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Kim RG, Huang W, Findinier J, Bunbury F, Redekop P, Shrestha R, Grismer TS, Vilarrasa-Blasi J, Jinkerson RE, Fakhimi N, Fauser F, Jonikas MC, Onishi M, Xu SL, Grossman AR. Chloroplast Methyltransferase Homolog RMT2 is Involved in Photosystem I Biogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.12.21.572672. [PMID: 38187728 PMCID: PMC10769443 DOI: 10.1101/2023.12.21.572672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
Oxygen (O2), a dominant element in the atmosphere and essential for most life on Earth, is produced by the photosynthetic oxidation of water. However, metabolic activity can cause accumulation of reactive O2 species (ROS) and severe cell damage. To identify and characterize mechanisms enabling cells to cope with ROS, we performed a high-throughput O2 sensitivity screen on a genome-wide insertional mutant library of the unicellular alga Chlamydomonas reinhardtii. This screen led to identification of a gene encoding a protein designated Rubisco methyltransferase 2 (RMT2). Although homologous to methyltransferases, RMT2 has not been experimentally demonstrated to have methyltransferase activity. Furthermore, the rmt2 mutant was not compromised for Rubisco (first enzyme of Calvin-Benson Cycle) levels but did exhibit a marked decrease in accumulation/activity of photosystem I (PSI), which causes light sensitivity, with much less of an impact on other photosynthetic complexes. This mutant also shows increased accumulation of Ycf3 and Ycf4, proteins critical for PSI assembly. Rescue of the mutant phenotype with a wild-type (WT) copy of RMT2 fused to the mNeonGreen fluorophore indicates that the protein localizes to the chloroplast and appears to be enriched in/around the pyrenoid, an intrachloroplast compartment present in many algae that is packed with Rubisco and potentially hypoxic. These results indicate that RMT2 serves an important role in PSI biogenesis which, although still speculative, may be enriched around or within the pyrenoid.
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Affiliation(s)
- Rick G. Kim
- Department of Biosphere Science and Engineering, Carnegie Institution for Science, Stanford, CA 94305, USA
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Weichao Huang
- Department of Biosphere Science and Engineering, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Justin Findinier
- Department of Biosphere Science and Engineering, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Freddy Bunbury
- Department of Biosphere Science and Engineering, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Petra Redekop
- Department of Biosphere Science and Engineering, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Ruben Shrestha
- Department of Biosphere Science and Engineering, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - TaraBryn S Grismer
- Department of Biosphere Science and Engineering, Carnegie Institution for Science, Stanford, CA 94305, USA
| | | | - Robert E. Jinkerson
- Department of Chemical and Environmental Engineering, University of California, Riverside, CA 92521, USA
| | - Neda Fakhimi
- Department of Biosphere Science and Engineering, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Friedrich Fauser
- Department of Biosphere Science and Engineering, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Martin C. Jonikas
- Department of Molecular Biology, Princeton University, Princeton, NJ 08540, USA
| | - Masayuki Onishi
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - Shou-Ling Xu
- Department of Biosphere Science and Engineering, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Arthur R. Grossman
- Department of Biosphere Science and Engineering, Carnegie Institution for Science, Stanford, CA 94305, USA
- Department of Biology, Stanford University, Stanford, CA 94305, USA
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Wietrzynski W, Traverso E, Wollman FA, Wostrikoff K. The state of oligomerization of Rubisco controls the rate of synthesis of the Rubisco large subunit in Chlamydomonas reinhardtii. THE PLANT CELL 2021; 33:1706-1727. [PMID: 33625514 PMCID: PMC8254502 DOI: 10.1093/plcell/koab061] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 02/12/2021] [Indexed: 05/22/2023]
Abstract
Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) is present in all photosynthetic organisms and is a key enzyme for photosynthesis-driven life on Earth. Its most prominent form is a hetero-oligomer in which small subunits (SSU) stabilize the core of the enzyme built from large subunits (LSU), yielding, after a chaperone-assisted multistep assembly process, an LSU8SSU8 hexadecameric holoenzyme. Here we use Chlamydomonas reinhardtii and a combination of site-directed mutants to dissect the multistep biogenesis pathway of Rubisco in vivo. We identify assembly intermediates, in two of which LSU are associated with the RAF1 chaperone. Using genetic and biochemical approaches we further unravel a major regulation process during Rubisco biogenesis, in which LSU translation is controlled by its ability to assemble with the SSU, via the mechanism of control by epistasy of synthesis (CES). Altogether this leads us to propose a model whereby the last assembly intermediate, an LSU8-RAF1 complex, provides the platform for SSU binding to form the Rubisco enzyme, and when SSU is not available, converts to a key regulatory form that exerts negative feedback on the initiation of LSU translation.
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Affiliation(s)
- Wojciech Wietrzynski
- Sorbonne Université, CNRS, Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, 75005 Paris, France
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
- Helmholtz Pioneer Campus, Helmholtz Zentrum München, 85764 Neuherberg, Germany
| | - Eleonora Traverso
- Sorbonne Université, CNRS, Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, 75005 Paris, France
| | - Francis-André Wollman
- Sorbonne Université, CNRS, Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, 75005 Paris, France
| | - Katia Wostrikoff
- Sorbonne Université, CNRS, Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, 75005 Paris, France
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3
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Macedo-Osorio KS, Martínez-Antonio A, Badillo-Corona JA. Pas de Trois: An Overview of Penta-, Tetra-, and Octo-Tricopeptide Repeat Proteins From Chlamydomonas reinhardtii and Their Role in Chloroplast Gene Expression. FRONTIERS IN PLANT SCIENCE 2021; 12:775366. [PMID: 34868174 PMCID: PMC8635915 DOI: 10.3389/fpls.2021.775366] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 10/26/2021] [Indexed: 05/05/2023]
Abstract
Penta-, Tetra-, and Octo-tricopeptide repeat (PPR, TPR, and OPR) proteins are nucleus-encoded proteins composed of tandem repeats of 35, 34, and 38-40 amino acids, respectively. They form helix-turn-helix structures that interact with mRNA or other proteins and participate in RNA stabilization, processing, maturation, and act as translation enhancers of chloroplast and mitochondrial mRNAs. These helical repeat proteins are unevenly present in plants and algae. While PPR proteins are more abundant in plants than in algae, OPR proteins are more abundant in algae. In Arabidopsis, maize, and rice there have been 450, 661, and 477 PPR proteins identified, respectively, which contrasts with only 14 PPR proteins identified in Chlamydomonas reinhardtii. Likewise, more than 120 OPR proteins members have been predicted from the nuclear genome of C. reinhardtii and only one has been identified in Arabidopsis thaliana. Due to their abundance in land plants, PPR proteins have been largely characterized making it possible to elucidate their RNA-binding code. This has even allowed researchers to generate engineered PPR proteins with defined affinity to a particular target, which has served as the basis to develop tools for gene expression in biotechnological applications. However, fine elucidation of the helical repeat proteins code in Chlamydomonas is a pending task. In this review, we summarize the current knowledge on the role PPR, TPR, and OPR proteins play in chloroplast gene expression in the green algae C. reinhardtii, pointing to relevant similarities and differences with their counterparts in plants. We also recapitulate on how these proteins have been engineered and shown to serve as mRNA regulatory factors for biotechnological applications in plants and how this could be used as a starting point for applications in algae.
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Affiliation(s)
- Karla S. Macedo-Osorio
- Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Biotecnología, México City, México
- Biological Engineering Laboratory, Genetic Engineering Department, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional-Unidad Irapuato, Irapuato, México
- División de Ciencias Biológicas y de la Salud, Universidad Autónoma Metropolitana-Xochimilco, México City, México
- *Correspondence: Karla S. Macedo-Osorio,
| | - Agustino Martínez-Antonio
- Biological Engineering Laboratory, Genetic Engineering Department, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional-Unidad Irapuato, Irapuato, México
| | - Jesús A. Badillo-Corona
- Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Biotecnología, México City, México
- Jesús A. Badillo-Corona,
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4
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Bertgen L, Mühlhaus T, Herrmann JM. Clingy genes: Why were genes for ribosomal proteins retained in many mitochondrial genomes? BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2020; 1861:148275. [PMID: 32712152 DOI: 10.1016/j.bbabio.2020.148275] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/14/2020] [Accepted: 07/19/2020] [Indexed: 11/18/2022]
Abstract
Why mitochondria still retain their own genome is a puzzle given the enormous effort to maintain a mitochondrial translation machinery. Most mitochondrially encoded proteins are membrane-embedded subunits of the respiratory chain. Their hydrophobicity presumably impedes their import into mitochondria. However, many mitochondrial genomes also encode protein subunits of the mitochondrial ribosome. These proteins lack transmembrane domains and hydrophobicity cannot explain why their genes remained in mitochondria. In this review, we provide an overview about mitochondrially encoded subunits of mitochondrial ribosomes of fungi, plants and protists. Moreover, we discuss and evaluate different hypotheses which were put forward to explain why (ribosomal) proteins remained mitochondrially encoded. It seems likely that the synthesis of ribosomal proteins in the mitochondrial matrix is used to regulate the assembly of the mitochondrial ribosome within mitochondria and to avoid problems that mitochondrial proteins might pose for cytosolic proteostasis and for the assembly of cytosolic ribosomes.
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Affiliation(s)
- Lea Bertgen
- Cell Biology, University of Kaiserslautern, Erwin-Schrödinger-Straße 13, 67663 Kaiserslautern, Germany
| | - Timo Mühlhaus
- Computational Systems Biology, University of Kaiserslautern, Erwin-Schrödinger-Straße 23, 67663 Kaiserslautern, Germany
| | - Johannes M Herrmann
- Cell Biology, University of Kaiserslautern, Erwin-Schrödinger-Straße 13, 67663 Kaiserslautern, Germany.
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Majeran W, Wostrikoff K, Wollman FA, Vallon O. Role of ClpP in the Biogenesis and Degradation of RuBisCO and ATP Synthase in Chlamydomonas reinhardtii. PLANTS (BASEL, SWITZERLAND) 2019; 8:E191. [PMID: 31248038 PMCID: PMC6681370 DOI: 10.3390/plants8070191] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 06/17/2019] [Accepted: 06/19/2019] [Indexed: 01/17/2023]
Abstract
Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) associates a chloroplast- and a nucleus-encoded subunit (LSU and SSU). It constitutes the major entry point of inorganic carbon into the biosphere as it catalyzes photosynthetic CO2 fixation. Its abundance and richness in sulfur-containing amino acids make it a prime source of N and S during nutrient starvation, when photosynthesis is downregulated and a high RuBisCO level is no longer needed. Here we show that translational attenuation of ClpP1 in the green alga Chlamydomonas reinhardtii results in retarded degradation of RuBisCO during S- and N-starvation, suggesting that the Clp protease is a major effector of RubisCO degradation in these conditions. Furthermore, we show that ClpP cannot be attenuated in the context of rbcL point mutations that prevent LSU folding. The mutant LSU remains in interaction with the chloroplast chaperonin complex. We propose that degradation of the mutant LSU by the Clp protease is necessary to prevent poisoning of the chaperonin. In the total absence of LSU, attenuation of ClpP leads to a dramatic stabilization of unassembled SSU, indicating that Clp is responsible for its degradation. In contrast, attenuation of ClpP in the absence of SSU does not lead to overaccumulation of LSU, whose translation is controlled by assembly. Altogether, these results point to RuBisCO degradation as one of the major house-keeping functions of the essential Clp protease. In addition, we show that non-assembled subunits of the ATP synthase are also stabilized when ClpP is attenuated. In the case of the atpA-FUD16 mutation, this can even allow the assembly of a small amount of CF1, which partially restores phototrophy.
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Affiliation(s)
- Wojciech Majeran
- Institute of Plant Sciences Paris-Saclay (IPS2), CNRS, Université Paris-Diderot, Université Paris-Sud, INRA, Université Evry, Université Paris-Saclay, Rue de Noetzlin, 91190 Gif-sur-Yvette, France.
| | - Katia Wostrikoff
- UMR7141 CNRS/Sorbonne Université, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France.
| | - Francis-André Wollman
- UMR7141 CNRS/Sorbonne Université, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France.
| | - Olivier Vallon
- UMR7141 CNRS/Sorbonne Université, Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, 75005 Paris, France.
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6
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Viola S, Cavaiuolo M, Drapier D, Eberhard S, Vallon O, Wollman FA, Choquet Y. MDA1, a nucleus-encoded factor involved in the stabilization and processing of the atpA transcript in the chloroplast of Chlamydomonas. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 98:1033-1047. [PMID: 30809889 DOI: 10.1111/tpj.14300] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 02/11/2019] [Accepted: 02/18/2019] [Indexed: 05/21/2023]
Abstract
In Chlamydomonas reinhardtii, chloroplast gene expression is tightly regulated post-transcriptionally by gene-specific trans-acting protein factors. Here, we report the molecular identification of an OctotricoPeptide Repeat (OPR) protein, MDA1, which governs the maturation and accumulation of the atpA transcript, encoding subunit α of the chloroplast ATP synthase. As does TDA1, another OPR protein required for the translation of the atpA mRNA, MDA1 targets the atpA 5'-untranslated region (UTR). Unexpectedly, it binds within a region of approximately 100 nt in the middle of the atpA 5'-UTR, at variance with the stabilization factors characterized so far, which bind to the 5'-end of their target mRNA to protect it from 5' → 3' exonucleases. It binds the same region as TDA1, with which it forms a high-molecular-weight complex that also comprises the atpA mRNA. This complex dissociates upon translation, promoting degradation of the atpA mRNA. We suggest that atpA transcripts, once translated, enter the degradation pathway because they cannot reassemble with MDA1 and TDA1, which preferentially bind to de novo transcribed mRNAs.
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Affiliation(s)
- Stefania Viola
- Laboratoire de Physiologie Membranaire et Moléculaire du Chloroplaste -UMR7141, IBPC, CNRS-Sorbonne Université, 13, rue Pierre et Marie Curie, 75005, Paris, France
| | - Marina Cavaiuolo
- Laboratoire de Physiologie Membranaire et Moléculaire du Chloroplaste -UMR7141, IBPC, CNRS-Sorbonne Université, 13, rue Pierre et Marie Curie, 75005, Paris, France
| | - Dominique Drapier
- Laboratoire de Physiologie Membranaire et Moléculaire du Chloroplaste -UMR7141, IBPC, CNRS-Sorbonne Université, 13, rue Pierre et Marie Curie, 75005, Paris, France
| | - Stephan Eberhard
- Laboratoire de Physiologie Membranaire et Moléculaire du Chloroplaste -UMR7141, IBPC, CNRS-Sorbonne Université, 13, rue Pierre et Marie Curie, 75005, Paris, France
| | - Olivier Vallon
- Laboratoire de Physiologie Membranaire et Moléculaire du Chloroplaste -UMR7141, IBPC, CNRS-Sorbonne Université, 13, rue Pierre et Marie Curie, 75005, Paris, France
| | - Francis-André Wollman
- Laboratoire de Physiologie Membranaire et Moléculaire du Chloroplaste -UMR7141, IBPC, CNRS-Sorbonne Université, 13, rue Pierre et Marie Curie, 75005, Paris, France
| | - Yves Choquet
- Laboratoire de Physiologie Membranaire et Moléculaire du Chloroplaste -UMR7141, IBPC, CNRS-Sorbonne Université, 13, rue Pierre et Marie Curie, 75005, Paris, France
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7
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Hosts for Hostile Protein Production: The Challenge of Recombinant Immunotoxin Expression. Biomedicines 2019; 7:biomedicines7020038. [PMID: 31108917 PMCID: PMC6630761 DOI: 10.3390/biomedicines7020038] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 05/07/2019] [Accepted: 05/13/2019] [Indexed: 12/12/2022] Open
Abstract
For the recombinant expression of toxin-based drugs, a crucial step lies not only in the choice of the production host(s) but also in the accurate design of the protein chimera. These issues are particularly important since such products may be toxic to the expressing host itself. To avoid or limit the toxicity to productive cells while obtaining a consistent yield in chimeric protein, several systems from bacterial to mammalian host cells have been employed. In this review, we will discuss the development of immunotoxin (IT) expression, placing special emphasis on advantages and on potential drawbacks, as one single perfect host for every chimeric protein toxin or ligand does not exist.
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Macedo-Osorio KS, Pérez-España VH, Garibay-Orijel C, Guzmán-Zapata D, Durán-Figueroa NV, Badillo-Corona JA. Intercistronic expression elements (IEE) from the chloroplast of Chlamydomonas reinhardtii can be used for the expression of foreign genes in synthetic operons. PLANT MOLECULAR BIOLOGY 2018; 98:303-317. [PMID: 30225747 DOI: 10.1007/s11103-018-0776-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 08/31/2018] [Indexed: 05/21/2023]
Abstract
Two intercistronic regions were identified as functional intercistronic expression elements (IEE) for the simultaneous expression of aphA-6 and gfp in a synthetic operon in the chloroplast of C. reinhardtii. Chlamydomonas reinhardtii, a biflagellate photosynthetic microalga, has been widely used in basic and applied science. Already three decades ago, Chlamydomonas had its chloroplast genome transformed and to this day constitutes the only alga routinely used in transplastomic technology. Despite the fact that over a 100 foreign genes have been expressed from the chloroplast genome, little has been done to address the challenge of expressing multiple genes in the form of operons, a development that is needed and crucial to push forward metabolic engineering and synthetic biology in this organism. Here, we studied five intercistronic regions and investigated if they can be used as intercistronic expression elements (IEE) in synthetic operons to drive the expression of foreign genes in the chloroplast of C. reinhardtii. The intercistronic regions were those from the psbB-psbT, psbN-psbH, psaC-petL, petL-trnN and tscA-chlN chloroplast operons, and the foreign genes were the aminoglycoside 3'-phosphotransferase (aphA-6), which confers resistance to kanamycin, and the green fluorescent protein gene (gfp). While all the intercistronic regions yielded lines that were resistant to kanamycin, only two (obtained with intercistronic regions from psbN-psbH and tscA-chlN) were identified as functional IEEs, yielding lines in which the second cistron (gfp) was translated and generated GFP. The IEEs we have identified could be useful for the stacking of genes for metabolic engineering or synthetic biology circuits in the chloroplast of C. reinhardtii.
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Affiliation(s)
- Karla S Macedo-Osorio
- Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Biotecnología, Av. Acueducto SN, Col. Barrio la Laguna Ticoman, Mexico City, Mexico
| | - Víctor H Pérez-España
- Universidad Autónoma del Estado de Hidalgo, Escuela Superior de Apan, Carretera Apan Calpulalpan km 8, Col. Chimalpa-Tlalayote, Apan, Hidalgo, Mexico
| | - Claudio Garibay-Orijel
- Labcitec, Camino a Atzacoalco 99, Col. Constitución de la República, Mexico City, Mexico
| | - Daniel Guzmán-Zapata
- Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Biotecnología, Av. Acueducto SN, Col. Barrio la Laguna Ticoman, Mexico City, Mexico
| | - Noé V Durán-Figueroa
- Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Biotecnología, Av. Acueducto SN, Col. Barrio la Laguna Ticoman, Mexico City, Mexico
| | - Jesús A Badillo-Corona
- Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Biotecnología, Av. Acueducto SN, Col. Barrio la Laguna Ticoman, Mexico City, Mexico.
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9
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Wittkopp TM, Saroussi S, Yang W, Johnson X, Kim RG, Heinnickel ML, Russell JJ, Phuthong W, Dent RM, Broeckling CD, Peers G, Lohr M, Wollman FA, Niyogi KK, Grossman AR. GreenCut protein CPLD49 of Chlamydomonas reinhardtii associates with thylakoid membranes and is required for cytochrome b 6 f complex accumulation. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 94:1023-1037. [PMID: 29602195 DOI: 10.1111/tpj.13915] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 02/23/2018] [Accepted: 03/06/2018] [Indexed: 06/08/2023]
Abstract
The GreenCut encompasses a suite of nucleus-encoded proteins with orthologs among green lineage organisms (plants, green algae), but that are absent or poorly conserved in non-photosynthetic/heterotrophic organisms. In Chlamydomonas reinhardtii, CPLD49 (Conserved in Plant Lineage and Diatoms49) is an uncharacterized GreenCut protein that is critical for maintaining normal photosynthetic function. We demonstrate that a cpld49 mutant has impaired photoautotrophic growth under high-light conditions. The mutant exhibits a nearly 90% reduction in the level of the cytochrome b6 f complex (Cytb6 f), which impacts linear and cyclic electron transport, but does not compromise the ability of the strain to perform state transitions. Furthermore, CPLD49 strongly associates with thylakoid membranes where it may be part of a membrane protein complex with another GreenCut protein, CPLD38; a mutant null for CPLD38 also impacts Cytb6 f complex accumulation. We investigated several potential functions of CPLD49, with some suggested by protein homology. Our findings are congruent with the hypothesis that CPLD38 and CPLD49 are part of a novel thylakoid membrane complex that primarily modulates accumulation, but also impacts the activity of the Cytb6 f complex. Based on motifs of CPLD49 and the activities of other CPLD49-like proteins, we suggest a role for this putative dehydrogenase in the synthesis of a lipophilic thylakoid membrane molecule or cofactor that influences the assembly and activity of Cytb6 f.
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Affiliation(s)
- Tyler M Wittkopp
- Department of Biology, Stanford University, Stanford, CA, 94305, USA
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA
| | - Shai Saroussi
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA
| | - Wenqiang Yang
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA
| | - Xenie Johnson
- Laboratoire de Bioénergétique et Biotechnologie des Bactéries et Microalgues, CEA Cadarache, Saint Paul lez Durance, France
| | - Rick G Kim
- Department of Biology, Stanford University, Stanford, CA, 94305, USA
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA
| | - Mark L Heinnickel
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA
| | - James J Russell
- Department of Biology, Stanford University, Stanford, CA, 94305, USA
| | - Witchukorn Phuthong
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, 94305, USA
| | - Rachel M Dent
- Department of Plant and Microbial Biology, Howard Hughes Medical Institute, University of California, Berkeley, CA, 94720-3102, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Corey D Broeckling
- Proteomics and Metabolomics Facility, Colorado State University, Fort Collins, CO, 80523, USA
| | - Graham Peers
- Department of Biology, Colorado State University, Fort Collins, CO, 80523, USA
| | - Martin Lohr
- Institut für Molekulare Physiologie - Pflanzenbiochemie, Johannes Gutenberg-Universität, 55099, Mainz, Germany
| | | | - Krishna K Niyogi
- Department of Plant and Microbial Biology, Howard Hughes Medical Institute, University of California, Berkeley, CA, 94720-3102, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Arthur R Grossman
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA
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10
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Scharff LB, Ehrnthaler M, Janowski M, Childs LH, Hasse C, Gremmels J, Ruf S, Zoschke R, Bock R. Shine-Dalgarno Sequences Play an Essential Role in the Translation of Plastid mRNAs in Tobacco. THE PLANT CELL 2017; 29:3085-3101. [PMID: 29133466 PMCID: PMC5757275 DOI: 10.1105/tpc.17.00524] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 10/27/2017] [Accepted: 11/08/2017] [Indexed: 05/23/2023]
Abstract
In prokaryotic systems, the translation initiation of many, though not all, mRNAs depends on interaction between a sequence element upstream of the start codon (the Shine-Dalgarno sequence [SD]) and a complementary sequence in the 3' end of the 16S rRNA (anti-Shine-Dalgarno sequence [aSD]). Although many chloroplast mRNAs harbor putative SDs in their 5' untranslated regions and the aSD displays strong conservation, the functional relevance of SD-aSD interactions in plastid translation is unclear. Here, by generating transplastomic tobacco (Nicotiana tabacum) mutants with point mutations in the aSD coupled with genome-wide analysis of translation by ribosome profiling, we provide a global picture of SD-dependent translation in plastids. We observed a pronounced correlation between weakened predicted SD-aSD interactions and reduced translation efficiency. However, multiple lines of evidence suggest that the strength of the SD-aSD interaction is not the only determinant of the translational output of many plastid mRNAs. Finally, the translation efficiency of mRNAs with strong secondary structures around the start codon is more dependent on the SD-aSD interaction than weakly structured mRNAs. Thus, our data reveal the importance of the aSD in plastid translation initiation, uncover chloroplast genes whose translation is influenced by SD-aSD interactions, and provide insights into determinants of translation efficiency in plastids.
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Affiliation(s)
- Lars B Scharff
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D-14476 Potsdam-Golm, Germany
| | - Miriam Ehrnthaler
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D-14476 Potsdam-Golm, Germany
| | - Marcin Janowski
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D-14476 Potsdam-Golm, Germany
| | - Liam H Childs
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D-14476 Potsdam-Golm, Germany
| | - Claudia Hasse
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D-14476 Potsdam-Golm, Germany
| | - Jürgen Gremmels
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D-14476 Potsdam-Golm, Germany
| | - Stephanie Ruf
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D-14476 Potsdam-Golm, Germany
| | - Reimo Zoschke
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D-14476 Potsdam-Golm, Germany
| | - Ralph Bock
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, D-14476 Potsdam-Golm, Germany
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11
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Responses of the picoprasinophyte Micromonas commoda to light and ultraviolet stress. PLoS One 2017; 12:e0172135. [PMID: 28278262 PMCID: PMC5344333 DOI: 10.1371/journal.pone.0172135] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2016] [Accepted: 01/31/2017] [Indexed: 11/19/2022] Open
Abstract
Micromonas is a unicellular marine green alga that thrives from tropical to polar ecosystems. We investigated the growth and cellular characteristics of acclimated mid-exponential phase Micromonas commoda RCC299 over multiple light levels and over the diel cycle (14:10 hour light:dark). We also exposed the light:dark acclimated M. commoda to experimental shifts from moderate to high light (HL), and to HL plus ultraviolet radiation (HL+UV), 4.5 hours into the light period. Cellular responses of this prasinophyte were quantified by flow cytometry and changes in gene expression by qPCR and RNA-seq. While proxies for chlorophyll a content and cell size exhibited similar diel variations in HL and controls, with progressive increases during day and decreases at night, both parameters sharply decreased after the HL+UV shift. Two distinct transcriptional responses were observed among chloroplast genes in the light shift experiments: i) expression of transcription and translation-related genes decreased over the time course, and this transition occurred earlier in treatments than controls; ii) expression of several photosystem I and II genes increased in HL relative to controls, as did the growth rate within the same diel period. However, expression of these genes decreased in HL+UV, likely as a photoprotective mechanism. RNA-seq also revealed two genes in the chloroplast genome, ycf2-like and ycf1-like, that had not previously been reported. The latter encodes the second largest chloroplast protein in Micromonas and has weak homology to plant Ycf1, an essential component of the plant protein translocon. Analysis of several nuclear genes showed that the expression of LHCSR2, which is involved in non-photochemical quenching, and five light-harvesting-like genes, increased 30 to >50-fold in HL+UV, but was largely unchanged in HL and controls. Under HL alone, a gene encoding a novel nitrite reductase fusion protein (NIRFU) increased, possibly reflecting enhanced N-assimilation under the 625 μmol photons m-2 s-1 supplied in the HL treatment. NIRFU’s domain structure suggests it may have more efficient electron transfer than plant NIR proteins. Our analyses indicate that Micromonas can readily respond to abrupt environmental changes, such that strong photoinhibition was provoked by combined exposure to HL and UV, but a ca. 6-fold increase in light was stimulatory.
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12
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Sun Y, Zerges W. Translational regulation in chloroplasts for development and homeostasis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:809-20. [PMID: 25988717 DOI: 10.1016/j.bbabio.2015.05.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 04/13/2015] [Accepted: 05/10/2015] [Indexed: 11/16/2022]
Abstract
Chloroplast genomes encode 100-200 proteins which function in photosynthesis, the organellar genetic system, and other pathways and processes. These proteins are synthesized by a complete translation system within the chloroplast, with bacterial-type ribosomes and translation factors. Here, we review translational regulation in chloroplasts, focusing on changes in translation rates which occur in response to requirements for proteins encoded by the chloroplast genome for development and homeostasis. In addition, we delineate the developmental and physiological contexts and model organisms in which translational regulation in chloroplasts has been studied. This article is part of a Special Issue entitled: Chloroplast biogenesis.
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Affiliation(s)
- Yi Sun
- Biology Department and Center for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke W., Montreal, Quebec H4B 1R6, Canada
| | - William Zerges
- Biology Department and Center for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke W., Montreal, Quebec H4B 1R6, Canada.
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13
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Boulouis A, Drapier D, Razafimanantsoa H, Wostrikoff K, Tourasse NJ, Pascal K, Girard-Bascou J, Vallon O, Wollman FA, Choquet Y. Spontaneous dominant mutations in chlamydomonas highlight ongoing evolution by gene diversification. THE PLANT CELL 2015; 27:984-1001. [PMID: 25804537 PMCID: PMC4558696 DOI: 10.1105/tpc.15.00010] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 02/10/2015] [Accepted: 03/05/2015] [Indexed: 05/04/2023]
Abstract
We characterized two spontaneous and dominant nuclear mutations in the unicellular alga Chlamydomonas reinhardtii, ncc1 and ncc2 (for nuclear control of chloroplast gene expression), which affect two octotricopeptide repeat (OPR) proteins encoded in a cluster of paralogous genes on chromosome 15. Both mutations cause a single amino acid substitution in one OPR repeat. As a result, the mutated NCC1 and NCC2 proteins now recognize new targets that we identified in the coding sequences of the chloroplast atpA and petA genes, respectively. Interaction of the mutated proteins with these targets leads to transcript degradation; however, in contrast to the ncc1 mutation, the ncc2 mutation requires on-going translation to promote the decay of the petA mRNA. Thus, these mutants reveal a mechanism by which nuclear factors act on chloroplast mRNAs in Chlamydomonas. They illustrate how diversifying selection can allow cells to adapt the nuclear control of organelle gene expression to environmental changes. We discuss these data in the wider context of the evolution of regulation by helical repeat proteins.
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Affiliation(s)
- Alix Boulouis
- Unité Mixte de Recherche 7141, CNRS/UPMC, Institut de Biologie Physico-Chimique, F-75005 Paris, France
| | - Dominique Drapier
- Unité Mixte de Recherche 7141, CNRS/UPMC, Institut de Biologie Physico-Chimique, F-75005 Paris, France
| | - Hélène Razafimanantsoa
- Unité Mixte de Recherche 7141, CNRS/UPMC, Institut de Biologie Physico-Chimique, F-75005 Paris, France
| | - Katia Wostrikoff
- Unité Mixte de Recherche 7141, CNRS/UPMC, Institut de Biologie Physico-Chimique, F-75005 Paris, France
| | - Nicolas J Tourasse
- Unité Mixte de Recherche 7141, CNRS/UPMC, Institut de Biologie Physico-Chimique, F-75005 Paris, France
| | - Kevin Pascal
- Unité Mixte de Recherche 7141, CNRS/UPMC, Institut de Biologie Physico-Chimique, F-75005 Paris, France
| | - Jacqueline Girard-Bascou
- Unité Mixte de Recherche 7141, CNRS/UPMC, Institut de Biologie Physico-Chimique, F-75005 Paris, France
| | - Olivier Vallon
- Unité Mixte de Recherche 7141, CNRS/UPMC, Institut de Biologie Physico-Chimique, F-75005 Paris, France
| | - Francis-André Wollman
- Unité Mixte de Recherche 7141, CNRS/UPMC, Institut de Biologie Physico-Chimique, F-75005 Paris, France
| | - Yves Choquet
- Unité Mixte de Recherche 7141, CNRS/UPMC, Institut de Biologie Physico-Chimique, F-75005 Paris, France
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Levey T, Westhoff P, Meierhoff K. Expression of a nuclear-encoded psbH gene complements the plastidic RNA processing defect in the PSII mutant hcf107 in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 80:292-304. [PMID: 25081859 DOI: 10.1111/tpj.12632] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 07/28/2014] [Accepted: 07/29/2014] [Indexed: 06/03/2023]
Abstract
The helical-repeat RNA-binding protein HCF107 is required for processing, stabilization and translation of plastid-encoded psbH mRNA. The psbH gene encodes a small, hydrophilic subunit of the PSII complex and is part of the plastidic psbB-psbT-psbH-petB-petD transcription unit. In Arabidopsis hcf107 mutants, only trace amounts of PSII proteins can be detected. Beside drastically reduced synthesis of PsbH, the synthesis of CP47 was also reduced in these mutants, although the corresponding psbB transcripts accumulate to wild type levels. This situation raises the question, whether the reduction of CP47 is a direct consequence of the mutation, based on targeting of HCF107 to the psbB mRNA, or a secondary affect due to the absent PsbH. To clarify this issue we introduced a chimeric psbH construct comprising a sequence encoding a chloroplast transit peptide into the hcf107-2 background. We found that the nucleus-localized psbH was able to complement the mutant defect resulting in photoautotrophic plants. The PSII proteins CP47 and D1 accumulated to barely half of the wild type level. Further experiments showed that cytosolically synthesized PsbH was imported into chloroplasts and assembled into PSII complexes. Using this approach, we showed that the tetratricopeptide repeat protein HCF107 of Arabidopsis is only responsible for expression of PsbH and not for synthesis of CP47. In addition the data suggest the necessity of the small, one-helix membrane spanning protein PsbH for the accumulation of CP47 in higher plants.
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Affiliation(s)
- Tatjana Levey
- Institut für Entwicklungs- und Molekularbiologie der Pflanzen, Heinrich-Heine-Universität, Universitätsstr. 1, 40225, Düsseldorf, Germany
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15
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Tiller N, Bock R. The translational apparatus of plastids and its role in plant development. MOLECULAR PLANT 2014; 7:1105-20. [PMID: 24589494 PMCID: PMC4086613 DOI: 10.1093/mp/ssu022] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 02/26/2014] [Indexed: 05/18/2023]
Abstract
Chloroplasts (plastids) possess a genome and their own machinery to express it. Translation in plastids occurs on bacterial-type 70S ribosomes utilizing a set of tRNAs that is entirely encoded in the plastid genome. In recent years, the components of the chloroplast translational apparatus have been intensely studied by proteomic approaches and by reverse genetics in the model systems tobacco (plastid-encoded components) and Arabidopsis (nucleus-encoded components). This work has provided important new insights into the structure, function, and biogenesis of chloroplast ribosomes, and also has shed fresh light on the molecular mechanisms of the translation process in plastids. In addition, mutants affected in plastid translation have yielded strong genetic evidence for chloroplast genes and gene products influencing plant development at various levels, presumably via retrograde signaling pathway(s). In this review, we describe recent progress with the functional analysis of components of the chloroplast translational machinery and discuss the currently available evidence that supports a significant impact of plastid translational activity on plant anatomy and morphology.
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Affiliation(s)
- Nadine Tiller
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
| | - Ralph Bock
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam-Golm, Germany
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16
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Malnoë A, Wang F, Girard-Bascou J, Wollman FA, de Vitry C. Thylakoid FtsH protease contributes to photosystem II and cytochrome b6f remodeling in Chlamydomonas reinhardtii under stress conditions. THE PLANT CELL 2014; 26:373-90. [PMID: 24449688 PMCID: PMC3963582 DOI: 10.1105/tpc.113.120113] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 11/28/2013] [Accepted: 12/18/2013] [Indexed: 05/18/2023]
Abstract
FtsH is the major thylakoid membrane protease found in organisms performing oxygenic photosynthesis. Here, we show that FtsH from Chlamydomonas reinhardtii forms heterooligomers comprising two subunits, FtsH1 and FtsH2. We characterized this protease using FtsH mutants that we identified through a genetic suppressor approach that restored phototrophic growth of mutants originally defective for cytochrome b6f accumulation. We thus extended the spectrum of FtsH substrates in the thylakoid membranes beyond photosystem II, showing the susceptibility of cytochrome b6f complexes (and proteins involved in the ci heme binding pathway to cytochrome b6) to FtsH. We then show how FtsH is involved in the response of C. reinhardtii to macronutrient stress. Upon phosphorus starvation, photosynthesis inactivation results from an FtsH-sensitive photoinhibition process. In contrast, we identified an FtsH-dependent loss of photosystem II and cytochrome b6f complexes in darkness upon sulfur deprivation. The D1 fragmentation pattern observed in the latter condition was similar to that observed in photoinhibitory conditions, which points to a similar degradation pathway in these two widely different environmental conditions. Our experiments thus provide extensive evidence that FtsH plays a major role in the quality control of thylakoid membrane proteins and in the response of C. reinhardtii to light and macronutrient stress.
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17
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Lu Y, Wang HR, Li H, Cui HR, Feng YG, Wang XY. A chloroplast membrane protein LTO1/AtVKOR involving in redox regulation and ROS homeostasis. PLANT CELL REPORTS 2013; 32:1427-40. [PMID: 23689258 DOI: 10.1007/s00299-013-1455-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Revised: 04/20/2013] [Accepted: 04/29/2013] [Indexed: 05/08/2023]
Abstract
The role of LTO1/ At VKOR-DsbA in ROS homeostasis and in redox regulation of cysteine-containing proteins in chloroplast was studied in lto1 - 2 mutant, and a potential target of LTO1 was captured. A chloroplast membrane protein LTO1/AtVKOR-DsbA encoded by the gene At4g35760 was recently found to be an oxidoreductase and involved in assembly of PSII. Here, the growth of a mutant lto1-2 line of Arabidopsis was found to be severely stunted and transgenic complementation ultimately demonstrated the phenotype changes were due to this gene. A proteomic experiment identified 23 proteins presenting a differential abundance in lto1-2 compared with wild-type plants, including components in PSII and proteins scavenging active oxygen. Three scavengers of active oxygen, L-ascorbate peroxidase 1, peroxisomal catalase 2, dehydroascorbate reductase 1, are reduced in lto1-2 plants, corresponding to high levels of accumulation of reactive oxygen species (ROS). The photosynthetic activities of PSII and the quantity of core protein D1 decreased significantly in lto1-2. Further investigation showed the synthesis of D1 was not affected in mutants both at transcription and translation levels. The soluble DsbA-like domain of LTO1 was found to have reduction, oxidation and isomerization activities, and could promote the formation of disulfide bonds in a lumenal protein, FKBP13. A potential target of LTO1 was captured which was involving in chlorophyll degradation and photooxidative stress response. Experimental results imply that LTO1 plays important roles in redox regulation, ROS homeostasis and maintenance of PSII.
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Affiliation(s)
- Ying Lu
- College of Life Science, Shandong Agricultural University, Taian 271018, Shandong, People's Republic of China
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18
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Rochaix JD. Redox regulation of thylakoid protein kinases and photosynthetic gene expression. Antioxid Redox Signal 2013; 18:2184-201. [PMID: 23339452 PMCID: PMC3629850 DOI: 10.1089/ars.2012.5110] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
SIGNIFICANCE Photosynthetic organisms are subjected to frequent changes in their environment that include fluctuations in light quality and quantity, temperature, CO(2) concentration, and nutrient availability. They have evolved complex responses to these changes that allow them to protect themselves against photo-oxidative damage and to optimize their growth under these adverse conditions. In the case of light changes, these acclimatory processes can occur in either the short or the long term and are mainly mediated through the redox state of the plastoquinone pool and the ferredoxin/thioredoxin system. RECENT ADVANCES Short-term responses involve a dynamic reorganization of photosynthetic complexes, and long-term responses (LTRs) modulate the chloroplast and nuclear gene expression in such a way that the levels of the photosystems and their antennae are rebalanced for an optimal photosynthetic performance. These changes are mediated through a complex signaling network with several protein kinases and phosphatases that are conserved in land plants and algae. The phosphorylation status of the light-harvesting proteins of photosystem II and its core proteins is mainly determined by two complementary kinase-phosphatase pairs corresponding to STN7/PPH1 and STN8/PBCP, respectively. CRITICAL ISSUES The activity of the Stt7 kinase is principally regulated by the redox state of the plastoquinone pool, which in turn depends on the light irradiance, ambient CO(2) concentration, and cellular energy status. In addition, this kinase is also involved in the LTR. FUTURE DIRECTIONS Other chloroplast kinases modulate the activity of the plastid transcriptional machinery, but the global signaling network that connects all of the identified kinases and phosphatases is still largely unknown.
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Affiliation(s)
- Jean-David Rochaix
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland.
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19
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Fontanesi F. Mechanisms of mitochondrial translational regulation. IUBMB Life 2013; 65:397-408. [PMID: 23554047 DOI: 10.1002/iub.1156] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 01/31/2013] [Indexed: 11/11/2022]
Abstract
The mitochondrial oxidative phosphorylation system is formed by multimeric enzymes. In the yeast Saccharomyces cerevisiae, the bc1 complex, cytochrome c oxidase and the F1 FO ATP synthase contain subunits of dual genetic origin. It has been recently established that key subunits of these enzymes, translated on mitochondrial ribosomes, are the subjects of assembly-dependent translational regulation. This type of control of gene expression plays a pivotal role in optimizing the biogenesis of mitochondrial respiratory membranes by coordinating protein synthesis and complex assembly and by limiting the accumulation of potentially harmful assembly intermediates. Here, the author will discuss the mechanisms governing translational regulation in yeast mitochondria in the light of the most recent discoveries in the field.
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Affiliation(s)
- Flavia Fontanesi
- Department of Neurology, University of Miami, Miller School of Medicine, Miami, FL, USA.
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20
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Transmembrane signaling and assembly of the cytochrome b6f-lipidic charge transfer complex. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1827:1295-308. [PMID: 23507619 DOI: 10.1016/j.bbabio.2013.03.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 02/27/2013] [Accepted: 03/06/2013] [Indexed: 12/30/2022]
Abstract
Structure-function properties of the cytochrome b6f complex are sufficiently unique compared to those of the cytochrome bc1 complex that b6f should not be considered a trivially modified bc1 complex. A unique property of the dimeric b6f complex is its involvement in transmembrane signaling associated with the p-side oxidation of plastoquinol. Structure analysis of lipid binding sites in the cyanobacterial b6f complex prepared by hydrophobic chromatography shows that the space occupied by the H transmembrane helix in the cytochrome b subunit of the bc1 complex is mostly filled by a lipid in the b6f crystal structure. It is suggested that this space can be filled by the domain of a transmembrane signaling protein. The identification of lipid sites and likely function defines the intra-membrane conserved central core of the b6f complex, consisting of the seven trans-membrane helices of the cytochrome b and subunit IV polypeptides. The other six TM helices, contributed by cytochrome f, the iron-sulfur protein, and the four peripheral single span subunits, define a peripheral less conserved domain of the complex. The distribution of conserved and non-conserved domains of each monomer of the complex, and the position and inferred function of a number of the lipids, suggests a model for the sequential assembly in the membrane of the eight subunits of the b6f complex, in which the assembly is initiated by formation of the cytochrome b6-subunit IV core sub-complex in a monomer unit. Two conformations of the unique lipidic chlorophyll a, defined in crystal structures, are described, and functions of the outlying β-carotene, a possible 'latch' in supercomplex formation, are discussed. This article is part of a Special Issue entitled: Respiratory complex III and related bc complexes.
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21
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Suzuki Y, Makino A. Translational downregulation of RBCL is operative in the coordinated expression of Rubisco genes in senescent leaves in rice. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:1145-52. [PMID: 23349140 PMCID: PMC3580822 DOI: 10.1093/jxb/ers398] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Rubisco gene expression was examined in detail in rice (Oryza sativa L.) leaves at different positions, i.e. expanding, mature, and senescent leaves. Rubisco small subunit (RBCS) synthesis and RBCS mRNA levels were maximal in expanding leaves and gradually became lower in mature and senescent leaves, with declines in those of the large subunit (RBCL) being relatively slower. The amount of synthesized RBCL per unit level of RBCL mRNA and polysome loading of RBCL mRNA declined in senescent leaves, whereas such phenomena were not observed for RBCS. These results suggested that gene expression of RBCL is downregulated at the level of its translation when a balance between RBCL and RBCS expression is disturbed by leaf senescence. It has been suggested that RBCS protein is a positive regulator for RBCL mRNA level in expanding rice leaves, as judged from their stoichiometric relationship in RBCS transgenic rice plants. However, the ratio of the RBCL mRNA level to the amount of synthesized RBCS in senescent leaves was significantly higher than that in expanding leaves. Therefore, it is suggested that the decline in RBCL mRNA level in senescent leaves is not fully accounted for by that in the amount of synthesized RBCS. Effects of other factors such as the stability of RBCL mRNA may come into play.
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MESH Headings
- Cell Death
- Down-Regulation
- Gene Expression Regulation, Enzymologic
- Gene Expression Regulation, Plant
- Genes, Plant
- Oryza/enzymology
- Oryza/genetics
- Oryza/growth & development
- Plant Leaves/enzymology
- Plant Leaves/genetics
- Plant Leaves/growth & development
- Plants, Genetically Modified/genetics
- Plants, Genetically Modified/growth & development
- Plants, Genetically Modified/metabolism
- Polyribosomes/enzymology
- Polyribosomes/genetics
- Polyribosomes/metabolism
- Protein Biosynthesis
- RNA Stability
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Plant/genetics
- RNA, Plant/metabolism
- Ribulose-Bisphosphate Carboxylase/genetics
- Ribulose-Bisphosphate Carboxylase/metabolism
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Affiliation(s)
- Yuji Suzuki
- Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Sendai, Japan.
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22
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Lyska D, Meierhoff K, Westhoff P. How to build functional thylakoid membranes: from plastid transcription to protein complex assembly. PLANTA 2013; 237:413-28. [PMID: 22976450 PMCID: PMC3555230 DOI: 10.1007/s00425-012-1752-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 08/10/2012] [Indexed: 05/06/2023]
Abstract
Chloroplasts are the endosymbiotic descendants of cyanobacterium-like prokaryotes. Present genomes of plant and green algae chloroplasts (plastomes) contain ~100 genes mainly encoding for their transcription-/translation-machinery, subunits of the thylakoid membrane complexes (photosystems II and I, cytochrome b (6) f, ATP synthase), and the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase. Nevertheless, proteomic studies have identified several thousand proteins in chloroplasts indicating that the majority of the plastid proteome is not encoded by the plastome. Indeed, plastid and host cell genomes have been massively rearranged in the course of their co-evolution, mainly through gene loss, horizontal gene transfer from the cyanobacterium/chloroplast to the nucleus of the host cell, and the emergence of new nuclear genes. Besides structural components of thylakoid membrane complexes and other (enzymatic) complexes, the nucleus provides essential factors that are involved in a variety of processes inside the chloroplast, like gene expression (transcription, RNA-maturation and translation), complex assembly, and protein import. Here, we provide an overview on regulatory factors that have been described and characterized in the past years, putting emphasis on mechanisms regulating the expression and assembly of the photosynthetic thylakoid membrane complexes.
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Affiliation(s)
- Dagmar Lyska
- Entwicklungs- und Molekularbiologie der Pflanzen, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse 1, Düsseldorf, Germany.
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Heinnickel ML, Alric J, Wittkopp T, Yang W, Catalanotti C, Dent R, Niyogi KK, Wollman FA, Grossman AR. Novel thylakoid membrane GreenCut protein CPLD38 impacts accumulation of the cytochrome b6f complex and associated regulatory processes. J Biol Chem 2013; 288:7024-36. [PMID: 23303190 PMCID: PMC3591612 DOI: 10.1074/jbc.m112.427476] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Based on previous comparative genomic analyses, a set of nearly 600 polypeptides was identified that is present in green algae and flowering and nonflowering plants but is not present (or is highly diverged) in nonphotosynthetic organisms. The gene encoding one of these “GreenCut” proteins, CPLD38, is in the same operon as ndhL in most cyanobacteria; the NdhL protein is part of a complex essential for cyanobacterial respiration. A cpld38 mutant of Chlamydomonas reinhardtii does not grow on minimal medium, is high light-sensitive under photoheterotrophic conditions, has lower accumulation of photosynthetic complexes, reduced photosynthetic electron flow to P700+, and reduced photochemical efficiency of photosystem II (ΦPSII); these phenotypes are rescued by a wild-type copy of CPLD38. Single turnover flash experiments and biochemical analyses demonstrated that cytochrome b6f function was severely compromised, and the levels of transcripts and polypeptide subunits of the cytochrome b6f complex were also significantly lower in the cpld38 mutant. Furthermore, subunits of the cytochrome b6f complex in mutant cells turned over much more rapidly than in wild-type cells. Interestingly, PTOX2 and NDA2, two major proteins involved in chlororespiration, were more than 5-fold higher in mutants relative to wild-type cells, suggesting a shift in the cpld38 mutant from photosynthesis toward chlororespiratory metabolism, which is supported by experiments that quantify the reduction state of the plastoquinone pool. Together, these findings support the hypothesis that CPLD38 impacts the stability of the cytochrome b6f complex and possibly plays a role in balancing redox inputs to the quinone pool from photosynthesis and chlororespiration.
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Affiliation(s)
- Mark L Heinnickel
- Department of Plant Biology, Carnegie Institute for Science, Stanford, California 94305, USA.
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24
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Meierhoff K, Westhoff P. The Biogenesis of the Thylakoid Membrane: Photosystem II, a Case Study. PLASTID DEVELOPMENT IN LEAVES DURING GROWTH AND SENESCENCE 2013. [DOI: 10.1007/978-94-007-5724-0_4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Xiao J, Li J, Ouyang M, Yun T, He B, Ji D, Ma J, Chi W, Lu C, Zhang L. DAC is involved in the accumulation of the cytochrome b6/f complex in Arabidopsis. PLANT PHYSIOLOGY 2012; 160:1911-22. [PMID: 23043079 PMCID: PMC3510120 DOI: 10.1104/pp.112.204891] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The biogenesis and assembly of photosynthetic multisubunit protein complexes is assisted by a series of nucleus-encoded auxiliary protein factors. In this study, we characterize the dac mutant of Arabidopsis (Arabidopsis thaliana), which shows a severe defect in the accumulation of the cytochrome b(6)/f complex, and provide evidence suggesting that the efficiency of cytochrome b(6)/f complex assembly is affected in the mutant. DAC is a thylakoid membrane protein with two predicted transmembrane domains that is conserved from cyanobacteria to vascular plants. Yeast (Saccharomyces cerevisiae) two-hybrid and coimmunoprecipitation analyses revealed a specific interaction between DAC and PetD, a subunit of the cytochrome b(6)/f complex. However, DAC was found not to be an intrinsic component of the cytochrome b(6)/f complex. In vivo chloroplast protein labeling experiments showed that the labeling rates of the PetD and cytochrome f proteins were greatly reduced, whereas that of the cytochrome b(6) protein remained normal in the dac mutant. DAC appears to be a novel factor involved in the assembly/stabilization of the cytochrome b(6)/f complex, possibly through interaction with the PetD protein.
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Rahire M, Laroche F, Cerutti L, Rochaix JD. Identification of an OPR protein involved in the translation initiation of the PsaB subunit of photosystem I. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 72:652-61. [PMID: 22817760 DOI: 10.1111/j.1365-313x.2012.05111.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Genetic analysis of mutants deficient in the biosynthesis of the photosystem I complex has revealed several nucleus-encoded factors that act at different post-transcriptional steps of chloroplast gene expression. Here we have identified and characterized the gene affected in the tab 1-F15 mutant, which is specifically deficient in the translation of the photosystem I reaction center protein PsaB as the result of a single nucleotide deletion. This gene encodes Tab 1, a 1287 amino acid protein that contains 10 tandem 38-40 amino acid degenerate repeats of the PPPEW/OPR (octatricopeptide repeat) family, first described for the chloroplast translation factor Tbc2. These repeats are involved in the binding of Tab 1 to the 5'-untranslated region of the psaB mRNA based on gel mobility shift assays. Tab 1 is part of a large family of proteins in Chlamydomonas that are also found in several bacteria and protozoans, but are rare in land plants.
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Affiliation(s)
- Michèle Rahire
- Departments of Molecular Biology and Plant Biology, University of Geneva, 30, Quai Ernest Ansermet, Geneva 1211, Switzerland
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27
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Stable plastid transformation for high-level recombinant protein expression: promises and challenges. J Biomed Biotechnol 2012; 2012:158232. [PMID: 23093835 PMCID: PMC3474547 DOI: 10.1155/2012/158232] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Revised: 08/10/2012] [Accepted: 08/24/2012] [Indexed: 12/22/2022] Open
Abstract
Plants are a promising expression system for the production of recombinant proteins. However, low protein productivity remains a major obstacle that limits extensive commercialization of whole plant and plant cell bioproduction platform. Plastid genetic engineering offers several advantages, including high levels of transgenic expression, transgenic containment via maternal inheritance, and multigene expression in a single transformation event. In recent years, the development of optimized expression strategies has given a huge boost to the exploitation of plastids in molecular farming. The driving forces behind the high expression level of plastid bioreactors include codon optimization, promoters and UTRs, genotypic modifications, endogenous enhancer and regulatory elements, posttranslational modification, and proteolysis. Exciting progress of the high expression level has been made with the plastid-based production of two particularly important classes of pharmaceuticals: vaccine antigens, therapeutic proteins, and antibiotics and enzymes. Approaches to overcome and solve the associated challenges of this culture system that include low transformation frequencies, the formation of inclusion bodies, and purification of recombinant proteins will also be discussed.
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28
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Suzuki Y, Makino A. Availability of Rubisco small subunit up-regulates the transcript levels of large subunit for stoichiometric assembly of its holoenzyme in rice. PLANT PHYSIOLOGY 2012; 160:533-40. [PMID: 22811433 PMCID: PMC3440226 DOI: 10.1104/pp.112.201459] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 07/15/2012] [Indexed: 05/20/2023]
Abstract
Rubisco is composed of eight small subunits coded for by the nuclear RBCS multigene family and eight large subunits coded for by the rbcL gene in the plastome. For synthesis of the Rubisco holoenzyme, both genes need to be expressed coordinately. To investigate this molecular mechanism, the protein synthesis of two subunits of Rubisco was characterized in transgenic rice (Oryza sativa) plants with overexpression or antisense suppression of the RBCS gene. Total RBCS and rbcL messenger RNA (mRNA) levels and RBCS and RbcL synthesis simultaneously increased in RBCS-sense plants, although the increase in total RBCS mRNA level was greater. In RBCS-antisense plants, the levels of these mRNAs and the synthesis of the corresponding proteins declined to a similar extent. The amount of RBCS synthesized was tightly correlated with rbcL mRNA level among genotypes but not associated with changes in mRNA levels of other major chloroplast-encoded photosynthetic genes. The level of rbcL mRNA, in turn, was tightly correlated with the amount of RbcL synthesized, the molar ratio of RBCS synthesis to RbcL synthesis being identical irrespective of genotype. Polysome loading of rbcL mRNA was not changed. These results demonstrate that the availability of RBCS protein up-regulates the gene expression of rbcL primarily at the transcript level in a quantitative manner for stoichiometric assembly of Rubisco holoenzyme.
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MESH Headings
- Cell Culture Techniques/methods
- Chloroplasts/enzymology
- Chloroplasts/genetics
- Enzyme Activation
- Gene Expression Regulation, Enzymologic
- Gene Expression Regulation, Plant
- Genes, Plant
- Holoenzymes/genetics
- Holoenzymes/metabolism
- Oryza/enzymology
- Oryza/genetics
- Photosynthesis
- Plant Leaves/enzymology
- Plant Leaves/genetics
- Plant Proteins/genetics
- Plants, Genetically Modified/enzymology
- Plants, Genetically Modified/genetics
- Plants, Genetically Modified/metabolism
- Polyribosomes/metabolism
- Protein Biosynthesis
- Protein Subunits/genetics
- Protein Subunits/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- RNA, Plant/analysis
- RNA, Plant/genetics
- RNA, Plant/metabolism
- Ribulose-Bisphosphate Carboxylase/genetics
- Ribulose-Bisphosphate Carboxylase/metabolism
- Transcription, Genetic
- Up-Regulation
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Affiliation(s)
- Yuji Suzuki
- Graduate School of Agricultural Science, Tohoku University, Sendai 981-8555, Japan.
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29
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Kallas T. Cytochrome b 6 f Complex at the Heart of Energy Transduction and Redox Signaling. PHOTOSYNTHESIS 2012. [DOI: 10.1007/978-94-007-1579-0_21] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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30
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Eberhard S, Loiselay C, Drapier D, Bujaldon S, Girard-Bascou J, Kuras R, Choquet Y, Wollman FA. Dual functions of the nucleus-encoded factor TDA1 in trapping and translation activation of atpA transcripts in Chlamydomonas reinhardtii chloroplasts. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2011; 67:1055-66. [PMID: 21623973 DOI: 10.1111/j.1365-313x.2011.04657.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
After endosymbiosis, organelles lost most of their initial genome. Moreover, expression of the few remaining genes became tightly controlled by the nucleus through trans-acting protein factors that are required for post-transcriptional expression (maturation/stability or translation) of a single (or a few) specific organelle target mRNA(s). Here, we characterize the nucleus-encoded TDA1 factor, which is specifically required for translation of the chloroplast atpA transcript that encodes subunit α of ATP synthase in Chlamydomonas reinhardtii. The sequence of TDA1 contains eight copies of a degenerate 38-residue motif, that we named octotrico peptide repeat (OPR), which has been previously described in a few other trans-acting factors targeted to the C. reinhardtii chloroplast. Interestingly, a proportion of the untranslated atpA transcripts are sequestered into high-density, non-polysomic, ribonucleoprotein complexes. Our results suggest that TDA1 has a dual function: (i) trapping a subset of untranslated atpA transcripts into non-polysomic complexes, and (ii) translational activation of these transcripts. We discuss these results in light of our previous observation that only a proportion of atpA transcripts are translated at any given time in the chloroplast of C. reinhardtii.
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Affiliation(s)
- Stephan Eberhard
- Unité Mixte de Recherche (UMR) 7141, Centre National de la Recherche Scientifique (CNRS) and Université Pierre et Marie Curie (UPMC - Paris 06), Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie Curie, F-75005 Paris, France.
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31
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Rasala BA, Muto M, Sullivan J, Mayfield SP. Improved heterologous protein expression in the chloroplast of Chlamydomonas reinhardtii through promoter and 5' untranslated region optimization. PLANT BIOTECHNOLOGY JOURNAL 2011; 9:674-83. [PMID: 21535358 DOI: 10.1111/j.1467-7652.2011.00620.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Microalgae have the potential to be a valuable biotechnological platform for the production of recombinant proteins. However, because of the complex regulatory network that tightly controls chloroplast gene expression, heterologous protein accumulation in a wild-type, photosynthetic-competent algal chloroplast remains low. High levels of heterologous protein accumulation have been achieved using the psbA promoter/5' untranslated region (UTR), but only in a psbA-deficient genetic background, because of psbA/D1-dependent auto-attenuation. Here, we examine the effect of fusing the strong 16S rRNA promoter to the 5' UTR of the psbA and atpA genes on transgene expression in the chloroplast of Chlamydomonas reinhardtii. We show that fusion of the 16S promoter had little impact on protein accumulation from the psbA 5' UTR in a psbA-deficient genetic background. Furthermore, the 16S/psbA promoter/UTR fusion was silenced in the presence of wild-type levels of D1 protein, confirming that the psbA 5' UTR is the primary target for D1-dependent auto-repression. However, fusion of the 16S promoter to the atpA 5' UTR significantly boosts mRNA levels and supports high levels of heterologous protein accumulation in photosynthetic-competent cells. The 16S/atpA promoter/UTR drove LUXCT protein accumulation to levels close to that of psbA in a psbA- background, and drove expression of a human therapeutic protein to levels only twofold lower than the psbA 5' UTR. The 16S/atpA promoter/UTR combination should have utility for heterologous protein production when expression from a photosynthetic-competent microalgal strain is required.
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Affiliation(s)
- Beth A Rasala
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, USA
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32
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De Marchis F, Pompa A, Mannucci R, Morosinotto T, Bellucci M. A plant secretory signal peptide targets plastome-encoded recombinant proteins to the thylakoid membrane. PLANT MOLECULAR BIOLOGY 2011; 76:427-41. [PMID: 20714919 DOI: 10.1007/s11103-010-9676-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2010] [Accepted: 07/21/2010] [Indexed: 05/29/2023]
Abstract
Plastids are considered promising bioreactors for the production of recombinant proteins, but the knowledge of the mechanisms regulating foreign protein folding, targeting, and accumulation in these organelles is still incomplete. Here we demonstrate that a plant secretory signal peptide is able to target a plastome-encoded recombinant protein to the thylakoid membrane. The fusion protein zeolin with its native signal peptide expressed by tobacco (Nicotiana tabacum) transplastomic plants was directed into the chloroplast thylakoid membranes, whereas the zeolin mutant devoid of the signal peptide, Δzeolin, is instead accumulated in the stroma. We also show that zeolin folds in the thylakoid membrane where it accumulates as trimers able to form disulphide bonds. Disulphide bonds contribute to protein accumulation since zeolin shows a higher accumulation level with respect to stromal Δzeolin, whose folding is hampered as the protein accumulates at low amounts in a monomeric form and it is not oxidized. Thus, post-transcriptional processes seem to regulate the stability and accumulation of plastid-synthesized zeolin. The most plausible zeolin targeting mechanism to thylakoid is discussed herein.
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Affiliation(s)
- Francesca De Marchis
- Istituto di Genetica Vegetale, Consiglio Nazionale delle Ricerche (CNR), via della Madonna Alta 130, 06128 Perugia, Italy
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33
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Mulo P, Sakurai I, Aro EM. Strategies for psbA gene expression in cyanobacteria, green algae and higher plants: from transcription to PSII repair. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1817:247-57. [PMID: 21565160 DOI: 10.1016/j.bbabio.2011.04.011] [Citation(s) in RCA: 161] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Revised: 04/06/2011] [Accepted: 04/07/2011] [Indexed: 11/26/2022]
Abstract
The Photosystem (PS) II of cyanobacteria, green algae and higher plants is prone to light-induced inactivation, the D1 protein being the primary target of such damage. As a consequence, the D1 protein, encoded by the psbA gene, is degraded and re-synthesized in a multistep process called PSII repair cycle. In cyanobacteria, a small gene family codes for the various, functionally distinct D1 isoforms. In these organisms, the regulation of the psbA gene expression occurs mainly at the level of transcription, but the expression is fine-tuned by regulation of translation elongation. In plants and green algae, the D1 protein is encoded by a single psbA gene located in the chloroplast genome. In chloroplasts of Chlamydomonas reinhardtii the psbA gene expression is strongly regulated by mRNA processing, and particularly at the level of translation initiation. In chloroplasts of higher plants, translation elongation is the prevalent mechanism for regulation of the psbA gene expression. The pre-existing pool of psbA transcripts forms translation initiation complexes in plant chloroplasts even in darkness, while the D1 synthesis can be completed only in the light. Replacement of damaged D1 protein requires also the assistance by a number of auxiliary proteins, which are encoded by the nuclear genome in green algae and higher plants. Nevertheless, many of these chaperones are conserved between prokaryotes and eukaryotes. Here, we describe the specific features and fundamental differences of the psbA gene expression and the regeneration of the PSII reaction center protein D1 in cyanobacteria, green algae and higher plants. This article is part of a Special Issue entitled Photosystem II.
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Affiliation(s)
- Paula Mulo
- Department of Biochemistry and Food Chemistry, University of Turku, Finland.
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34
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Boulouis A, Raynaud C, Bujaldon S, Aznar A, Wollman FA, Choquet Y. The nucleus-encoded trans-acting factor MCA1 plays a critical role in the regulation of cytochrome f synthesis in Chlamydomonas chloroplasts. THE PLANT CELL 2011; 23:333-49. [PMID: 21216944 PMCID: PMC3051260 DOI: 10.1105/tpc.110.078170] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 11/26/2010] [Accepted: 12/07/2010] [Indexed: 05/18/2023]
Abstract
Organelle gene expression is characterized by nucleus-encoded trans-acting factors that control posttranscriptional steps in a gene-specific manner. As a typical example, in Chlamydomonas reinhardtii, expression of the chloroplast petA gene encoding cytochrome f, a major subunit of the cytochrome b(6)f complex, depends on MCA1 and TCA1, required for the accumulation and translation of the petA mRNA. Here, we show that these two proteins associate in high molecular mass complexes that also contain the petA mRNA. We demonstrate that MCA1 is degraded upon interaction with unassembled cytochrome f that transiently accumulates during the biogenesis of the cytochrome b(6)f complex. Strikingly, this interaction relies on the very same residues that form the repressor motif involved in the Control by Epistasy of cytochrome f Synthesis (CES), a negative feedback mechanism that downregulates cytochrome f synthesis when its assembly within the cytochrome b(6)f complex is compromised. Based on these new findings, we present a revised picture for the CES regulation of petA mRNA translation that involves proteolysis of the translation enhancer MCA1, triggered by its interaction with unassembled cytochrome f.
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Affiliation(s)
| | | | | | | | | | - Yves Choquet
- Unité Mixte de Recherche 7141, Centre National de la Recherche Scientifique/Université Pierre et Marie Curie, Institut de Biologie Physico-Chimique, F-75005 Paris, France
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35
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Perez-Martinez X, Butler CA, Shingu-Vazquez M, Fox TD. Dual functions of Mss51 couple synthesis of Cox1 to assembly of cytochrome c oxidase in Saccharomyces cerevisiae mitochondria. Mol Biol Cell 2009; 20:4371-80. [PMID: 19710419 DOI: 10.1091/mbc.e09-06-0522] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Functional interactions of the translational activator Mss51 with both the mitochondrially encoded COX1 mRNA 5'-untranslated region and with newly synthesized unassembled Cox1 protein suggest that it has a key role in coupling Cox1 synthesis with assembly of cytochrome c oxidase. Mss51 is present at levels that are near rate limiting for expression of a reporter gene inserted at COX1 in mitochondrial DNA, and a substantial fraction of Mss51 is associated with Cox1 protein in assembly intermediates. Thus, sequestration of Mss51 in assembly intermediates could limit Cox1 synthesis in wild type, and account for the reduced Cox1 synthesis caused by most yeast mutations that block assembly. Mss51 does not stably interact with newly synthesized Cox1 in a mutant lacking Cox14, suggesting that the failure of nuclear cox14 mutants to decrease Cox1 synthesis, despite their inability to assemble cytochrome c oxidase, is due to a failure to sequester Mss51. The physical interaction between Mss51 and Cox14 is dependent upon Cox1 synthesis, indicating dynamic assembly of early cytochrome c oxidase intermediates nucleated by Cox1. Regulation of COX1 mRNA translation by Mss51 seems to be an example of a homeostatic mechanism in which a positive effector of gene expression interacts with the product it regulates in a posttranslational assembly process.
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Affiliation(s)
- Xochitl Perez-Martinez
- Departamento de Bioquímica, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, México D.F. 04510, México
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36
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Cai W, Ji D, Peng L, Guo J, Ma J, Zou M, Lu C, Zhang L. LPA66 is required for editing psbF chloroplast transcripts in Arabidopsis. PLANT PHYSIOLOGY 2009; 150:1260-71. [PMID: 19448041 PMCID: PMC2705037 DOI: 10.1104/pp.109.136812] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Accepted: 05/11/2009] [Indexed: 05/18/2023]
Abstract
To gain insight into the molecular mechanism of RNA editing, we have characterized the low psii accumulation66 (lpa66) Arabidopsis (Arabidopsis thaliana) mutant, which displays a high chlorophyll fluorescence phenotype. Its perturbed chlorophyll fluorescence is reflected in reduced levels of photosystem II (PSII) proteins. In vivo protein labeling showed that synthesis rates of the PSII reaction center protein D1/D2 were lower, and turnover rates of PSII core proteins higher, than in wild-type counterparts. The assembly of newly synthesized proteins into PSII occurs in the lpa66 mutant but with reduced efficiency compared with the wild type. LPA66 encodes a chloroplast protein of the pentatricopeptide repeat family. In lpa66 mutants, editing of psbF that converts serine to phenylalanine is specifically impaired. Thus, LPA66 is specifically required for editing the psbF transcripts in Arabidopsis, and the amino acid alternation due to lack of editing strongly affects the efficiency of the assembly of PSII complexes.
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Affiliation(s)
- Wenhe Cai
- Photosynthesis Research Center, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
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37
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Loiselay C, Gumpel NJ, Girard-Bascou J, Watson AT, Purton S, Wollman FA, Choquet Y. Molecular identification and function of cis- and trans-acting determinants for petA transcript stability in Chlamydomonas reinhardtii chloroplasts. Mol Cell Biol 2008; 28:5529-42. [PMID: 18573878 PMCID: PMC2519735 DOI: 10.1128/mcb.02056-07] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2007] [Revised: 02/25/2008] [Accepted: 06/13/2008] [Indexed: 11/20/2022] Open
Abstract
In organelles, the posttranscriptional steps of gene expression are tightly controlled by nucleus-encoded factors, most often acting in a gene-specific manner. Despite the molecular identification of a growing number of factors, their mode of action remains largely unknown. In the green alga Chlamydomonas reinhardtii, expression of the chloroplast petA gene, which codes for cytochrome f, depends on two specific nucleus-encoded factors. MCA1 controls the accumulation of the transcript, while TCA1 is required for its translation. We report here the cloning of MCA1, the first pentatricopeptide repeat protein functionally identified in this organism. By chloroplast transformation with modified petA genes, we investigated the function of MCA1 in vivo. We demonstrate that MCA1 acts on the very first 21 nucleotides of the petA 5' untranslated region to protect the whole transcript from 5'-->3' degradation but does not process the 5' end of the petA mRNA. MCA1 and TCA1 recognize adjacent targets and probably interact together for efficient expression of petA mRNA. MCA1, although not strictly required for translation, shows features of a translational enhancer, presumably by assisting the binding of TCA1 to its own target. Conversely, TCA1 participates to the full stabilization of the transcript through its interaction with MCA1.
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Affiliation(s)
- Christelle Loiselay
- UMR 7141 CNRS/UPMC, Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, F-75005 Paris, France
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38
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Ichikawa K, Miyake C, Iwano M, Sekine M, Shinmyo A, Kato K. Ribulose 1,5-bisphosphate carboxylase/oxygenase large subunit translation is regulated in a small subunit-independent manner in the expanded leaves of tobacco. PLANT & CELL PHYSIOLOGY 2008; 49:214-25. [PMID: 18178584 DOI: 10.1093/pcp/pcm179] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
Ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is composed of small subunits (SSs) encoded by rbcS on the nuclear genome and large subunits (LSs) encoded by rbcL on the chloroplast genome, and it is localized in the chloroplast stroma. Constitutive knockdown of the rbcS gene reportedly causes a reduction in LS quantity and the level of translation in tobacco and the unicellular green alga Chlamydomonas. Constitutively knockdown of the rbcS gene also causes a reduction in photosynthesis, which influences the expression of photosynthetic genes, including the rbcL gene. Here, to investigate the influence of the knockdown of the rbcS gene on the expression of the rbcL gene under normal photosynthetic conditions, we generated transgenic tobacco plants in which the amount of endogenous rbcS mRNA can be reduced by inducible expression of antisense rbcS mRNA with dexamethasone (DEX) treatment at later stages of growth. In already expanded leaves, after DEX treatment, the level of photosynthesis, RuBisCO quantity and the chloroplast ultrastructure were normal, but the amount of rbcS mRNA was reduced. An in vivo pulse labeling experiment and polysome analysis showed that LSs were translated at the same rate as in wild-type leaves. On the other hand, in newly emerging leaves, the rbcS mRNA quantity, the level of photosynthesis and the quantity of RuBisCO were reduced, and chloroplasts failed to develop. In these leaves, the level of LS translation was inhibited, as previously described. These results suggest that LS translation is regulated in an SS-independent manner in expanded leaves under normal photosynthetic conditions.
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Affiliation(s)
- Katsuhiko Ichikawa
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
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Gudynaite-Savitch L, Loiselay C, Savitch LV, Simmonds J, Kohalmi SE, Choquet Y, Hüner NPA. The small domain of cytochrome f from the psychrophile Chlamydomonas raudensis UWO 241 modulates the apparent molecular mass and decreases the accumulation of cytochrome f in the mesophile Chlamydomonas reinhardtii. Biochem Cell Biol 2008; 85:616-27. [PMID: 17901903 DOI: 10.1139/o07-066] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cytochrome f from the psychrophile Chlamydomonas raudensis UWO 241 has a lower thermostability of its c-type heme and an apparent molecular mass that is 7 kDa lower than that of the model mesophilic green alga Chlamydomonas reinhardtii. We combined chloroplast transformation, site-directed mutagensis, and the creation of chimeric fusion constructs to assess the contribution of specific domains and (or) amino acids residues to the structure, stability, and accumulation of cytochrome f, as well as its function in photosynthetic intersystem electron transport. We demonstrate that differences in the amino acid sequence of the small domain and specific charged amino acids in the large domain of cytochrome f alter the physical properties of this protein but do not affect either the thermostability of the c-type heme, the apparent half-life of cytochrome f in the presence of the chloroplastic protein synthesis inhibitor chloramphenicol, or the capacity for photosynthetic intersystem electron transport, measured as e-/P700. However, pulse-labeling with [14C]acetate, combined with immunoblotting, indicated that the negative autoregulation of cytochrome f accumulation observed in mesophilic C. reinhardtii transformed with chimeric constructs from the psychrophile was likely the result of the defective association of the chimeric forms of cytochrome f with the other subunits of the cytochrome b6/f complex native to the C. reinhardtii wild type. These results are discussed in terms of the unique fatty acid composition of the thylakoid membranes of C. raudensis UWO 241 adapted to cold environments.
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Affiliation(s)
- Loreta Gudynaite-Savitch
- Department of Biology and The Biotron, University of Western Ontario, London, ON N6A 5B7, Canada.
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40
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Marín-Navarro J, Manuell AL, Wu J, P Mayfield S. Chloroplast translation regulation. PHOTOSYNTHESIS RESEARCH 2007; 94:359-74. [PMID: 17661159 DOI: 10.1007/s11120-007-9183-z] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Accepted: 04/19/2007] [Indexed: 05/16/2023]
Abstract
Chloroplast gene expression is primarily controlled during the translation of plastid mRNAs. Translation is regulated in response to a variety of biotic and abiotic factors, and requires a coordinate expression with the nuclear genome. The translational apparatus of chloroplasts is related to that of bacteria, but has adopted novel mechanisms in order to execute the specific roles that this organelle performs within a eukaryotic cell. Accordingly, plastid ribosomes contain a number of chloroplast-unique proteins and domains that may function in translational regulation. Chloroplast translation regulation involves cis-acting RNA elements (located in the mRNA 5' UTR) as well as a set of corresponding trans-acting protein factors. While regulation of chloroplast translation is primarily controlled at the initiation steps through these RNA-protein interactions, elongation steps are also targets for modulating chloroplast gene expression. Translation of chloroplast mRNAs is regulated in response to light, and the molecular mechanisms underlying this response involve changes in the redox state of key elements related to the photosynthetic electron chain, fluctuations of the ADP/ATP ratio and the generation of a proton gradient. Photosynthetic complexes also experience assembly-related autoinhibition of translation to coordinate the expression of different subunits of the same complex. Finally, the localization of all these molecular events among the different chloroplast subcompartments appear to be a crucial component of the regulatory mechanisms of chloroplast gene expression.
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Affiliation(s)
- Julia Marín-Navarro
- Department of Cell Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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41
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Surzycki R, Cournac L, Peltier G, Rochaix JD. Potential for hydrogen production with inducible chloroplast gene expression in Chlamydomonas. Proc Natl Acad Sci U S A 2007; 104:17548-53. [PMID: 17951433 PMCID: PMC2077293 DOI: 10.1073/pnas.0704205104] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2007] [Indexed: 11/18/2022] Open
Abstract
An inducible chloroplast gene expression system was developed in Chlamydomonas reinhardtii by taking advantage of the properties of the copper-sensitive cytochrome c(6) promoter and of the nucleus-encoded Nac2 chloroplast protein. This protein is specifically required for the stable accumulation of the chloroplast psbD RNA and acts on its 5' UTR. A construct containing the Nac2 coding sequence fused to the cytochrome c(6) promoter was introduced into the nac2-26 mutant strain deficient in Nac2. In this transformant, psbD is expressed in copper-depleted but not in copper-replete medium. Because psbD encodes the D2 reaction center polypeptide of photosystem II (PSII), the repression of psbD leads to the loss of PSII. We have tested this system for hydrogen production. Upon addition of copper to cells pregrown in copper-deficient medium, PSII levels declined to a level at which oxygen consumption by respiration exceeded oxygen evolution by PSII. The resulting anaerobic conditions led to the induction of hydrogenase activity. Because the Cyc6 promoter is also induced under anaerobic conditions, this system opens possibilities for sustained cycling hydrogen production. Moreover, this inducible gene expression system is applicable to any chloroplast gene by replacing its 5' UTR with the psbD 5' UTR in the same genetic background. To make these strains phototrophic, the 5' UTR of the psbD gene was replaced by the petA 5' UTR. As an example, we show that the reporter gene aadA driven by the psbD 5' UTR confers resistance to spectinomycin in the absence of copper and sensitivity in its presence in the culture medium.
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Affiliation(s)
- Raymond Surzycki
- *Departments of Molecular Biology and Plant Biology, University of Geneva, 30 Quai Ernest Ansermet, 1211 Geneva, Switzerland
| | - Laurent Cournac
- Commissariat à l'Energie Atomique (CEA), Direction des Sciences du Vivant (DSV), Institut de Biologie Environmennetale et Biotechnologie (IBEB), Laboratoire de Bioénergétique et Biotechnologie des Bactéries et Microalgues (LB3M), F-13108 Saint-Paul-lez-Durance, France
- Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 6191, F-13108 Saint-Paul-lez-Durance, France; and
- Université de la Méditerranée, UMR 6191, F-13108 Saint-Paul-lez-Durance, France
| | - Gilles Peltier
- Commissariat à l'Energie Atomique (CEA), Direction des Sciences du Vivant (DSV), Institut de Biologie Environmennetale et Biotechnologie (IBEB), Laboratoire de Bioénergétique et Biotechnologie des Bactéries et Microalgues (LB3M), F-13108 Saint-Paul-lez-Durance, France
- Centre National de la Recherche Scientifique (CNRS), Unité Mixte de Recherche (UMR) 6191, F-13108 Saint-Paul-lez-Durance, France; and
- Université de la Méditerranée, UMR 6191, F-13108 Saint-Paul-lez-Durance, France
| | - Jean-David Rochaix
- *Departments of Molecular Biology and Plant Biology, University of Geneva, 30 Quai Ernest Ansermet, 1211 Geneva, Switzerland
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Drapier D, Rimbault B, Vallon O, Wollman FA, Choquet Y. Intertwined translational regulations set uneven stoichiometry of chloroplast ATP synthase subunits. EMBO J 2007; 26:3581-91. [PMID: 17660748 PMCID: PMC1948998 DOI: 10.1038/sj.emboj.7601802] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2007] [Accepted: 06/25/2007] [Indexed: 11/08/2022] Open
Abstract
The (C)F1 sector from H(+)-ATP synthases comprises five subunits: alpha, beta, gamma, delta and epsilon, assembled in a 3:3:1:1:1 stoichiometry. Here, we describe the molecular mechanism ensuring this unique stoichiometry, required for the functional assembly of the chloroplast enzyme. It relies on a translational feedback loop operating in two steps along the assembly pathway of CF1. In Chlamydomonas, production of the nucleus-encoded subunit gamma is required for sustained translation of the chloroplast-encoded subunit beta, which in turn stimulates the expression of the chloroplast-encoded subunit alpha. Translational downregulation of subunits beta or alpha, when not assembled, is born by the 5'UTRs of their own mRNAs, pointing to a regulation of translation initiation. We show that subunit gamma, by assembling with alpha(3)beta(3) hexamers, releases a negative feedback exerted by alpha/beta assembly intermediates on translation of subunit beta. Moreover, translation of subunit alpha is transactivated by subunit beta, an observation unprecedented in the biogenesis of organelle proteins.
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Affiliation(s)
- Dominique Drapier
- UMR 7141 CNRS/UPMC, Institut de Biologie Physico-Chimique, Paris, France
| | - Blandine Rimbault
- UMR 7141 CNRS/UPMC, Institut de Biologie Physico-Chimique, Paris, France
| | - Olivier Vallon
- UMR 7141 CNRS/UPMC, Institut de Biologie Physico-Chimique, Paris, France
| | | | - Yves Choquet
- UMR 7141 CNRS/UPMC, Institut de Biologie Physico-Chimique, Paris, France
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43
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Raynaud C, Loiselay C, Wostrikoff K, Kuras R, Girard-Bascou J, Wollman FA, Choquet Y. Evidence for regulatory function of nucleus-encoded factors on mRNA stabilization and translation in the chloroplast. Proc Natl Acad Sci U S A 2007; 104:9093-8. [PMID: 17494733 PMCID: PMC1885633 DOI: 10.1073/pnas.0703162104] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2007] [Indexed: 11/18/2022] Open
Abstract
A salient feature of organelle gene expression is the requirement for nucleus-encoded factors that act posttranscriptionally in a gene-specific manner. A central issue is to understand whether these factors are merely constitutive or have a regulatory function. In the unicellular alga Chlamydomonas reinhardtii, expression of the chloroplast petA gene-encoding cytochrome f, a major subunit of the cytochrome b(6)f complex, depends on two specific nucleus-encoded factors: MCA1, required for stable accumulation of the petA transcript, and TCA1, required for its translation. We cloned the TCA1 gene, encoding a pioneer protein, and transformed appropriate mutant strains with tagged versions of MCA1 and TCA1. In transformed strains expressing decreasing amounts of MCA1 or TCA1, the concentration of these factors proved limiting for petA mRNA accumulation and cytochrome f translation, respectively. This observation suggests that in exponentially growing cells, the abundance of MCA1 sets the pool of petA transcripts, some of which are TCA1-selected for an assembly-dependent translation of cytochrome f. We show that MCA1 is a short-lived protein. Its abundance varies rapidly with physiological conditions that deeply affect expression of the petA gene in vivo, for instance in aging cultures or upon changes in nitrogen availability. We observed similar but more limited changes in the abundance of TCA1. We conclude that in conditions where de novo biogenesis of cytochrome b(6)f complexes is not required, a rapid drop in MCA1 exhausts the pool of petA transcripts, and the progressive loss of TCA1 further prevents translation of cytochrome f.
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Affiliation(s)
- Cécile Raynaud
- Centre National de la Recherche Scientifique/Université Pierre et Marie Curie, UMR 7141, Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Christelle Loiselay
- Centre National de la Recherche Scientifique/Université Pierre et Marie Curie, UMR 7141, Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Katia Wostrikoff
- Centre National de la Recherche Scientifique/Université Pierre et Marie Curie, UMR 7141, Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Richard Kuras
- Centre National de la Recherche Scientifique/Université Pierre et Marie Curie, UMR 7141, Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Jacqueline Girard-Bascou
- Centre National de la Recherche Scientifique/Université Pierre et Marie Curie, UMR 7141, Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Francis-André Wollman
- Centre National de la Recherche Scientifique/Université Pierre et Marie Curie, UMR 7141, Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, 75005 Paris, France
| | - Yves Choquet
- Centre National de la Recherche Scientifique/Université Pierre et Marie Curie, UMR 7141, Institut de Biologie Physico-Chimique, 13 Rue Pierre et Marie Curie, 75005 Paris, France
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Wostrikoff K, Stern D. Rubisco large-subunit translation is autoregulated in response to its assembly state in tobacco chloroplasts. Proc Natl Acad Sci U S A 2007; 104:6466-71. [PMID: 17404229 PMCID: PMC1851044 DOI: 10.1073/pnas.0610586104] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2006] [Indexed: 01/01/2023] Open
Abstract
Plants rely on ribulose bisphosphate carboxylase/oxygenase (Rubisco) for carbon fixation. Higher plant Rubisco possesses an L(8)S(8) structure, with the large subunit (LS) encoded in the chloroplast by rbcL and the small subunit encoded by the nuclear RBCS gene family. Because its components accumulate stoichiometrically but are encoded in two genetic compartments, rbcL and RBCS expression must be tightly coordinated. Although this coordination has been observed, the underlying mechanisms have not been defined. Here, we use tobacco to understand how LS translation is related to its assembly status. To do so, two transgenic lines deficient in LS biogenesis were created: a chloroplast transformant expressing a truncated and unstable LS polypeptide, and a line where a homolog of the maize Rubisco-specific chaperone, BSD2, was repressed by RNAi. We found that in both lines, LS translation is no longer regulated by the availability of small subunit (SS), indicating that LS translation is not activated by the presence of its assembly partner but, rather, undergoes an autoregulation of translation. Pulse labeling experiments indicate that LS is synthesized but not accumulated in the transgenic lines, suggesting that accumulation of a repressor motif is required for LS assembly-dependent translational regulation.
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Affiliation(s)
- Katia Wostrikoff
- Boyce Thompson Institute for Plant Research, Cornell University, Tower Road, Ithaca, NY 14853
| | - David Stern
- Boyce Thompson Institute for Plant Research, Cornell University, Tower Road, Ithaca, NY 14853
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45
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Rochaix JD. The Role of Nucleus- and Chloroplast-Encoded Factors in the Synthesis of the Photosynthetic Apparatus. ACTA ACUST UNITED AC 2007. [DOI: 10.1007/978-1-4020-4061-0_7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
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46
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47
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Translation and translational regulation in chloroplasts. CELL AND MOLECULAR BIOLOGY OF PLASTIDS 2007. [DOI: 10.1007/4735_2007_0234] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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48
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Barneche F, Winter V, Crèvecœur M, Rochaix JD. ATAB2 is a novel factor in the signalling pathway of light-controlled synthesis of photosystem proteins. EMBO J 2006; 25:5907-18. [PMID: 17139246 PMCID: PMC1698907 DOI: 10.1038/sj.emboj.7601472] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2006] [Accepted: 11/06/2006] [Indexed: 01/24/2023] Open
Abstract
Plastid translational control depends to a large extent on the light conditions, and is presumably mediated by nucleus-encoded proteins acting on organelle gene expression. However, the molecular mechanisms of light signalling involved in translation are still poorly understood. We investigated the role of the Arabidopsis ortholog of Tab2, a nuclear gene specifically required for translation of the PsaB photosystem I subunit in the unicellular alga Chlamydomonas. Inactivation of ATAB2 strongly affects Arabidopsis development and thylakoid membrane biogenesis and leads to an albino phenotype. Moreover the rate of synthesis of the photosystem reaction center subunits is decreased and the association of their mRNAs with polysomes is affected. ATAB2 is a chloroplast A/U-rich RNA-binding protein that presumably functions as an activator of translation with at least two targets, one for each photosystem. During early seedling development, ATAB2 blue-light induction is lowered in photoreceptor mutants, notably in those lacking cryptochromes. Considering its role in protein synthesis and its photoreceptor-mediated expression, ATAB2 represents a novel factor in the signalling pathway of light-controlled translation of photosystem proteins during early plant development.
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Affiliation(s)
- Frédy Barneche
- Departments of Molecular Biology and Plant Biology, University of Geneva, Geneva, Switzerland
| | - Veronika Winter
- Departments of Molecular Biology and Plant Biology, University of Geneva, Geneva, Switzerland
| | - Michèle Crèvecœur
- Departments of Molecular Biology and Plant Biology, University of Geneva, Geneva, Switzerland
| | - Jean-David Rochaix
- Departments of Molecular Biology and Plant Biology, University of Geneva, Geneva, Switzerland
- Departments of Molecular Biology and Plant Biology, University of Geneva, 30, Quai Ernest Ansermet, 1211 Geneva 4, Switzerland. Tel.: +41 22 379 6187; Fax: +41 22 379 6868; E-mail:
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49
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Cohen I, Sapir Y, Shapira M. A conserved mechanism controls translation of Rubisco large subunit in different photosynthetic organisms. PLANT PHYSIOLOGY 2006; 141:1089-97. [PMID: 16731581 PMCID: PMC1489886 DOI: 10.1104/pp.106.079046] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2006] [Revised: 04/30/2006] [Accepted: 05/04/2006] [Indexed: 05/09/2023]
Abstract
We previously proposed a mechanism for control of Rubisco expression and assembly during oxidative stress in Chlamydomonas reinhardtii. The N terminus of the large subunit (LSU) comprises an RNA recognition motif (RRM) that is normally buried in the protein, but becomes exposed under oxidizing conditions when the glutathione pool shifts toward its oxidized form. Thus, de novo translation and assembly of Rubisco LSU stop with similar kinetics and the unpaired small subunit (SSU) is rapidly degraded. Here we show that the structure of the N-terminal domain is highly conserved throughout evolution, despite its relatively low sequence similarity. Furthermore, Rubisco from a broad evolutionary range of photosynthetic organisms binds RNA under oxidizing conditions, with dissociation constant values in the nanomolar range. In line with these observations, oxidative stress indeed causes a translational arrest in land plants as well as in Rhodospirillum rubrum, a purple bacterium that lacks the SSU. We highlight an evolutionary conserved element located within alpha-helix B, which is located in the center of the RRM and is also involved in the intramolecular interactions between two LSU chains. Thus, assembly masks the N terminus of the LSU hiding the RRM. When assembly is interrupted due to structural changes that occur under oxidizing conditions or in the absence of a dedicated chaperone, the N-terminal domain can become exposed, leading to the translational arrest of Rubisco LSU. Taken together, these results support a model by which LSU translation is governed by its dimerization. In the case that regulation of type I and type II Rubisco is conserved, the SSU does not appear to be directly involved in LSU translation.
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Affiliation(s)
- Idan Cohen
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
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50
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Peng L, Ma J, Chi W, Guo J, Zhu S, Lu Q, Lu C, Zhang L. LOW PSII ACCUMULATION1 is involved in efficient assembly of photosystem II in Arabidopsis thaliana. THE PLANT CELL 2006; 18:955-69. [PMID: 16531500 PMCID: PMC1425854 DOI: 10.1105/tpc.105.037689] [Citation(s) in RCA: 181] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2005] [Revised: 01/26/2006] [Accepted: 02/14/2006] [Indexed: 05/07/2023]
Abstract
To gain insight into the processes involved in photosystem II (PSII) biogenesis and maintenance, we characterized the low psii accumulation1 (lpa1) mutant of Arabidopsis thaliana, which generally accumulates lower than wild-type levels of the PSII complex. In vivo protein labeling experiments showed that synthesis of the D1 and D2 proteins was greatly reduced in the lpa1 mutant, while other plastid-encoded proteins were translated at rates similar to the wild type. In addition, turnover rates of the PSII core proteins CP47, CP43, D1, and D2 were higher in lpa1 than in wild-type plants. The newly synthesized PSII proteins were assembled into functional protein complexes, but the assembly was less efficient in the mutant. LPA1 encodes a chloroplast protein that contains two tetratricopeptide repeat domains and is an intrinsic membrane protein but not an integral subunit of PSII. Yeast two-hybrid studies revealed that LPA1 interacts with D1 but not with D2, cytochrome b6, or Alb3. Thus, LPA1 appears to be an integral membrane chaperone that is required for efficient PSII assembly, probably through direct interaction with the PSII reaction center protein D1.
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Affiliation(s)
- Lianwei Peng
- Photosynthesis Research Center, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
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