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Kameniarová M, Černý M, Novák J, Ondrisková V, Hrušková L, Berka M, Vankova R, Brzobohatý B. Light Quality Modulates Plant Cold Response and Freezing Tolerance. FRONTIERS IN PLANT SCIENCE 2022; 13:887103. [PMID: 35755673 PMCID: PMC9221075 DOI: 10.3389/fpls.2022.887103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 05/02/2022] [Indexed: 05/04/2023]
Abstract
The cold acclimation process is regulated by many factors like ambient temperature, day length, light intensity, or hormonal status. Experiments with plants grown under different light quality conditions indicate that the plant response to cold is also a light-quality-dependent process. Here, the role of light quality in the cold response was studied in 1-month-old Arabidopsis thaliana (Col-0) plants exposed for 1 week to 4°C at short-day conditions under white (100 and 20 μmol m-2s-1), blue, or red (20 μmol m-2s-1) light conditions. An upregulated expression of CBF1, inhibition of photosynthesis, and an increase in membrane damage showed that blue light enhanced the effect of low temperature. Interestingly, cold-treated plants under blue and red light showed only limited freezing tolerance compared to white light cold-treated plants. Next, the specificity of the light quality signal in cold response was evaluated in Arabidopsis accessions originating from different and contrasting latitudes. In all but one Arabidopsis accession, blue light increased the effect of cold on photosynthetic parameters and electrolyte leakage. This effect was not found for Ws-0, which lacks functional CRY2 protein, indicating its role in the cold response. Proteomics data confirmed significant differences between red and blue light-treated plants at low temperatures and showed that the cold response is highly accession-specific. In general, blue light increased mainly the cold-stress-related proteins and red light-induced higher expression of chloroplast-related proteins, which correlated with higher photosynthetic parameters in red light cold-treated plants. Altogether, our data suggest that light modulates two distinct mechanisms during the cold treatment - red light-driven cell function maintaining program and blue light-activated specific cold response. The importance of mutual complementarity of these mechanisms was demonstrated by significantly higher freezing tolerance of cold-treated plants under white light.
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Affiliation(s)
- Michaela Kameniarová
- Department of Molecular Biology and Radiobiology, Faculty of AgriSciences, Mendel University in Brno, Brno, Czechia
| | - Martin Černý
- Department of Molecular Biology and Radiobiology, Faculty of AgriSciences, Mendel University in Brno, Brno, Czechia
| | - Jan Novák
- Department of Molecular Biology and Radiobiology, Faculty of AgriSciences, Mendel University in Brno, Brno, Czechia
- *Correspondence: Jan Novák
| | - Vladěna Ondrisková
- Department of Molecular Biology and Radiobiology, Faculty of AgriSciences, Mendel University in Brno, Brno, Czechia
| | - Lenka Hrušková
- Department of Molecular Biology and Radiobiology, Faculty of AgriSciences, Mendel University in Brno, Brno, Czechia
| | - Miroslav Berka
- Department of Molecular Biology and Radiobiology, Faculty of AgriSciences, Mendel University in Brno, Brno, Czechia
| | - Radomira Vankova
- Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany, The Czech Academy of Sciences, Prague, Czechia
| | - Bretislav Brzobohatý
- Department of Molecular Biology and Radiobiology, Faculty of AgriSciences, Mendel University in Brno, Brno, Czechia
- Central European Institute of Technology, Faculty of AgriSciences, Mendel University in Brno, Brno, Czechia
- Institute of Biophysics of the Czech Academy of Sciences, Brno, Czechia
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Zhang Y, Zhang X, Cui H, Ma X, Hu G, Wei J, He Y, Hu Y. Residue 49 of AtMinD1 Plays a Key Role in the Guidance of Chloroplast Division by Regulating the ARC6-AtMinD1 Interaction. FRONTIERS IN PLANT SCIENCE 2021; 12:752790. [PMID: 34880885 PMCID: PMC8646090 DOI: 10.3389/fpls.2021.752790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 10/11/2021] [Indexed: 06/13/2023]
Abstract
Chloroplasts evolved from a free-living cyanobacterium through endosymbiosis. Similar to bacterial cell division, chloroplasts replicate by binary fission, which is controlled by the Minicell (Min) system through confining FtsZ ring formation at the mid-chloroplast division site. MinD, one of the most important members of the Min system, regulates the placement of the division site in plants and works cooperatively with MinE, ARC3, and MCD1. The loss of MinD function results in the asymmetric division of chloroplasts. In this study, we isolated one large dumbbell-shaped and asymmetric division chloroplast Arabidopsis mutant Chloroplast Division Mutant 75 (cdm75) that contains a missense mutation, changing the arginine at residue 49 to a histidine (R49H), and this mutant point is located in the N-terminal Conserved Terrestrial Sequence (NCTS) motif of AtMinD1, which is only typically found in terrestrial plants. This study provides sufficient evidence to prove that residues 1-49 of AtMinD1 are transferred into the chloroplast, and that the R49H mutation does not affect the function of the AtMinD1 chloroplast transit peptide. Subsequently, we showed that the point mutation of R49H could remove the punctate structure caused by residues 1-62 of the AtMinD1 sequence in the chloroplast, suggesting that the arginine in residue 49 (Arg49) is essential for localizing the punctate structure of AtMinD11 - 62 on the chloroplast envelope. Unexpectedly, we found that AtMinD1 could interact directly with ARC6, and that the R49H mutation could prevent not only the previously observed interaction between AtMinD1 and MCD1 but also the interaction between AtMinD1 and ARC6. Thus, we believe that these results show that the AtMinD1 NCTS motif is required for their protein interaction. Collectively, our results show that AtMinD1 can guide the placement of the division site to the mid chloroplast through its direct interaction with ARC6 and reveal the important role of AtMinD1 in regulating the AtMinD1-ARC6 interaction.
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Modulation of photosynthesis and other proteins during water-stress. Mol Biol Rep 2021; 48:3681-3693. [PMID: 33856605 DOI: 10.1007/s11033-021-06329-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 03/31/2021] [Indexed: 10/25/2022]
Abstract
Protein changes under drought or water stress conditions have been widely investigated. These investigations have given us enormous understanding of how drought is manifested in plants and how plants respond and adopt to such conditions. Chlorophyll fluoroescence, gas exchange, OMICS, biochemical and molecular analyses have shed light on regulation of physiology and photosynthesis of plants under drought. Use of proteomics has greatly increased the repertoire of drought-associated proteins which nevertheless, need to be investigated for their mechanistic and functional roles. Roles of such proteins have been succinctly discussed in various review articles, however more information on their functional role in countering drought is needed. In this review, recent developments in the field, alterations in the abundance of plant proteins in response to drought, monitored through numerous proteomic and immuno-blot analyses, and how these could affect plants growth and development, are discussed.
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Barrett J, Girr P, Mackinder LCM. Pyrenoids: CO 2-fixing phase separated liquid organelles. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2021; 1868:118949. [PMID: 33421532 DOI: 10.1016/j.bbamcr.2021.118949] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 12/11/2020] [Accepted: 12/12/2020] [Indexed: 02/06/2023]
Abstract
Pyrenoids are non-membrane bound organelles found in chloroplasts of algae and hornwort plants that can be seen by light-microscopy. Pyrenoids are formed by liquid-liquid phase separation (LLPS) of Rubisco, the primary CO2 fixing enzyme, with an intrinsically disordered multivalent Rubisco-binding protein. Pyrenoids are the heart of algal and hornwort biophysical CO2 concentrating mechanisms, which accelerate photosynthesis and mediate about 30% of global carbon fixation. Even though LLPS may underlie the apparent convergent evolution of pyrenoids, our current molecular understanding of pyrenoid formation comes from a single example, the model alga Chlamydomonas reinhardtii. In this review, we summarise current knowledge about pyrenoid assembly, regulation and structural organization in Chlamydomonas and highlight evidence that LLPS is the general principle underlying pyrenoid formation across algal lineages and hornworts. Detailed understanding of the principles behind pyrenoid assembly, regulation and structural organization within diverse lineages will provide a fundamental understanding of this biogeochemically important organelle and help guide ongoing efforts to engineer pyrenoids into crops to increase photosynthetic performance and yields.2.
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Affiliation(s)
- James Barrett
- Department of Biology, University of York, York YO10 5DD, UK
| | - Philipp Girr
- Department of Biology, University of York, York YO10 5DD, UK
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Chloroplast division protein ARC3 acts on FtsZ2 by preventing filament bundling and enhancing GTPase activity. Biochem J 2018; 475:99-115. [PMID: 29138260 DOI: 10.1042/bcj20170697] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Revised: 11/09/2017] [Accepted: 11/10/2017] [Indexed: 01/28/2023]
Abstract
Chloroplasts evolved from cyanobacterial endosymbiotic ancestors and their division is a complex process initiated by the assembly of cytoskeletal FtsZ (Filamentous temperature sensitive Z) proteins into a ring structure at the division site (Z-ring). The cyanobacterial Z-ring positioning system (MinCDE proteins) is also conserved in chloroplasts, except that MinC was lost and replaced by the eukaryotic ARC3 (accumulation and replication of chloroplasts). Both MinC and ARC3 act as negative regulators of FtsZ assembly, but ARC3 bears little sequence similarity with MinC. Here, light scattering assays, co-sedimentation, GTPase assay and transmission electron microscopy in conjunction with single-particle analysis have been used to elucidate the structure of ARC3 and its effect on its main target in chloroplast division, FtsZ2. Analysis of FtsZ2 in vitro assembly reactions in the presence and absence of GMPCPP showed that ARC3 promotes FtsZ2 debundling and disassembly of existing filaments in a concentration-dependent manner and requires GTP hydrolysis. Three-dimensional reconstruction of ARC3 revealed an almost circular molecule in which the FtsZ-binding N-terminus and the C-terminal PARC6 (paralog of ARC6)-binding MORN (Membrane Occupation and Recognition Nexus) domain are in close proximity and suggest a model for PARC6-enabled binding of ARC3 to FtsZ2. The latter is corroborated by in vivo data.
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Fujiwara MT, Yasuzawa M, Sasaki S, Nakano T, Niwa Y, Yoshida S, Abe T, Itoh RD. The Arabidopsis minD mutation causes aberrant FtsZ1 ring placement and moderate heterogeneity of chloroplasts in the leaf epidermis. PLANT SIGNALING & BEHAVIOR 2017. [PMID: 28644708 PMCID: PMC5586359 DOI: 10.1080/15592324.2017.1343776] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Symmetric division of leaf mesophyll chloroplasts requires MinD and MinE, which work together to suppress division other than at the mid-chloroplast. arc11 is a MinD loss-of-function mutant of Arabidopsis thaliana. In arc11 plants, asymmetric chloroplast division, as well as its delay or arrest, results in extreme size polymorphism of chloroplasts in mature mesophyll cells. The current study examined chloroplast phenotypes in the epidermis of arc11 leaves. Fluorescence microscopy analysis revealed that epidermal chloroplasts in mature leaves exhibited moderate heterogeneity in size. This probably resulted from completion of many of the previous non-equatorial or multiple division events in expanding leaves. Additionally, analyses of plastids found that epidermal chloroplasts in arc11 mutants showed several phenotypes that have not previously been described.
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Affiliation(s)
- Makoto T. Fujiwara
- Nishina Center and Plant Functions Laboratory, RIKEN, Wako, Saitama, Japan
- Department of Biology, Sophia University, Chiyoda, Tokyo, Japan
- CONTACT Makoto T. Fujiwara Department of Biology, Sophia University, 7–1 Kioicho, Chiyoda, Tokyo, 102-8554, Japan
| | - Mana Yasuzawa
- Department of Biology, Sophia University, Chiyoda, Tokyo, Japan
| | - Shun Sasaki
- Department of Biology, Sophia University, Chiyoda, Tokyo, Japan
| | - Takeshi Nakano
- Gene Discovery Research Group, RIKEN Center for Sustainable Resource Science, Wako, Saitama, Japan
- CREST, JST (Japan Science and Technology Agency), Kawaguchi, Saitama, Japan
| | - Yasuo Niwa
- Laboratory of Plant Molecular Improvement, Graduate School of Nutritional and Environmental Sciences, University of Shizuoka, Suruga, Shizuoka, Japan
| | - Shigeo Yoshida
- Nishina Center and Plant Functions Laboratory, RIKEN, Wako, Saitama, Japan
| | - Tomoko Abe
- Nishina Center and Plant Functions Laboratory, RIKEN, Wako, Saitama, Japan
| | - Ryuuichi D. Itoh
- Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, Nishihara, Okinawa, Japan
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Kobayashi Y, Ando H, Hanaoka M, Tanaka K. Abscisic Acid Participates in the Control of Cell Cycle Initiation Through Heme Homeostasis in the Unicellular Red Alga Cyanidioschyzon merolae. PLANT & CELL PHYSIOLOGY 2016; 57:953-60. [PMID: 27044672 DOI: 10.1093/pcp/pcw054] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 03/09/2016] [Indexed: 05/08/2023]
Abstract
ABA is a phytohormone that is synthesized in response to abiotic stresses and other environmental changes, inducing various physiological responses. While ABA has been found in unicellular photosynthetic organisms, such as cyanobacteria and eukaryotic algae, its function in these organisms is poorly understood. Here, we found that ABA accumulated in the unicellular red alga Cyanidioschyzon merolae under conditions of salt stress and that the cell cycle G1/S transition was inhibited when ABA was added to the culture medium. A gene encoding heme-scavenging tryptophan-rich sensory protein-related protein (CmTSPO; CMS231C) was positively regulated by ABA, as in Arabidopsis, and CmTSPO bound heme in vitro. The intracellular content of total heme was increased by addition of ABA, but unfettered heme decreased, presumably due to scavenging by CmTSPO. The inhibition of DNA replication by ABA was negated by addition of heme to the culture medium. Thus, we propose a regulatory role for ABA and heme in algal cell cycle initiation. Finally, we found that a C. merolae mutant that is defective in ABA production was more susceptible to salt stress, indicating the importance of ABA to stress resistance in red algae.
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Affiliation(s)
- Yuki Kobayashi
- Chemical Resources Laboratory, Tokyo Institute of Technology, 4259-R1-29 Nagatsuta, Midori-ku, Yokohama, 226-8503 Japan
| | - Hiroyuki Ando
- Graduate School of Horticulture, Chiba University, 648 Matsudo, Matsudo, Chiba, 271-8510 Japan
| | - Mitsumasa Hanaoka
- Graduate School of Horticulture, Chiba University, 648 Matsudo, Matsudo, Chiba, 271-8510 Japan
| | - Kan Tanaka
- Chemical Resources Laboratory, Tokyo Institute of Technology, 4259-R1-29 Nagatsuta, Midori-ku, Yokohama, 226-8503 Japan Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), Saitama, 332-0012 Japan
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8
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Fujiwara MT, Kojo KH, Kazama Y, Sasaki S, Abe T, Itoh RD. The Arabidopsis minE mutation causes new plastid and FtsZ1 localization phenotypes in the leaf epidermis. FRONTIERS IN PLANT SCIENCE 2015; 6:823. [PMID: 26500667 PMCID: PMC4593956 DOI: 10.3389/fpls.2015.00823] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 09/22/2015] [Indexed: 05/25/2023]
Abstract
Plastids in the leaf epidermal cells of plants are regarded as immature chloroplasts that, like mesophyll chloroplasts, undergo binary fission. While mesophyll chloroplasts have generally been used to study plastid division, recent studies have suggested the presence of tissue- or plastid type-dependent regulation of plastid division. Here, we report the detailed morphology of plastids and their stromules, and the intraplastidic localization of the chloroplast division-related protein AtFtsZ1-1, in the leaf epidermis of an Arabidopsis mutant that harbors a mutation in the chloroplast division site determinant gene AtMinE1. In atminE1, the size and shape of epidermal plastids varied widely, which contrasts with the plastid phenotype observed in atminE1 mesophyll cells. In particular, atminE1 epidermal plastids occasionally displayed grape-like morphology, a novel phenotype induced by a plastid division mutation. Observation of an atminE1 transgenic line harboring an AtMinE1 promoter::AtMinE1-yellow fluorescent protein fusion gene confirmed the expression and plastidic localization of AtMinE1 in the leaf epidermis. Further examination revealed that constriction of plastids and stromules mediated by the FtsZ1 ring contributed to the plastid pleomorphism in the atminE1 epidermis. These results illustrate that a single plastid division mutation can have dramatic consequences for epidermal plastid morphology, thereby implying that plastid division and morphogenesis are differentially regulated in epidermal and mesophyll plastids.
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Affiliation(s)
- Makoto T. Fujiwara
- RIKEN Nishina CenterSaitama, Japan
- Graduate School of Science and Technology, Sophia UniversityTokyo, Japan
| | - Kei H. Kojo
- Graduate School of Science and Technology, Sophia UniversityTokyo, Japan
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of TokyoKashiwa, Japan
- LPixel Inc.Tokyo, Japan
| | | | - Shun Sasaki
- Graduate School of Science and Technology, Sophia UniversityTokyo, Japan
| | | | - Ryuuichi D. Itoh
- Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the RyukyusOkinawa, Japan
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9
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Nagashima A, Hanaoka M, Motohashi R, Seki M, Shinozaki K, Kanamaru K, Takahashi H, Tanaka K. DNA Microarray Analysis of Plastid Gene Expression in anArabidopsisMutant Deficient in a Plastid Transcription Factor Sigma, SIG2. Biosci Biotechnol Biochem 2014; 68:694-704. [PMID: 15056905 DOI: 10.1271/bbb.68.694] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The plastid genome of higher plants contains more than one hundred genes for photosynthesis, gene expression, and other processes. Plastid transcription is done by two types of RNA polymerase, PEP and NEP. PEP is a eubacteria-type RNA polymerase that is essential for chloroplast development. In Arabidopsis thaliana, six sigma factors (SIG1-6) are encoded by the nuclear genome, and postulated to determine the transcription specificity of PEP. In this study, we constructed a DNA microarray for all of the plastid protein-coding genes, and analyzed the effects of the sig2 lesion on the global plastid gene expression. Of the 79 plastid protein genes, it was found that only the psaJ transcript was decreased in the mutant, whereas transcripts of 47 genes were rather increased. Since many of the up-regulated genes are under the control of NEP, it was suggested that the NEP activity was increased in the sig2-1 mutant.
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Affiliation(s)
- Akitomo Nagashima
- Laboratory of Molecular Genetics, Department of Molecular Biology, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Japan
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Further Evaluation of the Localization and Functionality of Hemagglutinin Epitope- and Fluorescent Protein-Tagged AtMinD1 inArabidopsis thaliana. Biosci Biotechnol Biochem 2014; 73:1693-7. [DOI: 10.1271/bbb.90309] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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11
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Chikkala VRN, Nugent GD, Stalker DM, Mouradov A, Stevenson TW. Expression of Brassica oleracea FtsZ1-1 and MinD alters chloroplast division in Nicotiana tabacum generating macro- and mini-chloroplasts. PLANT CELL REPORTS 2012; 31:917-28. [PMID: 22193339 DOI: 10.1007/s00299-011-1212-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Revised: 12/02/2011] [Accepted: 12/11/2011] [Indexed: 05/31/2023]
Abstract
FtsZ1-1 and MinD plastid division-related genes were identified and cloned from Brassica oleracea var. botrytis. Transgenic tobacco plants expressing BoFtsZ1-1 or BoMinD exhibited cells with either fewer but abnormally large chloroplasts or more but smaller chloroplasts relative to wild-type tobacco plants. An abnormal chloroplast phenotype in guard cells was found in BoMinD transgenic tobacco plants but not in BoFtsZ1-1 transgenic tobacco plants. Transgenic tobacco plants bearing the macro-chloroplast phenotype had 10 to 20-fold increased levels of total FtsZ1-1 or MinD, whilst the transgenic tobacco plants bearing the mini-chloroplast phenotype had lower increased FtsZ1-1 or absence of detectable MinD. We also described for the first time, plastid transformation of macro-chloroplast bearing tobacco shoots with a gene cassette allowing for expression of green fluorescent protein (GFP). Homoplasmic plastid transformants from normal chloroplast and macro-chloroplast tobacco plants expressing GFP were obtained. Both types of transformants accumulated GFP at ~6% of total soluble protein, thus indicating that cells containing macro-chloroplasts can regenerate shoots in tissue culture and can stably integrate and express a foreign gene to similar levels as plant cells containing a normal chloroplast size and number.
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Affiliation(s)
- Veera R N Chikkala
- School of Applied Sciences, RMIT University, Bundoora, VIC 3083, Australia
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Abstract
The cytoskeleton is a system of intracellular filaments crucial for cell shape, division, and function in all three domains of life. The simple cytoskeletons of prokaryotes show surprising plasticity in composition, with none of the core filament-forming proteins conserved in all lineages. In contrast, eukaryotic cytoskeletal function has been hugely elaborated by the addition of accessory proteins and extensive gene duplication and specialization. Much of this complexity evolved before the last common ancestor of eukaryotes. The distribution of cytoskeletal filaments puts constraints on the likely prokaryotic line that made this leap of eukaryogenesis.
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Affiliation(s)
- Bill Wickstead
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, England, UK.
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Wilson ME, Jensen GS, Haswell ES. Two mechanosensitive channel homologs influence division ring placement in Arabidopsis chloroplasts. THE PLANT CELL 2011; 23:2939-49. [PMID: 21810996 PMCID: PMC3180802 DOI: 10.1105/tpc.111.088112] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Revised: 07/14/2011] [Accepted: 07/18/2011] [Indexed: 05/18/2023]
Abstract
Chloroplasts must divide repeatedly to maintain their population during plant growth and development. A number of proteins required for chloroplast division have been identified, and the functional relationships between them are beginning to be elucidated. In both chloroplasts and bacteria, the future site of division is specified by placement of the Filamentous temperature sensitive Z (FtsZ) ring, and the Min system serves to restrict FtsZ ring formation to mid-chloroplast or mid-cell. How the Min system is regulated in response to environmental and developmental factors is largely unstudied. Here, we investigated the role in chloroplast division played by two Arabidopsis thaliana homologs of the bacterial mechanosensitive (MS) channel MscS: MscS-Like 2 (MSL2) and MSL3. Immunofluorescence microscopy and live imaging approaches demonstrated that msl2 msl3 double mutants have enlarged chloroplasts containing multiple FtsZ rings. Genetic analyses indicate that MSL2, MSL3, and components of the Min system function in the same pathway to regulate chloroplast size and FtsZ ring formation. In addition, an Escherichia coli strain lacking MS channels also showed aberrant FtsZ ring assembly. These results establish MS channels as components of the chloroplast division machinery and suggest that their role is evolutionarily conserved.
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Yun MS, Kawagoe Y. Septum formation in amyloplasts produces compound granules in the rice endosperm and is regulated by plastid division proteins. PLANT & CELL PHYSIOLOGY 2010; 51:1469-79. [PMID: 20685968 DOI: 10.1093/pcp/pcq116] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Storage tissues such as seed endosperm and tubers store starch in the form of granules in the amyloplast. In the rice (Oryza sativa) endosperm, each amyloplast produces compound granules consisting of several dozen polyhedral, sharp-edged and easily separable granules; whereas in other cereals, including wheat (Triticum aestivum), barley (Hordeum vulgare) and maize (Zea mays), each amyloplast synthesizes one granule. Despite extensive studies on mutants of starch synthesis in cereals, the molecular mechanisms involved in compound granule synthesis in rice have remained elusive. In this study, we expressed green fluorescent protein (GFP) fused to rice Brittle1 (BT1), an inner envelope membrane protein, to characterize dividing amyloplasts in the rice endosperm. Confocal microscopic analyses revealed that a septum-like structure, or cross-wall, containing BT1-GFP divides granules in the amyloplast. Plastid division proteins including FtsZ, Min and PDV2 play significant roles not only in amyloplast division, but also in septum synthesis, suggesting that amyloplast division and septum synthesis are related processes that share common factors. We propose that successive septum syntheses which create sections inside the amyloplast and de novo granule synthesis in each section are primarily responsible for the synthesis of compound granules.
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Affiliation(s)
- Min-Soo Yun
- Division of Plant Sciences, National Institute of Agrobiological Sciences, 2-1-2 Kannondai, Tsukuba 305-8602, Japan
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15
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Itoh RD, Yamasaki H, Septiana A, Yoshida S, Fujiwara MT. Chemical induction of rapid and reversible plastid filamentation in Arabidopsis thaliana roots. PHYSIOLOGIA PLANTARUM 2010; 139:144-58. [PMID: 20088905 DOI: 10.1111/j.1399-3054.2010.01352.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Plastids assume various morphologies depending on their developmental status, but the basis for developmentally regulated plastid morphogenesis is poorly understood. Chemical induction of alterations in plastid morphology would be a useful tool for studying this; however, no such chemicals have been identified. Here, we show that antimycin A, an effective respiratory inhibitor, can change plastid morphology rapidly and reversibly in Arabidopsis thaliana. In the root cortex, hypocotyls, cotyledon epidermis and true leaf epidermis, significant differences in mitochondrial morphology were not observed between antimycin-treated and untreated tissues. In contrast, antimycin caused extreme filamentation of plastids in the mature cortices of main roots. This phenomenon was specifically observed in the mature root cortex. Other mitochondrial respiratory inhibitors (rotenone and carbonyl cyanide m-chlorophenylhydrazone), hydrogen peroxide, S-nitroso-N-acetylpenicillamine [a nitric oxide (NO) donor] and 3-(3,4-dichlorophenyl)-1,1-dimethylurea did not mimic the phenomenon under the present study conditions. Antimycin-induced plastid filamentation was initiated within 5 min after the onset of chemical treatment and appeared to complete within 1 h. Plastid morphology was restored within 7 h after the washout of antimycin, suggesting that the filamentation was reversible. Co-applications of antimycin and cytoskeletal inhibitors (demecolcine or latrunculin B) or protein synthesis inhibitors (cycloheximide or chloramphenicol) still caused plastid filamentation. Antimycin A was also effective for plastid filamentation in the chloroplast division mutants atftsZ1-1 and atminE1. Salicylhydroxamic acid, an alternative oxidase inhibitor, was solely found to suppress the filamentation, implying the possibility that this phenomenon was partly mediated by an antimycin-activated alternative oxidase in the mitochondria.
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Affiliation(s)
- Ryuuichi D Itoh
- Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus, Senbaru 1, Nishihara, Okinawa 903-0213, Japan.
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Fujiwara MT, Hashimoto H, Kazama Y, Hirano T, Yoshioka Y, Aoki S, Sato N, Itoh RD, Abe T. Dynamic morphologies of pollen plastids visualised by vegetative-specific FtsZ1-GFP in Arabidopsis thaliana. PROTOPLASMA 2010; 242:19-33. [PMID: 20195657 DOI: 10.1007/s00709-010-0119-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Accepted: 02/05/2010] [Indexed: 05/22/2023]
Abstract
The behaviour and multiplication of pollen plastids have remained elusive despite their crucial involvement in cytoplasmic inheritance. Here, we present live images of plastids in pollen grains and growing tubes from transgenic Arabidopsis thaliana lines expressing stroma-localised FtsZ1-green-fluorescent protein fusion in a vegetative cell-specific manner. Vegetative cells in mature pollen contained a morphologically heterogeneous population of round to ellipsoidal plastids, whilst those in late-developing (maturing) pollen included plastids that could have one or two constriction sites. Furthermore, plastids in pollen tubes exhibited remarkable tubulation, stromule (stroma-filled tubule) extension, and back-and-forth movement along the direction of tube growth. Plastid division, which involves the FtsZ1 ring, was rarely observed in mature pollen grains.
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17
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Imamura S, Terashita M, Ohnuma M, Maruyama S, Minoda A, Weber APM, Inouye T, Sekine Y, Fujita Y, Omata T, Tanaka K. Nitrate assimilatory genes and their transcriptional regulation in a unicellular red alga Cyanidioschyzon merolae: genetic evidence for nitrite reduction by a sulfite reductase-like enzyme. PLANT & CELL PHYSIOLOGY 2010; 51:707-17. [PMID: 20375110 DOI: 10.1093/pcp/pcq043] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Cyanidioschyzon merolae is a unicellular red alga living in acid hot springs, which is able to grow on ammonium, as well as nitrate as sole nitrogen source. Based on the complete genome sequence, proteins for nitrate utilization, nitrate transporter (NRT) and nitrate reductase (NR), were predicted to be encoded by the neighboring nuclear genes CMG018C and CMG019C, respectively, but no typical nitrite reductase (NiR) gene was found by similarity searches. On the other hand, two candidate genes for sulfite reductase (SiR) were found, one of which (CMG021C) is located next to the above-noted nitrate-related genes. Given that transcripts of CMG018C, CMG019C and CMG021C accumulate in nitrate-containing media, but are repressed by ammonium, and that SiR and NiR are structurally related enzymes, we hypothesized that the CMG021C gene product functions as an NiR in C. merolae. To test this hypothesis, we developed a method for targeted gene disruption in C. merolae. In support of our hypothesis, we found that a CMG021G null mutant in comparison with the parental strain showed decreased cell growth in nitrate-containing but not in ammonium-containing media. Furthermore, expression of CMG021C in the nirA mutant of a cyanobacterium, Leptolyngbya boryana (formerly Plectonema boryanum), could genetically complement the NiR defect. Immunofluorescent analysis indicated the localization of CMG021C in chloroplasts, and hence we propose an overall scheme for nitrate assimilation in C. merolae.
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Affiliation(s)
- Sousuke Imamura
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032 Japan
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18
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Holzinger A, Kwok EY, Hanson MR. Effects of arc3, arc5 and arc6 mutations on plastid morphology and stromule formation in green and nongreen tissues of Arabidopsis thaliana. Photochem Photobiol 2008; 84:1324-35. [PMID: 18764889 DOI: 10.1111/j.1751-1097.2008.00437.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mutations in the ARC3, ARC5 and ARC6 genes of Arabidopsis thaliana affect chloroplast division. We investigated whether ARC3, ARC5 and ARC6 are also involved in determining plastid morphology in nongreen tissues, where stromules, stroma-filled tubular extensions of the plastid envelope membrane, are more abundant than in mesophyll cells. Using plastid-targeted green fluorescent protein to observe plastids throughout the organs of these mutants, we have discovered a number of new mutant phenotypes. The size of arc3 plastids was heterogeneous in various tissues. arc5 plastids appeared wild-type in the majority of nongreen tissues examined. However, in cells of stamen filaments, the arc5 mutant showed an increase in the frequency of stromules. Increased stromule frequency was observed for a number of organs in the arc6 mutant. Some arc6 cells contained heterogeneous mixtures of plastids; epidermal cells of hypocotyls, stamen filaments and the bases of petals possessed both very large chloroplasts as well as much smaller nongreen plastids. Quantitative analysis in hypocotyl cells revealed that the alteration in stromule length in arc3 and arc6 mutants occurred despite wild-type plastid densities. Thus, in hypocotyls, the effects of the arc3 and arc6 mutations on stromule length and frequency are independent of changes in plastid division. Although electron micrographs of stromules emanating from chloroplasts have rarely been reported, within the arc3 mutant, narrow, 40-50 nm diameter, recoiled stromules could be followed for about 10 microm in electron micrographs of leaf tissue.
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Affiliation(s)
- Andreas Holzinger
- Institute of Botany, Department of Physiology and Cell Physiology of Alpine Plants, University of Innsbruck, Innsbruck, Austria
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19
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Fujiwara MT, Hashimoto H, Kazama Y, Abe T, Yoshida S, Sato N, Itoh RD. The Assembly of the FtsZ Ring at the Mid-Chloroplast Division Site Depends on a Balance Between the Activities of AtMinE1 and ARC11/AtMinD1. ACTA ACUST UNITED AC 2008; 49:345-61. [DOI: 10.1093/pcp/pcn012] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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20
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Maple J, Mateo* A, Møller SG. Plastid Division Regulation and Interactions with the Environment. PLANT CELL MONOGRAPHS 2008. [DOI: 10.1007/7089_2008_20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
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21
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Liu W, Hu Y, Zhang R, Zhou W, Zhu J, Liu X, He Y. Transfer of a eubacteria-type cell division site-determining factor CrMinD gene to the nucleus from the chloroplast genome in Chlamydomonas reinhardtii. CHINESE SCIENCE BULLETIN-CHINESE 2007. [DOI: 10.1007/s11434-007-0375-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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22
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Tavva VS, Collins GB, Dinkins RD. Targeted overexpression of the Escherichia coli MinC protein in higher plants results in abnormal chloroplasts. PLANT CELL REPORTS 2006; 25:341-8. [PMID: 16341725 DOI: 10.1007/s00299-005-0086-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2005] [Revised: 10/17/2005] [Accepted: 10/26/2005] [Indexed: 05/05/2023]
Abstract
Higher plant chloroplast division involves some of the same types of proteins that are required in prokaryotic cell division. These include two of the three Min proteins, MinD and MinE, encoded by the min operon in bacteria. Noticeably absent from annotated sequences from higher plants is a MinC homologue. A higher plant functional MinC homologue that would interfere with FtsZ polymerization, has yet to be identified. We sought to determine whether expression of the bacterial MinC in higher plants could affect chloroplast division. The Escherichia coli minC (EcMinC) gene was isolated and inserted behind the Arabidopsis thaliana RbcS transit peptide sequence for chloroplast targeting. This TP-EcMinC gene driven by the CaMV 35S(2) constitutive promoter was then transformed into tobacco (Nicotiana tabacum L.). Abnormally large chloroplasts were observed in the transgenic plants suggesting that overexpression of the E. coli MinC perturbed higher plant chloroplast division.
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Affiliation(s)
- Venkata S Tavva
- Department of Plant and Soil Sciences, University of Kentucky, 1405 Veterans Road, Lexington, KY 40546-0312, USA
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23
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Osanai T, Kanesaki Y, Nakano T, Takahashi H, Asayama M, Shirai M, Kanehisa M, Suzuki I, Murata N, Tanaka K. Positive Regulation of Sugar Catabolic Pathways in the Cyanobacterium Synechocystis sp. PCC 6803 by the Group 2 σ Factor SigE. J Biol Chem 2005; 280:30653-9. [PMID: 15944148 DOI: 10.1074/jbc.m505043200] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The sigE gene of Synechocystis sp. PCC 6803 encodes a group 2 sigma factor for RNA polymerase and has been proposed to function in transcriptional regulation of nitrogen metabolism. By using microarray and Northern analyses, we demonstrated that the abundance of transcripts derived from genes important for glycolysis, the oxidative pentose phosphate pathway, and glycogen catabolism is reduced in a sigE mutant of Synechocystis maintained under the normal growth condition. Furthermore, the activities of the two key enzymes of the oxidative pentose phosphate pathway, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, encoded by the zwf and gnd genes were also reduced in the sigE mutant. The dark enhancements in both enzyme activity and transcript abundance apparent in the wild type were eliminated by the mutation. In addition, the sigE mutant showed a reduced rate of glucose uptake and an increased intracellular level of glycogen. Moreover, it was unable to proliferate under the light-activated heterotrophic growth conditions. These results indicate that SigE functions in the transcriptional activation of sugar catabolic pathways in Synechocystis sp. PCC 6803.
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Affiliation(s)
- Takashi Osanai
- Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
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24
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Itoh RD, Takechi K, Hayashida A, Katsura SI, Takano H. Cytogenetic and Hematological Effects of the Antibiotic Chloramphenicol on Calves. CYTOLOGIA 2005. [DOI: 10.1508/cytologia.70.87] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Ryuuichi D. Itoh
- Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus
| | | | | | - Shin-ichiro Katsura
- Department of Chemistry, Biology and Marine Science, Faculty of Science, University of the Ryukyus
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25
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Fujiwara MT, Nakamura A, Itoh R, Shimada Y, Yoshida S, Møller SG. Chloroplast division site placement requires dimerization of the ARC11/AtMinD1 protein in Arabidopsis. J Cell Sci 2004; 117:2399-410. [PMID: 15126639 DOI: 10.1242/jcs.01092] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chloroplast division is mediated by the coordinated action of a prokaryote-derived division system(s) and a host eukaryote-derived membrane fission system(s). The evolutionary conserved prokaryote-derived system comprises several nucleus-encoded proteins, two of which are thought to control division site placement at the midpoint of the organelle: a stromal ATPase MinD and a topological specificity factor MinE. Here, we show that arc11, one of 12 recessive accumulation and replication of chloroplasts (arc) mutants in Arabidopsis, contains highly elongated and multiple-arrayed chloroplasts in developing green tissues. Genomic sequence analysis revealed that arc11 contains a missense mutation in α-helix 11 of the chloroplast-targeted AtMinD1 changing an Ala at position 296 to Gly (A296G). Introduction of wild-type AtMinD1 restores the chloroplast division defects of arc11 and quantitative RT-PCR analysis showed that the degree of complementation was highly dependent on transgene expression levels. Overexpression of the mutant ARC11/AtMinD1 in transgenic plants results in the inhibition of chloroplast division, showing that the mutant protein has retained its division inhibition activity. However, in contrast to the defined and punctate intraplastidic localization patterns of an AtMinD1-YFP fusion protein, the single A296G point mutation in ARC11/AtMinD1 results in aberrant localization patterns inside chloroplasts. We further show that AtMinD1 is capable of forming homodimers and that this dimerization capacity is abolished by the A296G mutation in ARC11/AtMinD1. Our data show that arc11 is a loss-of-function mutant of AtMinD1 and suggest that the formation of functional AtMinD1 homodimers is paramount for appropriate AtMinD1 localization, ultimately ensuring correct division machinery placement and chloroplast division in plants.
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Affiliation(s)
- Makoto T Fujiwara
- Department of Biology, University of Leicester, University Road, Leicester, LE1 7RH, UK.
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26
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Nagashima A, Hanaoka M, Shikanai T, Fujiwara M, Kanamaru K, Takahashi H, Tanaka K. The Multiple-Stress Responsive Plastid Sigma Factor, SIG5, Directs Activation of the psbD Blue Light-Responsive Promoter (BLRP) in Arabidopsis thaliana. ACTA ACUST UNITED AC 2004; 45:357-68. [PMID: 15111710 DOI: 10.1093/pcp/pch050] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Transcription in higher plant plastids is performed by two types of RNA polymerases called NEP and PEP, and expression of photosynthesis genes in chloroplasts is largely dependent on PEP, a eubacteria-type multi-subunit enzyme. The transcription specificity of PEP is modulated by six nuclear-encoded sigma factors (SIG1 to SIG6) in Arabidopsis thaliana. Here, we show that one of the six sigma factors, SIG5, is induced under various stress conditions, such as high light, low temperature, high salt and high osmotic conditions. Interestingly, transcription from the psbD blue light-responsive promoter (psbD-BLRP) was activated by not only light but also various stresses, and the transcription and the transcriptional activation of psbD-BLRP were abolished in a sig5-2 mutant. This suggests that the PEP holoenzyme containing SIG5 transcribes the psbD-BLRP in response to multiple stresses. Since the seed germination under saline conditions and recovery from damage to the PSII induced by high light were delayed in the sig5-2 mutant, we postulate that SIG5 protects plants from stresses by enhancing repair of the PSII reaction center.
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Affiliation(s)
- Akitomo Nagashima
- Laboratory of Molecular Genetics, Department of Molecular Biology, Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032 Japan
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27
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Foth BJ, McFadden GI. The apicoplast: a plastid in Plasmodium falciparum and other Apicomplexan parasites. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 224:57-110. [PMID: 12722949 DOI: 10.1016/s0074-7696(05)24003-2] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Apicomplexan parasites cause severe diseases such as malaria, toxoplasmosis, and coccidiosis (caused by Plasmodium spp., Toxoplasma, and Eimeria, respectively). These parasites contain a relict plastid-termed "apicoplast"--that originated from the engulfment of an organism of the red algal lineage. The apicoplast is indispensable but its exact role in parasites is unknown. The apicoplast has its own genome and expresses a small number of genes, but the vast majority of the apicoplast proteome is encoded in the nuclear genome. The products of these nuclear genes are posttranslationally targeted to the organelle via the secretory pathway courtesy of a bipartite N-terminal leader sequence. Apicoplasts are nonphotosynthetic but retain other typical plastid functions such as fatty acid, isoprenoid and heme synthesis, and products of these pathways might be exported from the apicoplast for use by the parasite. Apicoplast pathways are essentially prokaryotic and therefore excellent drug targets. Some antibiotics inhibiting these molecular processes are already in chemotherapeutic use, whereas many new drugs will hopefully spring from our growing understanding of this intriguing organelle.
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Affiliation(s)
- Bernardo J Foth
- Plant Cell Biology Research Centre, School of Botany, University of Melbourne, Parkville, Victoria 3010, Australia
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28
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Miyagishima SY, Nishida K, Kuroiwa T. An evolutionary puzzle: chloroplast and mitochondrial division rings. TRENDS IN PLANT SCIENCE 2003; 8:432-438. [PMID: 13678910 DOI: 10.1016/s1360-1385(03)00193-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Consistent with their bacterial origin, chloroplasts and primitive mitochondria retain a FtsZ ring for division. However, chloroplasts and mitochondria have lost most of the proteins required for bacterial division other than FtsZ and certain homologues of the Min proteins, but they do contain plastid and mitochondrion dividing rings, which were recently shown to be distinct from the FtsZ ring. Moreover, recent studies have revealed that rings of the eukaryote-specific dynamin-related family of GTPases regulate the division of chloroplasts and mitochondria, and these proteins emerged early in eukaryotic evolution. These findings suggest that the division of chloroplasts and primitive mitochondria involve very similar systems, consisting of an amalgamation of rings from bacteria and eukaryotes.
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Affiliation(s)
- Shin-ya Miyagishima
- Department of Life Science, College of Science, Rikkyo (St Paul's) University, 3-34-1 Nishiikebukuro, Toshima-ku, Tokyo 171-8501, Japan.
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29
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Vitha S, Froehlich JE, Koksharova O, Pyke KA, van Erp H, Osteryoung KW. ARC6 is a J-domain plastid division protein and an evolutionary descendant of the cyanobacterial cell division protein Ftn2. THE PLANT CELL 2003; 15:1918-33. [PMID: 12897262 PMCID: PMC167179 DOI: 10.1105/tpc.013292] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2003] [Accepted: 05/21/2003] [Indexed: 05/18/2023]
Abstract
Replication of chloroplasts is essential for achieving and maintaining optimal plastid numbers in plant cells. The plastid division machinery contains components of both endosymbiotic and host cell origin, but little is known about the regulation and molecular mechanisms that govern the division process. The Arabidopsis mutant arc6 is defective in plastid division, and its leaf mesophyll cells contain only one or two grossly enlarged chloroplasts. We show here that arc6 chloroplasts also exhibit abnormal localization of the key plastid division proteins FtsZ1 and FtsZ2. Whereas in wild-type plants, the FtsZ proteins assemble into a ring at the plastid division site, chloroplasts in the arc6 mutant contain numerous short, disorganized FtsZ filament fragments. We identified the mutation in arc6 and show that the ARC6 gene encodes a chloroplast-targeted DnaJ-like protein localized to the plastid envelope membrane. An ARC6-green fluorescent protein fusion protein was localized to a ring at the center of the chloroplasts and rescued the chloroplast division defect in the arc6 mutant. The ARC6 gene product is related closely to Ftn2, a prokaryotic cell division protein unique to cyanobacteria. Based on the FtsZ filament morphology observed in the arc6 mutant and in plants that overexpress ARC6, we hypothesize that ARC6 functions in the assembly and/or stabilization of the plastid-dividing FtsZ ring. We also analyzed FtsZ localization patterns in transgenic plants in which plastid division was blocked by altered expression of the division site-determining factor AtMinD. Our results indicate that MinD and ARC6 act in opposite directions: ARC6 promotes and MinD inhibits FtsZ filament formation in the chloroplast.
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Affiliation(s)
- Stanislav Vitha
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
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30
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Szeto TH, Rowland SL, Rothfield LI, King GF. Membrane localization of MinD is mediated by a C-terminal motif that is conserved across eubacteria, archaea, and chloroplasts. Proc Natl Acad Sci U S A 2002; 99:15693-8. [PMID: 12424340 PMCID: PMC137778 DOI: 10.1073/pnas.232590599] [Citation(s) in RCA: 199] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2002] [Accepted: 09/30/2002] [Indexed: 11/18/2022] Open
Abstract
MinD is a widely conserved ATPase that has been demonstrated to play a pivotal role in selection of the division site in eubacteria and chloroplasts. It is a member of the large ParA superfamily of ATPases that are characterized by a deviant Walker-type ATP-binding motif. MinD localizes to the cytoplasmic face of the inner membrane in Escherichia coli, and its association with the inner membrane is a prerequisite for membrane recruitment of the septation inhibitor MinC. However, the mechanism by which MinD associates with the membrane has proved enigmatic; it seems to lack a transmembrane domain and the amino acid sequence is devoid of hydrophobic tracts that might predispose the protein to interaction with lipids. In this study, we show that the extreme C-terminal region of MinD contains a highly conserved 8- to 12-residue sequence motif that is essential for membrane localization of the protein. We provide evidence that this motif forms an amphipathic helix that most likely mediates a direct interaction between MinD and membrane phospholipids. A model is proposed whereby the membrane-targeting motif mediates the rapid cycles of membrane attachment-release-reattachment that are presumed to occur during pole-to-pole oscillation of MinD in E. coli.
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Affiliation(s)
- Tim H Szeto
- Department of Biochemistry, University of Connecticut Health Center, 263 Farmington Avenue, 06032, USA
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31
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Maple J, Chua NH, Møller SG. The topological specificity factor AtMinE1 is essential for correct plastid division site placement in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2002; 31:269-277. [PMID: 12164807 DOI: 10.1046/j.1365-313x.2002.01358.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In plant cells, plastids divide by binary fission involving a complex pathway of events. Although there are clear similarities between bacterial and plastid division, limited information exists regarding the mechanism of plastid division in higher plants. Here we demonstrate that AtMinE1, an Arabidopsis homologue of the bacterial MinE topological specificity factor, is an essential integral component of the plastid division machinery. In prokaryotes MinE imparts topological specificity during cell division by blocking division apparatus assembly at sites other than midcell. We demonstrate that overexpression of AtMinE1 in E. coli results in loss of topological specificity and minicell formation suggesting evolutionary conservation of MinE mode of action. We further show that AtMinE1 can indeed act as a topological specificity factor during plastid division revealing that AtMinE1 overexpression in Arabidopsis seedlings results in division site misplacement giving rise to multiple constrictions along the length of plastids. In agreement with cell division studies in bacteria, AtMinE1 and AtMinD1 show distinct intraplastidic localisation patterns suggestive of dynamic localisation behaviour. Taken together our findings demonstrate that AtMinE1 is an evolutionary conserved topological specificity factor, most probably acting in concert with AtMinD1, required for correct plastid division in Arabidopsis.
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Affiliation(s)
- Jodi Maple
- Department of Biology, University of Leicester, University Road, Leicester LE1 7RH, UK
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32
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Itoh R, Fujiwara M, Nagata N, Yoshida S. A chloroplast protein homologous to the eubacterial topological specificity factor minE plays a role in chloroplast division. PLANT PHYSIOLOGY 2001; 127:1644-1655. [PMID: 11743109 DOI: 10.1104/pp.010386] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
We report the identification of a nucleus-encoded minE gene, designated AtMinE1, of Arabidopsis. The encoded AtMinE1 protein possesses both N- and C-terminal extensions, relative to the eubacterial and algal chloroplast-encoded MinE proteins. The N-terminal extension functioned as a chloroplast-targeting transit peptide, as revealed by a transient expression assay using an N terminus:green fluorescent protein fusion. Histochemical beta-glucuronidase staining of transgenic Arabidopsis lines harboring an AtMinE1 promoter::uidA reporter fusion unveiled specific activation of the promoter in green tissues, especially at the shoot apex, which suggests a requirement for cell division-associated AtMinE1 expression for proplastid division in green tissues. In addition, we generated transgenic plants overexpressing a full-length AtMinE1 cDNA and examined the subcellular structures of those plants. Giant heteromorphic chloroplasts were observed in transgenic plants, with a reduced number per cell, whereas mitochondrial morphology remained similar to that of wild-type plants. Taken together, these observations suggest that MinE is the third conserved component involved in chloroplast division.
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Affiliation(s)
- R Itoh
- Plant Science Center, RIKEN, Wako, Saitama 351-0198, Japan.
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33
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Kanamaru K, Nagashima A, Fujiwara M, Shimada H, Shirano Y, Nakabayashi K, Shibata D, Tanaka K, Takahashi H. An Arabidopsis sigma factor (SIG2)-dependent expression of plastid-encoded tRNAs in chloroplasts. PLANT & CELL PHYSIOLOGY 2001; 42:1034-43. [PMID: 11673617 DOI: 10.1093/pcp/pce155] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
A eubacteria-type RNA polymerase (PEP) plays crucial roles for chloroplast development in higher plants. The core subunits are encoded on plastid DNA (rpo genes) while the regulatory sigma factors are encoded on the nuclear DNA (SIG genes). However, the definite gene specificity of each sigma factor is unknown. We recently identified an Arabidopsis recessive pale-green mutant abc1 in which T-DNA is inserted in SIG2 (sigB). In this mutant, almost normal etioplasts were developed under dark conditions while the small chloroplasts with poor thylakoid membranes and stacked lamellar were developed under light conditions. The sig2-1 mutant was deficient in accumulating enough photosynthetic and photosynthesis-related proteins as well as chlorophyll. However, mRNAs of their structural genes were not significantly reduced. Further analyses revealed that several plastid-encoded tRNAs including trnE-UUC that has dual function for protein and ALA biosyntheses were drastically reduced in the sig2-1 mutant. In contrast, nucleus-encoded T7 phage-type RNA polymerase (NEP)-dependent gene transcripts were steadily accumulated in the mutant. These results indicate that progress of chloroplast development requires SIG2-dependent expression of plastid genes, particularly some of the tRNA genes.
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Affiliation(s)
- K Kanamaru
- Laboratory of Molecular Genetics, Department of Molecular Biology, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, 113-0032 Japan
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Fujiwara M, Yoshida S. Chloroplast targeting of chloroplast division FtsZ2 proteins in Arabidopsis. Biochem Biophys Res Commun 2001; 287:462-7. [PMID: 11554751 DOI: 10.1006/bbrc.2001.5588] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Plant nuclear genomes encode chloroplast division proteins homologous to the eubacterial cell division protein FtsZ. In higher plants, FtsZ genes constitute a small gene family that consists of two subgroups, FtsZ1 and FtsZ2. It was previously hypothesized that members of one family (FtsZ1) targeted chloroplasts, while members of the other family (FtsZ2) localized in the cytoplasm. We determined the full-length cDNA sequences of two FtsZ2 genes from Arabidopsis thaliana (AtFtsZ2-1 and AtFtsZ2-2) and found that the genes encode polypeptides of 478 and 473 amino acids, respectively, and both contain N-terminal extensions beyond what have previously been predicted. The N-terminal regions of both AtFtsZ2-1 and AtFtsZ2-2 were expressed as green fluorescent protein (GFP) fusions under the cauliflower mosaic virus 35S promoter in bombarded tobacco cells. Confocal laser scanning microscopy revealed both fusions exclusively localized to chloroplasts, demonstrating that the N-terminal regions function as chloroplast-targeting signals in vivo. Thus, FtsZ2 proteins function within chloroplasts.
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Affiliation(s)
- M Fujiwara
- Plant Functions Laboratory, RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198, Japan.
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35
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Abstract
Among the events that accompanied the evolution of chloroplasts from their endosymbiotic ancestors was the host cell recruitment of the prokaryotic cell division protein FtsZ to function in chloroplast division. FtsZ, a structural homologue of tubulin, mediates cell division in bacteria by assembling into a ring at the midcell division site. In higher plants, two nuclear-encoded forms of FtsZ, FtsZ1 and FtsZ2, play essential and functionally distinct roles in chloroplast division, but whether this involves ring formation at the division site has not been determined previously. Using immunofluorescence microscopy and expression of green fluorescent protein fusion proteins in Arabidopsis thaliana, we demonstrate here that FtsZ1 and FtsZ2 localize to coaligned rings at the chloroplast midpoint. Antibodies specific for recognition of FtsZ1 or FtsZ2 proteins in Arabidopsis also recognize related polypeptides and detect midplastid rings in pea and tobacco, suggesting that midplastid ring formation by FtsZ1 and FtsZ2 is universal among flowering plants. Perturbation in the level of either protein in transgenic plants is accompanied by plastid division defects and assembly of FtsZ1 and FtsZ2 into filaments and filament networks not observed in wild-type, suggesting that previously described FtsZ-containing cytoskeletal-like networks in chloroplasts may be artifacts of FtsZ overexpression.
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Affiliation(s)
- Stanislav Vitha
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
| | - Rosemary S. McAndrew
- Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824
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36
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Shirano Y, Shimada H, Kanamaru K, Fujiwara M, Tanaka K, Takahashi H, Unno K, Sato S, Tabata S, Hayashi H, Miyake C, Yokota A, Shibata D. Chloroplast development in Arabidopsis thaliana requires the nuclear-encoded transcription factor sigma B. FEBS Lett 2000; 485:178-82. [PMID: 11094163 DOI: 10.1016/s0014-5793(00)02216-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Development of plastids into chloroplasts, the organelles of photosynthesis, is triggered by light. However, little is known of the factors involved in the complex coordination of light-induced plastid gene expression, which must be directed by both nuclear and plastid genomes. We have isolated an Arabidopsis mutant, abc1, with impaired chloroplast development, which results in a pale green leaf phenotype. The mutated nuclear gene encodes a sigma factor, SigB, presumably for the eubacterial-like plastid RNA polymerase. Our results provide direct evidence that a nuclear-derived prokaryotic-like SigB protein, plays a critical role in the coordination of the two genomes for chloroplast development.
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Affiliation(s)
- Y Shirano
- Mitsui Plant Biotechnology Research Institute, Tsukuba, Ibaraki, Japan
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