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Wu XX, Mu WH, Li F, Sun SY, Cui CJ, Kim C, Zhou F, Zhang Y. Cryo-EM structures of the plant plastid-encoded RNA polymerase. Cell 2024; 187:1127-1144.e21. [PMID: 38428393 DOI: 10.1016/j.cell.2024.01.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 12/12/2023] [Accepted: 01/16/2024] [Indexed: 03/03/2024]
Abstract
Chloroplasts are green plastids in the cytoplasm of eukaryotic algae and plants responsible for photosynthesis. The plastid-encoded RNA polymerase (PEP) plays an essential role during chloroplast biogenesis from proplastids and functions as the predominant RNA polymerase in mature chloroplasts. The PEP-centered transcription apparatus comprises a bacterial-origin PEP core and more than a dozen eukaryotic-origin PEP-associated proteins (PAPs) encoded in the nucleus. Here, we determined the cryo-EM structures of Nicotiana tabacum (tobacco) PEP-PAP apoenzyme and PEP-PAP transcription elongation complexes at near-atomic resolutions. Our data show the PEP core adopts a typical fold as bacterial RNAP. Fifteen PAPs bind at the periphery of the PEP core, facilitate assembling the PEP-PAP supercomplex, protect the complex from oxidation damage, and likely couple gene transcription with RNA processing. Our results report the high-resolution architecture of the chloroplast transcription apparatus and provide the structural basis for the mechanistic and functional study of transcription regulation in chloroplasts.
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Affiliation(s)
- Xiao-Xian Wu
- Key Laboratory of Synthetic Biology, Key Laboratory of Plant Design, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Wen-Hui Mu
- Key Laboratory of Synthetic Biology, Key Laboratory of Plant Design, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China; State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng 475004, China
| | - Fan Li
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - Shu-Yi Sun
- Key Laboratory of Synthetic Biology, Key Laboratory of Plant Design, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Chao-Jun Cui
- University of Chinese Academy of Sciences, Beijing 100049, China; Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Chanhong Kim
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Fei Zhou
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China.
| | - Yu Zhang
- Key Laboratory of Synthetic Biology, Key Laboratory of Plant Design, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China.
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Structure of a TOC-TIC supercomplex spanning two chloroplast envelope membranes. Cell 2022; 185:4788-4800.e13. [PMID: 36413996 DOI: 10.1016/j.cell.2022.10.030] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 09/07/2022] [Accepted: 10/28/2022] [Indexed: 11/23/2022]
Abstract
The TOC and TIC complexes are essential translocons that facilitate the import of the nuclear genome-encoded preproteins across the two envelope membranes of chloroplast, but their exact molecular identities and assembly remain unclear. Here, we report a cryoelectron microscopy structure of TOC-TIC supercomplex from Chlamydomonas, containing a total of 14 identified components. The preprotein-conducting pore of TOC is a hybrid β-barrel co-assembled by Toc120 and Toc75, while the potential translocation path of TIC is formed by transmembrane helices from Tic20 and YlmG, rather than a classic model of Tic110. A rigid intermembrane space (IMS) scaffold bridges two chloroplast membranes, and a large hydrophilic cleft on the IMS scaffold connects TOC and TIC, forming a pathway for preprotein translocation. Our study provides structural insights into the TOC-TIC supercomplex composition, assembly, and preprotein translocation mechanism, and lays a foundation to interpret the evolutionary conservation and diversity of this fundamental translocon machinery.
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Domb K, Wang N, Hummel G, Liu C. Spatial Features and Functional Implications of Plant 3D Genome Organization. ANNUAL REVIEW OF PLANT BIOLOGY 2022; 73:173-200. [PMID: 35130445 DOI: 10.1146/annurev-arplant-102720-022810] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The advent of high-throughput sequencing-based methods for chromatin conformation, accessibility, and immunoprecipitation assays has been a turning point in 3D genomics. Altogether, these new tools have been pushing upward the interpretation of pioneer cytogenetic evidence for a higher order in chromatin packing. Here, we review the latest development in our understanding of plant spatial genome structures and different levels of organization and discuss their functional implications. Then, we spotlight the complexity of organellar (i.e., mitochondria and plastids) genomes and discuss their 3D packing into nucleoids. Finally, we propose unaddressed research axes to investigate functional links between chromatin-like dynamics and transcriptional regulation within organellar nucleoids.
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Affiliation(s)
- Katherine Domb
- Institute of Biology, University of Hohenheim, Stuttgart, Germany;
| | - Nan Wang
- Institute of Biology, University of Hohenheim, Stuttgart, Germany;
| | - Guillaume Hummel
- Institute of Biology, University of Hohenheim, Stuttgart, Germany;
| | - Chang Liu
- Institute of Biology, University of Hohenheim, Stuttgart, Germany;
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New Insights into the Chloroplast Outer Membrane Proteome and Associated Targeting Pathways. Int J Mol Sci 2022; 23:ijms23031571. [PMID: 35163495 PMCID: PMC8836251 DOI: 10.3390/ijms23031571] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/24/2022] [Accepted: 01/27/2022] [Indexed: 12/04/2022] Open
Abstract
Plastids are a dynamic class of organelle in plant cells that arose from an ancient cyanobacterial endosymbiont. Over the course of evolution, most genes encoding plastid proteins were transferred to the nuclear genome. In parallel, eukaryotic cells evolved a series of targeting pathways and complex proteinaceous machinery at the plastid surface to direct these proteins back to their target organelle. Chloroplasts are the most well-characterized plastids, responsible for photosynthesis and other important metabolic functions. The biogenesis and function of chloroplasts rely heavily on the fidelity of intracellular protein trafficking pathways. Therefore, understanding these pathways and their regulation is essential. Furthermore, the chloroplast outer membrane proteome remains relatively uncharted territory in our understanding of protein targeting. Many key players in the cytosol, receptors at the organelle surface, and insertases that facilitate insertion into the chloroplast outer membrane remain elusive for this group of proteins. In this review, we summarize recent advances in the understanding of well-characterized chloroplast outer membrane protein targeting pathways as well as provide new insights into novel targeting signals and pathways more recently identified using a bioinformatic approach. As a result of our analyses, we expand the known number of chloroplast outer membrane proteins from 117 to 138.
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5
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Suzuki S, Matsuzaki R, Yamaguchi H, Kawachi M. What happened before losses of photosynthesis in cryptophyte algae? Mol Biol Evol 2022; 39:6513384. [PMID: 35079797 PMCID: PMC8829904 DOI: 10.1093/molbev/msac001] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
In many lineages of algae and land plants, photosynthesis was lost multiple times independently. Comparative analyses of photosynthetic and secondary nonphotosynthetic relatives have revealed the essential functions of plastids, beyond photosynthesis. However, evolutionary triggers and processes that drive the loss of photosynthesis remain unknown. Cryptophytes are microalgae with complex plastids derived from a red alga. They include several secondary nonphotosynthetic species with closely related photosynthetic taxa. In this study, we found that a cryptophyte, Cryptomonas borealis, is in a stage just prior to the loss of photosynthesis. Cryptomonas borealis was mixotrophic, possessed photosynthetic activity, and grew independent of light. The plastid genome of C. borealis had distinct features, including increases of group II introns with mobility, frequent genome rearrangements, incomplete loss of inverted repeats, and abundant small/medium/large-sized structural variants. These features provide insight into the evolutionary process leading to the loss of photosynthesis.
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Affiliation(s)
- Shigekatsu Suzuki
- Biodiversity Division, National Institute for Environmental Studies, Tsukuba, Ibaraki, 305-8506, Japan
| | - Ryo Matsuzaki
- Biodiversity Division, National Institute for Environmental Studies, Tsukuba, Ibaraki, 305-8506, Japan
- Faculty of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8577, Japan
| | - Haruyo Yamaguchi
- Biodiversity Division, National Institute for Environmental Studies, Tsukuba, Ibaraki, 305-8506, Japan
| | - Masanobu Kawachi
- Biodiversity Division, National Institute for Environmental Studies, Tsukuba, Ibaraki, 305-8506, Japan
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6
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Martins-Duarte ÉS, Sheiner L, Reiff SB, de Souza W, Striepen B. Replication and partitioning of the apicoplast genome of Toxoplasma gondii is linked to the cell cycle and requires DNA polymerase and gyrase. Int J Parasitol 2021; 51:493-504. [PMID: 33581138 PMCID: PMC8113025 DOI: 10.1016/j.ijpara.2020.11.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 10/30/2020] [Accepted: 11/08/2020] [Indexed: 10/26/2022]
Abstract
Apicomplexans are the causative agents of numerous important infectious diseases including malaria and toxoplasmosis. Most of them harbour a chloroplast-like organelle called the apicoplast that is essential for the parasites' metabolism and survival. While most apicoplast proteins are nuclear encoded, the organelle also maintains its own genome, a 35 kb circle. In this study we used Toxoplasma gondii to identify and characterise essential proteins involved in apicoplast genome replication and to understand how apicoplast genome segregation unfolds over time. We demonstrated that the DNA replication enzymes Prex, DNA gyrase and DNA single stranded binding protein localise to the apicoplast. We show in knockdown experiments that apicoplast DNA Gyrase A and B, and Prex are required for apicoplast genome replication and growth of the parasite. Analysis of apicoplast genome replication by structured illumination microscopy in T. gondii tachyzoites showed that apicoplast nucleoid division and segregation initiate at the beginning of S phase and conclude during mitosis. Thus, the replication and division of the apicoplast nucleoid is highly coordinated with nuclear genome replication and mitosis. Our observations highlight essential components of apicoplast genome maintenance and shed light on the timing of this process in the context of the overall parasite cell cycle.
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Affiliation(s)
- Érica S Martins-Duarte
- Laboratório de Quimioterapia de Protozoários Egler Chiari, Departamento de Parasitologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil; Núcleo de Biologia Estrutural e Bioimagens (CENABIO) - Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Biomagens (INBEB), Rio de Janeiro, RJ, Brazil.
| | - Lilach Sheiner
- Wellcome Centre for Integrative Parasitology, University of Glasgow, 120 University Place Glasgow, United Kingdom
| | - Sarah B Reiff
- Department of Cellular Biology, University of Georgia, Athens, GA, USA
| | - Wanderley de Souza
- Núcleo de Biologia Estrutural e Bioimagens (CENABIO) - Instituto Nacional de Ciência e Tecnologia em Biologia Estrutural e Biomagens (INBEB), Rio de Janeiro, RJ, Brazil; Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Boris Striepen
- Department of Cellular Biology, University of Georgia, Athens, GA, USA; Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA. USA
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Abstract
The division and cell wall (dcw) cluster is a highly conserved region of the bacterial genome consisting of genes that encode several cell division and cell wall synthesis factors, including the central division protein FtsZ. The region immediately downstream of ftsZ encodes the ylm genes and is conserved across diverse lineages of Gram-positive bacteria and Cyanobacteria In some organisms, this region remains part of the dcw cluster, but in others, it appears as an independent operon. A well-studied protein coded from this region is the positive FtsZ regulator SepF (YlmF), which anchors FtsZ to the membrane. Recent developments have shed light on the importance of SepF in a range of species. Additionally, new studies are highlighting the importance of the other conserved genes in this neighborhood. In this minireview, we aim to bring together the current research linking the ylm region to cell division and highlight further questions surrounding these conserved genes.
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Springstein BL, Nürnberg DJ, Weiss GL, Pilhofer M, Stucken K. Structural Determinants and Their Role in Cyanobacterial Morphogenesis. Life (Basel) 2020; 10:E355. [PMID: 33348886 PMCID: PMC7766704 DOI: 10.3390/life10120355] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 12/04/2020] [Accepted: 12/09/2020] [Indexed: 12/16/2022] Open
Abstract
Cells have to erect and sustain an organized and dynamically adaptable structure for an efficient mode of operation that allows drastic morphological changes during cell growth and cell division. These manifold tasks are complied by the so-called cytoskeleton and its associated proteins. In bacteria, FtsZ and MreB, the bacterial homologs to tubulin and actin, respectively, as well as coiled-coil-rich proteins of intermediate filament (IF)-like function to fulfil these tasks. Despite generally being characterized as Gram-negative, cyanobacteria have a remarkably thick peptidoglycan layer and possess Gram-positive-specific cell division proteins such as SepF and DivIVA-like proteins, besides Gram-negative and cyanobacterial-specific cell division proteins like MinE, SepI, ZipN (Ftn2) and ZipS (Ftn6). The diversity of cellular morphologies and cell growth strategies in cyanobacteria could therefore be the result of additional unidentified structural determinants such as cytoskeletal proteins. In this article, we review the current advances in the understanding of the cyanobacterial cell shape, cell division and cell growth.
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Affiliation(s)
- Benjamin L. Springstein
- Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Dennis J. Nürnberg
- Department of Physics, Biophysics and Biochemistry of Photosynthetic Organisms, Freie Universität Berlin, 14195 Berlin, Germany;
| | - Gregor L. Weiss
- Department of Biology, Institute of Molecular Biology & Biophysics, ETH Zürich, 8092 Zürich, Switzerland; (G.L.W.); (M.P.)
| | - Martin Pilhofer
- Department of Biology, Institute of Molecular Biology & Biophysics, ETH Zürich, 8092 Zürich, Switzerland; (G.L.W.); (M.P.)
| | - Karina Stucken
- Department of Food Engineering, Universidad de La Serena, La Serena 1720010, Chile;
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Kuroiwa T, Ohnuma M, Imoto Y, Yagisawa F, Misumi O, Nagata N, Kuroiwa H. Evolutionary significance of the ring-like plastid nucleus in the primitive red alga Cyanidioschyzon merolae as revealed by drying. PROTOPLASMA 2020; 257:1069-1078. [PMID: 32185527 DOI: 10.1007/s00709-020-01496-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 02/20/2020] [Indexed: 06/10/2023]
Abstract
Primary plastids originated from a free-living cyanobacterial ancestor and possess their own genomes-probably a few DNA copies. These genomes, which are organized in centrally located plastid nuclei (CN-type pt-nuclei), are produced from preexisting plastids by binary division. Ancestral algae with a CN-type pt-nucleus diverged and evolved into two basal eukaryotic lineages: red algae with circular (CL-type) pt-nuclei and green algae with scattered small (SN-type) pt-nuclei. Although the molecular dynamics of pt-nuclei in green algae and plants are now being analyzed, the process of the conversion of the original algae with a CN-type pt-nucleus to red algae with a CL-type one has not been studied. Here, we show that the CN-type pt-nucleus in the primitive red alga Cyanidioschyzon merolae can be changed to the CL-type by application of drying to produce slight cell swelling. This result implies that CN-type pt-nuclei are produced by compact packing of CL-type ones, which suggests that a C. merolae-like alga was the original progenitor of the red algal lineage. We also observed that the CL-type pt-nucleus has a chain-linked bead-like structure. Each bead is most likely a small unit of DNA, similar to CL-type pt-nuclei in brown algae. Our results thus suggest a C. merolae-like alga as the candidate for the secondary endosymbiont of brown algae.
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Affiliation(s)
- Tsuneyoshi Kuroiwa
- Department of Chemical and Biological Sciences, Japan Women's University, 2-8-1 Mejirodai, Bunkyo-ku, Tokyo, 112-8681, Japan.
| | - Mio Ohnuma
- Institute of Technology, Hiroshima College, 4272-1 Higashino, Osakikamijima-cho Toyota-gun, Hiroshima, 725-0231, Japan
| | - Yuuta Imoto
- Department of Cell Biology, Johns Hopkins University School of Medicine, 725 N. Wolf Street, Biophysics 100, Baltimore, MD, 21205, USA
| | - Fumi Yagisawa
- Center for Research Advancement and Collaboration, University of the Ryukyus, Okinawa, 903-0213, Japan
| | - Osami Misumi
- Department of Biological Science and Chemistry, Faculty of Science, Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yamaguchi, 753-8512, Japan
| | - Noriko Nagata
- Department of Chemical and Biological Sciences, Japan Women's University, 2-8-1 Mejirodai, Bunkyo-ku, Tokyo, 112-8681, Japan
| | - Haruko Kuroiwa
- Department of Chemical and Biological Sciences, Japan Women's University, 2-8-1 Mejirodai, Bunkyo-ku, Tokyo, 112-8681, Japan
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Chen H, Li S, Li L, Hu H, Zhao J. Arabidopsis EMB1990 Encoding a Plastid-Targeted YlmG Protein Is Required for Chloroplast Biogenesis and Embryo Development. FRONTIERS IN PLANT SCIENCE 2018; 9:181. [PMID: 29503657 PMCID: PMC5820536 DOI: 10.3389/fpls.2018.00181] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Accepted: 01/31/2018] [Indexed: 05/24/2023]
Abstract
In higher plants, embryo development originated from fertilized egg cell is the first step of the life cycle. The chloroplast participates in many essential metabolic pathways, and its function is highly associated with embryo development. However, the mechanisms and relevant genetic components by which the chloroplast functions in embryogenesis are largely uncharacterized. In this paper, we describe the Arabidopsis EMB1990 gene, encoding a plastid-targeted YlmG protein which is required for chloroplast biogenesis and embryo development. Loss of the EMB1990/YLMG1-1 resulted in albino seeds containing abortive embryos, and the morphological development of homozygous emb1990 embryos was disrupted after the globular stage. Our results showed that EMB1990/YLMG1-1 was expressed in the primordia and adaxial region of cotyledon during embryogenesis, and the encoded protein was targeted to the chloroplast. TEM observation of cellular ultrastructure showed that chloroplast biogenesis was impaired in emb1990 embryo cells. Expression of certain plastid genes was also affected in the loss-of-function mutants, including genes encoding core protein complex subunits located in the thylakoid membrane. Moreover, the tissue-specific genes of embryo development were misexpressed in emb1990 mutant, including genes known to delineate cell fate decisions in the SAM (shoot apical meristem), cotyledon and hypophysis. Taken together, we propose that the nuclear-encoded YLMG1-1 is targeted to the chloroplast and required for normal plastid gene expression. Hence, YLMG1-1 plays a critical role in Arabidopsis embryogenesis through participating in chloroplast biogenesis.
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Schmelling NM, Lehmann R, Chaudhury P, Beck C, Albers SV, Axmann IM, Wiegard A. Minimal tool set for a prokaryotic circadian clock. BMC Evol Biol 2017; 17:169. [PMID: 28732467 PMCID: PMC5520375 DOI: 10.1186/s12862-017-0999-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 06/15/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Circadian clocks are found in organisms of almost all domains including photosynthetic Cyanobacteria, whereby large diversity exists within the protein components involved. In the model cyanobacterium Synechococcus elongatus PCC 7942 circadian rhythms are driven by a unique KaiABC protein clock, which is embedded in a network of input and output factors. Homologous proteins to the KaiABC clock have been observed in Bacteria and Archaea, where evidence for circadian behavior in these domains is accumulating. However, interaction and function of non-cyanobacterial Kai-proteins as well as homologous input and output components remain mainly unclear. RESULTS Using a universal BLAST analyses, we identified putative KaiC-based timing systems in organisms outside as well as variations within Cyanobacteria. A systematic analyses of publicly available microarray data elucidated interesting variations in circadian gene expression between different cyanobacterial strains, which might be correlated to the diversity of genome encoded clock components. Based on statistical analyses of co-occurrences of the clock components homologous to Synechococcus elongatus PCC 7942, we propose putative networks of reduced and fully functional clock systems. Further, we studied KaiC sequence conservation to determine functionally important regions of diverged KaiC homologs. Biochemical characterization of exemplary cyanobacterial KaiC proteins as well as homologs from two thermophilic Archaea demonstrated that kinase activity is always present. However, a KaiA-mediated phosphorylation is only detectable in KaiC1 orthologs. CONCLUSION Our analysis of 11,264 genomes clearly demonstrates that components of the Synechococcus elongatus PCC 7942 circadian clock are present in Bacteria and Archaea. However, all components are less abundant in other organisms than Cyanobacteria and KaiA, Pex, LdpA, and CdpA are only present in the latter. Thus, only reduced KaiBC-based or even simpler, solely KaiC-based timing systems might exist outside of the cyanobacterial phylum, which might be capable of driving diurnal oscillations.
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Affiliation(s)
- Nicolas M. Schmelling
- Institute for Synthetic Microbiology, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University Duesseldorf, Universitaetsstrasse 1, Duesseldorf, 40225 Germany
| | - Robert Lehmann
- Institute for Theoretical Biology, Humboldt University Berlin, Invalidenstrasse 43, Berlin, 10115 Germany
| | - Paushali Chaudhury
- Molecular Biology of Archaea, Albert-Ludwigs-University Freiburg, Institute of Biology II, Schaenzlestrasse 1, Freiburg, 79104 Germany
| | - Christian Beck
- Institute for Theoretical Biology, Humboldt University Berlin, Invalidenstrasse 43, Berlin, 10115 Germany
| | - Sonja-Verena Albers
- Molecular Biology of Archaea, Albert-Ludwigs-University Freiburg, Institute of Biology II, Schaenzlestrasse 1, Freiburg, 79104 Germany
| | - Ilka M. Axmann
- Institute for Synthetic Microbiology, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University Duesseldorf, Universitaetsstrasse 1, Duesseldorf, 40225 Germany
| | - Anika Wiegard
- Institute for Synthetic Microbiology, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University Duesseldorf, Universitaetsstrasse 1, Duesseldorf, 40225 Germany
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12
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Zhang L, Willemse J, Claessen D, van Wezel GP. SepG coordinates sporulation-specific cell division and nucleoid organization in Streptomyces coelicolor. Open Biol 2016; 6:150164. [PMID: 27053678 PMCID: PMC4852450 DOI: 10.1098/rsob.150164] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Bacterial cell division is a highly complex process that requires tight coordination between septum formation and chromosome replication and segregation. In bacteria that divide by binary fission a single septum is formed at mid-cell, a process that is coordinated by the conserved cell division scaffold protein FtsZ. In contrast, during sporulation-specific cell division in streptomycetes, up to a hundred rings of FtsZ (Z rings) are produced almost simultaneously, dividing the multinucleoid aerial hyphae into long chains of unigenomic spores. This involves the active recruitment of FtsZ by the SsgB protein, and at the same time requires sophisticated systems to regulate chromosome dynamics. Here, we show that SepG is required for the onset of sporulation and acts by ensuring that SsgB is localized to future septum sites. Förster resonance energy transfer imaging suggests direct interaction between SepG and SsgB. The beta-lactamase reporter system showed that SepG is a transmembrane protein with its central domain oriented towards the cytoplasm. Without SepG, SsgB fails to localize properly, consistent with a crucial role for SepG in the membrane localization of the SsgB-FtsZ complex. While SsgB remains associated with FtsZ, SepG re-localizes to the (pre)spore periphery. Expanded doughnut-shaped nucleoids are formed in sepG null mutants, suggesting that SepG is required for nucleoid compaction. Taken together, our work shows that SepG, encoded by one of the last genes in the conserved dcw cluster of cell division and cell-wall-related genes in Gram-positive bacteria whose function was still largely unresolved,coordinates septum synthesis and chromosome organization in Streptomyces.
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Affiliation(s)
- Le Zhang
- Molecular Biotechnology, Institute of Biology, Leiden University, PO Box 9505, 2300RA Leiden, The Netherlands
| | - Joost Willemse
- Molecular Biotechnology, Institute of Biology, Leiden University, PO Box 9505, 2300RA Leiden, The Netherlands
| | - Dennis Claessen
- Molecular Biotechnology, Institute of Biology, Leiden University, PO Box 9505, 2300RA Leiden, The Netherlands
| | - Gilles P van Wezel
- Molecular Biotechnology, Institute of Biology, Leiden University, PO Box 9505, 2300RA Leiden, The Netherlands
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13
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Oldenburg DJ, Bendich AJ. DNA maintenance in plastids and mitochondria of plants. FRONTIERS IN PLANT SCIENCE 2015; 6:883. [PMID: 26579143 PMCID: PMC4624840 DOI: 10.3389/fpls.2015.00883] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 10/05/2015] [Indexed: 05/02/2023]
Abstract
The DNA molecules in plastids and mitochondria of plants have been studied for over 40 years. Here, we review the data on the circular or linear form, replication, repair, and persistence of the organellar DNA (orgDNA) in plants. The bacterial origin of orgDNA appears to have profoundly influenced ideas about the properties of chromosomal DNA molecules in these organelles to the point of dismissing data inconsistent with ideas from the 1970s. When found at all, circular genome-sized molecules comprise a few percent of orgDNA. In cells active in orgDNA replication, most orgDNA is found as linear and branched-linear forms larger than the size of the genome, likely a consequence of a virus-like DNA replication mechanism. In contrast to the stable chromosomal DNA molecules in bacteria and the plant nucleus, the molecular integrity of orgDNA declines during leaf development at a rate that varies among plant species. This decline is attributed to degradation of damaged-but-not-repaired molecules, with a proposed repair cost-saving benefit most evident in grasses. All orgDNA maintenance activities are proposed to occur on the nucleoid tethered to organellar membranes by developmentally-regulated proteins.
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14
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Chlamydia trachomatis In Vivo to In Vitro Transition Reveals Mechanisms of Phase Variation and Down-Regulation of Virulence Factors. PLoS One 2015. [PMID: 26207372 PMCID: PMC4514472 DOI: 10.1371/journal.pone.0133420] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Research on the obligate intracellular bacterium Chlamydia trachomatis demands culture in cell-lines, but the adaptive process behind the in vivo to in vitro transition is not understood. We assessed the genomic and transcriptomic dynamics underlying C. trachomatis in vitro adaptation of strains representing the three disease groups (ocular, epithelial-genital and lymphogranuloma venereum) propagated in epithelial cells over multiple passages. We found genetic features potentially underlying phase variation mechanisms mediating the regulation of a lipid A biosynthesis enzyme (CT533/LpxC), and the functionality of the cytotoxin (CT166) through an ON/OFF mechanism. We detected inactivating mutations in CT713/porB, a scenario suggesting metabolic adaptation to the available carbon source. CT135 was inactivated in a tropism-specific manner, with CT135-negative clones emerging for all epithelial-genital populations (but not for LGV and ocular populations) and rapidly increasing in frequency (~23% mutants per 10 passages). RNA-sequencing analyses revealed that a deletion event involving CT135 impacted the expression of multiple virulence factors, namely effectors known to play a role in the C. trachomatis host-cell invasion or subversion (e.g., CT456/Tarp, CT694, CT875/TepP and CT868/ChlaDub1). This reflects a scenario of attenuation of C. trachomatis virulence in vitro, which may take place independently or in a cumulative fashion with the also observed down-regulation of plasmid-related virulence factors. This issue may be relevant on behalf of the recent advances in Chlamydia mutagenesis and transformation where culture propagation for selecting mutants/transformants is mandatory. Finally, there was an increase in the growth rate for all strains, reflecting gradual fitness enhancement over time. In general, these data shed light on the adaptive process underlying the C. trachomatis in vivo to in vitro transition, and indicates that it would be prudent to restrict culture propagation to minimal passages and check the status of the CT135 genotype in order to avoid the selection of CT135-negative mutants, likely originating less virulent strains.
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Powikrowska M, Oetke S, Jensen PE, Krupinska K. Dynamic composition, shaping and organization of plastid nucleoids. FRONTIERS IN PLANT SCIENCE 2014; 5:424. [PMID: 25237313 PMCID: PMC4154389 DOI: 10.3389/fpls.2014.00424] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 08/08/2014] [Indexed: 05/18/2023]
Abstract
In this article recent progress on the elucidation of the dynamic composition and structure of plastid nucleoids is reviewed from a structural perspective. Plastid nucleoids are compact structures of multiple copies of different forms of ptDNA, RNA, enzymes for replication and gene expression as well as DNA binding proteins. Although early electron microscopy suggested that plastid DNA is almost free of proteins, it is now well established that the DNA in nucleoids similarly as in the nuclear chromatin is associated with basic proteins playing key roles in organization of the DNA architecture and in regulation of DNA associated enzymatic activities involved in transcription, replication, and recombination. This group of DNA binding proteins has been named plastid nucleoid associated proteins (ptNAPs). Plastid nucleoids are unique with respect to their variable number, genome copy content and dynamic distribution within different types of plastids. The mechanisms underlying the shaping and reorganization of plastid nucleoids during chloroplast development and in response to environmental conditions involve posttranslational modifications of ptNAPs, similarly to those changes known for histones in the eukaryotic chromatin, as well as changes in the repertoire of ptNAPs, as known for nucleoids of bacteria. Attachment of plastid nucleoids to membranes is proposed to be important not only for regulation of DNA availability for replication and transcription, but also for the coordination of photosynthesis and plastid gene expression.
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Affiliation(s)
- Marta Powikrowska
- Department of Plant and Environmental Sciences, VILLUM Research Centre for Plant Plasticity and Copenhagen Plant Science Centre, University of CopenhagenCopenhagen, Denmark
| | - Svenja Oetke
- Plant Cell Biology, Institute of Botany, Christian-Albrechts-University of KielKiel, Germany
| | - Poul E. Jensen
- Department of Plant and Environmental Sciences, VILLUM Research Centre for Plant Plasticity and Copenhagen Plant Science Centre, University of CopenhagenCopenhagen, Denmark
| | - Karin Krupinska
- Plant Cell Biology, Institute of Botany, Christian-Albrechts-University of KielKiel, Germany
- *Correspondence: Karin Krupinska, Plant Cell Biology, Institute of Botany, Christian-Albrechts-University of Kiel, Olshausenstrasse 40, 24098 Kiel, Germany e-mail:
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Seki Y, Nitta K, Kaneko Y. Observation of polyphosphate bodies and DNA during the cell division cycle of Synechococcus elongatus PCC 7942. PLANT BIOLOGY (STUTTGART, GERMANY) 2014; 16:258-263. [PMID: 23574545 DOI: 10.1111/plb.12008] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2012] [Accepted: 12/21/2012] [Indexed: 06/02/2023]
Abstract
Although most cyanobacterial cells contain prominent polyphosphate bodies in the central cytoplasmic area enclosed by the peripheral thylakoid membranes, their roles are not fully understood. Storing phosphate for nucleotide production might be one of their important roles in survival of the cells. As a step towards identifying a possible contribution of the polyphosphate bodies to DNA synthesis, the relationship between polyphosphate bodies and DNA throughout cell division cycle of Synechococcus elongatus PCC 7942 cells cultured under light/dark cycles was investigated with light and electron microscopy. During the dark period, the average size of polyphosphate bodies increased gradually without significant change in their number and distribution. However, during the light period, the number of polyphosphate bodies increased, while the size of each polyphosphate body decreased and cells elongated until the end of the light period, when most cells divided. The ratio of the content of polyphosphate bodies to cell length increased gradually during the dark period and decreased during the light period. Hoechst 33342-stained DNA appeared diffuse during the dark period, but in the light period it became condensed and eventually formed a wavy, rope-like structure prior to cell division. Close association between fibres containing DNA and polyphosphate bodies was demonstrated by TEM using DNA-specific staining and BrdU labelling. These regular coordinated changes of polyphosphate bodies and DNA shape during the cell division cycle, together with their intimate interaction, imply a role of polyphosphate bodies in supplying material for DNA.
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Affiliation(s)
- Y Seki
- Graduate School of Science and Engineering, Saitama University, Saitama, Kanagawa, Japan
| | - K Nitta
- Analysis Technology Center, Research and Developmental Management Headquarters, Fuji Photo Film Co. Ltd., Minamiashigara, Kanagawa, Japan
| | - Y Kaneko
- Biology Section in the Faculty of Education; Graduate School of Science and Engineering; Institute for Environmental Science and Technology, Saitama University, Saitama, Japan
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Conserved pyridoxal protein that regulates Ile and Val metabolism. J Bacteriol 2013; 195:5439-49. [PMID: 24097949 DOI: 10.1128/jb.00593-13] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli YggS is a member of the highly conserved uncharacterized protein family that binds pyridoxal 5'-phosphate (PLP). To assist with the functional assignment of the YggS family, in vivo and in vitro analyses were performed using a yggS-deficient E. coli strain (ΔyggS) and a purified form of YggS, respectively. In the stationary phase, the ΔyggS strain exhibited a completely different intracellular pool of amino acids and produced a significant amount of l-Val in the culture medium. The log-phase ΔyggS strain accumulated 2-ketobutyrate, its aminated compound 2-aminobutyrate, and, to a lesser extent, l-Val. It also exhibited a 1.3- to 2.6-fold increase in the levels of Ile and Val metabolic enzymes. The fact that similar phenotypes were induced in wild-type E. coli by the exogenous addition of 2-ketobutyrate and 2-aminobutyrate indicates that the 2 compounds contribute to the ΔyggS phenotypes. We showed that the initial cause of the keto acid imbalance was the reduced availability of coenzyme A (CoA); supplementation with pantothenate, which is a CoA precursor, fully reversed phenotypes conferred by the yggS mutation. The plasmid-borne expression of YggS and orthologs from Bacillus subtilis, Saccharomyces cerevisiae, and humans fully rescued the ΔyggS phenotypes. Expression of a mutant YggS lacking PLP-binding ability, however, did not reverse the ΔyggS phenotypes. These results demonstrate for the first time that YggS controls Ile and Val metabolism by modulating 2-ketobutyrate and CoA availability. Its function depends on PLP, and it is highly conserved in a wide range species, from bacteria to humans.
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Massidda O, Nováková L, Vollmer W. From models to pathogens: how much have we learned about Streptococcus pneumoniae cell division? Environ Microbiol 2013; 15:3133-57. [PMID: 23848140 DOI: 10.1111/1462-2920.12189] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 06/08/2013] [Accepted: 06/09/2013] [Indexed: 12/22/2022]
Abstract
Streptococcus pneumoniae is an oval-shaped Gram-positive coccus that lives in intimate association with its human host, both as a commensal and pathogen. The seriousness of pneumococcal infections and the spread of multi-drug resistant strains call for new lines of intervention. Bacterial cell division is an attractive target to develop antimicrobial drugs. This review discusses the recent advances in understanding S. pneumoniae growth and division, in comparison with the best studied rod-shaped models, Escherichia coli and Bacillus subtilis. To maintain their shape, these bacteria propagate by peripheral and septal peptidoglycan synthesis, involving proteins that assemble into distinct complexes called the elongasome and the divisome, respectively. Many of these proteins are conserved in S. pneumoniae, supporting the notion that the ovococcal shape is also achieved by rounds of elongation and division. Importantly, S. pneumoniae and close relatives with similar morphology differ in several aspects from the model rods. Overall, the data support a model in which a single large machinery, containing both the peripheral and septal peptidoglycan synthesis complexes, assembles at midcell and governs growth and division. The mechanisms generating the ovococcal or coccal shape in lactic-acid bacteria have likely evolved by gene reduction from a rod-shaped ancestor of the same group.
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Affiliation(s)
- Orietta Massidda
- Department of Surgical Sciences, University of Cagliari, Via Porcell, 4, 09100, Cagliari, Italy
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Kim J, Olinares PD, Oh SH, Ghisaura S, Poliakov A, Ponnala L, van Wijk KJ. Modified Clp protease complex in the ClpP3 null mutant and consequences for chloroplast development and function in Arabidopsis. PLANT PHYSIOLOGY 2013; 162:157-79. [PMID: 23548781 PMCID: PMC3641200 DOI: 10.1104/pp.113.215699] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Accepted: 03/27/2013] [Indexed: 05/18/2023]
Abstract
The plastid ClpPRT protease consists of two heptameric rings of ClpP1/ClpR1/ClpR2/ClpR3/ClpR4 (the R-ring) and ClpP3/ClpP4/ClpP5/ClpP6 (the P-ring) and peripherally associated ClpT1/ClpT2 subunits. Here, we address the contributions of ClpP3 and ClpP4 to ClpPRT core organization and function in Arabidopsis (Arabidopsis thaliana). ClpP4 is strictly required for embryogenesis, similar to ClpP5. In contrast, loss of ClpP3 (clpp3-1) leads to arrest at the hypocotyl stage; this developmental arrest can be removed by supplementation with sucrose or glucose. Heterotrophically grown clpp3-1 can be transferred to soil and generate viable seed, which is surprising, since we previously showed that CLPR2 and CLPR4 null alleles are always sterile and die on soil. Based on native gels and mass spectrometry-based quantification, we show that despite the loss of ClpP3, modified ClpPR core(s) could be formed, albeit at strongly reduced levels. A large portion of ClpPR subunits accumulated in heptameric rings, with overaccumulation of ClpP1/ClpP5/ClpP6 and ClpR3. Remarkably, the association of ClpT1 to the modified Clp core was unchanged. Large-scale quantitative proteomics assays of clpp3-1 showed a 50% loss of photosynthetic capacity and the up-regulation of plastoglobules and all chloroplast stromal chaperone systems. Specific chloroplast proteases were significantly up-regulated, whereas the major thylakoid protease (FtsH1/FtsH2/FtsH5/FtsH8) was clearly unchanged, indicating a controlled protease network response. clpp3-1 showed a systematic decrease of chloroplast-encoded proteins that are part of the photosynthetic apparatus but not of chloroplast-encoded proteins with other functions. Candidate substrates and an explanation for the differential phenotypes between the CLPP3, CLPP4, and CLPP5 null mutants are discussed.
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Kabeya Y, Miyagishima SY. Chloroplast DNA replication is regulated by the redox state independently of chloroplast division in Chlamydomonas reinhardtii. PLANT PHYSIOLOGY 2013; 161:2102-12. [PMID: 23447524 PMCID: PMC3613479 DOI: 10.1104/pp.113.216291] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Chloroplasts arose from a cyanobacterial endosymbiont and multiply by division. In algal cells, chloroplast division is regulated by the cell cycle so as to occur only once, in the S phase. Chloroplasts possess multiple copies of their own genome that must be replicated during chloroplast proliferation. In order to examine how chloroplast DNA replication is regulated in the green alga Chlamydomonas reinhardtii, we first asked whether it is regulated by the cell cycle, as is the case for chloroplast division. Chloroplast DNA is replicated in the light and not the dark phase, independent of the cell cycle or the timing of chloroplast division in photoautotrophic culture. Inhibition of photosynthetic electron transfer blocked chloroplast DNA replication. However, chloroplast DNA was replicated when the cells were grown heterotrophically in the dark, raising the possibility that chloroplast DNA replication is coupled with the reducing power supplied by photosynthesis or the uptake of acetate. When dimethylthiourea, a reactive oxygen species scavenger, was added to the photoautotrophic culture, chloroplast DNA was replicated even in the dark. In contrast, when methylviologen, a reactive oxygen species inducer, was added, chloroplast DNA was not replicated in the light. Moreover, the chloroplast DNA replication activity in both the isolated chloroplasts and nucleoids was increased by dithiothreitol, while it was repressed by diamide, a specific thiol-oxidizing reagent. These results suggest that chloroplast DNA replication is regulated by the redox state that is sensed by the nucleoids and that the disulfide bonds in nucleoid-associated proteins are involved in this regulatory activity.
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Krupinska K, Melonek J, Krause K. New insights into plastid nucleoid structure and functionality. PLANTA 2013; 237:653-64. [PMID: 23212213 DOI: 10.1007/s00425-012-1817-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Accepted: 11/09/2012] [Indexed: 05/04/2023]
Abstract
Investigations over many decades have revealed that nucleoids of higher plant plastids are highly dynamic with regard to their number, their structural organization and protein composition. Membrane attachment and environmental cues seem to determine the activity and functionality of the nucleoids and point to a highly regulated structure-function relationship. The heterogeneous composition and the many functions that are seemingly associated with the plastid nucleoids could be related to the high number of chromosomes per plastid. Recent proteomic studies have brought novel nucleoid-associated proteins into the spotlight and indicated that plastid nucleoids are an evolutionary hybrid possessing prokaryotic nucleoid features and eukaryotic (nuclear) chromatin components, several of which are dually targeted to the nucleus and chloroplasts. Future studies need to unravel if and how plastid-nucleus communication depends on nucleoid structure and plastid gene expression.
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Affiliation(s)
- Karin Krupinska
- Institute of Botany, University of Kiel, Olshausenstraße 40, 24098, Kiel, Germany.
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Shanmugabalaji V, Besagni C, Piller LE, Douet V, Ruf S, Bock R, Kessler F. Dual targeting of a mature plastoglobulin/fibrillin fusion protein to chloroplast plastoglobules and thylakoids in transplastomic tobacco plants. PLANT MOLECULAR BIOLOGY 2013; 81:13-25. [PMID: 23086498 DOI: 10.1007/s11103-012-9977-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Accepted: 10/08/2012] [Indexed: 05/10/2023]
Abstract
Plastoglobules (PG) are lipid droplets in chloroplasts and other plastid types having important functions in lipid metabolism. Plastoglobulins (PGL) also known as fibrillins (FBN) are evolutionary conserved proteins present at the PG surface but also to various extents at the thylakoid membrane. PGLs are thought to have structural functions in PG formation and maintenance. The targeting of an Arabidopsis PGL (PGL34) to PG required the full protein sequence with the exception of a short C-terminal stretch. This indicated that PGL targeting relies on correct folding rather than a discrete sequence. PGLs lack strongly hydrophic regions and may therefore extrinsically associate with PG and thylakoid membranes via interaction with hydrophilic headgroups of surface lipids. Here, we report on the expression of the Arabidopsis plastoglobulin of 35kD (PGL35 or FBN1a) expressed as a mature protein fused to HIVp24 (human immunodeficiency virus capsid particle p24) or HCV (hepatitis C virus core protein) in transplastomic tobacco. A PGL35-HIVp24 fusion targeted in part to plastoglobules but a larger proportion was recovered in the thylakoid fraction. The findings indicate that transplastomic PGL35-HIVp24 folded correctly after its synthesis inside the chloroplast and then dually targeted to plastoglobules as well as thylakoid membranes.
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Kobayashi K, Narise T, Sonoike K, Hashimoto H, Sato N, Kondo M, Nishimura M, Sato M, Toyooka K, Sugimoto K, Wada H, Masuda T, Ohta H. Role of galactolipid biosynthesis in coordinated development of photosynthetic complexes and thylakoid membranes during chloroplast biogenesis in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 73:250-61. [PMID: 22978702 DOI: 10.1111/tpj.12028] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2011] [Revised: 08/21/2012] [Accepted: 09/10/2012] [Indexed: 05/17/2023]
Abstract
The galactolipids monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) are the predominant lipids in thylakoid membranes and indispensable for photosynthesis. Among the three isoforms that catalyze MGDG synthesis in Arabidopsis thaliana, MGD1 is responsible for most galactolipid synthesis in chloroplasts, whereas MGD2 and MGD3 are required for DGDG accumulation during phosphate (Pi) starvation. A null mutant of Arabidopsis MGD1 (mgd1-2), which lacks both galactolipids and shows a severe defect in chloroplast biogenesis under nutrient-sufficient conditions, accumulated large amounts of DGDG, with a strong induction of MGD2/3 expression, during Pi starvation. In plastids of Pi-starved mgd1-2 leaves, biogenesis of thylakoid-like internal membranes, occasionally associated with invagination of the inner envelope, was observed, together with chlorophyll accumulation. Moreover, the mutant accumulated photosynthetic membrane proteins upon Pi starvation, indicating a compensation for MGD1 deficiency by Pi stress-induced galactolipid biosynthesis. However, photosynthetic activity in the mutant was still abolished, and light-harvesting/photosystem core complexes were improperly formed, suggesting a requirement for MGDG for proper assembly of these complexes. During Pi starvation, distribution of plastid nucleoids changed concomitantly with internal membrane biogenesis in the mgd1-2 mutant. Moreover, the reduced expression of nuclear- and plastid-encoded photosynthetic genes observed in the mgd1-2 mutant under Pi-sufficient conditions was restored after Pi starvation. In contrast, Pi starvation had no such positive effects in mutants lacking chlorophyll biosynthesis. These observations demonstrate that galactolipid biosynthesis and subsequent membrane biogenesis inside the plastid strongly influence nucleoid distribution and the expression of both plastid- and nuclear-encoded photosynthetic genes, independently of photosynthesis.
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Affiliation(s)
- Koichi Kobayashi
- Graduate School of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Tokyo, 153-8902, Japan
- RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan
| | - Takafumi Narise
- Center for Biological Resources and Informatics, Tokyo Institute of Technology, 4259-B-65 Nagatsuta-cho, Yokohama, 226-8501, Midori-ku, Japan
| | - Kintake Sonoike
- Faculty of Education and Integrated Arts and Sciences, Waseda University, 2-2 Wakamatsu-cho, Tokyo, 162-8480, Shinjuku-ku, Japan
| | - Haruki Hashimoto
- Graduate School of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Tokyo, 153-8902, Japan
| | - Naoki Sato
- Graduate School of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Tokyo, 153-8902, Japan
| | - Maki Kondo
- Department of Cell Biology, National Institute for Basic Biology, Okazaki, 444-8585, Japan
| | - Mikio Nishimura
- Department of Cell Biology, National Institute for Basic Biology, Okazaki, 444-8585, Japan
| | - Mayuko Sato
- RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan
| | - Kiminori Toyooka
- RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan
| | - Keiko Sugimoto
- RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan
| | - Hajime Wada
- Graduate School of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Tokyo, 153-8902, Japan
| | - Tatsuru Masuda
- Graduate School of Arts and Sciences, University of Tokyo, Komaba 3-8-1, Tokyo, 153-8902, Japan
| | - Hiroyuki Ohta
- Center for Biological Resources and Informatics, Tokyo Institute of Technology, 4259-B-65 Nagatsuta-cho, Yokohama, 226-8501, Midori-ku, Japan
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Development-Dependent Changes in the Amount and Structural Organization of Plastid DNA. PLASTID DEVELOPMENT IN LEAVES DURING GROWTH AND SENESCENCE 2013. [DOI: 10.1007/978-94-007-5724-0_11] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Majeran W, Friso G, Asakura Y, Qu X, Huang M, Ponnala L, Watkins KP, Barkan A, van Wijk KJ. Nucleoid-enriched proteomes in developing plastids and chloroplasts from maize leaves: a new conceptual framework for nucleoid functions. PLANT PHYSIOLOGY 2012; 158:156-89. [PMID: 22065420 PMCID: PMC3252073 DOI: 10.1104/pp.111.188474] [Citation(s) in RCA: 182] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Accepted: 11/06/2011] [Indexed: 05/18/2023]
Abstract
Plastids contain multiple copies of the plastid chromosome, folded together with proteins and RNA into nucleoids. The degree to which components of the plastid gene expression and protein biogenesis machineries are nucleoid associated, and the factors involved in plastid DNA organization, repair, and replication, are poorly understood. To provide a conceptual framework for nucleoid function, we characterized the proteomes of highly enriched nucleoid fractions of proplastids and mature chloroplasts isolated from the maize (Zea mays) leaf base and tip, respectively, using mass spectrometry. Quantitative comparisons with proteomes of unfractionated proplastids and chloroplasts facilitated the determination of nucleoid-enriched proteins. This nucleoid-enriched proteome included proteins involved in DNA replication, organization, and repair as well as transcription, mRNA processing, splicing, and editing. Many proteins of unknown function, including pentatricopeptide repeat (PPR), tetratricopeptide repeat (TPR), DnaJ, and mitochondrial transcription factor (mTERF) domain proteins, were identified. Strikingly, 70S ribosome and ribosome assembly factors were strongly overrepresented in nucleoid fractions, but protein chaperones were not. Our analysis strongly suggests that mRNA processing, splicing, and editing, as well as ribosome assembly, take place in association with the nucleoid, suggesting that these processes occur cotranscriptionally. The plastid developmental state did not dramatically change the nucleoid-enriched proteome but did quantitatively shift the predominating function from RNA metabolism in undeveloped plastids to translation and homeostasis in chloroplasts. This study extends the known maize plastid proteome by hundreds of proteins, including more than 40 PPR and mTERF domain proteins, and provides a resource for targeted studies on plastid gene expression. Details of protein identification and annotation are provided in the Plant Proteome Database.
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de Vitry C. Cytochrome c maturation system on the negative side of bioenergetic membranes: CCB or System IV. FEBS J 2011; 278:4189-97. [DOI: 10.1111/j.1742-4658.2011.08373.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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