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Huo Y, Cheng M, Tang M, Zhang M, Yang X, Zheng Y, Zhao T, He P, Yu J. GhCTSF1, a short PPR protein with a conserved role in chloroplast development and photosynthesis, participates in intron splicing of rpoC1 and ycf3-2 transcripts in cotton. PLANT COMMUNICATIONS 2024; 5:100858. [PMID: 38444162 PMCID: PMC11211521 DOI: 10.1016/j.xplc.2024.100858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Revised: 02/29/2024] [Accepted: 03/04/2024] [Indexed: 03/07/2024]
Abstract
Cotton is one of the most important textile fibers worldwide. As crucial agronomic traits, leaves play an essential role in the growth, disease resistance, fiber quality, and yield of cotton plants. Pentatricopeptide repeat (PPR) proteins are a large family of nuclear-encoded proteins involved in organellar or nuclear RNA metabolism. Using a virus-induced gene silencing assay, we found that cotton plants displayed variegated yellow leaf phenotypes with decreased chlorophyll content when expression of the PPR gene GhCTSF1 was silenced. GhCTSF1 encodes a chloroplast-localized protein that contains only two PPR motifs. Disruption of GhCTSF1 substantially reduces the splicing efficiency of rpoC1 intron 1 and ycf3 intron 2. Loss of function of the GhCTSF1 ortholog EMB1417 causes splicing defects in rpoC1 and ycf3-2, leading to impaired chloroplast structure and decreased photosynthetic rates in Arabidopsis. We also found that GhCTSF1 interacts with two splicing factors, GhCRS2 and GhWTF1. Defects in GhCRS2 and GhWTF1 severely affect intron splicing of rpoC1 and ycf3-2 in cotton, leading to defects in chloroplast development and a reduction in photosynthesis. Our results suggest that GhCTSF1 is specifically required for splicing rpoC1 and ycf3-2 in cooperation with GhCRS2 and GhWTF1.
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Affiliation(s)
- Yuzhu Huo
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, China
| | - Mengxue Cheng
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, China
| | - Meiju Tang
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, China
| | - Meng Zhang
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, China
| | - Xiaofan Yang
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, China
| | - Yating Zheng
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, China
| | - Tong Zhao
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, China
| | - Peng He
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, China.
| | - Jianing Yu
- College of Life Sciences, Shaanxi Normal University, Xi'an 710119, China.
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Zhang Y, Tian L, Lu C. Chloroplast gene expression: Recent advances and perspectives. PLANT COMMUNICATIONS 2023; 4:100611. [PMID: 37147800 PMCID: PMC10504595 DOI: 10.1016/j.xplc.2023.100611] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 04/11/2023] [Accepted: 05/01/2023] [Indexed: 05/07/2023]
Abstract
Chloroplasts evolved from an ancient cyanobacterial endosymbiont more than 1.5 billion years ago. During subsequent coevolution with the nuclear genome, the chloroplast genome has remained independent, albeit strongly reduced, with its own transcriptional machinery and distinct features, such as chloroplast-specific innovations in gene expression and complicated post-transcriptional processing. Light activates the expression of chloroplast genes via mechanisms that optimize photosynthesis, minimize photodamage, and prioritize energy investments. Over the past few years, studies have moved from describing phases of chloroplast gene expression to exploring the underlying mechanisms. In this review, we focus on recent advances and emerging principles that govern chloroplast gene expression in land plants. We discuss engineering of pentatricopeptide repeat proteins and its biotechnological effects on chloroplast RNA research; new techniques for characterizing the molecular mechanisms of chloroplast gene expression; and important aspects of chloroplast gene expression for improving crop yield and stress tolerance. We also discuss biological and mechanistic questions that remain to be answered in the future.
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Affiliation(s)
- Yi Zhang
- National Key Laboratory of Wheat Improvement, College of Life Sciences, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Lin Tian
- National Key Laboratory of Wheat Improvement, College of Life Sciences, Shandong Agricultural University, Taian, Shandong 271018, China
| | - Congming Lu
- National Key Laboratory of Wheat Improvement, College of Life Sciences, Shandong Agricultural University, Taian, Shandong 271018, China.
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3
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Small I, Melonek J, Bohne AV, Nickelsen J, Schmitz-Linneweber C. Plant organellar RNA maturation. THE PLANT CELL 2023; 35:1727-1751. [PMID: 36807982 PMCID: PMC10226603 DOI: 10.1093/plcell/koad049] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Revised: 01/05/2023] [Accepted: 01/17/2023] [Indexed: 05/30/2023]
Abstract
Plant organellar RNA metabolism is run by a multitude of nucleus-encoded RNA-binding proteins (RBPs) that control RNA stability, processing, and degradation. In chloroplasts and mitochondria, these post-transcriptional processes are vital for the production of a small number of essential components of the photosynthetic and respiratory machinery-and consequently for organellar biogenesis and plant survival. Many organellar RBPs have been functionally assigned to individual steps in RNA maturation, often specific to selected transcripts. While the catalog of factors identified is ever-growing, our knowledge of how they achieve their functions mechanistically is far from complete. This review summarizes the current knowledge of plant organellar RNA metabolism taking an RBP-centric approach and focusing on mechanistic aspects of RBP functions and the kinetics of the processes they are involved in.
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Affiliation(s)
- Ian Small
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, Crawley 6009, Australia
| | - Joanna Melonek
- Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, The University of Western Australia, Crawley 6009, Australia
| | | | - Jörg Nickelsen
- Department of Molecular Plant Sciences, LMU Munich, 82152 Martinsried, Germany
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Zeng C, Jiao Q, Jia T, Hu X. Updated Progress on Group II Intron Splicing Factors in Plant Chloroplasts. Curr Issues Mol Biol 2022; 44:4229-4239. [PMID: 36135202 PMCID: PMC9497791 DOI: 10.3390/cimb44090290] [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] [Received: 07/26/2022] [Revised: 09/05/2022] [Accepted: 09/08/2022] [Indexed: 11/16/2022] Open
Abstract
Group II introns are large catalytic RNAs (ribozymes) in the bacteria and organelle genomes of several lower eukaryotes. Many critical photosynthesis-related genes in the plant chloroplast genome also contain group II introns, and their splicing is critical for chloroplast biogenesis and photosynthesis processes. The structure of chloroplast group II introns was altered during evolution, resulting in the loss of intron self-splicing. Therefore, the assistance of protein factors was required for their splicing processes. As an increasing number of studies focus on the mechanism of chloroplast intron splicing; many new nuclear-encoded splicing factors that are involved in the chloroplast intron splicing process have been reported. This report reviewed the research progress of the updated splicing factors found to be involved in the splicing of chloroplast group II introns. We discuss the main problems that remain in this research field and suggest future research directions.
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Affiliation(s)
- Chu Zeng
- Jiangsu Provincial Key Laboratory of Crop Genetics and Physiology/Jiangsu Provincial Key Laboratory of Crop Genomics and Molecular Breeding/Key Laboratory of Plant Functional Genomics of the Ministry of Education, Yangzhou University, Yangzhou 225009, China
- Co-Innovation Center for Modern Production Technology of Grain Crops of Jiangsu Province/Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou 225009, China
| | - Qingsong Jiao
- Jiangsu Provincial Key Laboratory of Crop Genetics and Physiology/Jiangsu Provincial Key Laboratory of Crop Genomics and Molecular Breeding/Key Laboratory of Plant Functional Genomics of the Ministry of Education, Yangzhou University, Yangzhou 225009, China
- Co-Innovation Center for Modern Production Technology of Grain Crops of Jiangsu Province/Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou 225009, China
| | - Ting Jia
- Co-Innovation Center for Modern Production Technology of Grain Crops of Jiangsu Province/Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou 225009, China
| | - Xueyun Hu
- Jiangsu Provincial Key Laboratory of Crop Genetics and Physiology/Jiangsu Provincial Key Laboratory of Crop Genomics and Molecular Breeding/Key Laboratory of Plant Functional Genomics of the Ministry of Education, Yangzhou University, Yangzhou 225009, China
- Co-Innovation Center for Modern Production Technology of Grain Crops of Jiangsu Province/Joint International Research Laboratory of Agriculture and Agri-Product Safety of the Ministry of Education of China, Yangzhou University, Yangzhou 225009, China
- Correspondence:
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Wang Y, Yang Z, Zhang M, Ai P. A chloroplast-localized pentatricopeptide repeat protein involved in RNA editing and splicing and its effects on chloroplast development in rice. BMC PLANT BIOLOGY 2022; 22:437. [PMID: 36096762 PMCID: PMC9469629 DOI: 10.1186/s12870-022-03819-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Accepted: 08/24/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND The chloroplast is the organelle responsible for photosynthesis in higher plants. The generation of functional chloroplasts depends on the precise coordination of gene expression in the nucleus and chloroplasts and is essential for the development of plants. However, little is known about nuclear-plastid regulatory mechanisms at the early stage of chloroplast generation in rice. RESULTS In this study, we identified a rice (Oryza sativa) mutant that exhibited albino and seedling-lethal phenotypes and named it ssa1(seedling stage albino1). Transmission electron microscopy (TEM) analysis indicated that the chloroplasts of ssa1 did not have organized thylakoid lamellae and that the chloroplast structure was destroyed. Genetic analysis revealed that the albino phenotypes of ssa1 were controlled by a pair of recessive nuclear genes. Map-based cloning experiments found that SSA1 encoded a pentapeptide repeat (PPR) protein that was allelic to OSOTP51,which was previously reported to participate in Photosystem I (PSI) assembly. The albino phenotype was reversed to the wild type (WT) phenotype when the normal SSA1 sequence was expressed in ssa1 under the drive of the actin promoter. Knockout experiments further created mutants ssa1-2/1-9, which had a phenotype similar to that of ssa1. SSA1 consisted of 7 pentatricopeptide repeat domains and two C-terminal LAGLIDADG tandem sequence motifs and was located in the chloroplast. GUS staining and qRT-PCR analysis showed that SSA1 was mainly expressed in young leaves and stems. In the ssa1 mutants, plastid genes transcribed by plastid-encoded RNA polymerase decreased, while those transcribed by nuclear-encoded RNA polymerase increased at the mRNA level. Loss-of-function SSA1 destroys RNA editing of ndhB-737 and intron splicing of atpF and ycf3-2 in the plastid genome. Yeast two-hybrid and BiFC assays revealed that SSA1 physically interacted with two new RNA editing partners, OsMORF8 and OsTRXz, which have potential functions in RNA editing and chloroplast biogenesis. CONCLUSIONS Rice SSA1 encodes a pentatricopeptide repeat protein, which is targeted to the chloroplast. SSA1 regulates early chloroplast development and plays a critical role in RNA editing and intron splicing in rice. These data will facilitate efforts to further elucidate the molecular mechanism of chloroplast biogenesis.
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Affiliation(s)
- Yanwei Wang
- Collage of Food and Biology, Hebei University of Science and Technology, Shijiazhuang, 050018, Hebei, China
| | - Zhimin Yang
- Collage of Food and Biology, Hebei University of Science and Technology, Shijiazhuang, 050018, Hebei, China
| | - Meng Zhang
- Collage of Food and Biology, Hebei University of Science and Technology, Shijiazhuang, 050018, Hebei, China
| | - Pengfei Ai
- Collage of Food and Biology, Hebei University of Science and Technology, Shijiazhuang, 050018, Hebei, China.
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Wang X, Wang J, Li S, Lu C, Sui N. An overview of RNA splicing and functioning of splicing factors in land plant chloroplasts. RNA Biol 2022; 19:897-907. [PMID: 35811474 PMCID: PMC9275481 DOI: 10.1080/15476286.2022.2096801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
RNA splicing refers to a process by which introns of a pre-mRNA are excised and the exons at both ends are joined together. Chloroplast introns are inherently self-splicing ribozymes, but over time, they have lost self-splicing ability due to the degeneration of intronic elements. Thus, the splicing of chloroplast introns relies heavily on nuclear-encoded splicing factors, which belong to diverse protein families. Different splicing factors and their shared intron targets are supposed to form ribonucleoprotein particles (RNPs) to facilitate intron splicing. As characterized in a previous review, around 14 chloroplast intron splicing factors were identified until 2010. However, only a few genetic and biochemical evidence has shown that these splicing factors are required for the splicing of one or several introns. The roles of splicing factors are generally believed to facilitate intron folding; however, the precise role of each protein in RNA splicing remains ambiguous. This may be because the precise binding site of most of these splicing factors remains unexplored. In the last decade, several new splicing factors have been identified. Also, several splicing factors were found to bind to specific sequences within introns, which enhanced the understanding of splicing factors. Here, we summarize recent progress on the splicing factors in land plant chloroplasts and discuss their possible roles in chloroplast RNA splicing based on previous studies.
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Affiliation(s)
- Xuemei Wang
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan, Western Shandong, China
| | - Jingyi Wang
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan, Western Shandong, China
| | - Simin Li
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan, Western Shandong, China
| | - Congming Lu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, Western Shandong, China
| | - Na Sui
- Shandong Provincial Key Laboratory of Plant Stress, College of Life Sciences, Shandong Normal University, Jinan, Western Shandong, China
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7
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Zhang L, Chen J, Zhang L, Wei Y, Li Y, Xu X, Wu H, Yang ZN, Huang J, Hu F, Huang W, Cui YL. The pentatricopeptide repeat protein EMB1270 interacts with CFM2 to splice specific group II introns in Arabidopsis chloroplasts. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2021; 63:1952-1966. [PMID: 34427970 DOI: 10.1111/jipb.13165] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 08/19/2021] [Indexed: 06/13/2023]
Abstract
Chloroplast biogenesis requires the coordinated expression of chloroplast and nuclear genes. Here, we show that EMB1270, a plastid-localized pentatricopeptide repeat (PPR) protein, is required for chloroplast biogenesis in Arabidopsis thaliana. Knockout of EMB1270 led to embryo arrest, whereas a mild knockdown mutant of EMB1270 displayed a virescent phenotype. Almost no photosynthetic proteins accumulated in the albino emb1270 knockout mutant. By contrast, in the emb1270 knockdown mutant, the levels of ClpP1 and photosystem I (PSI) subunits were significantly reduced, whereas the levels of photosystem II (PSII) subunits were normal. Furthermore, the splicing efficiencies of the clpP1.2, ycf3.1, ndhA, and ndhB plastid introns were dramatically reduced in both emb1270 mutants. RNA immunoprecipitation revealed that EMB1270 associated with these introns in vivo. In an RNA electrophoretic mobility shift assay (REMSA), a truncated EMB1270 protein containing the 11 N-terminal PPR motifs bound to the predicted sequences of the clpP1.2, ycf3.1, and ndhA introns. In addition, EMB1270 specifically interacted with CRM Family Member 2 (CFM2). Given that CFM2 is known to be required for splicing the same plastid RNAs, our results suggest that EMB1270 associates with CFM2 to facilitate the splicing of specific group II introns in Arabidopsis.
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Affiliation(s)
- Li Zhang
- Shanghai Key Laboratory of Plant Molecular Sciences, Development Center of Plant Germplasm Resources, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Jingli Chen
- Shanghai Key Laboratory of Plant Molecular Sciences, Development Center of Plant Germplasm Resources, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Liqun Zhang
- Shanghai Key Laboratory of Plant Molecular Sciences, Development Center of Plant Germplasm Resources, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Ying Wei
- Shanghai Key Laboratory of Plant Molecular Sciences, Development Center of Plant Germplasm Resources, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Yajuan Li
- Shanghai Key Laboratory of Plant Molecular Sciences, Development Center of Plant Germplasm Resources, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Xinyun Xu
- Shanghai Key Laboratory of Plant Molecular Sciences, Development Center of Plant Germplasm Resources, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Hui Wu
- Shanghai Key Laboratory of Plant Molecular Sciences, Development Center of Plant Germplasm Resources, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Zhong-Nan Yang
- Shanghai Key Laboratory of Plant Molecular Sciences, Development Center of Plant Germplasm Resources, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Jirong Huang
- Shanghai Key Laboratory of Plant Molecular Sciences, Development Center of Plant Germplasm Resources, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Fenhong Hu
- Shanghai Key Laboratory of Plant Molecular Sciences, Development Center of Plant Germplasm Resources, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Weihua Huang
- Shanghai Key Laboratory of Plant Molecular Sciences, Development Center of Plant Germplasm Resources, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
| | - Yong-Lan Cui
- Shanghai Key Laboratory of Plant Molecular Sciences, Development Center of Plant Germplasm Resources, College of Life Sciences, Shanghai Normal University, Shanghai, 200234, China
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8
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Yamamoto H, Sato N, Shikanai T. Critical Role of NdhA in the Incorporation of the Peripheral Arm into the Membrane-Embedded Part of the Chloroplast NADH Dehydrogenase-Like Complex. PLANT & CELL PHYSIOLOGY 2021; 62:1131-1145. [PMID: 33169158 DOI: 10.1093/pcp/pcaa143] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 10/19/2020] [Indexed: 06/11/2023]
Abstract
The chloroplast NADH dehydrogenase-like (NDH) complex mediates ferredoxin-dependent plastoquinone reduction in the thylakoid membrane. In angiosperms, chloroplast NDH is composed of five subcomplexes and further forms a supercomplex with photosystem I (PSI). Subcomplex A (SubA) mediates the electron transport and consists of eight subunits encoded by both plastid and nuclear genomes. The assembly of SubA in the stroma has been extensively studied, but it is unclear how SubA is incorporated into the membrane-embedded part of the NDH complex. Here, we isolated a novel Arabidopsis mutant chlororespiratory reduction 16 (crr16) defective in NDH activity. CRR16 encodes a chloroplast-localized P-class pentatricopeptide repeat protein conserved in angiosperms. Transcript analysis of plastid-encoded ndh genes indicated that CRR16 was responsible for the efficient splicing of the group II intron in the ndhA transcript, which encodes a membrane-embedded subunit localized to the connecting site between SubA and the membrane subcomplex (SubM). To analyze the roles of NdhA in the assembly and stability of the NDH complex, the homoplastomic knockout plant of ndhA (ΔndhA) was generated in tobacco (Nicotiana tabacum). Biochemical analyses of crr16 and ΔndhA plants indicated that NdhA was essential for stabilizing SubA and SubE but not for the accumulation of the other three subcomplexes. Furthermore, the crr16 mutant accumulated the SubA assembly intermediates in the stroma more than that in the wild type. These results suggest that NdhA biosynthesis is essential for the incorporation of SubA into the membrane-embedded part of the NDH complex at the final assembly step of the NDH-PSI supercomplex.
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Affiliation(s)
- Hiroshi Yamamoto
- Department of Botany, Graduate School of Science, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto, 606-8502 Japan
| | - Nozomi Sato
- Department of Botany, Graduate School of Science, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto, 606-8502 Japan
- Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo Motoyama, Kita-ku, Kyoto 603-8555, Japan
| | - Toshiharu Shikanai
- Department of Botany, Graduate School of Science, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto, 606-8502 Japan
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9
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Fan K, Ren Z, Zhang X, Liu Y, Fu J, Qi C, Tatar W, Rasmusson AG, Wang G, Liu Y. The pentatricopeptide repeat protein EMP603 is required for the splicing of mitochondrial Nad1 intron 2 and seed development in maize. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:6933-6948. [PMID: 34279607 DOI: 10.1093/jxb/erab339] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 07/16/2021] [Indexed: 06/13/2023]
Abstract
Intron splicing is an essential event in post-transcriptional RNA processing in plant mitochondria, which requires the participation of diverse nuclear-encoded splicing factors. However, it is presently unclear how these proteins cooperatively take part in the splicing of specific introns. In this study, we characterized a nuclear-encoded mitochondrial P-type pentatricopeptide repeat (PPR) protein named EMP603. This protein is essential for splicing of intron 2 in the Nad1 gene and interacts with the mitochondria-localized DEAD-box RNA helicase PMH2-5140, the RAD52-like proteins ODB1-0814 and ODB1-5061, and the CRM domain-containing protein Zm-mCSF1. Further study revealed that the N-terminal region of EMP603 interacts with the DEAD-box of PMH2-5140, the CRM domain of Zm-mCSF1, and OBD1-5061, but not with OBD1-0814, whereas the PPR domain of EMP603 can interact with ODB1-0814, ODB1-5061, and PMH2-5140, but not with Zm-mCSF1. Defects in EMP603 severely disrupt the assembly and activity of mitochondrial complex I, leading to impaired mitochondrial function, and delayed seed development. The interactions revealed between EMP603 and PMH2-5140, ODB1-0814, ODB1-5061, and Zm-mCSF1 indicate a possible involvement of a dynamic 'spliceosome-like' complex in intron splicing, and may accelerate the elucidation of the intron splicing mechanism in plant mitochondria.
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Affiliation(s)
- Kaijian Fan
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Zhenjing Ren
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Xiaofeng Zhang
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yan Liu
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Junjie Fu
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Chunlai Qi
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Wurinile Tatar
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | | | - Guoying Wang
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yunjun Liu
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, China
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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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Karim MF, Johnson GN. Acclimation of Photosynthesis to Changes in the Environment Results in Decreases of Oxidative Stress in Arabidopsis thaliana. FRONTIERS IN PLANT SCIENCE 2021; 12:683986. [PMID: 34630448 PMCID: PMC8495028 DOI: 10.3389/fpls.2021.683986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 08/18/2021] [Indexed: 05/08/2023]
Abstract
The dynamic acclimation of photosynthesis plays an important role in increasing the fitness of a plant under variable light environments. Since acclimation is partially mediated by a glucose-6-phosphate/phosphate translocator 2 (GPT2), this study examined whether plants lacking GPT2, which consequently have defective acclimation to increases in light, are more susceptible to oxidative stress. To understand this mechanism, we used the model plant Arabidopsis thaliana [accession Wassilewskija-4 (Ws-4)] and compared it with mutants lacking GPT2. The plants were then grown at low light (LL) at 100 μmol m-2 s-1 for 7 weeks. For the acclimation experiments, a set of plants from LL was transferred to 400 μmol m-2 s-1 conditions for 7 days. Biochemical and physiological analyses showed that the gpt2 mutant plants had significantly greater activity for ascorbate peroxidase (APX), guiacol peroxidase (GPOX), and superoxide dismutase (SOD). Furthermore, the mutant plants had significantly lower maximum quantum yields of photosynthesis (Fv/Fm). A microarray analysis also showed that gpt2 plants exhibited a greater induction of stress-related genes relative to wild-type (WT) plants. We then concluded that photosynthetic acclimation to a higher intensity of light protects plants against oxidative stress.
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12
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Wang X, Yang Z, Zhang Y, Zhou W, Zhang A, Lu C. Pentatricopeptide repeat protein PHOTOSYSTEM I BIOGENESIS FACTOR2 is required for splicing of ycf3. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2020; 62:1741-1761. [PMID: 32250043 DOI: 10.1111/jipb.12936] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Accepted: 03/27/2020] [Indexed: 05/04/2023]
Abstract
To gain a better understanding of the molecular mechanisms of photosystem I (PSI) biogenesis, we characterized the Arabidopsis thaliana photosystem I biogenesis factor 2 (pbf2) mutant, which lacks PSI complex. PBF2 encodes a P-class pentatricopeptide repeat (PPR) protein. In the pbf2 mutants, we observed a striking decrease in the transcript level of only one gene, the chloroplast gene ycf3, which is essential for PSI assembly. Further analysis of ycf3 transcripts showed that PBF2 is specifically required for the splicing of ycf3 intron 1. Computational prediction of binding sequences and electrophoretic mobility shift assays reveal that PBF2 specifically binds to a sequence in ycf3 intron 1. Moreover, we found that PBF2 interacted with two general factors for group II intron splicing CHLOROPLAST RNA SPLICING2-ASSOCIATED FACTOR1 (CAF1) and CAF2, and facilitated the association of these two factors with ycf3 intron 1. Our results suggest that PBF2 is specifically required for the splicing of ycf3 intron 1 through cooperating with CAF1 and CAF2. Our results also suggest that additional proteins are required to contribute to the specificity of CAF-dependent group II intron splicing.
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Affiliation(s)
- Xuemei Wang
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhipan Yang
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yi Zhang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, China
| | - Wen Zhou
- Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Aihong Zhang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, China
| | - Congming Lu
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, China
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Schmid LM, Ohler L, Möhlmann T, Brachmann A, Muiño JM, Leister D, Meurer J, Manavski N. PUMPKIN, the Sole Plastid UMP Kinase, Associates with Group II Introns and Alters Their Metabolism. PLANT PHYSIOLOGY 2019; 179:248-264. [PMID: 30409856 PMCID: PMC6324238 DOI: 10.1104/pp.18.00687] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 10/29/2018] [Indexed: 05/07/2023]
Abstract
The chloroplast hosts photosynthesis and a variety of metabolic pathways that are essential for plant viability and acclimation processes. In this study, we show that the sole plastid UMP kinase (PUMPKIN) in Arabidopsis (Arabidopsis thaliana) associates specifically with the introns of the plastid transcripts trnG-UCC, trnV-UAC, petB, petD, and ndhA in vivo, as revealed by RNA immunoprecipitation coupled with deep sequencing (RIP-Seq); and that PUMPKIN can bind RNA efficiently in vitro. Analyses of target transcripts showed that PUMPKIN affects their metabolism. Null alleles and knockdowns of pumpkin were viable but clearly affected in growth, plastid translation, and photosynthetic performance. In pumpkin mutants, the levels of many plastid transcripts were reduced, while the amounts of others were increased, as revealed by RNA-Seq analysis. PUMPKIN is a homomultimeric, plastid-localized protein that forms in vivo RNA-containing megadalton-sized complexes and catalyzes the ATP-dependent conversion of UMP to UDP in vitro with properties characteristic of known essential eubacterial UMP kinases. A moonlighting function of PUMPKIN combining RNA and pyrimidine metabolism is discussed.
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Affiliation(s)
- Lisa-Marie Schmid
- Plant Sciences, Faculty of Biology, Ludwig-Maximilians-University Munich, Großhaderner Street 2-4, 82152 Planegg-Martinsried, Germany
| | - Lisa Ohler
- Plant Physiology, Faculty of Biology, University of Kaiserslautern, Erwin Schrödinger Street, 67653 Kaiserslautern, Germany
| | - Torsten Möhlmann
- Plant Physiology, Faculty of Biology, University of Kaiserslautern, Erwin Schrödinger Street, 67653 Kaiserslautern, Germany
| | - Andreas Brachmann
- Genetics, Faculty of Biology, Ludwig-Maximilians-University Munich, Großhaderner Street 2-4, 82152 Planegg-Martinsried, Germany
| | - Jose M Muiño
- Humboldt University, Faculty of Life Science, Philipp Street 13, 10115 Berlin, Germany
| | - Dario Leister
- Plant Sciences, Faculty of Biology, Ludwig-Maximilians-University Munich, Großhaderner Street 2-4, 82152 Planegg-Martinsried, Germany
| | - Jörg Meurer
- Plant Sciences, Faculty of Biology, Ludwig-Maximilians-University Munich, Großhaderner Street 2-4, 82152 Planegg-Martinsried, Germany
| | - Nikolay Manavski
- Plant Sciences, Faculty of Biology, Ludwig-Maximilians-University Munich, Großhaderner Street 2-4, 82152 Planegg-Martinsried, Germany
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Zhang B, Qiu HL, Qu DH, Ruan Y, Chen DH. Phylogeny-dominant classification of J-proteins in Arabidopsis thaliana and Brassica oleracea. Genome 2018; 61:405-415. [PMID: 29620479 DOI: 10.1139/gen-2017-0206] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Hsp40s or DnaJ/J-proteins are evolutionarily conserved in all organisms as co-chaperones of molecular chaperone HSP70s that mainly participate in maintaining cellular protein homeostasis, such as protein folding, assembly, stabilization, and translocation under normal conditions as well as refolding and degradation under environmental stresses. It has been reported that Arabidopsis J-proteins are classified into four classes (types A-D) according to domain organization, but their phylogenetic relationships are unknown. Here, we identified 129 J-proteins in the world-wide popular vegetable Brassica oleracea, a close relative of the model plant Arabidopsis, and also revised the information of Arabidopsis J-proteins based on the latest online bioresources. According to phylogenetic analysis with domain organization and gene structure as references, the J-proteins from Arabidopsis and B. oleracea were classified into 15 main clades (I-XV) separated by a number of undefined small branches with remote relationship. Based on the number of members, they respectively belong to multigene clades, oligo-gene clades, and mono-gene clades. The J-protein genes from different clades may function together or separately to constitute a complicated regulatory network. This study provides a constructive viewpoint for J-protein classification and an informative platform for further functional dissection and resistant genes discovery related to genetic improvement of crop plants.
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Affiliation(s)
- Bin Zhang
- a Key Laboratory of Education, Department of Hunan Province on Plant Genetics and Molecular Biology, College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China
| | - Han-Lin Qiu
- b State Key Laboratory of Subtropical Silviculture, Zhejiang A & F University, Hangzhou, Zhejiang 311300, China
| | - Dong-Hai Qu
- a Key Laboratory of Education, Department of Hunan Province on Plant Genetics and Molecular Biology, College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China
| | - Ying Ruan
- a Key Laboratory of Education, Department of Hunan Province on Plant Genetics and Molecular Biology, College of Bioscience and Biotechnology, Hunan Agricultural University, Changsha 410128, China
| | - Dong-Hong Chen
- b State Key Laboratory of Subtropical Silviculture, Zhejiang A & F University, Hangzhou, Zhejiang 311300, China
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15
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Tang J, Zhang W, Wen K, Chen G, Sun J, Tian Y, Tang W, Yu J, An H, Wu T, Kong F, Terzaghi W, Wang C, Wan J. OsPPR6, a pentatricopeptide repeat protein involved in editing and splicing chloroplast RNA, is required for chloroplast biogenesis in rice. PLANT MOLECULAR BIOLOGY 2017; 95:345-357. [PMID: 28856519 DOI: 10.1007/s11103-017-0654-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 08/18/2017] [Indexed: 05/10/2023]
Abstract
OsPPR6, a pentatricopeptide repeat protein involved in editing and splicing chloroplast RNA, is required for chloroplast biogenesis in rice. The chloroplast has its own genetic material and genetic system, but it is also regulated by nuclear-encoded genes. However, little is known about nuclear-plastid regulatory mechanisms underlying early chloroplast biogenesis in rice. In this study, we isolated and characterized a mutant, osppr6, that showed early chloroplast developmental defects leading to albino leaves and seedling death. We found that the osppr6 mutant failed to form thylakoid membranes. Using map-based cloning and complementation tests, we determined that OsPPR6 encoded a new Pentatricopeptide Repeat (PPR) protein localized in plastids. In the osppr6 mutants, mRNA levels of plastidic genes transcribed by the plastid-encoded RNA polymerase decreased, while those of genes transcribed by the nuclear-encoded RNA polymerase increased. Western blot analyses validated these expression results. We further investigated plastidic RNA editing and splicing in the osppr6 mutants and found that the ndhB transcript was mis-edited and the ycf3 transcript was mis-spliced. Therefore, we demonstrate that OsPPR6, a PPR protein, regulates early chloroplast biogenesis and participates in editing of ndhB and splicing of ycf3 transcripts in rice.
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Affiliation(s)
- Jianpeng Tang
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
- Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing, China
| | - Wenwei Zhang
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Kai Wen
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Gaoming Chen
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Juan Sun
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yunlu Tian
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Weijie Tang
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Jun Yu
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Hongzhou An
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Tingting Wu
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Fei Kong
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - William Terzaghi
- Department of Biology, Wilkes University, Wilkes-Barre, PA, 18766, USA
| | - Chunming Wang
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China.
- Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing, China.
| | - Jianmin Wan
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China.
- National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.
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16
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Yang H, Li P, Zhang A, Wen X, Zhang L, Lu C. Tetratricopeptide repeat protein Pyg7 is essential for photosystem I assembly by interacting with PsaC in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017. [PMID: 28636143 DOI: 10.1111/tpj.13618] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Although progress has been made in determining the structure and understanding the function of photosystem I (PSI), the PSI assembly process remains poorly understood. PsaC is an essential subunit of PSI and participates in the transfer of electrons to ferredoxin. However, how PsaC is assembled during accumulation of the PSI complex is unknown. In the present study, we showed that Pyg7 localized to the stromal thylakoid and associated with the PSI complex. We also showed that Pyg7 interacted with PsaC. Furthermore, we found that the PSI assembly process was blocked following formation of the PsaAB heterodimer in the pyg7 mutant. In addition, the analyses of PSI stability in Pyg7RNAi plants showed that Pyg7 is involved in maintaining the assembled PSI complex under excess-light conditions. Moreover, we demonstrated that decreased Pyg7 content resulted in decreased efficiency of PSI assembly in Pyg7RNAi plants. These findings suggest that the role of Pyg7 in PSI biogenesis has evolved as an essential assembly factor by interacting with PsaC in Arabidopsis, in addition to being a stability factor for PSI as seen in Synechocystis.
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Affiliation(s)
- Huixia Yang
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Pin Li
- 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
| | - Aihong Zhang
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Xiaogang Wen
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Lixin Zhang
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Congming Lu
- 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
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17
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Zhang C, Zhou Z, Yong H, Zhang X, Hao Z, Zhang F, Li M, Zhang D, Li X, Wang Z, Weng J. Analysis of the genetic architecture of maize ear and grain morphological traits by combined linkage and association mapping. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2017; 130:1011-1029. [PMID: 28215025 DOI: 10.1007/s00122-017-2867-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 01/24/2017] [Indexed: 05/05/2023]
Abstract
Using combined linkage and association mapping, 26 stable QTL and six stable SNPs were detected across multiple environments for eight ear and grain morphological traits in maize. One QTL, PKS2, might play an important role in maize yield improvement. In the present study, one bi-parental population and an association panel were used to identify quantitative trait loci (QTL) for eight ear and grain morphological traits. A total of 108 QTL related to these traits were detected across four environments using an ultra-high density bin map constructed using recombinant inbred lines (RILs) derived from a cross between Ye478 and Qi319, and 26 QTL were identified in more than two environments. Furthermore, 64 single nucleotide polymorphisms (SNPs) were found to be significantly associated with the eight ear and grain morphological traits (-log10(P) > 4) in an association panel of 240 maize inbred lines. Combining the two mapping populations, a total of 17 pleiotropic QTL/SNPs (pQTL/SNPs) were associated with various traits across multiple environments. PKS2, a stable locus influencing kernel shape identified on chromosome 2 in a genome-wide association study (GWAS), was within the QTL confidence interval defined by the RILs. The candidate region harbored a short 13-Kb LD block encompassing four SNPs (SYN11386, PHM14783.16, SYN11392, and SYN11378). In the association panel, 13 lines derived from the hybrid PI78599 possessed the same allele as Qi319 at the PHM14783.16 (GG) locus, with an average value of 0.21 for KS, significantly lower than that of the 34 lines derived from Ye478 that carried a different allele (0.25, P < 0.05). Therefore, further fine mapping of PKS2 will provide valuable information for understanding the genetic components of grain yield and improving molecular marker-assisted selection (MAS) in maize.
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Affiliation(s)
- Chaoshu Zhang
- College of Agronomy, Northeast Agricultural University, Mucai Street, XiangFang District, Harbin, 150030, Heilongjiang, China
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Zhongguancun South Street, Haidian District, Beijing, 100081, China
| | - Zhiqiang Zhou
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Zhongguancun South Street, Haidian District, Beijing, 100081, China
| | - Hongjun Yong
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Zhongguancun South Street, Haidian District, Beijing, 100081, China
| | - Xiaochong Zhang
- College of Agronomy, Northeast Agricultural University, Mucai Street, XiangFang District, Harbin, 150030, Heilongjiang, China
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Zhongguancun South Street, Haidian District, Beijing, 100081, China
| | - Zhuanfang Hao
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Zhongguancun South Street, Haidian District, Beijing, 100081, China
| | - Fangjun Zhang
- College of Agronomy, Northeast Agricultural University, Mucai Street, XiangFang District, Harbin, 150030, Heilongjiang, China
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Zhongguancun South Street, Haidian District, Beijing, 100081, China
| | - Mingshun Li
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Zhongguancun South Street, Haidian District, Beijing, 100081, China
| | - Degui Zhang
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Zhongguancun South Street, Haidian District, Beijing, 100081, China
| | - Xinhai Li
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Zhongguancun South Street, Haidian District, Beijing, 100081, China
| | - Zhenhua Wang
- College of Agronomy, Northeast Agricultural University, Mucai Street, XiangFang District, Harbin, 150030, Heilongjiang, China.
| | - Jianfeng Weng
- Institute of Crop Science, Chinese Academy of Agricultural Sciences, Zhongguancun South Street, Haidian District, Beijing, 100081, China.
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18
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Teubner M, Fuß J, Kühn K, Krause K, Schmitz-Linneweber C. The RNA recognition motif protein CP33A is a global ligand of chloroplast mRNAs and is essential for plastid biogenesis and plant development. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 89:472-485. [PMID: 27743418 DOI: 10.1111/tpj.13396] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 09/29/2016] [Accepted: 10/07/2016] [Indexed: 06/06/2023]
Abstract
Chloroplast RNA metabolism depends on a multitude of nuclear-encoded RNA-binding proteins (RBPs). Most known chloroplast RBPs address specific RNA targets and RNA-processing functions. However, members of the small chloroplast ribonucleoprotein family (cpRNPs) play a global role in processing and stabilizing chloroplast RNAs. Here, we show that the cpRNP CP33A localizes to a distinct sub-chloroplastic domain and is essential for chloroplast development. The loss of CP33A yields albino seedlings that exhibit aberrant leaf development and can only survive in the presence of an external carbon source. Genome-wide RNA association studies demonstrate that CP33A associates with all chloroplast mRNAs. For a given transcript, quantification of CP33A-bound versus free RNAs demonstrates that CP33A associates with the majority of most mRNAs analyzed. Our results further show that CP33A is required for the accumulation of a number of tested mRNAs, and is particularly relevant for unspliced and unprocessed precursor mRNAs. Finally, CP33A fails to associate with polysomes or to strongly co-precipitate with ribosomal RNA, suggesting that it defines a ribodomain that is separate from the chloroplast translation machinery. Collectively, these findings suggest that CP33A contributes to globally essential RNA processes in the chloroplasts of higher plants.
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Affiliation(s)
- Marlene Teubner
- Humboldt-Universität Berlin, Institut für Biologie, Chausseestrasse 117, 10115, Berlin, Germany
| | - Janina Fuß
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Dramsvegen 201, 9037, Tromsø, Norway
| | - Kristina Kühn
- Humboldt-Universität Berlin, Institut für Biologie, Chausseestrasse 117, 10115, Berlin, Germany
| | - Kirsten Krause
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Dramsvegen 201, 9037, Tromsø, Norway
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19
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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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20
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Belcher S, Williams-Carrier R, Stiffler N, Barkan A. Large-scale genetic analysis of chloroplast biogenesis in maize. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:1004-16. [PMID: 25725436 DOI: 10.1016/j.bbabio.2015.02.014] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 02/16/2015] [Indexed: 01/09/2023]
Abstract
BACKGROUND Chloroplast biogenesis involves a collaboration between several thousand nuclear genes and ~100 genes in the chloroplast. Many of the nuclear genes are of cyanobacterial ancestry and continue to perform their ancestral function. However, many others evolved subsequently and comprise a diverse set of proteins found specifically in photosynthetic eucaryotes. Genetic approaches have been key to the discovery of nuclear genes that participate in chloroplast biogenesis, especially those lacking close homologs outside the plant kingdom. SCOPE OF REVIEW This article summarizes contributions from a genetic resource in maize, the Photosynthetic Mutant Library (PML). The PML collection consists of ~2000 non-photosynthetic mutants induced by Mu transposons. We include a summary of mutant phenotypes for 20 previously unstudied maize genes, including genes encoding chloroplast ribosomal proteins, a PPR protein, tRNA synthetases, proteins involved in plastid transcription, a putative ribosome assembly factor, a chaperonin 60 isoform, and a NifU-domain protein required for Photosystem I biogenesis. MAJOR CONCLUSIONS Insertions in 94 maize genes have been linked thus far to visible and molecular phenotypes with the PML collection. The spectrum of chloroplast biogenesis genes that have been genetically characterized in maize is discussed in the context of related efforts in other organisms. This comparison shows how distinct organismal attributes facilitate the discovery of different gene classes, and reveals examples of functional divergence between monocot and dicot plants. GENERAL SIGNIFICANCE These findings elucidate the biology of an organelle whose activities are fundamental to agriculture and the biosphere. This article is part of a Special Issue entitled: Chloroplast Biogenesis.
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Affiliation(s)
- Susan Belcher
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | | | - Nicholas Stiffler
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Alice Barkan
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA.
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21
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Yang H, Liu J, Wen X, Lu C. Molecular mechanism of photosystem I assembly in oxygenic organisms. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:838-48. [PMID: 25582571 DOI: 10.1016/j.bbabio.2014.12.011] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 12/27/2014] [Accepted: 12/30/2014] [Indexed: 11/26/2022]
Abstract
Photosystem I, an integral membrane and multi-subunit complex, catalyzes the oxidation of plastocyanin and the reduction of ferredoxin by absorbed light energy. Photosystem I participates in photosynthetic acclimation processes by being involved in cyclic electron transfer and state transitions for sustaining efficient photosynthesis. The photosystem I complex is highly conserved from cyanobacteria to higher plants and contains the light-harvesting complex and the reaction center complex. The assembly of the photosystem I complex is highly complicated and involves the concerted assembly of multiple subunits and hundreds of cofactors. A suite of regulatory factors for the assembly of photosystem I subunits and cofactors have been identified that constitute an integrative network regulating PSI accumulation. This review aims to discuss recent findings in the field relating to how the photosystem I complex is assembled in oxygenic organisms. This article is part of a Special Issue entitled: Chloroplast Biogenesis.
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Affiliation(s)
- Huixia Yang
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Jun Liu
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA
| | - Xiaogang Wen
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Congming Lu
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
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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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23
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Fristedt R, Williams-Carrier R, Merchant SS, Barkan A. A thylakoid membrane protein harboring a DnaJ-type zinc finger domain is required for photosystem I accumulation in plants. J Biol Chem 2014; 289:30657-30667. [PMID: 25228689 DOI: 10.1074/jbc.m114.587758] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Photosystem I (PSI) is a large pigment-protein complex and one of the two photosystems that drive electron transfer in oxygenic photosynthesis. We identified a nuclear gene required specifically for the accumulation of PSI in a forward genetic analysis of chloroplast biogenesis in maize. This gene, designated psa2, belongs to the "GreenCut" gene set, a group of genes found in green algae and plants but not in non-photosynthetic organisms. Disruption of the psa2 ortholog in Arabidopsis likewise resulted in the specific loss of PSI proteins. PSA2 harbors a conserved domain found in DnaJ chaperones where it has been shown to form a zinc finger and to have protein-disulfide isomerase activity. Accordingly, PSA2 exhibited protein-disulfide reductase activity in vitro. PSA2 localized to the thylakoid lumen and was found in a ∼250-kDa complex harboring the peripheral PSI protein PsaG but lacking several core PSI subunits. PSA2 mRNA is coexpressed with mRNAs encoding various proteins involved in the biogenesis of the photosynthetic apparatus with peak expression preceding that of genes encoding structural components. PSA2 protein abundance was not decreased in the absence of PSI but was reduced in the absence of the PSI assembly factor Ycf3. These findings suggest that a complex harboring PSA2 and PsaG mediates thiol transactions in the thylakoid lumen that are important for the assembly of PSI.
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Affiliation(s)
- Rikard Fristedt
- Department of Chemistry and Biochemistry and UCLA, Los Angeles, California 90095; Institute for Genomics and Proteomics, UCLA, Los Angeles, California 90095 and
| | | | - Sabeeha S Merchant
- Department of Chemistry and Biochemistry and UCLA, Los Angeles, California 90095; Institute for Genomics and Proteomics, UCLA, Los Angeles, California 90095 and
| | - Alice Barkan
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403.
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24
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Hammani K, Barkan A. An mTERF domain protein functions in group II intron splicing in maize chloroplasts. Nucleic Acids Res 2014; 42:5033-42. [PMID: 24500208 PMCID: PMC4005652 DOI: 10.1093/nar/gku112] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The mitochondrial transcription termination factor (mTERF) proteins are nucleic acid binding proteins characterized by degenerate helical repeats of ∼30 amino acids. Metazoan genomes encode a small family of mTERF proteins whose members influence mitochondrial gene expression and DNA replication. The mTERF family in higher plants consists of roughly 30 members, which localize to mitochondria or chloroplasts. Effects of several mTERF proteins on plant development and physiology have been described, but molecular functions of mTERF proteins in plants are unknown. We show that a maize mTERF protein, Zm-mTERF4, promotes the splicing of group II introns in chloroplasts. Zm-mTERF4 coimmunoprecipitates with many chloroplast introns and the splicing of some of these introns is disrupted even in hypomorphic Zm-mterf4 mutants. Furthermore, Zm-mTERF4 is found in high molecular weight complexes that include known chloroplast splicing factors. The splicing of two transfer RNAs (trnI-GAU and trnA-UGC) and one ribosomal protein messenger RNA (rpl2) is particularly sensitive to the loss of Zm-mTERF4, accounting for the loss of plastid ribosomes in Zm-mTERF4 mutants. These findings extend the known functional repertoire of the mTERF family to include group II intron splicing and suggest that a conserved role in chloroplast RNA splicing underlies the physiological defects described for mutations in BSM/Rugosa2, the Zm-mTERF4 ortholog in Arabidopsis.
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Affiliation(s)
- Kamel Hammani
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
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25
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Berry JO, Yerramsetty P, Zielinski AM, Mure CM. Photosynthetic gene expression in higher plants. PHOTOSYNTHESIS RESEARCH 2013; 117:91-120. [PMID: 23839301 DOI: 10.1007/s11120-013-9880-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 06/26/2013] [Indexed: 05/08/2023]
Abstract
Within the chloroplasts of higher plants and algae, photosynthesis converts light into biological energy, fueling the assimilation of atmospheric carbon dioxide into biologically useful molecules. Two major steps, photosynthetic electron transport and the Calvin-Benson cycle, require many gene products encoded from chloroplast as well as nuclear genomes. The expression of genes in both cellular compartments is highly dynamic and influenced by a diverse range of factors. Light is the primary environmental determinant of photosynthetic gene expression. Working through photoreceptors such as phytochrome, light regulates photosynthetic genes at transcriptional and posttranscriptional levels. Other processes that affect photosynthetic gene expression include photosynthetic activity, development, and biotic and abiotic stress. Anterograde (from nucleus to chloroplast) and retrograde (from chloroplast to nucleus) signaling insures the highly coordinated expression of the many photosynthetic genes between these different compartments. Anterograde signaling incorporates nuclear-encoded transcriptional and posttranscriptional regulators, such as sigma factors and RNA-binding proteins, respectively. Retrograde signaling utilizes photosynthetic processes such as photosynthetic electron transport and redox signaling to influence the expression of photosynthetic genes in the nucleus. The basic C3 photosynthetic pathway serves as the default form used by most of the plant species on earth. High temperature and water stress associated with arid environments have led to the development of specialized C4 and CAM photosynthesis, which evolved as modifications of the basic default expression program. The goal of this article is to explain and summarize the many gene expression and regulatory processes that work together to support photosynthetic function in plants.
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Affiliation(s)
- James O Berry
- Department of Biological Sciences, University at Buffalo, Buffalo, NY, 14260, USA,
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26
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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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Chi W, Ma J, Zhang L. Regulatory factors for the assembly of thylakoid membrane protein complexes. Philos Trans R Soc Lond B Biol Sci 2013; 367:3420-9. [PMID: 23148269 DOI: 10.1098/rstb.2012.0065] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Major multi-protein photosynthetic complexes, located in thylakoid membranes, are responsible for the capture of light and its conversion into chemical energy in oxygenic photosynthetic organisms. Although the structures and functions of these photosynthetic complexes have been explored, the molecular mechanisms underlying their assembly remain elusive. In this review, we summarize current knowledge of the regulatory components involved in the assembly of thylakoid membrane protein complexes in photosynthetic organisms. Many of the known regulatory factors are conserved between prokaryotes and eukaryotes, whereas others appear to be newly evolved or to have expanded predominantly in eukaryotes. Their specific features and fundamental differences in cyanobacteria, green algae and land plants are discussed.
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Affiliation(s)
- Wei Chi
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, People's Republic of China
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28
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Germain A, Hotto AM, Barkan A, Stern DB. RNA processing and decay in plastids. WILEY INTERDISCIPLINARY REVIEWS-RNA 2013; 4:295-316. [PMID: 23536311 DOI: 10.1002/wrna.1161] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Plastids were derived through endosymbiosis from a cyanobacterial ancestor, whose uptake was followed by massive gene transfer to the nucleus, resulting in the compact size and modest coding capacity of the extant plastid genome. Plastid gene expression is essential for plant development, but depends on nucleus-encoded proteins recruited from cyanobacterial or host-cell origins. The plastid genome is heavily transcribed from numerous promoters, giving posttranscriptional events a critical role in determining the quantity and sizes of accumulating RNA species. The major events reviewed here are RNA editing, which restores protein conservation or creates correct open reading frames by converting C residues to U, RNA splicing, which occurs both in cis and trans, and RNA cleavage, which relies on a variety of exoribonucleases and endoribonucleases. Because the RNases have little sequence specificity, they are collectively able to remove extraneous RNAs whose ends are not protected by RNA secondary structures or sequence-specific RNA-binding proteins (RBPs). Other plastid RBPs, largely members of the helical-repeat superfamily, confer specificity to editing and splicing reactions. The enzymes that catalyze RNA processing are also the main actors in RNA decay, implying that these antagonistic roles are optimally balanced. We place the actions of RBPs and RNases in the context of a recent proteomic analysis that identifies components of the plastid nucleoid, a protein-DNA complex with multiple roles in gene expression. These results suggest that sublocalization and/or concentration gradients of plastid proteins could underpin the regulation of RNA maturation and degradation.
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29
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An RNA recognition motif-containing protein is required for plastid RNA editing in Arabidopsis and maize. Proc Natl Acad Sci U S A 2013; 110:E1169-78. [PMID: 23487777 DOI: 10.1073/pnas.1220162110] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Plant RNA editing modifies cytidines (C) to uridines (U) at specific sites in the transcripts of both mitochondria and plastids. Specific targeting of particular Cs is achieved by pentatricopeptide proteins that recognize cis elements upstream of the C that is edited. Members of the RNA-editing factor interacting protein (RIP) family in Arabidopsis have recently been shown to be essential components of the plant editosome. We have identified a gene that contains a pair of truncated RIP domains (RIP-RIP). Unlike any previously described RIP family member, the encoded protein carries an RNA recognition motif (RRM) at its C terminus and has therefore been named Organelle RRM protein 1 (ORRM1). ORRM1 is an essential plastid editing factor; in Arabidopsis and maize mutants, RNA editing is impaired at particular sites, with an almost complete loss of editing for 12 sites in Arabidopsis and 9 sites in maize. Transfection of Arabidopsis orrm1 mutant protoplasts with constructs encoding a region encompassing the RIP-RIP domain or a region spanning the RRM domain of ORRM1 demonstrated that the RRM domain is sufficient for the editing function of ORRM1 in vitro. According to a yeast two-hybrid assay, ORRM1 interacts selectively with pentatricopeptide transfactors via its RIP-RIP domain. Phylogenetic analysis reveals that the RRM in ORRM1 clusters with a clade of RRM proteins that are targeted to organelles. Taken together, these results suggest that other members of the ORRM family may likewise function in RNA editing.
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30
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Stoppel R, Meurer J. Complex RNA metabolism in the chloroplast: an update on the psbB operon. PLANTA 2013; 237:441-9. [PMID: 23065055 PMCID: PMC3555233 DOI: 10.1007/s00425-012-1782-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 09/28/2012] [Indexed: 05/03/2023]
Abstract
Expression of most plastid genes involves multiple post-transcriptional processing events, such as splicing, editing, and intercistronic processing. The latter involves the formation of mono-, di-, and multicistronic transcripts, which can further be regulated by differential stability and expression. The plastid pentacistronic psbB transcription unit has been well characterized in vascular plants. It encodes the subunits CP47 (psbB), T (psbT), and H (psbH) of photosystem II as well as cytochrome b (6) (petB) and subunit IV (petD) of the cytochrome b (6) f complex. Each of the petB and petD genes contains a group II intron, which is spliced during post-transcriptional modification. The small subunit of photosystem II, PsbN, is encoded in the intercistronic region between psbH and psbT but is transcribed in the opposite direction. Expression of the psbB gene cluster necessitates different processing events along with numerous newly evolved specificity factors conferring stability to many of the processed RNA transcripts, and thus exemplarily shows the complexity of RNA metabolism in the chloroplast.
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Affiliation(s)
- Rhea Stoppel
- Plant Molecular Biology (Botany), Department Biology I, Ludwig Maximilians University, Großhadernerstrasse 2-4, Planegg-Martinsried, Germany.
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31
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Dall'Osto L, Piques M, Ronzani M, Molesini B, Alboresi A, Cazzaniga S, Bassi R. The Arabidopsis nox mutant lacking carotene hydroxylase activity reveals a critical role for xanthophylls in photosystem I biogenesis. THE PLANT CELL 2013; 25:591-608. [PMID: 23396829 PMCID: PMC3608780 DOI: 10.1105/tpc.112.108621] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2012] [Revised: 01/15/2013] [Accepted: 01/18/2013] [Indexed: 05/05/2023]
Abstract
Carotenes, and their oxygenated derivatives xanthophylls, are essential components of the photosynthetic apparatus. They contribute to the assembly of photosynthetic complexes and participate in light absorption and chloroplast photoprotection. Here, we studied the role of xanthophylls, as distinct from that of carotenes, by characterizing a no xanthophylls (nox) mutant of Arabidopsis thaliana, which was obtained by combining mutations targeting the four carotenoid hydroxylase genes. nox plants retained α- and β-carotenes but were devoid in xanthophylls. The phenotype included depletion of light-harvesting complex (LHC) subunits and impairment of nonphotochemical quenching, two effects consistent with the location of xanthophylls in photosystem II antenna, but also a decreased efficiency of photosynthetic electron transfer, photosensitivity, and lethality in soil. Biochemical analysis revealed that the nox mutant was specifically depleted in photosystem I function due to a severe deficiency in PsaA/B subunits. While the stationary level of psaA/B transcripts showed no major differences between genotypes, the stability of newly synthesized PsaA/B proteins was decreased and translation of psaA/B mRNA was impaired in nox with respect to wild-type plants. We conclude that xanthophylls, besides their role in photoprotection and LHC assembly, are also needed for photosystem I core translation and stability, thus making these compounds indispensable for autotrophic growth.
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Affiliation(s)
- Luca Dall'Osto
- Dipartimento di Biotecnologie, Università di Verona, 37134 Verona, Italy.
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Liu J, Yang H, Lu Q, Wen X, Chen F, Peng L, Zhang L, Lu C. PsbP-domain protein1, a nuclear-encoded thylakoid lumenal protein, is essential for photosystem I assembly in Arabidopsis. THE PLANT CELL 2012; 24:4992-5006. [PMID: 23221595 PMCID: PMC3556971 DOI: 10.1105/tpc.112.106542] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
To gain insights into the molecular details of photosystem I (PSI) biogenesis, we characterized the PsbP-domain protein1 (ppd1) mutant of Arabidopsis thaliana that specifically lacks PSI activity. Deletion of PPD1 results in an inability of the mutant to grow photoautotrophically and a specific loss of the stable PSI complex. Unaltered transcription and translation of plastid-encoded PSI genes indicate that PPD1 acts at the posttranslational level. In vivo protein labeling experiments reveal that the rate of synthesis of PSI reaction center proteins PsaA/B in ppd1 is comparable to that of wild-type plants, whereas the rate of turnover of PsaA/B proteins is higher in ppd1 than in wild-type plants. With increasing leaf age, PPD1 content decreases considerably, while PSI content remains constant. PPD1 is a nuclear-encoded thylakoid lumenal protein and is associated with PSI but is not an integral subunit of PSI. Biochemical and molecular analyses reveal that PPD1 interacts directly and specifically with PsaB and PsaA. Yeast two-hybrid experiments show that PPD1 interacts with some lumenal loops of PsaB and PsaA. Our results suggest that PPD1 is a PSI assembly factor that assists the proper folding and integration of PsaB and PsaA into the thylakoid membrane.
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Affiliation(s)
- Jun Liu
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- Graduate University of Chinese Academy of Sciences, Beijing 100049, China
| | - Huixia Yang
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Qingtao Lu
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Xiaogang Wen
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Fan Chen
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Lianwei Peng
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Lixin Zhang
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- National Center for Plant Gene Research, Beijing 100093, China
| | - Congming Lu
- Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- National Center for Plant Gene Research, Beijing 100093, China
- Address correspondence to
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The role of reticulate evolution in creating innovation and complexity. INTERNATIONAL JOURNAL OF EVOLUTIONARY BIOLOGY 2012; 2012:418964. [PMID: 22844638 PMCID: PMC3403396 DOI: 10.1155/2012/418964] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 05/08/2012] [Accepted: 05/10/2012] [Indexed: 12/31/2022]
Abstract
Reticulate evolution encompasses processes that conflict with traditional Tree of Life efforts. These processes, horizontal gene transfer (HGT), gene and whole-genome duplications through allopolyploidization, are some of the main driving forces for generating innovation and complexity. HGT has a profound impact on prokaryotic and eukaryotic evolution. HGTs can lead to the invention of new metabolic pathways and the expansion and enhancement of previously existing pathways. It allows for organismal adaptation into new ecological niches and new host ranges. Although many HGTs appear to be selected for because they provide some benefit to their recipient lineage, other HGTs may be maintained by chance through random genetic drift. Moreover, some HGTs that may initially seem parasitic in nature can cause complexity to arise through pathways of neutral evolution. Another mechanism for generating innovation and complexity, occurring more frequently in eukaryotes than in prokaryotes, is gene and genome duplications, which often occur through allopolyploidizations. We discuss how these different evolutionary processes contribute to generating innovation and complexity.
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Asakura Y, Galarneau E, Watkins KP, Barkan A, van Wijk KJ. Chloroplast RH3 DEAD box RNA helicases in maize and Arabidopsis function in splicing of specific group II introns and affect chloroplast ribosome biogenesis. PLANT PHYSIOLOGY 2012; 159:961-74. [PMID: 22576849 PMCID: PMC3387720 DOI: 10.1104/pp.112.197525] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Accepted: 05/08/2012] [Indexed: 05/18/2023]
Abstract
Chloroplasts in angiosperms contain at least seven nucleus-encoded members of the DEAD box RNA helicase family. Phylogenetic analysis shows that five of these plastid members (RH22, -39, -47, -50, and -58) form a single clade and that RH3 forms a clade with two mitochondrial RH proteins (PMH1 and -2) functioning in intron splicing. The function of chloroplast RH3 in maize (Zea mays; ZmRH3) and Arabidopsis (Arabidopsis thaliana; AtRH3) was determined. ZmRH3 and AtRH3 are both under strong developmental control, and ZmRH3 abundance sharply peaked in the sink-source transition zone of developing maize leaves, coincident with the plastid biogenesis machinery. ZmRH3 coimmunoprecipitated with a specific set of plastid RNAs, including several group II introns, as well as pre23S and 23S ribosomal RNA (rRNA), but not 16S rRNA. Furthermore, ZmRH3 associated with 50S preribosome particles as well as nucleoids. AtRH3 null mutants are embryo lethal, whereas a weak allele (rh3-4) results in pale-green seedlings with defects in splicing of several group II introns and rRNA maturation as well as reduced levels of assembled ribosomes. These results provide strong evidence that RH3 functions in the splicing of group II introns and possibly also contributes to the assembly of the 50S ribosomal particle. Previously, we observed 5- to 10-fold up-regulation of AtRH3 in plastid Caseinolytic protease mutants. The results shown here indicate that AtRH3 up-regulation was not a direct consequence of reduced proteolysis but constituted a compensatory response at both RH3 transcript and protein levels to impaired chloroplast biogenesis; this response demonstrates that cross talk between the chloroplast and the nucleus is used to regulate RH3 levels.
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Affiliation(s)
- Yukari Asakura
- Department of Plant Biology, Cornell University, Ithaca, New York 14853, USA
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35
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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: 43] [Impact Index Per Article: 3.6] [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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Khrouchtchova A, Monde RA, Barkan A. A short PPR protein required for the splicing of specific group II introns in angiosperm chloroplasts. RNA (NEW YORK, N.Y.) 2012; 18:1197-209. [PMID: 22495966 PMCID: PMC3358642 DOI: 10.1261/rna.032623.112] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
A maize gene designated thylakoid assembly 8 (tha8) emerged from a screen for nuclear mutations that cause defects in the biogenesis of chloroplast thylakoid membranes. The tha8 gene encodes an unusual member of the pentatricopeptide repeat (PPR) family, a family of helical repeat proteins that participate in various aspects of organellar RNA metabolism. THA8 localizes to chloroplasts, where it associates specifically with the ycf3-2 and trnA group II introns. The splicing of ycf3-2 is eliminated in tha8 mutants, and trnA splicing is strongly compromised. Reverse-genetic analysis of the tha8 ortholog in Arabidopsis thaliana showed that these molecular functions are conserved, although null alleles are embryo lethal in Arabidopsis and seedling lethal in maize. Whereas most PPR proteins have more than 10 PPR motifs, THA8 belongs to a subfamily of plant PPR proteins with only four PPR motifs and little else. THA8 is the first member of this subfamily with a defined molecular function, and illustrates that even small PPR proteins have the potential to mediate specific intermolecular interactions in vivo.
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Affiliation(s)
| | - Rita-Ann Monde
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, USA
| | - Alice Barkan
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, USA
- Corresponding author.E-mail .
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Zhelyazkova P, Hammani K, Rojas M, Voelker R, Vargas-Suárez M, Börner T, Barkan A. Protein-mediated protection as the predominant mechanism for defining processed mRNA termini in land plant chloroplasts. Nucleic Acids Res 2012; 40:3092-105. [PMID: 22156165 PMCID: PMC3326301 DOI: 10.1093/nar/gkr1137] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 10/19/2011] [Accepted: 11/09/2011] [Indexed: 11/12/2022] Open
Abstract
Most chloroplast mRNAs are processed from larger precursors. Several mechanisms have been proposed to mediate these processing events, including site-specific cleavage and the stalling of exonucleases by RNA structures. A protein barrier mechanism was proposed based on analysis of the pentatricopeptide repeat (PPR) protein PPR10: PPR10 binds two intercistronic regions and impedes 5'- and 3'-exonucleases, resulting in processed RNAs with PPR10 bound at the 5'- or 3'-end. In this study, we provide evidence that protein barriers are the predominant means for defining processed mRNA termini in chloroplasts. First, we map additional RNA termini whose arrangement suggests biogenesis via a PPR10-like mechanism. Second, we show that the PPR protein HCF152 binds to the immediate 5'- or 3'-termini of transcripts that require HCF152 for their accumulation, providing evidence that HCF152 defines RNA termini by blocking exonucleases. Finally, we build on the observation that the PPR10 and HCF152 binding sites accumulate as small chloroplast RNAs to infer binding sites of other PPR proteins. We show that most processed mRNA termini are represented by small RNAs whose sequences are highly conserved. We suggest that each such small RNA is the footprint of a PPR-like protein that protects the adjacent RNA from degradation.
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Affiliation(s)
- Petya Zhelyazkova
- Institute for Biology (Genetics), Humboldt-University Berlin, D-10115 Berlin, Max Delbrück Center for Molecular Medicine, D-13092 Berlin, Germany and Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Kamel Hammani
- Institute for Biology (Genetics), Humboldt-University Berlin, D-10115 Berlin, Max Delbrück Center for Molecular Medicine, D-13092 Berlin, Germany and Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Margarita Rojas
- Institute for Biology (Genetics), Humboldt-University Berlin, D-10115 Berlin, Max Delbrück Center for Molecular Medicine, D-13092 Berlin, Germany and Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Rodger Voelker
- Institute for Biology (Genetics), Humboldt-University Berlin, D-10115 Berlin, Max Delbrück Center for Molecular Medicine, D-13092 Berlin, Germany and Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Martín Vargas-Suárez
- Institute for Biology (Genetics), Humboldt-University Berlin, D-10115 Berlin, Max Delbrück Center for Molecular Medicine, D-13092 Berlin, Germany and Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Thomas Börner
- Institute for Biology (Genetics), Humboldt-University Berlin, D-10115 Berlin, Max Delbrück Center for Molecular Medicine, D-13092 Berlin, Germany and Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
| | - Alice Barkan
- Institute for Biology (Genetics), Humboldt-University Berlin, D-10115 Berlin, Max Delbrück Center for Molecular Medicine, D-13092 Berlin, Germany and Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA
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Francs-Small CCD, Kroeger T, Zmudjak M, Ostersetzer-Biran O, Rahimi N, Small I, Barkan A. A PORR domain protein required for rpl2 and ccmF(C) intron splicing and for the biogenesis of c-type cytochromes in Arabidopsis mitochondria. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 69:996-1005. [PMID: 22060106 DOI: 10.1111/j.1365-313x.2011.04849.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Angiosperm mitochondria encode approximately 20 group II introns, which interrupt genes involved in the biogenesis and function of the respiratory chain. Nucleus-encoded splicing factors have been identified for approximately half of these introns. The splicing factors derive from several protein families defined by atypical RNA binding domains that function primarily in organelles. We show here that the Arabidopsis protein WTF9 is essential for the splicing of group II introns in two mitochondrial genes for which splicing factors had not previously been identified: rpl2 and ccmF(C). WTF9 harbors a recently recognized RNA binding domain, the PORR domain, which was originally characterized in the chloroplast splicing factor WTF1. These findings show that the PORR domain family also functions in plant mitochondria, and highlight the parallels between the machineries for group II intron splicing in plant mitochondria and chloroplasts. In addition, we used the splicing defects in wtf9 mutants as a means to functionally characterize the mitochondrial rpl2 and ccmF(C) genes. Loss of ccmF(C) expression correlates with the loss of cytochromes c and c₁, confirming a role for ccmF(C) in cytochrome biogenesis. By contrast, our results strongly suggest that splicing is not essential for the function of the mitochondrial rpl2 gene, and imply that the Rpl2 fragment encoded by rpl2 exon 1 functions in concert with a nuclear gene product that provides the remainder of this essential ribosomal protein in trans.
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Affiliation(s)
- Catherine Colas des Francs-Small
- Australian Research Council Centre of Excellence in Plant Energy Biology, University of Western Australia, Crawley 6009 WA, Australia.
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Majeran W, Friso G, Asakura Y, Qu X, Huang M, Ponnala L, Watkins KP, Barkan A, van Wijk KJ. Nucleoid-enriched proteomes in developing plastids and chloroplasts from maize leaves: a new conceptual framework for nucleoid functions. PLANT PHYSIOLOGY 2012; 158:156-89. [PMID: 22065420 PMCID: PMC3252073 DOI: 10.1104/pp.111.188474] [Citation(s) in RCA: 182] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Accepted: 11/06/2011] [Indexed: 05/18/2023]
Abstract
Plastids contain multiple copies of the plastid chromosome, folded together with proteins and RNA into nucleoids. The degree to which components of the plastid gene expression and protein biogenesis machineries are nucleoid associated, and the factors involved in plastid DNA organization, repair, and replication, are poorly understood. To provide a conceptual framework for nucleoid function, we characterized the proteomes of highly enriched nucleoid fractions of proplastids and mature chloroplasts isolated from the maize (Zea mays) leaf base and tip, respectively, using mass spectrometry. Quantitative comparisons with proteomes of unfractionated proplastids and chloroplasts facilitated the determination of nucleoid-enriched proteins. This nucleoid-enriched proteome included proteins involved in DNA replication, organization, and repair as well as transcription, mRNA processing, splicing, and editing. Many proteins of unknown function, including pentatricopeptide repeat (PPR), tetratricopeptide repeat (TPR), DnaJ, and mitochondrial transcription factor (mTERF) domain proteins, were identified. Strikingly, 70S ribosome and ribosome assembly factors were strongly overrepresented in nucleoid fractions, but protein chaperones were not. Our analysis strongly suggests that mRNA processing, splicing, and editing, as well as ribosome assembly, take place in association with the nucleoid, suggesting that these processes occur cotranscriptionally. The plastid developmental state did not dramatically change the nucleoid-enriched proteome but did quantitatively shift the predominating function from RNA metabolism in undeveloped plastids to translation and homeostasis in chloroplasts. This study extends the known maize plastid proteome by hundreds of proteins, including more than 40 PPR and mTERF domain proteins, and provides a resource for targeted studies on plastid gene expression. Details of protein identification and annotation are provided in the Plant Proteome Database.
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Fellerer C, Schweiger R, Schöngruber K, Soll J, Schwenkert S. Cytosolic HSP90 cochaperones HOP and FKBP interact with freshly synthesized chloroplast preproteins of Arabidopsis. MOLECULAR PLANT 2011; 4:1133-45. [PMID: 21596689 DOI: 10.1093/mp/ssr037] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Most chloroplast and mitochondrial proteins are synthesized in the cytosol of the plant cell and have to be imported into the organelles post-translationally. Molecular chaperones play an important role in preventing protein aggregation of freshly translated preproteins and assist in maintaining the preproteins in an import competent state. Preproteins can associate with HSP70, HSP90, and 14-3-3 proteins in the cytosol. In this study, we analyzed a large set of wheat germ-translated chloroplast preproteins with respect to their chaperone binding. Our results demonstrate that the formation of distinct 14-3-3 or HSP90 containing preprotein complexes is a common feature in post-translational protein transport in addition to preproteins that seem to interact solely with HSP70. We were able to identify a diverse and extensive class of preproteins as HSP90 substrates, thus providing a tool for the investigation of HSP90 client protein association. The analyses of chimeric HSP90 and 14-3-3 binding preproteins with exchanged transit peptides indicate an involvement of both the transit peptide and the mature part of the proteins, in HSP90 binding. We identified two partner components of the HSP90 cycle, which were present in the preprotein containing high-molecular-weight complexes, the HSP70/HSP90 organizing protein HOP, as well as the immunophilin FKBP73. The results establish chloroplast preproteins as a general class of HSP90 client proteins in plants using HOP and FKBP as novel cochaperones.
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Affiliation(s)
- Christine Fellerer
- Department of Biology I, Botany, Ludwig-Maximilians-Universität München, Grosshaderner Strasse 2-4, D-82152 Planegg-Martinsried, Germany
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Barkan A. Expression of plastid genes: organelle-specific elaborations on a prokaryotic scaffold. PLANT PHYSIOLOGY 2011; 155:1520-32. [PMID: 21346173 PMCID: PMC3091090 DOI: 10.1104/pp.110.171231] [Citation(s) in RCA: 219] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Accepted: 01/29/2011] [Indexed: 05/19/2023]
Affiliation(s)
- Alice Barkan
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, USA.
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