lisa-Marie Schmid
- Plant Molecular Biology, Faculty of Biology, Ludwig-Maximilians-University Munich, Großhaderner Street 2-4, Planegg-Martinsried 82152, Germany
| | - Nikolay Manavski
- Plant Molecular Biology, Faculty of Biology, Ludwig-Maximilians-University Munich, Großhaderner Street 2-4, Planegg-Martinsried 82152, Germany
| | - Wei Chi
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Jörg Meurer
- Plant Molecular Biology, Faculty of Biology, Ludwig-Maximilians-University Munich, Großhaderner Street 2-4, Planegg-Martinsried 82152, Germany
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2
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Sadessa K, Beyene Y, Ifie BE, Suresh LM, Olsen MS, Ogugo V, Wegary D, Tongoona P, Danquah E, Offei SK, Prasanna BM, Gowda M. Identification of Genomic Regions Associated with Agronomic and Disease Resistance Traits in a Large Set of Multiple DH Populations. Genes (Basel) 2022; 13:genes13020351. [PMID: 35205395 PMCID: PMC8872035 DOI: 10.3390/genes13020351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 02/08/2022] [Accepted: 02/08/2022] [Indexed: 11/17/2022] Open
Abstract
Breeding maize lines with the improved level of desired agronomic traits under optimum and drought conditions as well as increased levels of resistance to several diseases such as maize lethal necrosis (MLN) is one of the most sustainable approaches for the sub-Saharan African region. In this study, 879 doubled haploid (DH) lines derived from 26 biparental populations were evaluated under artificial inoculation of MLN, as well as under well-watered (WW) and water-stressed (WS) conditions for grain yield and other agronomic traits. All DH lines were used for analyses of genotypic variability, association studies, and genomic predictions for the grain yield and other yield-related traits. Genome-wide association study (GWAS) using a mixed linear FarmCPU model identified SNPs associated with the studied traits i.e., about seven and eight SNPs for the grain yield; 16 and 12 for anthesis date; seven and eight for anthesis silking interval; 14 and 5 for both ear and plant height; and 15 and 5 for moisture under both WW and WS environments, respectively. Similarly, about 13 and 11 SNPs associated with gray leaf spot and turcicum leaf blight were identified. Eleven SNPs associated with senescence under WS management that had depicted drought-stress-tolerant QTLs were identified. Under MLN artificial inoculation, a total of 12 and 10 SNPs associated with MLN disease severity and AUDPC traits, respectively, were identified. Genomic prediction under WW, WS, and MLN disease artificial inoculation revealed moderate-to-high prediction accuracy. The findings of this study provide useful information on understanding the genetic basis for the MLN resistance, grain yield, and other agronomic traits under MLN artificial inoculation, WW, and WS conditions. Therefore, the obtained information can be used for further validation and developing functional molecular markers for marker-assisted selection and for implementing genomic prediction to develop superior elite lines.
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Affiliation(s)
- Kassahun Sadessa
- Ethiopian Institute of Agricultural Research (EIAR), Ambo Agricultural Research Center, Ambo P.O. Box 37, West Shoa, Ethiopia;
- International Maize and Wheat Improvement Center (CIMMYT), ICRAF House, P.O. Box 1041-00621, Nairobi 00100, Kenya; (Y.B.); (L.M.S.); (M.S.O.); (V.O.); (B.M.P.)
- International Maize and Wheat Improvement Center (CIMMYT), 12.5 KM Peg, Harare P.O. Box MP163, Zimbabwe;
- West Africa Centre for Crop Improvement (WACCI), College of Basic and Applied Sciences, University of Ghana, Legon, P.O. Box LG23, Accra 00233, Ghana; (B.E.I.); (P.T.); (E.D.); (S.K.O.)
| | - Yoseph Beyene
- International Maize and Wheat Improvement Center (CIMMYT), ICRAF House, P.O. Box 1041-00621, Nairobi 00100, Kenya; (Y.B.); (L.M.S.); (M.S.O.); (V.O.); (B.M.P.)
| | - Beatrice E. Ifie
- West Africa Centre for Crop Improvement (WACCI), College of Basic and Applied Sciences, University of Ghana, Legon, P.O. Box LG23, Accra 00233, Ghana; (B.E.I.); (P.T.); (E.D.); (S.K.O.)
| | - L. M. Suresh
- International Maize and Wheat Improvement Center (CIMMYT), ICRAF House, P.O. Box 1041-00621, Nairobi 00100, Kenya; (Y.B.); (L.M.S.); (M.S.O.); (V.O.); (B.M.P.)
| | - Michael S. Olsen
- International Maize and Wheat Improvement Center (CIMMYT), ICRAF House, P.O. Box 1041-00621, Nairobi 00100, Kenya; (Y.B.); (L.M.S.); (M.S.O.); (V.O.); (B.M.P.)
| | - Veronica Ogugo
- International Maize and Wheat Improvement Center (CIMMYT), ICRAF House, P.O. Box 1041-00621, Nairobi 00100, Kenya; (Y.B.); (L.M.S.); (M.S.O.); (V.O.); (B.M.P.)
| | - Dagne Wegary
- International Maize and Wheat Improvement Center (CIMMYT), 12.5 KM Peg, Harare P.O. Box MP163, Zimbabwe;
| | - Pangirayi Tongoona
- West Africa Centre for Crop Improvement (WACCI), College of Basic and Applied Sciences, University of Ghana, Legon, P.O. Box LG23, Accra 00233, Ghana; (B.E.I.); (P.T.); (E.D.); (S.K.O.)
| | - Eric Danquah
- West Africa Centre for Crop Improvement (WACCI), College of Basic and Applied Sciences, University of Ghana, Legon, P.O. Box LG23, Accra 00233, Ghana; (B.E.I.); (P.T.); (E.D.); (S.K.O.)
| | - Samuel Kwame Offei
- West Africa Centre for Crop Improvement (WACCI), College of Basic and Applied Sciences, University of Ghana, Legon, P.O. Box LG23, Accra 00233, Ghana; (B.E.I.); (P.T.); (E.D.); (S.K.O.)
| | - Boddupalli M. Prasanna
- International Maize and Wheat Improvement Center (CIMMYT), ICRAF House, P.O. Box 1041-00621, Nairobi 00100, Kenya; (Y.B.); (L.M.S.); (M.S.O.); (V.O.); (B.M.P.)
| | - Manje Gowda
- International Maize and Wheat Improvement Center (CIMMYT), ICRAF House, P.O. Box 1041-00621, Nairobi 00100, Kenya; (Y.B.); (L.M.S.); (M.S.O.); (V.O.); (B.M.P.)
- Correspondence: ; Tel.: +254-727019454
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Kong M, Wu Y, Wang Z, Qu W, Lan Y, Chen X, Liu Y, Shahnaz P, Yang Z, Yu Q, Mi H. A Novel Chloroplast Protein RNA Processing 8 Is Required for the Expression of Chloroplast Genes and Chloroplast Development in Arabidopsis thaliana. FRONTIERS IN PLANT SCIENCE 2021; 12:700975. [PMID: 34956248 PMCID: PMC8695849 DOI: 10.3389/fpls.2021.700975] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 11/03/2021] [Indexed: 06/14/2023]
Abstract
Chloroplast development involves the coordinated expression of both plastids- and nuclear-encoded genes in higher plants. However, the underlying mechanism still remains largely unknown. In this study, we isolated and characterized an Arabidopsis mutant with an albino lethality phenotype named RNA processing 8 (rp8). Genetic complementation analysis demonstrated that the gene AT4G37920 (RP8) was responsible for the mutated phenotype. The RP8 gene was strongly expressed in photosynthetic tissues at both transcription and translation protein levels. The RP8 protein is localized in the chloroplast and associated with the thylakoid. Disruption of the RP8 gene led to a defect in the accumulation of the rpoA mature transcript, which reduced the level of the RpoA protein, and affected the transcription of PEP-dependent genes. The abundance of the chloroplast rRNA, including 23S, 16S, 4.5S, and 5S rRNA, were reduced in the rp8 mutant, respectively, and the amounts of chloroplast ribosome proteins, such as, PRPS1(uS1c), PRPS5(uS5c), PRPL2 (uL2c), and PRPL4 (uL4c), were substantially decreased in the rp8 mutant, which indicated that knockout of RP8 seriously affected chloroplast translational machinery. Accordingly, the accumulation of photosynthetic proteins was seriously reduced. Taken together, these results indicate that the RP8 protein plays an important regulatory role in the rpoA transcript processing, which is required for the expression of chloroplast genes and chloroplast development in Arabidopsis.
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Affiliation(s)
- Mengmeng Kong
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Yaozong Wu
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Ziyuan Wang
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Wantong Qu
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Yixin Lan
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Xin Chen
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Yanyun Liu
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Perveen Shahnaz
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Zhongnan Yang
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Qingbo Yu
- Shanghai Key Laboratory of Plant Molecular Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Hualing Mi
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
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Lu J, Pan C, Fan W, Liu W, Zhao H, Li D, Wang S, Hu L, He B, Qian K, Qin R, Ruan J, Lin Q, Lü S, Cui P. A Chromosome-level Assembly of A Wild Castor Genome Provides New Insights into the Adaptive Evolution in A Tropical Desert. GENOMICS PROTEOMICS & BIOINFORMATICS 2021; 20:42-59. [PMID: 34339842 PMCID: PMC9510866 DOI: 10.1016/j.gpb.2021.04.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 04/03/2021] [Accepted: 04/12/2021] [Indexed: 02/01/2023]
Abstract
Wild castor grows in the high-altitude tropical desert of the African Plateau, a region known for high ultraviolet radiation, strong light, and extremely dry condition. To investigate the potential genetic basis of adaptation to both highland and tropical deserts, we generated a chromosome-level genome sequence assembly of the wild castor accession WT05, with a genome size of 316 Mb, a scaffold N50 of 31.93 Mb, and a contig N50 of 8.96 Mb, respectively. Compared with cultivated castor and other Euphorbiaceae species, the wild castor exhibits positive selection and gene family expansion for genes involved in DNA repair, photosynthesis, and abiotic stress responses. Genetic variations associated with positive selection were identified in several key genes, such as LIG1, DDB2, and RECG1, involved in nucleotide excision repair. Moreover, a study of genomic diversity among wild and cultivated accessions revealed genomic regions containing selection signatures associated with the adaptation to extreme environments. The identification of the genes and alleles with selection signatures provides insights into the genetic mechanisms underlying the adaptation of wild castor to the high-altitude tropical desert and would facilitate direct improvement of modern castor varieties.
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Affiliation(s)
- Jianjun Lu
- CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Cheng Pan
- CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; Sino-Africa Joint Research Center, Chinese Academy of Sciences, Wuhan 430074, China
| | - Wei Fan
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
| | - Wanfei Liu
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
| | - Huayan Zhao
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan 434200, China
| | - Donghai Li
- CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Sen Wang
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
| | - Lianlian Hu
- CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Bing He
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
| | - Kun Qian
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
| | - Rui Qin
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
| | - Jue Ruan
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
| | - Qiang Lin
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China.
| | - Shiyou Lü
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan 434200, China.
| | - Peng Cui
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China.
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MacIntosh GC, Castandet B. Organellar and Secretory Ribonucleases: Major Players in Plant RNA Homeostasis. PLANT PHYSIOLOGY 2020; 183:1438-1452. [PMID: 32513833 PMCID: PMC7401137 DOI: 10.1104/pp.20.00076] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 05/31/2020] [Indexed: 05/05/2023]
Abstract
Organellar and secretory RNases, associated with different cellular compartments, are essential to maintain cellular homeostasis during development and in stress responses.
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Affiliation(s)
- Gustavo C MacIntosh
- Roy J. Carver Department of Biochemistry, Biophysics and Molecular Biology, Iowa State University, Ames, Iowa, 50011
| | - Benoît Castandet
- Université Paris-Saclay, Centre National de la Recherche Scientifique, Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement, Univ Evry, Institute of Plant Sciences Paris-Saclay (IPS2), 91405, Orsay, France
- Université de Paris, Centre National de la Recherche Scientifique, Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement, Institute of Plant Sciences Paris-Saclay (IPS2), 91405, Orsay, France
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6
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Essemine J, Lyu MJA, Qu M, Perveen S, Khan N, Song Q, Chen G, Zhu XG. Contrasting Responses of Plastid Terminal Oxidase Activity Under Salt Stress in Two C 4 Species With Different Salt Tolerance. FRONTIERS IN PLANT SCIENCE 2020; 11:1009. [PMID: 32733515 PMCID: PMC7359412 DOI: 10.3389/fpls.2020.01009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 06/19/2020] [Indexed: 05/07/2023]
Abstract
The present study reveals contrasting responses of photosynthesis to salt stress in two C4 species: a glycophyte Setaria viridis (SV) and a halophyte Spartina alterniflora (SA). Specifically, the effect of short-term salt stress treatment on the photosynthetic CO2 uptake and electron transport were investigated in SV and its salt-tolerant close relative SA. In this experiment, at the beginning, plants were grown in soil then were exposed to salt stress under hydroponic conditions for two weeks. SV demonstrated a much higher susceptibility to salt stress than SA; while, SV was incapable to survive subjected to about 100 mM, SA can tolerate salt concentrations up to 550 mM with slight effect on photosynthetic CO2 uptake rates and electrons transport chain conductance (gETC ). Regardless the oxygen concentration used, our results show an enhancement in the P700 oxidation with increasing O2 concentration for SV following NaCl treatment and almost no change for SA. We also observed an activation of the cyclic NDH-dependent pathway in SV by about 2.36 times upon exposure to 50 mM NaCl for 12 days (d); however, its activity in SA drops by about 25% compared to the control without salt treatment. Using PTOX inhibitor (n-PG) and that of the Qo-binding site of Cytb6/f (DBMIB), at two O2 levels (2 and 21%), to restrict electrons flow towards PSI, we successfully revealed the presence of a possible PTOX activity under salt stress for SA but not for SV. However, by q-PCR and western-blot analysis, we showed an increase in PTOX amount by about 3-4 times for SA under salt stress but not or very less for SV. Overall, this study provides strong proof for the existence of PTOX as an alternative electron pathway in C4 species (SA), which might play more than a photoprotective role under salt stress.
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Manavski N, Torabi S, Lezhneva L, Arif MA, Frank W, Meurer J. HIGH CHLOROPHYLL FLUORESCENCE145 Binds to and Stabilizes the psaA 5' UTR via a Newly Defined Repeat Motif in Embryophyta. THE PLANT CELL 2015; 27:2600-15. [PMID: 26307378 PMCID: PMC4815088 DOI: 10.1105/tpc.15.00234] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 08/06/2015] [Indexed: 05/10/2023]
Abstract
The seedling-lethal Arabidopsis thaliana high chlorophyll fluorescence145 (hcf145) mutation leads to reduced stability of the plastid tricistronic psaA-psaB-rps14 mRNA and photosystem I (PSI) deficiency. Here, we genetically mapped the HCF145 gene, which encodes a plant-specific, chloroplast-localized, modular protein containing two homologous domains related to the polyketide cyclase family comprising 37 annotated Arabidopsis proteins of unknown function. Two further highly conserved and previously uncharacterized tandem repeat motifs at the C terminus, herein designated the transcript binding motif repeat (TMR) domains, confer sequence-specific RNA binding capability to HCF145. Homologous TMR motifs are often found as multiple repeats in quite diverse proteins of green and red algae and in the cyanobacterium Microcoleus sp PCC 7113 with unknown function. HCF145 represents the only TMR protein found in vascular plants. Detailed analysis of hcf145 mutants in Arabidopsis and Physcomitrella patens as well as in vivo and in vitro RNA binding assays indicate that HCF145 has been recruited in embryophyta for the stabilization of the psaA-psaB-rps14 mRNA via specific binding to its 5' untranslated region. The polyketide cyclase-related motifs support association of the TMRs to the psaA RNA, presumably pointing to a regulatory role in adjusting PSI levels according to the requirements of the plant cell.
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Affiliation(s)
- Nikolay Manavski
- Biozentrum der LMU München, Department Biologie I, 82152 Planegg-Martinsried, Germany
| | - Salar Torabi
- Biozentrum der LMU München, Department Biologie I, 82152 Planegg-Martinsried, Germany
| | - Lina Lezhneva
- Biozentrum der LMU München, Department Biologie I, 82152 Planegg-Martinsried, Germany
| | - Muhammad Asif Arif
- Biozentrum der LMU München, Department Biologie I, 82152 Planegg-Martinsried, Germany
| | - Wolfgang Frank
- Biozentrum der LMU München, Department Biologie I, 82152 Planegg-Martinsried, Germany
| | - Jörg Meurer
- Biozentrum der LMU München, Department Biologie I, 82152 Planegg-Martinsried, Germany
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Aït-Bara S, Carpousis AJ. RNA degradosomes in bacteria and chloroplasts: classification, distribution and evolution of RNase E homologs. Mol Microbiol 2015; 97:1021-135. [PMID: 26096689 DOI: 10.1111/mmi.13095] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/15/2015] [Indexed: 11/29/2022]
Abstract
Ribonuclease E (RNase E) of Escherichia coli, which is the founding member of a widespread family of proteins in bacteria and chloroplasts, is a fascinating enzyme that still has not revealed all its secrets. RNase E is an essential single-strand specific endoribonuclease that is involved in the processing and degradation of nearly every transcript in E. coli. A striking enzymatic property is a preference for substrates with a 5' monophosphate end although recent work explains how RNase E can overcome the protection afforded by the 5' triphosphate end of a primary transcript. Other features of E. coli RNase E include its interaction with enzymes involved in RNA degradation to form the multienzyme RNA degradosome and its localization to the inner cytoplasmic membrane. The N-terminal catalytic core of the RNase E protomer associates to form a tetrameric holoenzyme. Each RNase E protomer has a large C-terminal intrinsically disordered (ID) noncatalytic region that contains sites for interactions with protein components of the RNA degradosome as well as RNA and phospholipid bilayers. In this review, RNase E homologs have been classified into five types based on their primary structure. A recent analysis has shown that type I RNase E in the γ-proteobacteria forms an orthologous group of proteins that has been inherited vertically. The RNase E catalytic core and a large ID noncatalytic region containing an RNA binding motif and a membrane targeting sequence are universally conserved features of these orthologs. Although the ID noncatalytic region has low composition and sequence complexity, it is possible to map microdomains, which are short linear motifs that are sites of interaction with protein and other ligands. Throughout bacteria, the composition of the multienzyme RNA degradosome varies with species, but interactions with exoribonucleases (PNPase, RNase R), glycolytic enzymes (enolase, aconitase) and RNA helicases (DEAD-box proteins, Rho) are common. Plasticity in RNA degradosome composition is due to rapid evolution of RNase E microdomains. Characterization of the RNase E-PNPase interaction in α-proteobacteria, γ-proteobacteria and cyanobacteria suggests that it arose independently several times during evolution, thus conferring an advantage in control and coordination of RNA processing and degradation.
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Affiliation(s)
- Soraya Aït-Bara
- Microbes, Intestin, Inflammation et Susceptibilité de l'Hôte, Institut, National de la Santé et de la Recherche Médicale & Université d'Auvergne, Clermont-Ferrand, 63001, France
| | - Agamemnon J Carpousis
- Laboratoire de Microbiologie et Génétique Moléculaires, UMR 5100, Centre National de la Recherche Scientifique et Université de Toulouse 3, Toulouse, 31062, France
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Han JH, Lee K, Lee KH, Jung S, Jeon Y, Pai HS, Kang H. A nuclear-encoded chloroplast-targeted S1 RNA-binding domain protein affects chloroplast rRNA processing and is crucial for the normal growth of Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 83:277-89. [PMID: 26031782 DOI: 10.1111/tpj.12889] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 05/05/2015] [Accepted: 05/13/2015] [Indexed: 05/22/2023]
Abstract
Despite the fact that a variety of nuclear-encoded RNA-binding proteins (RBPs) are targeted to the chloroplast and play essential roles during post-transcriptional RNA metabolism in the chloroplast, the physiological roles of the majority of chloroplast-targeted RBPs remain elusive. Here, we investigated the functional role of a nuclear-encoded S1 domain-containing RBP, designated SDP, in the growth and development of Arabidopsis thaliana. Confocal analysis of the SDP-green fluorescent protein revealed that SDP was localized to the chloroplast. The loss-of-function sdp mutant displayed retarded seed germination and pale-green phenotypes, and grew smaller than the wild-type plants. Chlorophyll a content and photosynthetic activity of the sdp mutant were much lower than those of wild-type plants, and the structures of the chloroplast and the prolamellar body were abnormal in the sdp mutant. The processing of rRNAs in the chloroplast was defective in the sdp mutant, and SDP was able to bind chloroplast 23S, 16S, 5S and 4.5S rRNAs. Notably, SDP possesses RNA chaperone activity. Transcript levels of the nuclear genes involved in chlorophyll biosynthesis were altered in the sdp mutant. Collectively, these results suggest that chloroplast-targeted SDP harboring RNA chaperone activity affects rRNA processing, chloroplast biogenesis and photosynthetic activity, which is crucial for normal growth of Arabidopsis.
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Affiliation(s)
- Ji Hoon Han
- Department of Plant Biotechnology, Chonnam National University, Gwangju, 500-757, Korea
| | - Kwanuk Lee
- Department of Plant Biotechnology, Chonnam National University, Gwangju, 500-757, Korea
| | - Kwang Ho Lee
- Department of Wood Science and Landscape Architecture, College of Agriculture and Life Sciences, Chonnam National University, Gwangju, 500-757, Korea
| | - Sunyo Jung
- School of Life Sciences and Biotechnology, Kyungpook National University, Daegu, 702-701, Korea
| | - Young Jeon
- Department of Systems Biology, Yonsei University, Seoul, 120-749, Korea
| | - Hyun-Sook Pai
- Department of Systems Biology, Yonsei University, Seoul, 120-749, Korea
| | - Hunseung Kang
- Department of Plant Biotechnology, Chonnam National University, Gwangju, 500-757, Korea
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10
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Scotti N, Sannino L, Idoine A, Hamman P, De Stradis A, Giorio P, Maréchal-Drouard L, Bock R, Cardi T. The HIV-1 Pr55 gag polyprotein binds to plastidial membranes and leads to severe impairment of chloroplast biogenesis and seedling lethality in transplastomic tobacco plants. Transgenic Res 2015; 24:319-31. [PMID: 25348481 DOI: 10.1007/s11248-014-9845-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2014] [Accepted: 10/21/2014] [Indexed: 11/25/2022]
Abstract
Chloroplast genetic engineering has long been recognised as a powerful technology to produce recombinant proteins. To date, however, little attention has been given to the causes of pleiotropic effects reported, in some cases, as consequence of the expression of foreign proteins in transgenic plastids. In this study, we investigated the phenotypic alterations observed in transplastomic tobacco plants accumulating the Pr55(gag) polyprotein of human immunodeficiency virus (HIV-1). The expression of Pr55(gag) at high levels in the tobacco plastome leads to a lethal phenotype of seedlings grown in soil, severe impairment of plastid development and photosynthetic activity, with chloroplasts largely resembling undeveloped proplastids. These alterations are associated to the binding of Pr55(gag) to thylakoids. During particle assembly in HIV-1 infected human cells, the binding of Pr55(gag) to a specific lipid [phosphatidylinositol-(4-5) bisphosphate] in the plasma membrane is mediated by myristoylation at the amino-terminus and the so-called highly basic region (HBR). Surprisingly, the non-myristoylated Pr55(gag) expressed in tobacco plastids was likely able, through the HBR motif, to bind to nonphosphorous glycerogalactolipids or other classes of lipids present in plastidial membranes. Although secondary consequences of disturbed chloroplast biogenesis on expression of nuclear-encoded plastid proteins cannot be ruled out, results of proteomic analyses suggest that their altered accumulation could be due to retrograde control in which chloroplasts relay their status to the nucleus for fine-tuning of gene expression.
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Affiliation(s)
- N Scotti
- CNR-IBBR, Institute of Biosciences and BioResources, National Research Council of Italy, Via Università 133, 80055, Portici, NA, Italy,
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11
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Stoppel R, Manavski N, Schein A, Schuster G, Teubner M, Schmitz-Linneweber C, Meurer J. RHON1 is a novel ribonucleic acid-binding protein that supports RNase E function in the Arabidopsis chloroplast. Nucleic Acids Res 2012; 40:8593-606. [PMID: 22735703 PMCID: PMC3458557 DOI: 10.1093/nar/gks613] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The Arabidopsis endonuclease RNase E (RNE) is localized in the chloroplast and is involved in processing of plastid ribonucleic acids (RNAs). By expression of a tandem affinity purification-tagged version of the plastid RNE in the Arabidopsis rne mutant background in combination with mass spectrometry, we identified the novel vascular plant-specific and co-regulated interaction partner of RNE, designated RHON1. RHON1 is essential for photoautotrophic growth and together with RNE forms a distinct ∼800 kDa complex. Additionally, RHON1 is part of various smaller RNA-containing complexes. RIP-chip and other association studies revealed that a helix-extended-helix-structured Rho-N motif at the C-terminus of RHON1 binds to and supports processing of specific plastid RNAs. In all respects, such as plastid RNA precursor accumulation, protein pattern, increased number and decreased size of chloroplasts and defective chloroplast development, the phenotype of rhon1 knockout mutants resembles that of rne lines. This strongly suggests that RHON1 supports RNE functions presumably by conferring sequence specificity to the endonuclease.
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Affiliation(s)
- Rhea Stoppel
- Department Biology 1, Biocenter of the Ludwig-Maximilians-University Munich, Chair of Plant Molecular Biology, Planegg-Martinsried D-82152, Germany
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12
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Stoppel R, Meurer J. The cutting crew - ribonucleases are key players in the control of plastid gene expression. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:1663-73. [PMID: 22140236 DOI: 10.1093/jxb/err401] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Chloroplast biogenesis requires constant adjustment of RNA homeostasis under conditions of on-going developmental and environmental change and its regulation is achieved mainly by post-transcriptional control mechanisms mediated by various nucleus-encoded ribonucleases. More than 180 ribonucleases are annotated in Arabidopsis, but only 17 are predicted to localize to the chloroplast. Although different ribonucleases act at different RNA target sites in vivo, most nucleases that attack RNA are thought to lack intrinsic cleavage specificity and show non-specific activity in vitro. In vivo, specificity is thought to be imposed by auxiliary RNA-binding proteins, including members of the huge pentatricopeptide repeat family, which protect RNAs from non-specific nucleolytic attack by masking otherwise vulnerable sites. RNA stability is also influenced by secondary structure, polyadenylation, and ribosome binding. Ribonucleases may cleave at internal sites (endonucleases) or digest successively from the 5' or 3' end of the polynucleotide chain (exonucleases). In bacteria, RNases act in the maturation of rRNA and tRNA precursors, as well as in initiating the degradation of mRNAs and small non-coding RNAs. Many ribonucleases in the chloroplasts of higher plants possess homologies to their bacterial counterparts, but their precise functions have rarely been described. However, many ribonucleases present in the chloroplast process polycistronic rRNAs, tRNAs, and mRNAs. The resulting production of monocistronic, translationally competent mRNAs may represent an adaptation to the eukaryotic cellular environment. This review provides a basic overview of the current knowledge of RNases in plastids and highlights gaps to stimulate future studies.
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Affiliation(s)
- Rhea Stoppel
- Biozentrum der Ludwig-Maximilians-Universität, Plant Molecular Biology/Botany, Großhaderner Str. 2, 82152 Planegg-Martinsried, Germany
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13
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From conformational chaos to robust regulation: the structure and function of the multi-enzyme RNA degradosome. Q Rev Biophys 2011; 45:105-45. [DOI: 10.1017/s003358351100014x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
AbstractThe RNA degradosome is a massive multi-enzyme assembly that occupies a nexus in RNA metabolism and post-transcriptional control of gene expression inEscherichia coliand many other bacteria. Powering RNA turnover and quality control, the degradosome serves also as a machine for processing structured RNA precursors during their maturation. The capacity to switch between destructive and processing modes involves cooperation between degradosome components and is analogous to the process of RNA surveillance in other domains of life. Recruitment of components and cellular compartmentalisation of the degradosome are mediated through small recognition domains that punctuate a natively unstructured segment within a scaffolding core. Dynamic in conformation, variable in composition and non-essential under certain laboratory conditions, the degradosome has nonetheless been maintained throughout the evolution of many bacterial species, due most likely to its diverse contributions in global cellular regulation. We describe the role of the degradosome and its components in RNA decay pathways inE. coli, and we broadly compare these pathways in other bacteria as well as archaea and eukaryotes. We discuss the modular architecture and molecular evolution of the degradosome, its roles in RNA degradation, processing and quality control surveillance, and how its activity is regulated by non-coding RNA. Parallels are drawn with analogous machinery in organisms from all life domains. Finally, we conjecture on roles of the degradosome as a regulatory hub for complex cellular processes.
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14
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Unexpected Diversity of Chloroplast Noncoding RNAs as Revealed by Deep Sequencing of the Arabidopsis Transcriptome. G3-GENES GENOMES GENETICS 2011; 1:559-70. [PMID: 22384367 PMCID: PMC3276175 DOI: 10.1534/g3.111.000752] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Accepted: 10/10/2011] [Indexed: 11/18/2022]
Abstract
Noncoding RNAs (ncRNA) are widely expressed in both prokaryotes and eukaryotes. Eukaryotic ncRNAs are commonly micro- and small-interfering RNAs (18-25 nt) involved in posttranscriptional gene silencing, whereas prokaryotic ncRNAs vary in size and are involved in various aspects of gene regulation. Given the prokaryotic origin of organelles, the presence of ncRNAs might be expected; however, the full spectrum of organellar ncRNAs has not been determined systematically. Here, strand-specific RNA-Seq analysis was used to identify 107 candidate ncRNAs from Arabidopsis thaliana chloroplasts, primarily encoded opposite protein-coding and tRNA genes. Forty-eight ncRNAs were shown to accumulate by RNA gel blot as discrete transcripts in wild-type (WT) plants and/or the pnp1-1 mutant, which lacks the chloroplast ribonuclease polynucleotide phosphorylase (cpPNPase). Ninety-eight percent of the ncRNAs detected by RNA gel blot had different transcript patterns between WT and pnp1-1, suggesting cpPNPase has a significant role in chloroplast ncRNA biogenesis and accumulation. Analysis of materials deficient for other major chloroplast ribonucleases, RNase R, RNase E, and RNase J, showed differential effects on ncRNA accumulation and/or form, suggesting specificity in RNase-ncRNA interactions. 5' end mapping demonstrates that some ncRNAs are transcribed from dedicated promoters, whereas others result from transcriptional read-through. Finally, correlations between accumulation of some ncRNAs and the symmetrically transcribed sense RNA are consistent with a role in RNA stability. Overall, our data suggest that this extensive population of ncRNAs has the potential to underpin a previously underappreciated regulatory mode in the chloroplast.
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15
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Sharwood RE, Halpert M, Luro S, Schuster G, Stern DB. Chloroplast RNase J compensates for inefficient transcription termination by removal of antisense RNA. RNA (NEW YORK, N.Y.) 2011; 17:2165-76. [PMID: 22033332 PMCID: PMC3222129 DOI: 10.1261/rna.028043.111] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 09/13/2011] [Indexed: 05/20/2023]
Abstract
Ribonuclease J is an essential enzyme, and the Bacillus subtilis ortholog possesses both endoribonuclease and 5' → 3' exoribonuclease activities. Chloroplasts also contain RNase J, which has been postulated to participate, as both an exo- and endonuclease, in the maturation of polycistronic mRNAs. Here we have examined recombinant Arabidopsis RNase J and found both 5' → 3' exoribonuclease and endonucleolytic activities. Virus-induced gene silencing was used to reduce RNase J expression in Arabidopsis and Nicotiana benthamiana, leading to chlorosis but surprisingly few disruptions in the cleavage of polycistronic rRNA and mRNA precursors. In contrast, antisense RNAs accumulated massively, suggesting that the failure of chloroplast RNA polymerase to terminate effectively leads to extensive symmetric transcription products that are normally eliminated by RNase J. Mung bean nuclease digestion and polysome analysis revealed that this antisense RNA forms duplexes with sense strand transcripts and prevents their translation. We conclude that a major role of chloroplast RNase J is RNA surveillance to prevent overaccumulation of antisense RNA, which would otherwise exert deleterious effects on chloroplast gene expression.
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Affiliation(s)
- Robert E. Sharwood
- Boyce Thompson Institute for Plant Research, Ithaca, New York 14853, USA
| | - Michal Halpert
- Department of Biology, Technion–Israel Institute of Technology, Haifa 32000, Israel
| | - Scott Luro
- Boyce Thompson Institute for Plant Research, Ithaca, New York 14853, USA
| | - Gadi Schuster
- Department of Biology, Technion–Israel Institute of Technology, Haifa 32000, Israel
| | - David B. Stern
- Boyce Thompson Institute for Plant Research, Ithaca, New York 14853, USA
- Corresponding author.E-mail .
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16
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Salvador ML, Suay L, Klein U. Messenger RNA degradation is initiated at the 5' end and follows sequence- and condition-dependent modes in chloroplasts. Nucleic Acids Res 2011; 39:6213-22. [PMID: 21507888 PMCID: PMC3152361 DOI: 10.1093/nar/gkr226] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Using reporter gene constructs, consisting of the bacterial uidA (GUS) coding region flanked by the 5′ and 3′ regions of the Chlamydomonas rbcL and psaB genes, respectively, we studied the degradation of mRNAs in the chloroplast of Chlamydomonas reinhardtii in vivo. Extending the 5′ terminus of transcripts of the reporter gene by more than 6 nucleotides triggered rapid degradation. Placing a poly(G) tract, known to pause exoribonucleases, in various positions downstream of the 5′ terminus blocked rapid degradation of the transcripts. In all these cases the 5′ ends of the accumulating GUS transcripts were found to be trimmed to the 5′ end of the poly(G) tracts indicating that a 5′→3′ exoribonuclease is involved in the degradation process. Several unstable variants of the GUS transcript could not be rescued from rapid degradation by a poly(G) tract showing that sequence/structure-dependent modes of mRNA breakdown exist in the Chlamydomonas chloroplast. Furthermore, degradation of poly(G)-stabilized transcripts that accumulated in cells maintained in the dark could be augmented by illuminating the cells, implying a photo-activated mode of mRNA degradation that is not blocked by a poly(G) tract. These results suggest sequence- and condition-dependent 5′→3′ mRNA-degrading pathways in the chloroplast of C. reinhardtii.
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Affiliation(s)
- Maria L Salvador
- Department of Biochemistry and Molecular Biology, University of Valencia, Dr Moliner 50, Burjassot, Valencia 46100, Spain
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17
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Sharwood RE, Hotto AM, Bollenbach TJ, Stern DB. Overaccumulation of the chloroplast antisense RNA AS5 is correlated with decreased abundance of 5S rRNA in vivo and inefficient 5S rRNA maturation in vitro. RNA (NEW YORK, N.Y.) 2011; 17:230-43. [PMID: 21148395 PMCID: PMC3022273 DOI: 10.1261/rna.2336611] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Accepted: 11/08/2010] [Indexed: 05/21/2023]
Abstract
Post-transcriptional regulation in the chloroplast is exerted by nucleus-encoded ribonucleases and RNA-binding proteins. One of these ribonucleases is RNR1, a 3'-to-5' exoribonuclease of the RNase II family. We have previously shown that Arabidopsis rnr1-null mutants exhibit specific abnormalities in the expression of the rRNA operon, including the accumulation of precursor 23S, 16S, and 4.5S species and a concomitant decrease in the mature species. 5S rRNA transcripts, however, accumulate to a very low level in both precursor and mature forms, suggesting that they are unstable in the rnr1 background. Here we demonstrate that rnr1 plants overaccumulate an antisense RNA, AS5, that is complementary to the 5S rRNA, its intergenic spacer, and the downstream trnR gene, which encodes tRNA(Arg), raising the possibility that AS5 destabilizes 5S rRNA or its precursor and/or blocks rRNA maturation. To investigate this, we used an in vitro system that supports 5S rRNA and trnR processing. We show that AS5 inhibits 5S rRNA maturation from a 5S-trnR precursor, and shorter versions of AS5 demonstrate that inhibition requires intergenic sequences. To test whether the sense and antisense RNAs form double-stranded regions in vitro, treatment with the single-strand-specific mung bean nuclease was used. These results suggest that 5S-AS5 duplexes interfere with a sense-strand secondary structure near the endonucleolytic cleavage site downstream from the 5S rRNA coding region. We hypothesize that these duplexes are degraded by a dsRNA-specific ribonuclease in vivo, contributing to the 5S rRNA deficiency observed in rnr1.
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Affiliation(s)
- Robert E Sharwood
- Boyce Thompson Institute for Plant Research, Ithaca, New York 14853, USA
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18
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Walter M, Piepenburg K, Schöttler MA, Petersen K, Kahlau S, Tiller N, Drechsel O, Weingartner M, Kudla J, Bock R. Knockout of the plastid RNase E leads to defective RNA processing and chloroplast ribosome deficiency. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 64:851-63. [PMID: 21105931 DOI: 10.1111/j.1365-313x.2010.04377.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Ribonuclease E (RNase E) represents a key enzyme in bacterial RNA metabolism. It plays multifarious roles in RNA processing and also initiates degradation of mRNA by endonucleolytic cleavage. Plastids (chloroplasts) are derived from formerly free-living bacteria and have largely retained eubacterial gene expression mechanisms. Here we report the functional characterization of a chloroplast RNase E that is encoded by a single-copy nuclear gene in the model plant Arabidopsis thaliana. Analysis of knockout plants revealed that, unlike in bacteria, RNase E is not essential for survival. Absence of RNase E results in multiple defects in chloroplast RNA metabolism. Most importantly, polycistronic precursor transcripts overaccumulate in the knockout plants, while several mature monocistronic mRNAs are strongly reduced, suggesting an important function of RNase E in intercistronic processing of primary transcripts from chloroplast operons. We further show that disturbed maturation of a transcript encoding essential ribosomal proteins results in plastid ribosome deficiency and, therefore, provides a molecular explanation for the observed mutant phenotype.
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Affiliation(s)
- Michael Walter
- Institut für Botanik, Universität Münster, Schlossplatz 4, 48149 Münster, Germany
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19
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Hardwick SW, Chan VSY, Broadhurst RW, Luisi BF. An RNA degradosome assembly in Caulobacter crescentus. Nucleic Acids Res 2010; 39:1449-59. [PMID: 20952404 PMCID: PMC3045602 DOI: 10.1093/nar/gkq928] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
In many bacterial species, the multi-enzyme RNA degradosome assembly makes key contributions to RNA metabolism. Powering the turnover of RNA and the processing of structural precursors, the RNA degradosome has differential activities on a spectrum of transcripts and contributes to gene regulation at a global level. Here, we report the isolation and characterization of an RNA degradosome assembly from the α-proteobacterium Caulobacter crescentus, which is a model organism for studying morphological development and cell-cycle progression. The principal components of the C. crescentus degradosome are the endoribonuclease RNase E, the exoribonuclease polynucleotide phosphorylase (PNPase), a DEAD-box RNA helicase and the Krebs cycle enzyme aconitase. PNPase and aconitase associate with specific segments in the C-terminal domain of RNase E that are predicted to have structural propensity. These recognition ‘microdomains’ punctuate structurally an extensive region that is otherwise predicted to be natively disordered. Finally, we observe that the abundance of RNase E varies through the cell cycle, with maxima at morphological differentiation and cell division. This variation may contribute to the program of gene expression during cell division.
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Affiliation(s)
- Steven W Hardwick
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK
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20
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Hotto AM, Huston ZE, Stern DB. Overexpression of a natural chloroplast-encoded antisense RNA in tobacco destabilizes 5S rRNA and retards plant growth. BMC PLANT BIOLOGY 2010; 10:213. [PMID: 20920268 PMCID: PMC3017836 DOI: 10.1186/1471-2229-10-213] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Accepted: 09/29/2010] [Indexed: 05/19/2023]
Abstract
BACKGROUND The roles of non-coding RNAs in regulating gene expression have been extensively studied in both prokaryotes and eukaryotes, however few reports exist as to their roles in organellar gene regulation. Evidence for accumulation of natural antisense RNAs (asRNAs) in chloroplasts comes from the expressed sequence tag database and cDNA libraries, while functional data have been largely obtained from artificial asRNAs. In this study, we used Nicotiana tabacum to investigate the effect on sense strand transcripts of overexpressing a natural chloroplast asRNA, AS5, which is complementary to the region which encodes the 5S rRNA and tRNAArg. RESULTS AS5-overexpressing (AS5ox) plants obtained by chloroplast transformation exhibited slower growth and slightly pale green leaves. Analysis of AS5 transcripts revealed four distinct species in wild-type (WT) and AS5ox plants, and additional AS5ox-specific products. Of the corresponding sense strand transcripts, tRNAArg overaccumulated several-fold in transgenic plants whereas 5S rRNA was unaffected. However, run-on transcription showed that the 5S-trnR region was transcribed four-fold more in the AS5ox plants compared to WT, indicating that overexpression of AS5 was associated with decreased stability of 5S rRNA. In addition, polysome analysis of the transformants showed less 5S rRNA and rbcL mRNA associated with ribosomes. CONCLUSIONS Our results suggest that AS5 can modulate 5S rRNA levels, giving it the potential to affect Chloroplast translation and plant growth. More globally, overexpression of asRNAs via chloroplast transformation may be a useful strategy for defining their functions.
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MESH Headings
- Gene Expression Regulation, Plant
- Phenotype
- Plants, Genetically Modified/genetics
- Plants, Genetically Modified/metabolism
- RNA, Antisense/genetics
- RNA, Antisense/metabolism
- RNA, Chloroplast/genetics
- RNA, Chloroplast/metabolism
- RNA, Plant/genetics
- RNA, Plant/metabolism
- RNA, Ribosomal, 5S/genetics
- RNA, Ribosomal, 5S/metabolism
- RNA, Transfer, Arg/genetics
- RNA, Transfer, Arg/metabolism
- Nicotiana/genetics
- Nicotiana/growth & development
- Nicotiana/metabolism
- Transformation, Genetic
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Affiliation(s)
- Amber M Hotto
- Boyce Thompson Institute for Plant Research, Cornell University, Tower Rd., Ithaca, NY 14853, USA
| | - Zoe E Huston
- Riverdale High School, 9727 SW Terwilliger Blvd., Portland, OR 97219, USA
| | - David B Stern
- Boyce Thompson Institute for Plant Research, Cornell University, Tower Rd., Ithaca, NY 14853, USA
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21
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Nishimura K, Ashida H, Ogawa T, Yokota A. A DEAD box protein is required for formation of a hidden break in Arabidopsis chloroplast 23S rRNA. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 63:766-77. [PMID: 20561259 DOI: 10.1111/j.1365-313x.2010.04276.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
In plant chloroplasts, the ribosomal RNA (rRNA) of the large subunit of the ribosome undergoes post-maturation fragmentation processing. This processing consists of site-specific cleavage that generates gapped, discontinuous rRNA molecules. However, the molecular mechanism underlying introduction of the gap structure (the 'hidden break') is poorly understood. Here, we found that the DEAD box protein RH39 plays a key role in introduction of the hidden break into the 23S rRNA in Arabidopsis chloroplasts. Genetic screening for an Arabidopsis plant with a drastically reduced level of ribulose-1,5-bisphosphate carboxylase/oxygenase identified an RH39 mutant. The levels of other chloroplast-encoded photosynthetic proteins were also severely reduced. The reductions were not due to a failure of transcription, but rather inefficiency in translation. RNA gel blotting revealed incomplete fragmentation of 23S rRNA in chloroplasts during maturation. In vitro analysis with recombinant RH39 suggested that the protein binds to the adjacent sequence upstream of the hidden break site to exert its function. We propose a molecular mechanism for the RH39-mediated fragmentation processing of 23S rRNA in chloroplasts.
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MESH Headings
- Amino Acid Sequence
- Arabidopsis/genetics
- Arabidopsis/metabolism
- Arabidopsis Proteins/genetics
- Arabidopsis Proteins/metabolism
- Blotting, Northern
- Blotting, Western
- Chloroplasts/metabolism
- DEAD-box RNA Helicases/genetics
- DEAD-box RNA Helicases/metabolism
- Genes, Essential/genetics
- Green Fluorescent Proteins/genetics
- Green Fluorescent Proteins/metabolism
- Molecular Sequence Data
- Mutation
- Protein Binding
- RNA, Chloroplast/genetics
- RNA, Chloroplast/metabolism
- RNA, Ribosomal, 23S/genetics
- RNA, Ribosomal, 23S/metabolism
- Recombinant Proteins/metabolism
- Ribulose-Bisphosphate Carboxylase/genetics
- Ribulose-Bisphosphate Carboxylase/metabolism
- Sequence Homology, Amino Acid
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Affiliation(s)
- Kenji Nishimura
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, Japan
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22
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Tomecki R, Dziembowski A. Novel endoribonucleases as central players in various pathways of eukaryotic RNA metabolism. RNA (NEW YORK, N.Y.) 2010; 16:1692-1724. [PMID: 20675404 PMCID: PMC2924532 DOI: 10.1261/rna.2237610] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
For a long time it has been assumed that the decay of RNA in eukaryotes is mainly carried out by exoribonucleases, which is in contrast to bacteria, where endoribonucleases are well documented to initiate RNA degradation. In recent years, several as yet unknown endonucleases have been described, which has changed our view on eukaryotic RNA metabolism. Most importantly, it was shown that the primary eukaryotic 3' --> 5' exonuclease, the exosome complex has the ability to endonucleolytically cleave its physiological RNA substrates, and novel endonucleases involved in both nuclear and cytoplasmic RNA surveillance pathways were discovered concurrently. In addition, endoribonucleases responsible for long-known processing steps in the maturation pathways of various RNA classes were recently identified. Moreover, one of the most intensely studied RNA decay pathways--RNAi--is controlled and stimulated by the action of different endonucleases. Furthermore, endoribonucleolytic cleavages executed by various enzymes are also the hallmark of RNA degradation and processing in plant chloroplasts. Finally, multiple context-specific endoribonucleases control qualitative and/or quantitative changes of selected transcripts under particular conditions in different eukaryotic organisms. The aim of this review is to discuss the impact of all of these discoveries on our current understanding of eukaryotic RNA metabolism.
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Affiliation(s)
- Rafal Tomecki
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, University of Warsaw, 02-106 Warsaw, Poland
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23
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Madesis P, Osathanunkul M, Georgopoulou U, Gisby MF, Mudd EA, Nianiou I, Tsitoura P, Mavromara P, Tsaftaris A, Day A. A hepatitis C virus core polypeptide expressed in chloroplasts detects anti-core antibodies in infected human sera. J Biotechnol 2010; 145:377-86. [PMID: 19969031 DOI: 10.1016/j.jbiotec.2009.12.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Revised: 11/27/2009] [Accepted: 12/01/2009] [Indexed: 01/19/2023]
Abstract
Hepatitis C virus (HCV) is a major disease agent affecting approximately 3% of the world's population. Expression in plant chloroplasts enables low-cost production of the conserved HCV core protein used in diagnostic tests to combat virus spread in developing countries with high infection rates. The bactericidal activity of the 21 kDa precore protein hinders cloning the core gene in plastid expression cassettes, which are active in bacteria due to the similarities between bacterial and plastid promoters and ribosome binding sites. This was overcome by using a topology-dependent expression cassette containing tandem rrn and psbA plastid promoters, whose activity was shown to be dependent on temperature. The viral core gene and a codon-optimised gene encoding a C-terminal truncated 16 kDa core polypeptide were expressed in tobacco chloroplasts. The codon-optimised gene increased monocistronic core mRNA levels by at least 2-fold and core polypeptides by over 5-fold, relative to the native viral gene. Expression of the 16 kDa core polypeptide was stable in leaves of different ages. Anti-core antibodies in HCV-infected human sera were detected by the 16 kDa core polypeptide in total leaf protein fractionated on Western blots providing a first step towards developing a chloroplast-based HCV diagnostic method.
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Affiliation(s)
- P Madesis
- Faculty of Life Sciences, The University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
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24
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Abstract
The chloroplast genome encodes proteins required for photosynthesis, gene expression, and other essential organellar functions. Derived from a cyanobacterial ancestor, the chloroplast combines prokaryotic and eukaryotic features of gene expression and is regulated by many nucleus-encoded proteins. This review covers four major chloroplast posttranscriptional processes: RNA processing, editing, splicing, and turnover. RNA processing includes the generation of transcript 5' and 3' termini, as well as the cleavage of polycistronic transcripts. Editing converts specific C residues to U and often changes the amino acid that is specified by the edited codon. Chloroplasts feature introns of groups I and II, which undergo protein-facilitated cis- or trans-splicing in vivo. Each of these RNA-based processes involves proteins of the pentatricopeptide motif-containing family, which does not occur in prokaryotes. Plant-specific RNA-binding proteins may underpin the adaptation of the chloroplast to the eukaryotic context.
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Affiliation(s)
- David B Stern
- Boyce Thompson Institute for Plant Research, Ithaca, New York 14853, USA.
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The Exosome and 3′–5′ RNA Degradation in Plants. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 702:50-62. [DOI: 10.1007/978-1-4419-7841-7_5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Site-specific binding of a PPR protein defines and stabilizes 5' and 3' mRNA termini in chloroplasts. EMBO J 2009; 28:2042-52. [PMID: 19424177 DOI: 10.1038/emboj.2009.121] [Citation(s) in RCA: 272] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2009] [Accepted: 03/26/2009] [Indexed: 12/30/2022] Open
Abstract
Chloroplast mRNA populations are characterized by overlapping transcripts derived by processing from polycistronic precursors. The mechanisms and functional significance of these processing events are poorly understood. We describe a pentatricopeptide repeat (PPR) protein, PPR10, whose binding defines mRNA segments derived from two transcription units in maize chloroplasts. PPR10 interacts in vivo and in vitro with two intergenic RNA regions of similar sequence. The processed 5' and 3' RNA termini in these regions overlap by approximately 25 nucleotides. The PPR10-binding sites map precisely to these overlapping sequences, and PPR10 is required specifically for the accumulation of RNAs with these termini. These findings show that PPR10 serves as a barrier to RNA decay from either the 5' or 3' direction and that a bound protein provides an alternative to an RNA hairpin as a barrier to 3' exonucleases. The results imply that protein 'caps' at both 5' and 3' ends can define the termini of chloroplast mRNA segments. These results, together with recent insights into bacterial RNA decay, suggest a unifying model for the biogenesis of chloroplast transcript populations and for the determinants of chloroplast mRNA stability.
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Stepien P, Johnson GN. Contrasting responses of photosynthesis to salt stress in the glycophyte Arabidopsis and the halophyte thellungiella: role of the plastid terminal oxidase as an alternative electron sink. PLANT PHYSIOLOGY 2009. [PMID: 19052149 DOI: 10.1104/pp.108] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The effects of short-term salt stress on gas exchange and the regulation of photosynthetic electron transport were examined in Arabidopsis (Arabidopsis thaliana) and its salt-tolerant close relative Thellungiella (Thellungiella halophila). Plants cultivated on soil were challenged for 2 weeks with NaCl. Arabidopsis showed a much higher sensitivity to salt than Thellungiella; while Arabidopsis plants were unable to survive exposure to greater than 150 mM salt, Thellugiella could tolerate concentrations as high as 500 mM with only minimal effects on gas exchange. Exposure of Arabidopsis to sublethal salt concentrations resulted in stomatal closure and inhibition of CO2 fixation. This lead to an inhibition of electron transport though photosystem II (PSII), an increase in cyclic electron flow involving only PSI, and increased nonphotochemical quenching of chlorophyll fluorescence. In contrast, in Thellungiella, although gas exchange was marginally inhibited by high salt and PSI was unaffected, there was a large increase in electron flow involving PSII. This additional electron transport activity is oxygen dependent and sensitive to the alternative oxidase inhibitor n-propyl gallate. PSII electron transport in Thellungiella showed a reduced sensitivity to 2'-iodo-6-isopropyl-3-methyl-2',4,4'-trinitrodiphenylether, an inhibitor of the cytochrome b6f complex. At the same time, we observed a substantial up-regulation of a protein reacting with antibodies raised against the plastid terminal oxidase. No such up-regulation was seen in Arabidopsis. We conclude that in salt-stressed Thellungiella, plastid terminal oxidase acts as an alternative electron sink, accounting for up to 30% of total PSII electron flow.
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Affiliation(s)
- Piotr Stepien
- Faculty of Life Sciences, Manchester M13 9PT, United Kingdom
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28
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Stepien P, Johnson GN. Contrasting responses of photosynthesis to salt stress in the glycophyte Arabidopsis and the halophyte thellungiella: role of the plastid terminal oxidase as an alternative electron sink. PLANT PHYSIOLOGY 2009; 149:1154-65. [PMID: 19052149 PMCID: PMC2633845 DOI: 10.1104/pp.108.132407] [Citation(s) in RCA: 222] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Accepted: 11/26/2008] [Indexed: 05/18/2023]
Abstract
The effects of short-term salt stress on gas exchange and the regulation of photosynthetic electron transport were examined in Arabidopsis (Arabidopsis thaliana) and its salt-tolerant close relative Thellungiella (Thellungiella halophila). Plants cultivated on soil were challenged for 2 weeks with NaCl. Arabidopsis showed a much higher sensitivity to salt than Thellungiella; while Arabidopsis plants were unable to survive exposure to greater than 150 mM salt, Thellugiella could tolerate concentrations as high as 500 mM with only minimal effects on gas exchange. Exposure of Arabidopsis to sublethal salt concentrations resulted in stomatal closure and inhibition of CO2 fixation. This lead to an inhibition of electron transport though photosystem II (PSII), an increase in cyclic electron flow involving only PSI, and increased nonphotochemical quenching of chlorophyll fluorescence. In contrast, in Thellungiella, although gas exchange was marginally inhibited by high salt and PSI was unaffected, there was a large increase in electron flow involving PSII. This additional electron transport activity is oxygen dependent and sensitive to the alternative oxidase inhibitor n-propyl gallate. PSII electron transport in Thellungiella showed a reduced sensitivity to 2'-iodo-6-isopropyl-3-methyl-2',4,4'-trinitrodiphenylether, an inhibitor of the cytochrome b6f complex. At the same time, we observed a substantial up-regulation of a protein reacting with antibodies raised against the plastid terminal oxidase. No such up-regulation was seen in Arabidopsis. We conclude that in salt-stressed Thellungiella, plastid terminal oxidase acts as an alternative electron sink, accounting for up to 30% of total PSII electron flow.
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Affiliation(s)
- Piotr Stepien
- Faculty of Life Sciences, Manchester M13 9PT, United Kingdom
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Carpousis AJ, Luisi BF, McDowall KJ. Endonucleolytic initiation of mRNA decay in Escherichia coli. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2009; 85:91-135. [PMID: 19215771 DOI: 10.1016/s0079-6603(08)00803-9] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Instability is a fundamental property of mRNA that is necessary for the regulation of gene expression. In E. coli, the turnover of mRNA involves multiple, redundant pathways involving 3'-exoribonucleases, endoribonucleases, and a variety of other enzymes that modify RNA covalently or affect its conformation. Endoribonucleases are thought to initiate or accelerate the process of mRNA degradation. A major endoribonuclease in this process is RNase E, which is a key component of the degradative machinery amongst the Proteobacteria. RNase E is the central element in a multienzyme complex known as the RNA degradosome. Structural and functional data are converging on models for the mechanism of activation and regulation of RNase E and its paralog, RNase G. Here, we discuss current models for mRNA degradation in E. coli and we present current thinking on the structure and function of RNase E based on recent crystal structures of its catalytic core.
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Affiliation(s)
- Agamemnon J Carpousis
- Laboratoire de Microbiologie et Génétique Moléculaires, CNRS et Université Paul Sabatier, 31062 Toulouse, France
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Schuster G, Stern D. RNA polyadenylation and decay in mitochondria and chloroplasts. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2009; 85:393-422. [PMID: 19215778 DOI: 10.1016/s0079-6603(08)00810-6] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Mitochondria and chloroplasts were originally acquired by eukaryotic cells through endosymbiotic events and retain their own gene expression machinery. One hallmark of gene regulation in these two organelles is the predominance of posttranscriptional control, which is exerted both at the gene-specific and global levels. This review focuses on their mechanisms of RNA degradation, and therefore mainly on the polyadenylation-stimulated degradation pathway. Overall, mitochondria and chloroplasts have retained the prokaryotic RNA decay system, despite evolution in the number and character of the enzymes involved. However, several significant differences exist, of which the presence of stable poly(A) tails, and the location of PNPase in the intermembrane space in animal mitochondria, are perhaps the most remarkable. The known and predicted proteins taking part in polyadenylation-stimulated degradation pathways are described, both in chloroplasts and four mitochondrial types: plant, yeast, trypanosome, and animal.
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Affiliation(s)
- Gadi Schuster
- Department of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
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