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Sjuts I, Soll J, Bölter B. Import of Soluble Proteins into Chloroplasts and Potential Regulatory Mechanisms. FRONTIERS IN PLANT SCIENCE 2017; 8:168. [PMID: 28228773 PMCID: PMC5296341 DOI: 10.3389/fpls.2017.00168] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 01/26/2017] [Indexed: 05/20/2023]
Abstract
Chloroplasts originated from an endosymbiotic event in which a free-living cyanobacterium was engulfed by an ancestral eukaryotic host. During evolution the majority of the chloroplast genetic information was transferred to the host cell nucleus. As a consequence, proteins formerly encoded by the chloroplast genome are now translated in the cytosol and must be subsequently imported into the chloroplast. This process involves three steps: (i) cytosolic sorting procedures, (ii) binding to the designated receptor-equipped target organelle and (iii) the consecutive translocation process. During import, proteins have to overcome the two barriers of the chloroplast envelope, namely the outer envelope membrane (OEM) and the inner envelope membrane (IEM). In the majority of cases, this is facilitated by two distinct multiprotein complexes, located in the OEM and IEM, respectively, designated TOC and TIC. Plants are constantly exposed to fluctuating environmental conditions such as temperature and light and must therefore regulate protein composition within the chloroplast to ensure optimal functioning of elementary processes such as photosynthesis. In this review we will discuss the recent models of each individual import stage with regard to short-term strategies that plants might use to potentially acclimate to changes in their environmental conditions and preserve the chloroplast protein homeostasis.
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Affiliation(s)
- Inga Sjuts
- Department Biologie I-Botanik, Ludwig-Maximilians-UniversitätPlanegg-Martinsried, Germany
| | - Jürgen Soll
- Department Biologie I-Botanik, Ludwig-Maximilians-UniversitätPlanegg-Martinsried, Germany
- Munich Center for Integrated Protein Science CiPSM, Ludwig-Maximilians-UniversitätMunich, Germany
| | - Bettina Bölter
- Department Biologie I-Botanik, Ludwig-Maximilians-UniversitätPlanegg-Martinsried, Germany
- Munich Center for Integrated Protein Science CiPSM, Ludwig-Maximilians-UniversitätMunich, Germany
- *Correspondence: Bettina Bölter,
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153
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Ravin NV, Gruzdev EV, Beletsky AV, Mazur AM, Prokhortchouk EB, Filyushin MA, Kochieva EZ, Kadnikov VV, Mardanov AV, Skryabin KG. The loss of photosynthetic pathways in the plastid and nuclear genomes of the non-photosynthetic mycoheterotrophic eudicot Monotropa hypopitys. BMC PLANT BIOLOGY 2016; 16:238. [PMID: 28105941 PMCID: PMC5123295 DOI: 10.1186/s12870-016-0929-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
BACKGROUND Chloroplasts of most plants are responsible for photosynthesis and contain a conserved set of about 110 genes that encode components of housekeeping gene expression machinery and photosynthesis-related functions. Heterotrophic plants obtaining nutrients from other organisms and their plastid genomes represent model systems in which to study the effects of relaxed selective pressure on photosynthetic function. The most evident is a reduction in the size and gene content of the plastome, which correlates with the loss of genes encoding photosynthetic machinery which become unnecessary. Transition to a non-photosynthetic lifestyle is expected also to relax the selective pressure on photosynthetic machinery in the nuclear genome, however, the corresponding changes are less known. RESULTS Here we report the complete sequence of the plastid genome of Monotropa hypopitys, an achlorophyllous obligately mycoheterotrophic plant belonging to the family Ericaceae. The plastome of M. hypopitys is greatly reduced in size (35,336 bp) and lacks the typical quadripartite structure with two single-copy regions and an inverted repeat. Only 45 genes remained presumably intact- those encoding ribosomal proteins, ribosomal and transfer RNA and housekeeping genes infA, matK, accD and clpP. The clpP and accD genes probably remain functional, although their sequences are highly diverged. The sets of genes for ribosomal protein and transfer RNA are incomplete relative to chloroplasts of a photosynthetic plant. Comparison of the plastid genomes of two subspecies-level isolates of M. hypopitys revealed major structural rearrangements associated with repeat-driven recombination and the presence of isolate-specific tRNA genes. Analysis of the M. hypopitys transcriptome by RNA-Seq showed the absence of expression of nuclear-encoded components of photosystem I and II reaction center proteins, components of cytochrome b6f complex, ATP synthase, ribulose bisphosphate carboxylase components, as well as chlorophyll from protoporphyrin IX biosynthesis pathway. CONCLUSIONS With the complete loss of genes related to photosynthesis, NADH dehydrogenase, plastid-encoded RNA polymerase and ATP synthase, the M. hypopitys plastid genome is among the most functionally reduced ones characteristic of obligate non-photosynthetic parasitic species. Analysis of the M. hypopitys transcriptome revealed coordinated evolution of the nuclear and plastome genomes and the loss of photosynthesis-related functions in both genomes.
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Affiliation(s)
- Nikolai V. Ravin
- Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russia
| | - Eugeny V. Gruzdev
- Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russia
| | - Alexey V. Beletsky
- Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russia
| | - Alexander M. Mazur
- Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russia
| | - Egor B. Prokhortchouk
- Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russia
| | - Mikhail A. Filyushin
- Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russia
| | - Elena Z. Kochieva
- Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russia
| | - Vitaly V. Kadnikov
- Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russia
| | - Andrey V. Mardanov
- Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russia
| | - Konstantin G. Skryabin
- Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russia
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154
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Wagner R, von Sydow L, Aigner H, Netotea S, Brugière S, Sjögren L, Ferro M, Clarke A, Funk C. Deletion of FtsH11 protease has impact on chloroplast structure and function in Arabidopsis thaliana when grown under continuous light. PLANT, CELL & ENVIRONMENT 2016; 39:2530-2544. [PMID: 27479913 DOI: 10.1111/pce.12808] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Revised: 07/12/2016] [Accepted: 07/17/2016] [Indexed: 05/20/2023]
Abstract
The membrane-integrated metalloprotease FtsH11 of Arabidopsis thaliana is proposed to be dual-targeted to mitochondria and chloroplasts. A bleached phenotype was observed in ftsh11 grown at long days or continuous light, pointing to disturbances in the chloroplast. Within the chloroplast, FtsH11 was found to be located exclusively in the envelope. Two chloroplast-located proteins of unknown function (Tic22-like protein and YGGT-A) showed significantly higher abundance in envelope membranes and intact chloroplasts of ftsh11 and therefore qualify as potential substrates for the FtsH11 protease. No proteomic changes were observed in the mitochondria of 6-week-old ftsh11 compared with wild type, and FtsH11 was not immunodetected in these organelles. The abundance of plastidic proteins, especially of photosynthetic proteins, was altered even during standard growth conditions in total leaves of ftsh11. At continuous light, the amount of photosystem I decreased relative to photosystem II, accompanied by a drastic change of the chloroplast morphology and a drop of non-photochemical quenching. FtsH11 is crucial for chloroplast structure and function during growth in prolonged photoperiod.
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Affiliation(s)
- Raik Wagner
- Department of Chemistry, Umeå University, SE-901 87, Umeå, Sweden
| | - Lotta von Sydow
- Department of Chemistry, Umeå University, SE-901 87, Umeå, Sweden
| | - Harald Aigner
- Department of Chemistry, Umeå University, SE-901 87, Umeå, Sweden
| | - Sergiu Netotea
- Department of Chemistry, Umeå University, SE-901 87, Umeå, Sweden
- Bioinformatics Infrastructure for Life Sciences (BILS), Linköping, Sweden
| | - Sabine Brugière
- U1038 INSERM/CEA/UJ, Institut de Recherches en Technologies et Sciences pour le Vivant, Grenoble, Cedex 9, France
| | - Lars Sjögren
- Department of Biological and Environmental Sciences, Gothenburg University, 40530, Gothenburg, Sweden
| | - Myriam Ferro
- U1038 INSERM/CEA/UJ, Institut de Recherches en Technologies et Sciences pour le Vivant, Grenoble, Cedex 9, France
| | - Adrian Clarke
- Department of Biological and Environmental Sciences, Gothenburg University, 40530, Gothenburg, Sweden
| | - Christiane Funk
- Department of Chemistry, Umeå University, SE-901 87, Umeå, Sweden.
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155
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Parker N, Wang Y, Meinke D. Analysis of Arabidopsis Accessions Hypersensitive to a Loss of Chloroplast Translation. PLANT PHYSIOLOGY 2016; 172:1862-1875. [PMID: 27707889 PMCID: PMC5100756 DOI: 10.1104/pp.16.01291] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 10/03/2016] [Indexed: 05/04/2023]
Abstract
Natural accessions of Arabidopsis (Arabidopsis thaliana) differ in their ability to tolerate a loss of chloroplast translation. These differences can be attributed in part to variation in a duplicated nuclear gene (ACC2) that targets homomeric acetyl-coenzyme A carboxylase (ACCase) to plastids. This functional redundancy allows limited fatty acid biosynthesis to occur in the absence of heteromeric ACCase, which is encoded in part by the plastid genome. In the presence of functional ACC2, tolerant alleles of several nuclear genes, not yet identified, enhance the growth of seedlings and embryos disrupted in chloroplast translation. ACC2 knockout mutants, by contrast, are hypersensitive. Here we describe an expanded search for hypersensitive accessions of Arabidopsis, evaluate whether all of these accessions are defective in ACC2, and characterize genotype-to-phenotype relationships for homomeric ACCase variants identified among 855 accessions with sequenced genomes. Null alleles with ACC2 nonsense mutations, frameshift mutations, small deletions, genomic rearrangements, and defects in RNA splicing are included among the most sensitive accessions examined. By contrast, most missense mutations affecting highly conserved residues failed to eliminate ACC2 function. Several accessions were identified where sensitivity could not be attributed to a defect in either ACC2 or Tic20-IV, the chloroplast membrane channel required for ACC2 uptake. Overall, these results underscore the central role of ACC2 in mediating Arabidopsis response to a loss of chloroplast translation, highlight future applications of this system to analyzing chloroplast protein import, and provide valuable insights into the mutational landscape of an important metabolic enzyme that is highly conserved throughout eukaryotes.
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Affiliation(s)
- Nicole Parker
- Department of Plant Biology, Ecology, and Evolution, Oklahoma State University, Stillwater, Oklahoma 74078
| | - Yixing Wang
- Department of Plant Biology, Ecology, and Evolution, Oklahoma State University, Stillwater, Oklahoma 74078
| | - David Meinke
- Department of Plant Biology, Ecology, and Evolution, Oklahoma State University, Stillwater, Oklahoma 74078
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156
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Wollman FA. An antimicrobial origin of transit peptides accounts for early endosymbiotic events. Traffic 2016; 17:1322-1328. [DOI: 10.1111/tra.12446] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 09/07/2016] [Accepted: 09/08/2016] [Indexed: 12/11/2022]
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157
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Olejniczak SA, Łojewska E, Kowalczyk T, Sakowicz T. Chloroplasts: state of research and practical applications of plastome sequencing. PLANTA 2016; 244:517-27. [PMID: 27259501 PMCID: PMC4983300 DOI: 10.1007/s00425-016-2551-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 05/29/2016] [Indexed: 05/07/2023]
Abstract
This review presents origins, structure and expression of chloroplast genomes. It also describes their sequencing, analysis and modification, focusing on potential practical uses and biggest challenges of chloroplast genome modification. During the evolution of eukaryotes, cyanobacteria are believed to have merged with host heterotrophic cell. Afterward, most of cyanobacterial genes from cyanobacteria were transferred to cell nucleus or lost in the process of endosymbiosis. As a result of these changes, a primary plastid was established. Nowadays, plastid genome (plastome) is almost always circular, has a size of 100-200 kbp (120-160 in land plants), and harbors 100-120 highly conserved unique genes. Plastids have their own gene expression system, which is similar to one of their cyanobacterial ancestors. Two different polymerases, plastid-derived PEP and nucleus-derived NEP, participate in transcription. Translation is similar to the one observed in cyanobacteria, but it also utilizes protein translation factors and positive regulatory mRNA elements absent from bacteria. Plastoms play an important role in genetic transformation. Transgenes are introduced into them either via gene gun (in undamaged tissues) or polyethylene glycol treatment (when protoplasts are targeted). Antibiotic resistance markers are the most common tool used for selection of transformed plants. In recent years, plastome transformation emerged as a promising alternative to nuclear transformation because of (1) high yield of target protein, (2) removing the risk of outcrossing with weeds, (3) lack of silencing mechanisms, and (4) ability to engineer the entire metabolic pathways rather than single gene traits. Currently, the main directions of such research regard: developing efficient enzyme, vaccine antigen, and biopharmaceutical protein production methods in plant cells and improving crops by increasing their resistance to a wide array of biotic and abiotic stresses. Because of that, the detailed knowledge of plastome structure and mechanism of functioning started to play a major role.
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Affiliation(s)
- Szymon Adam Olejniczak
- Department of Genetics and Plant Molecular Biology and Biotechnology, The University of Lodz, Banacha Street 12/16, 90-237, Lodz, Poland.
| | - Ewelina Łojewska
- Department of Genetics and Plant Molecular Biology and Biotechnology, The University of Lodz, Banacha Street 12/16, 90-237, Lodz, Poland
| | - Tomasz Kowalczyk
- Department of Genetics and Plant Molecular Biology and Biotechnology, The University of Lodz, Banacha Street 12/16, 90-237, Lodz, Poland
| | - Tomasz Sakowicz
- Department of Genetics and Plant Molecular Biology and Biotechnology, The University of Lodz, Banacha Street 12/16, 90-237, Lodz, Poland
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158
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Logacheva MD, Schelkunov MI, Shtratnikova VY, Matveeva MV, Penin AA. Comparative analysis of plastid genomes of non-photosynthetic Ericaceae and their photosynthetic relatives. Sci Rep 2016; 6:30042. [PMID: 27452401 PMCID: PMC4958920 DOI: 10.1038/srep30042] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 06/27/2016] [Indexed: 12/24/2022] Open
Abstract
Although plastid genomes of flowering plants are typically highly conserved regarding their size, gene content and order, there are some exceptions. Ericaceae, a large and diverse family of flowering plants, warrants special attention within the context of plastid genome evolution because it includes both non-photosynthetic and photosynthetic species with rearranged plastomes and putative losses of "essential" genes. We characterized plastid genomes of three species of Ericaceae, non-photosynthetic Monotropa uniflora and Hypopitys monotropa and photosynthetic Pyrola rotundifolia, using high-throughput sequencing. As expected for non-photosynthetic plants, M. uniflora and H. monotropa have small plastid genomes (46 kb and 35 kb, respectively) lacking genes related to photosynthesis, whereas P. rotundifolia has a larger genome (169 kb) with a gene set similar to other photosynthetic plants. The examined genomes contain an unusually high number of repeats and translocations. Comparative analysis of the expanded set of Ericaceae plastomes suggests that the genes clpP and accD that are present in the plastid genomes of almost all plants have not been lost in this family (as was previously thought) but rather persist in these genomes in unusual forms. Also we found a new gene in P. rotundifolia that emerged as a result of duplication of rps4 gene.
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Affiliation(s)
- Maria D. Logacheva
- Lomonosov Moscow State University, A.N Belozersky Institute of Physico-Chemical Biology, Moscow, Russia
- Kazan Federal University, Institute of Fundamental Biology and Medicine, Kazan, Russia
| | - Mikhail I. Schelkunov
- Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russia
| | - Victoria Y. Shtratnikova
- Lomonosov Moscow State University, Department of Bioengineering and Bioinformatics, Moscow, Russia
| | - Maria V. Matveeva
- Kazan Federal University, Institute of Fundamental Biology and Medicine, Kazan, Russia
| | - Aleksey A. Penin
- Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russia
- Lomonosov Moscow State University, Department of Genetics, Moscow, Russia
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159
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Suzuki S, Hirakawa Y, Kofuji R, Sugita M, Ishida KI. Plastid genome sequences of Gymnochlora stellata, Lotharella vacuolata, and Partenskyella glossopodia reveal remarkable structural conservation among chlorarachniophyte species. JOURNAL OF PLANT RESEARCH 2016; 129:581-590. [PMID: 26920842 DOI: 10.1007/s10265-016-0804-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 12/21/2015] [Indexed: 06/05/2023]
Abstract
Chlorarachniophyte algae have complex plastids acquired by the uptake of a green algal endosymbiont, and this event is called secondary endosymbiosis. Interestingly, the plastids possess a relict endosymbiont nucleus, referred to as the nucleomorph, in the intermembrane space, and the nucleomorphs contain an extremely reduced and compacted genome in comparison with green algal nuclear genomes. Therefore, chlorarachniophyte plastids consist of two endosymbiotically derived genomes, i.e., the plastid and nucleomorph genomes. To date, complete nucleomorph genomes have been sequenced in four different species, whereas plastid genomes have been reported in only two species in chlorarachniophytes. To gain further insight into the evolution of endosymbiotic genomes in chlorarachniophytes, we newly sequenced the plastid genomes of three species, Gymnochlora stellata, Lotharella vacuolata, and Partenskyella glossopodia. Our findings reveal that chlorarachniophyte plastid genomes are highly conserved in size, gene content, and gene order among species, but their nucleomorph genomes are divergent in such features. Accordingly, the current architecture of the plastid genomes of chlorarachniophytes evolved in a common ancestor, and changed very little during their subsequent diversification. Furthermore, our phylogenetic analyses using multiple plastid genes suggest that chlorarachniophyte plastids are derived from a green algal lineage that is closely related to Bryopsidales in the Ulvophyceae group.
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Affiliation(s)
- Shigekatsu Suzuki
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan
| | - Yoshihisa Hirakawa
- Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan
| | - Rumiko Kofuji
- Graduate School of Natural Science and Technology, Kanazawa University, Ishikawa, Japan
| | - Mamoru Sugita
- Center for Gene Research, Nagoya University, Aichi, Japan
| | - Ken-Ichiro Ishida
- Faculty of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan.
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160
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Yang Y, Zhou T, Duan D, Yang J, Feng L, Zhao G. Comparative Analysis of the Complete Chloroplast Genomes of Five Quercus Species. FRONTIERS IN PLANT SCIENCE 2016; 7:959. [PMID: 27446185 PMCID: PMC4923075 DOI: 10.3389/fpls.2016.00959] [Citation(s) in RCA: 144] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 06/15/2016] [Indexed: 05/08/2023]
Abstract
Quercus is considered economically and ecologically one of the most important genera in the Northern Hemisphere. Oaks are taxonomically perplexing because of shared interspecific morphological traits and intraspecific morphological variation, which are mainly attributed to hybridization. Universal plastid markers cannot provide a sufficient number of variable sites to explore the phylogeny of this genus, and chloroplast genome-scale data have proven to be useful in resolving intractable phylogenetic relationships. In this study, the complete chloroplast genomes of four Quercus species were sequenced, and one published chloroplast genome of Quercus baronii was retrieved for comparative analyses. The five chloroplast genomes ranged from 161,072 bp (Q. baronii) to 161,237 bp (Q. dolicholepis) in length, and their gene organization and order, and GC content, were similar to those of other Fagaceae species. We analyzed nucleotide substitutions, indels, and repeats in the chloroplast genomes, and found 19 relatively highly variable regions that will potentially provide plastid markers for further taxonomic and phylogenetic studies within Quercus. We observed that four genes (ndhA, ndhK, petA, and ycf1) were subject to positive selection. The phylogenetic relationships of the Quercus species inferred from the chloroplast genomes obtained moderate-to-high support, indicating that chloroplast genome data may be useful in resolving relationships in this genus.
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Affiliation(s)
| | | | | | | | | | - Guifang Zhao
- Key Laboratory of Resource Biology and Biotechnology in Western China (Ministry of Education), College of Life Sciences, Northwest UniversityXi’an, China
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161
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Bölter B, Soll J. Once upon a Time - Chloroplast Protein Import Research from Infancy to Future Challenges. MOLECULAR PLANT 2016; 9:798-812. [PMID: 27142186 DOI: 10.1016/j.molp.2016.04.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 04/25/2016] [Accepted: 04/27/2016] [Indexed: 05/08/2023]
Abstract
Protein import into chloroplasts has been a focus of research for several decades. The first publications dealing with this fascinating topic appeared in the 1970s. From the initial realization that many plastid proteins are being encoded for in the nucleus and require transport into their target organelle to the identification of import components in the cytosol, chloroplast envelopes, and stroma, as well as elucidation of some mechanistic details, more fascinating aspects are still being unraveled. With this overview, we present a survey of the beginnings of chloroplast protein import research, the first steps on this winding road, and end with a glimpse into the future.
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Affiliation(s)
- Bettina Bölter
- Department Biologie I-Botanik, Ludwig-Maximilians-Universität, Großhaderner Straße 2-4, 82152 Planegg-Martinsried, Germany; Munich Center for Integrated Protein Science CiPSM, Ludwig-Maximilians-Universität, Feodor-Lynen-Strasse 25, 81377 Munich, Germany.
| | - Jürgen Soll
- Department Biologie I-Botanik, Ludwig-Maximilians-Universität, Großhaderner Straße 2-4, 82152 Planegg-Martinsried, Germany; Munich Center for Integrated Protein Science CiPSM, Ludwig-Maximilians-Universität, Feodor-Lynen-Strasse 25, 81377 Munich, Germany
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162
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PBR1 selectively controls biogenesis of photosynthetic complexes by modulating translation of the large chloroplast gene Ycf1 in Arabidopsis. Cell Discov 2016; 2:16003. [PMID: 27462450 PMCID: PMC4870678 DOI: 10.1038/celldisc.2016.3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 01/27/2016] [Indexed: 11/14/2022] Open
Abstract
The biogenesis of photosystem I (PSI), cytochrome b6f (Cytb6f) and NADH dehydrogenase (NDH) complexes relies on the spatially and temporally coordinated expression and translation of both nuclear and chloroplast genes. Here we report the identification of photosystem biogenesis regulator 1 (PBR1), a nuclear-encoded chloroplast RNA-binding protein that regulates the concerted biogenesis of NDH, PSI and Cytb6f complexes. We identified Ycf1, one of the two largest chloroplast genome-encoded open reading frames as the direct downstream target protein of PBR1. Biochemical and molecular analyses reveal that PBR1 regulates Ycf1 translation by directly binding to its mRNA. Surprisingly, we further demonstrate that relocation of the chloroplast gene Ycf1 fused with a plastid-transit sequence to the nucleus bypasses the requirement of PBR1 for Ycf1 translation, which sufficiently complements the defects in biogenesis of NDH, PSI and Cytb6f complexes in PBR1-deficient plants. Remarkably, the nuclear-encoded PBR1 tightly controls the expression of the chloroplast gene Ycf1 at the translational level, which is sufficient to sustain the coordinated biogenesis of NDH, PSI and Cytb6f complexes as a whole. Our findings provide deep insights into better understanding of how a predominant nuclear-encoded factor can act as a migratory mediator and undergoes selective translational regulation of the target plastid gene in controlling biogenesis of photosynthetic complexes.
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163
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Uehara S, Adachi F, Ito-Inaba Y, Inaba T. Specific and Efficient Targeting of Cyanobacterial Bicarbonate Transporters to the Inner Envelope Membrane of Chloroplasts in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2016; 7:16. [PMID: 26870048 PMCID: PMC4735556 DOI: 10.3389/fpls.2016.00016] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 01/08/2016] [Indexed: 05/18/2023]
Abstract
Installation of cyanobacterial bicarbonate transporters to the inner envelope membrane (IEM) of chloroplasts in C3 plants has been thought to improve photosynthetic performance. However, the method to deliver cyanobacterial bicarbonate transporters to the chloroplast IEM remains to be established. In this study, we provide evidence that the cyanobacterial bicarbonate transporters, BicA and SbtA, can be specifically installed into the chloroplast IEM using the chloroplast IEM targeting signal in conjunction with the transit peptide. We fused the transit peptide and the mature portion of Cor413im1, whose targeting mechanism to the IEM has been characterized in detail, to either BicA or SbtA isolated from Synechocystis sp. PCC6803. Among the seven chimeric constructs tested, we confirmed that four chimeric bicarbonate transporters, designated as BicAI, BicAII, SbtAII, and SbtAIII, were expressed in Arabidopsis. Furthermore, these chimeric transporters were specifically targeted to the chloroplast IEM. They were also resistant to alkaline extraction but can be solubilized by Triton X-100, indicating that they are integral membrane proteins in the chloroplast IEM. One of the transporters, BicA, could reside in the chloroplast IEM even after removal of the IEM targeting signal. Taken together, our results indicate that the addition of IEM targeting signal, as well as the transit peptide, to bicarbonate transporters allows us to efficiently target nuclear-encoded chimeric bicarbonate transporters to the chloroplast IEM.
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Affiliation(s)
- Susumu Uehara
- Department of Agricultural and Environmental Sciences, Faculty of Agriculture, University of MiyazakiMiyazaki, Japan
| | - Fumi Adachi
- Department of Agricultural and Environmental Sciences, Faculty of Agriculture, University of MiyazakiMiyazaki, Japan
| | - Yasuko Ito-Inaba
- Department of Agricultural and Environmental Sciences, Faculty of Agriculture, University of MiyazakiMiyazaki, Japan
- Organization for Promotion of Tenure Track, University of MiyazakiMiyazaki, Japan
| | - Takehito Inaba
- Department of Agricultural and Environmental Sciences, Faculty of Agriculture, University of MiyazakiMiyazaki, Japan
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164
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Naumann J, Der JP, Wafula EK, Jones SS, Wagner ST, Honaas LA, Ralph PE, Bolin JF, Maass E, Neinhuis C, Wanke S, dePamphilis CW. Detecting and Characterizing the Highly Divergent Plastid Genome of the Nonphotosynthetic Parasitic Plant Hydnora visseri (Hydnoraceae). Genome Biol Evol 2016; 8:345-63. [PMID: 26739167 PMCID: PMC4779604 DOI: 10.1093/gbe/evv256] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/15/2015] [Indexed: 11/14/2022] Open
Abstract
Plastid genomes of photosynthetic flowering plants are usually highly conserved in both structure and gene content. However, the plastomes of parasitic and mycoheterotrophic plants may be released from selective constraint due to the reduction or loss of photosynthetic ability. Here we present the greatly reduced and highly divergent, yet functional, plastome of the nonphotosynthetic holoparasite Hydnora visseri (Hydnoraceae, Piperales). The plastome is 27 kb in length, with 24 genes encoding ribosomal proteins, ribosomal RNAs, tRNAs, and a few nonbioenergetic genes, but no genes related to photosynthesis. The inverted repeat and the small single copy region are only approximately 1.5 kb, and intergenic regions have been drastically reduced. Despite extreme reduction, gene order and orientation are highly similar to the plastome of Piper cenocladum, a related photosynthetic plant in Piperales. Gene sequences in Hydnora are highly divergent and several complementary approaches using the highest possible sensitivity were required for identification and annotation of this plastome. Active transcription is detected for all of the protein-coding genes in the plastid genome, and one of two introns is appropriately spliced out of rps12 transcripts. The whole-genome shotgun read depth is 1,400× coverage for the plastome, whereas the mitochondrial genome is covered at 40× and the nuclear genome at 2×. Despite the extreme reduction of the genome and high sequence divergence, the presence of syntenic, long transcriptionally active open-reading frames with distant similarity to other plastid genomes and a high plastome stoichiometry relative to the mitochondrial and nuclear genomes suggests that the plastome remains functional in H. visseri. A four-stage model of gene reduction, including the potential for complete plastome loss, is proposed to account for the range of plastid genomes in nonphotosynthetic plants.
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Affiliation(s)
- Julia Naumann
- Institut für Botanik, Technische Universität Dresden, Germany Department of Biology and Institute of Molecular Evolutionary Genetics, The Pennsylvania State University
| | - Joshua P Der
- Department of Biology and Institute of Molecular Evolutionary Genetics, The Pennsylvania State University Department of Biological Science, California State University Fullerton
| | - Eric K Wafula
- Department of Biology and Institute of Molecular Evolutionary Genetics, The Pennsylvania State University
| | - Samuel S Jones
- Department of Biology and Institute of Molecular Evolutionary Genetics, The Pennsylvania State University Intercollege Graduate Program in Plant Biology, The Pennsylvania State University
| | - Sarah T Wagner
- Institut für Botanik, Technische Universität Dresden, Germany
| | - Loren A Honaas
- Department of Biology and Institute of Molecular Evolutionary Genetics, The Pennsylvania State University
| | - Paula E Ralph
- Department of Biology and Institute of Molecular Evolutionary Genetics, The Pennsylvania State University
| | | | - Erika Maass
- Department of Biological Sciences, University of Namibia, Windhoek, Namibia
| | | | - Stefan Wanke
- Institut für Botanik, Technische Universität Dresden, Germany
| | - Claude W dePamphilis
- Department of Biology and Institute of Molecular Evolutionary Genetics, The Pennsylvania State University Intercollege Graduate Program in Plant Biology, The Pennsylvania State University
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165
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López-Millán AF, Duy D, Philippar K. Chloroplast Iron Transport Proteins - Function and Impact on Plant Physiology. FRONTIERS IN PLANT SCIENCE 2016; 7:178. [PMID: 27014281 DOI: 10.3389/fpls201600178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/02/2016] [Indexed: 05/22/2023]
Abstract
Chloroplasts originated about three billion years ago by endosymbiosis of an ancestor of today's cyanobacteria with a mitochondria-containing host cell. During evolution chloroplasts of higher plants established as the site for photosynthesis and thus became the basis for all life dependent on oxygen and carbohydrate supply. To fulfill this task, plastid organelles are loaded with the transition metals iron, copper, and manganese, which due to their redox properties are essential for photosynthetic electron transport. In consequence, chloroplasts for example represent the iron-richest system in plant cells. However, improvement of oxygenic photosynthesis in turn required adaptation of metal transport and homeostasis since metal-catalyzed generation of reactive oxygen species (ROS) causes oxidative damage. This is most acute in chloroplasts, where radicals and transition metals are side by side and ROS-production is a usual feature of photosynthetic electron transport. Thus, on the one hand when bound by proteins, chloroplast-intrinsic metals are a prerequisite for photoautotrophic life, but on the other hand become toxic when present in their highly reactive, radical generating, free ionic forms. In consequence, transport, storage and cofactor-assembly of metal ions in plastids have to be tightly controlled and are crucial throughout plant growth and development. In the recent years, proteins for iron transport have been isolated from chloroplast envelope membranes. Here, we discuss their putative functions and impact on cellular metal homeostasis as well as photosynthetic performance and plant metabolism. We further consider the potential of proteomic analyses to identify new players in the field.
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Affiliation(s)
- Ana F López-Millán
- Department of Pediatrics, Children's Nutrition Research Center, Baylor College of Medicine, United States Department of Agriculture/Agricultural Research Service, Houston TX, USA
| | - Daniela Duy
- Plastid Fatty Acid and Iron Transport - Plant Biochemistry and Physiology, Department Biology I, Ludwig-Maximilians-University of Munich Munich, Germany
| | - Katrin Philippar
- Plastid Fatty Acid and Iron Transport - Plant Biochemistry and Physiology, Department Biology I, Ludwig-Maximilians-University of Munich Munich, Germany
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166
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López-Millán AF, Duy D, Philippar K. Chloroplast Iron Transport Proteins - Function and Impact on Plant Physiology. FRONTIERS IN PLANT SCIENCE 2016; 7:178. [PMID: 27014281 PMCID: PMC4780311 DOI: 10.3389/fpls.2016.00178] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 02/02/2016] [Indexed: 05/08/2023]
Abstract
Chloroplasts originated about three billion years ago by endosymbiosis of an ancestor of today's cyanobacteria with a mitochondria-containing host cell. During evolution chloroplasts of higher plants established as the site for photosynthesis and thus became the basis for all life dependent on oxygen and carbohydrate supply. To fulfill this task, plastid organelles are loaded with the transition metals iron, copper, and manganese, which due to their redox properties are essential for photosynthetic electron transport. In consequence, chloroplasts for example represent the iron-richest system in plant cells. However, improvement of oxygenic photosynthesis in turn required adaptation of metal transport and homeostasis since metal-catalyzed generation of reactive oxygen species (ROS) causes oxidative damage. This is most acute in chloroplasts, where radicals and transition metals are side by side and ROS-production is a usual feature of photosynthetic electron transport. Thus, on the one hand when bound by proteins, chloroplast-intrinsic metals are a prerequisite for photoautotrophic life, but on the other hand become toxic when present in their highly reactive, radical generating, free ionic forms. In consequence, transport, storage and cofactor-assembly of metal ions in plastids have to be tightly controlled and are crucial throughout plant growth and development. In the recent years, proteins for iron transport have been isolated from chloroplast envelope membranes. Here, we discuss their putative functions and impact on cellular metal homeostasis as well as photosynthetic performance and plant metabolism. We further consider the potential of proteomic analyses to identify new players in the field.
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Affiliation(s)
- Ana F. López-Millán
- Department of Pediatrics, Children’s Nutrition Research Center, Baylor College of Medicine, United States Department of Agriculture/Agricultural Research Service, HoustonTX, USA
| | - Daniela Duy
- Plastid Fatty Acid and Iron Transport – Plant Biochemistry and Physiology, Department Biology I, Ludwig-Maximilians-University of MunichMunich, Germany
| | - Katrin Philippar
- Plastid Fatty Acid and Iron Transport – Plant Biochemistry and Physiology, Department Biology I, Ludwig-Maximilians-University of MunichMunich, Germany
- *Correspondence: Katrin Philippar,
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167
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Qiao J, Cai M, Yan G, Wang N, Li F, Chen B, Gao G, Xu K, Li J, Wu X. High-throughput multiplex cpDNA resequencing clarifies the genetic diversity and genetic relationships among Brassica napus, Brassica rapa and Brassica oleracea. PLANT BIOTECHNOLOGY JOURNAL 2016; 14:409-18. [PMID: 26031705 DOI: 10.1111/pbi.12395] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2014] [Revised: 03/26/2015] [Accepted: 04/09/2015] [Indexed: 05/14/2023]
Abstract
Brassica napus (rapeseed) is a recent allotetraploid plant and the second most important oilseed crop worldwide. The origin of B. napus and the genetic relationships with its diploid ancestor species remain largely unresolved. Here, chloroplast DNA (cpDNA) from 488 B. napus accessions of global origin, 139 B. rapa accessions and 49 B. oleracea accessions were populationally resequenced using Illumina Solexa sequencing technologies. The intraspecific cpDNA variants and their allelic frequencies were called genomewide and further validated via EcoTILLING analyses of the rpo region. The cpDNA of the current global B. napus population comprises more than 400 variants (SNPs and short InDels) and maintains one predominant haplotype (Bncp1). Whole-genome resequencing of the cpDNA of Bncp1 haplotype eliminated its direct inheritance from any accession of the B. rapa or B. oleracea species. The distribution of the polymorphism information content (PIC) values for each variant demonstrated that B. napus has much lower cpDNA diversity than B. rapa; however, a vast majority of the wild and cultivated B. oleracea specimens appeared to share one same distinct cpDNA haplotype, in contrast to its wild C-genome relatives. This finding suggests that the cpDNA of the three Brassica species is well differentiated. The predominant B. napus cpDNA haplotype may have originated from uninvestigated relatives or from interactions between cpDNA mutations and natural/artificial selection during speciation and evolution. These exhaustive data on variation in cpDNA would provide fundamental data for research on cpDNA and chloroplasts.
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Affiliation(s)
- Jiangwei Qiao
- Key laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, China
| | - Mengxian Cai
- Key laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, China
| | - Guixin Yan
- Key laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, China
| | - Nian Wang
- Key laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, China
| | - Feng Li
- Key laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, China
| | - Binyun Chen
- Key laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, China
| | - Guizhen Gao
- Key laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, China
| | - Kun Xu
- Key laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, China
| | - Jun Li
- Key laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, China
| | - Xiaoming Wu
- Key laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Wuhan, China
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168
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Colzani M, Altomare A, Caliendo M, Aldini G, Righetti PG, Fasoli E. The secrets of Oriental panacea: Panax ginseng. J Proteomics 2016; 130:150-9. [DOI: 10.1016/j.jprot.2015.09.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 09/11/2015] [Accepted: 09/17/2015] [Indexed: 02/05/2023]
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169
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Bellot S, Renner SS. The Plastomes of Two Species in the Endoparasite Genus Pilostyles (Apodanthaceae) Each Retain Just Five or Six Possibly Functional Genes. Genome Biol Evol 2015; 8:189-201. [PMID: 26660355 PMCID: PMC4758247 DOI: 10.1093/gbe/evv251] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The 23 species of mycoheterotrophic or exoparasitic land plants (from 15 genera and 6 families) studied so far all retain a minimal set of 17 of the normally 116 plastome genes. Only Rafflesia lagascae, an endoparasite concealed in its host except when flowering, has been reported as perhaps lacking a plastome, although it still possesses plastid-like compartments. We analyzed two other endoparasites, the African Apodanthaceae Pilostyles aethiopica and the Australian Pilostyles hamiltonii, both living inside Fabaceae. Illumina and 454 data and Sanger resequencing yielded circularized plastomes of 11,348 and 15,167 bp length, with both species containing five possibly functional genes (accD, rps3, rps4, rrn16, rrn23) and two/three pseudogenes (rpoC2 in P. aethiopica and rpl2 and rps12 in both species; rps12 may be functional in P. hamiltonii). Previously known smallest land plant plastomes contain 27–29 genes, making these Apodanthaceae plastomes the most reduced in size and gene content. A similar extent of divergence might have caused the plastome of Rafflesia to escape detection. The higher plastome degeneration in both these families of endoparasites, Rafflesiaceae and Apodanthaceae, of similar high age, compared with exoparasites points to a difference of plastome function between those two modes of parasitic life.
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Affiliation(s)
- Sidonie Bellot
- Department of Biology, Ludwig Maximilian University, Munich, Germany
| | - Susanne S Renner
- Department of Biology, Ludwig Maximilian University, Munich, Germany
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170
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Li C, Shen Y, Meeley R, McCarty DR, Tan BC. Embryo defective 14 encodes a plastid-targeted cGTPase essential for embryogenesis in maize. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 84:785-799. [PMID: 26771182 DOI: 10.1111/tpj.13045] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 09/24/2015] [Indexed: 06/05/2023]
Abstract
The embryo defective (emb) mutants in maize genetically define a unique class of loci that is required for embryogenesis but not endosperm development, allowing dissection of two developmental processes of seed formation. Through characterization of the emb14 mutant, we report here that Emb14 gene encodes a circular permuted, YqeH class GTPase protein that likely functions in 30S ribosome formation in plastids. Loss of Emb14 function in the null mutant arrests embryogenesis at the early transition stage. Emb14 was cloned by transposon tagging and was confirmed by analysis of four alleles. Subcellular localization indicated that the EMB14 is targeted to chloroplasts. Recombinant EMB14 is shown to hydrolyze GTP in vitro (Km = 2.42 ± 0.3 μm). Emb14 was constitutively expressed in all tissues examined and high level of expression was found in transition stage embryos. Comparison of emb14 and WT indicated that loss of EMB14 function severely impairs accumulation of 16S rRNA and several plastid encoded ribosomal genes. We show that an EMB14 transgene complements the pale green, slow growth phenotype conditioned by mutations in AtNOA1, a closely related YqeH GTPase of Arabidopsis. Taken together, we propose that the EMB14/AtNOA1/YqeH class GTPases function in assembly of the 30S subunit of the chloroplast ribosome, and that this function is essential to embryogenesis in plants.
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Affiliation(s)
- Cuiling Li
- Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Sciences, Shandong University, Jinan, Shandong, 250100, China
| | - Yun Shen
- State Key Lab of Agrobiotechnology, Institute of Plant Molecular Biology and Agrobiotechnology, School of Life Science, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Robert Meeley
- DuPont Pioneer AgBiotech Research, Johnston, Iowa, 50131-1004, USA
| | - Donald R McCarty
- Horticultural Sciences Department, University of Florida, Gainesville, FL, 32611, USA
| | - Bao-Cai Tan
- Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Sciences, Shandong University, Jinan, Shandong, 250100, China
- State Key Lab of Agrobiotechnology, Institute of Plant Molecular Biology and Agrobiotechnology, School of Life Science, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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171
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Kunze M, Berger J. The similarity between N-terminal targeting signals for protein import into different organelles and its evolutionary relevance. Front Physiol 2015; 6:259. [PMID: 26441678 PMCID: PMC4585086 DOI: 10.3389/fphys.2015.00259] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 09/04/2015] [Indexed: 12/04/2022] Open
Abstract
The proper distribution of proteins between the cytosol and various membrane-bound compartments is crucial for the functionality of eukaryotic cells. This requires the cooperation between protein transport machineries that translocate diverse proteins from the cytosol into these compartments and targeting signal(s) encoded within the primary sequence of these proteins that define their cellular destination. The mechanisms exerting protein translocation differ remarkably between the compartments, but the predominant targeting signals for mitochondria, chloroplasts and the ER share the N-terminal position, an α-helical structural element and the removal from the core protein by intraorganellar cleavage. Interestingly, similar properties have been described for the peroxisomal targeting signal type 2 mediating the import of a fraction of soluble peroxisomal proteins, whereas other peroxisomal matrix proteins encode the type 1 targeting signal residing at the extreme C-terminus. The structural similarity of N-terminal targeting signals poses a challenge to the specificity of protein transport, but allows the generation of ambiguous targeting signals that mediate dual targeting of proteins into different compartments. Dual targeting might represent an advantage for adaptation processes that involve a redistribution of proteins, because it circumvents the hierarchy of targeting signals. Thus, the co-existence of two equally functional import pathways into peroxisomes might reflect a balance between evolutionary constant and flexible transport routes.
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Affiliation(s)
- Markus Kunze
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna Vienna, Austria
| | - Johannes Berger
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna Vienna, Austria
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172
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Lee DW, Woo S, Geem KR, Hwang I. Sequence Motifs in Transit Peptides Act as Independent Functional Units and Can Be Transferred to New Sequence Contexts. PLANT PHYSIOLOGY 2015; 169:471-84. [PMID: 26149569 PMCID: PMC4577419 DOI: 10.1104/pp.15.00842] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Accepted: 07/02/2015] [Indexed: 05/04/2023]
Abstract
A large number of nuclear-encoded proteins are imported into chloroplasts after they are translated in the cytosol. Import is mediated by transit peptides (TPs) at the N termini of these proteins. TPs contain many small motifs, each of which is critical for a specific step in the process of chloroplast protein import; however, it remains unknown how these motifs are organized to give rise to TPs with diverse sequences. In this study, we generated various hybrid TPs by swapping domains between Rubisco small subunit (RbcS) and chlorophyll a/b-binding protein, which have highly divergent sequences, and examined the abilities of the resultant TPs to deliver proteins into chloroplasts. Subsequently, we compared the functionality of sequence motifs in the hybrid TPs with those of wild-type TPs. The sequence motifs in the hybrid TPs exhibited three different modes of functionality, depending on their domain composition, as follows: active in both wild-type and hybrid TPs, active in wild-type TPs but inactive in hybrid TPs, and inactive in wild-type TPs but active in hybrid TPs. Moreover, synthetic TPs, in which only three critical motifs from RbcS or chlorophyll a/b-binding protein TPs were incorporated into an unrelated sequence, were able to deliver clients to chloroplasts with a comparable efficiency to RbcS TP. Based on these results, we propose that diverse sequence motifs in TPs are independent functional units that interact with specific translocon components at various steps during protein import and can be transferred to new sequence contexts.
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Affiliation(s)
- Dong Wook Lee
- Division of Integrative Biosciences and Biotechnology (D.W.L., S.W., I.H.) and Department of Life Sciences (K.R.G., I.H.), Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Seungjin Woo
- Division of Integrative Biosciences and Biotechnology (D.W.L., S.W., I.H.) and Department of Life Sciences (K.R.G., I.H.), Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Kyoung Rok Geem
- Division of Integrative Biosciences and Biotechnology (D.W.L., S.W., I.H.) and Department of Life Sciences (K.R.G., I.H.), Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Inhwan Hwang
- Division of Integrative Biosciences and Biotechnology (D.W.L., S.W., I.H.) and Department of Life Sciences (K.R.G., I.H.), Pohang University of Science and Technology, Pohang 790-784, Korea
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173
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Reyes-Prieto A. The basic genetic toolkit to move in with your photosynthetic partner. Front Ecol Evol 2015. [DOI: 10.3389/fevo.2015.00100] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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174
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Nakai M. YCF1: A Green TIC: Response to the de Vries et al. Commentary. THE PLANT CELL 2015; 27:1834-8. [PMID: 26071422 PMCID: PMC4531358 DOI: 10.1105/tpc.15.00363] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 06/01/2015] [Accepted: 06/02/2015] [Indexed: 05/07/2023]
Abstract
This response to a recent Commentary article by de Vries et al. highlights critical errors in the annotation and identification of Ycf1 homologs in the sequenced chloroplast genomes. Contrary to what is reported by de Vries et al., the majority of chloroplast genomes sequenced to date appear to have retained a typical Ycf1 sequence (i.e., including the N-terminal 6TM domain and a variable hydrophilic C-terminal domain) as my group previously reported. Our evidence continues to support the model that Ycf1 forms an essential component of a "green TIC" that is largely conserved among the Chlorophyta and land plants. Since the establishment of this green TIC with Tic20 as the core component, some cases of loss of Ycf1 during the evolution of the green lineages might be regarded as modifications or alterations of the complex. Here, I discuss our working model that the presence of an alternative "nonphotosynthetic-type" or "ancestral-type" TIC might explain other (or specific) cases of the lack of Ycf1, not only in early lineages, including Glaucophyta and Rhodophyta, but also in the grasses.
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Affiliation(s)
- Masato Nakai
- Institute for Protein Research, Osaka University, Suita, Osaka 565-0871, Japan
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175
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Complete Chloroplast Genome of the Wollemi Pine (Wollemia nobilis): Structure and Evolution. PLoS One 2015; 10:e0128126. [PMID: 26061691 PMCID: PMC4464890 DOI: 10.1371/journal.pone.0128126] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Accepted: 04/23/2015] [Indexed: 11/19/2022] Open
Abstract
The Wollemi pine (Wollemia nobilis) is a rare Southern conifer with striking morphological similarity to fossil pines. A small population of W. nobilis was discovered in 1994 in a remote canyon system in the Wollemi National Park (near Sydney, Australia). This population contains fewer than 100 individuals and is critically endangered. Previous genetic studies of the Wollemi pine have investigated its evolutionary relationship with other pines in the family Araucariaceae, and have suggested that the Wollemi pine genome contains little or no variation. However, these studies were performed prior to the widespread use of genome sequencing, and their conclusions were based on a limited fraction of the Wollemi pine genome. In this study, we address this problem by determining the entire sequence of the W. nobilis chloroplast genome. A detailed analysis of the structure of the genome is presented, and the evolution of the genome is inferred by comparison with the chloroplast sequences of other members of the Araucariaceae and the related family Podocarpaceae. Pairwise alignments of whole genome sequences, and the presence of unique pseudogenes, gene duplications and insertions in W. nobilis and Araucariaceae, indicate that the W. nobilis chloroplast genome is most similar to that of its sister taxon Agathis. However, the W. nobilis genome contains an unusually high number of repetitive sequences, and these could be used in future studies to investigate and conserve any remnant genetic diversity in the Wollemi pine.
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176
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Hu S, Sablok G, Wang B, Qu D, Barbaro E, Viola R, Li M, Varotto C. Plastome organization and evolution of chloroplast genes in Cardamine species adapted to contrasting habitats. BMC Genomics 2015; 16:306. [PMID: 25887666 PMCID: PMC4446112 DOI: 10.1186/s12864-015-1498-0] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2014] [Accepted: 03/27/2015] [Indexed: 11/10/2022] Open
Abstract
Background Plastid genomes, also known as plastomes, are shaped by the selective forces acting on the fundamental cellular functions they code for and thus they are expected to preserve signatures of the adaptive path undertaken by different plant species during evolution. To identify molecular signatures of positive selection associated to adaptation to contrasting ecological niches, we sequenced with Solexa technology the plastomes of two congeneric Brassicaceae species with different habitat preference, Cardamine resedifolia and Cardamine impatiens. Results Following in-depth characterization of plastome organization, repeat patterns and gene space, the comparison of the newly sequenced plastomes between each other and with 15 fully sequenced Brassicaceae plastomes publically available in GenBank uncovered dynamic variation of the IR boundaries in the Cardamine lineage. We further detected signatures of positive selection in ten of the 75 protein-coding genes of the examined plastomes, identifying a range of chloroplast functions putatively involved in adaptive processes within the family. For instance, the three residues found to be under positive selection in RUBISCO could possibly be involved in the modulation of RUBISCO aggregation/activation and enzymatic specificty in Brassicaceae. In addition, our results points to differential evolutionary rates in Cardamine plastomes. Conclusions Overall our results support the existence of wider signatures of positive selection in the plastome of C. resedifolia, possibly as a consequence of adaptation to high altitude environments. We further provide a first characterization of the selective patterns shaping the Brassicaceae plastomes, which could help elucidate the driving forces underlying adaptation and evolution in this important plant family. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1498-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Shiliang Hu
- Ecogenomics Laboratory, Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, 38010 S, Michele all'Adige (TN), Italy.
| | - Gaurav Sablok
- Ecogenomics Laboratory, Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, 38010 S, Michele all'Adige (TN), Italy.
| | - Bo Wang
- Ecogenomics Laboratory, Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, 38010 S, Michele all'Adige (TN), Italy.
| | - Dong Qu
- Ecogenomics Laboratory, Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, 38010 S, Michele all'Adige (TN), Italy. .,College of Horticulture, Northwest Agricultural and Forest University, 712100, Yangling, Shaanxi, PR China.
| | - Enrico Barbaro
- Ecogenomics Laboratory, Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, 38010 S, Michele all'Adige (TN), Italy.
| | - Roberto Viola
- Ecogenomics Laboratory, Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, 38010 S, Michele all'Adige (TN), Italy.
| | - Mingai Li
- Ecogenomics Laboratory, Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, 38010 S, Michele all'Adige (TN), Italy.
| | - Claudio Varotto
- Ecogenomics Laboratory, Department of Biodiversity and Molecular Ecology, Research and Innovation Centre, Fondazione Edmund Mach, Via E. Mach 1, 38010 S, Michele all'Adige (TN), Italy.
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177
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Metabolic connectivity as a driver of host and endosymbiont integration. Proc Natl Acad Sci U S A 2015; 112:10208-15. [PMID: 25825767 DOI: 10.1073/pnas.1421375112] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The origin of oxygenic photosynthesis in the Archaeplastida common ancestor was foundational for the evolution of multicellular life. It is very likely that the primary endosymbiosis that explains plastid origin relied initially on the establishment of a metabolic connection between the host cell and captured cyanobacterium. We posit that these connections were derived primarily from existing host-derived components. To test this idea, we used phylogenomic and network analysis to infer the phylogenetic origin and evolutionary history of 37 validated plastid innermost membrane (permeome) metabolite transporters from the model plant Arabidopsis thaliana. Our results show that 57% of these transporter genes are of eukaryotic origin and that the captured cyanobacterium made a relatively minor (albeit important) contribution to the process. We also tested the hypothesis that the bacterium-derived hexose-phosphate transporter UhpC might have been the primordial sugar transporter in the Archaeplastida ancestor. Bioinformatic and protein localization studies demonstrate that this protein in the extremophilic red algae Galdieria sulphuraria and Cyanidioschyzon merolae are plastid targeted. Given this protein is also localized in plastids in the glaucophyte alga Cyanophora paradoxa, we suggest it played a crucial role in early plastid endosymbiosis by connecting the endosymbiont and host carbon storage networks. In summary, our work significantly advances understanding of plastid integration and favors a host-centric view of endosymbiosis. Under this view, nuclear genes of either eukaryotic or bacterial (noncyanobacterial) origin provided key elements of the toolkit needed for establishing metabolic connections in the primordial Archaeplastida lineage.
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Bogdanova VS, Zaytseva OO, Mglinets AV, Shatskaya NV, Kosterin OE, Vasiliev GV. Nuclear-cytoplasmic conflict in pea (Pisum sativum L.) is associated with nuclear and plastidic candidate genes encoding acetyl-CoA carboxylase subunits. PLoS One 2015; 10:e0119835. [PMID: 25789472 PMCID: PMC4366379 DOI: 10.1371/journal.pone.0119835] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 01/16/2015] [Indexed: 11/18/2022] Open
Abstract
In crosses of wild and cultivated peas (Pisum sativum L.), nuclear-cytoplasmic incompatibility frequently occurs manifested as decreased pollen fertility, male gametophyte lethality, sporophyte lethality. High-throughput sequencing of plastid genomes of one cultivated and four wild pea accessions differing in cross-compatibility was performed. Candidate genes for involvement in the nuclear-plastid conflict were searched in the reconstructed plastid genomes. In the annotated Medicago truncatula genome, nuclear candidate genes were searched in the portion syntenic to the pea chromosome region known to harbor a locus involved in the conflict. In the plastid genomes, a substantial variability of the accD locus represented by nucleotide substitutions and indels was found to correspond to the pattern of cross-compatibility among the accessions analyzed. Amino acid substitutions in the polypeptides encoded by the alleles of a nuclear locus, designated as Bccp3, with a complementary function to accD, fitted the compatibility pattern. The accD locus in the plastid genome encoding beta subunit of the carboxyltransferase of acetyl-coA carboxylase and the nuclear locus Bccp3 encoding biotin carboxyl carrier protein of the same multi-subunit enzyme were nominated as candidate genes for main contribution to nuclear-cytoplasmic incompatibility in peas. Existence of another nuclear locus involved in the accD-mediated conflict is hypothesized.
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Affiliation(s)
- Vera S. Bogdanova
- Institute of Cytology and Genetics of Siberian Division of Russian Academy of Sciences, Novosibirsk, Russia
| | - Olga O. Zaytseva
- Institute of Cytology and Genetics of Siberian Division of Russian Academy of Sciences, Novosibirsk, Russia
- Novosibirsk State University, Novosibirsk, Russia
| | - Anatoliy V. Mglinets
- Institute of Cytology and Genetics of Siberian Division of Russian Academy of Sciences, Novosibirsk, Russia
| | - Natalia V. Shatskaya
- Institute of Cytology and Genetics of Siberian Division of Russian Academy of Sciences, Novosibirsk, Russia
| | - Oleg E. Kosterin
- Institute of Cytology and Genetics of Siberian Division of Russian Academy of Sciences, Novosibirsk, Russia
- Novosibirsk State University, Novosibirsk, Russia
| | - Gennadiy V. Vasiliev
- Institute of Cytology and Genetics of Siberian Division of Russian Academy of Sciences, Novosibirsk, Russia
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179
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Genome-wide analysis of thylakoid-bound ribosomes in maize reveals principles of cotranslational targeting to the thylakoid membrane. Proc Natl Acad Sci U S A 2015; 112:E1678-87. [PMID: 25775549 DOI: 10.1073/pnas.1424655112] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Chloroplast genomes encode ∼ 37 proteins that integrate into the thylakoid membrane. The mechanisms that target these proteins to the membrane are largely unexplored. We used ribosome profiling to provide a comprehensive, high-resolution map of ribosome positions on chloroplast mRNAs in separated membrane and soluble fractions in maize seedlings. The results show that translation invariably initiates off the thylakoid membrane and that ribosomes synthesizing a subset of membrane proteins subsequently become attached to the membrane in a nuclease-resistant fashion. The transition from soluble to membrane-attached ribosomes occurs shortly after the first transmembrane segment in the nascent peptide has emerged from the ribosome. Membrane proteins whose translation terminates before emergence of a transmembrane segment are translated in the stroma and targeted to the membrane posttranslationally. These results indicate that the first transmembrane segment generally comprises the signal that links ribosomes to thylakoid membranes for cotranslational integration. The sole exception is cytochrome f, whose cleavable N-terminal cpSecA-dependent signal sequence engages the thylakoid membrane cotranslationally. The distinct behavior of ribosomes synthesizing the inner envelope protein CemA indicates that sorting signals for the thylakoid and envelope membranes are distinguished cotranslationally. In addition, the fractionation behavior of ribosomes in polycistronic transcription units encoding both membrane and soluble proteins adds to the evidence that the removal of upstream ORFs by RNA processing is not typically required for the translation of internal genes in polycistronic chloroplast mRNAs.
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180
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Köhler D, Montandon C, Hause G, Majovsky P, Kessler F, Baginsky S, Agne B. Characterization of chloroplast protein import without Tic56, a component of the 1-megadalton translocon at the inner envelope membrane of chloroplasts. PLANT PHYSIOLOGY 2015; 167:972-90. [PMID: 25588737 PMCID: PMC4348784 DOI: 10.1104/pp.114.255562] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Accepted: 01/14/2015] [Indexed: 05/17/2023]
Abstract
We report on the characterization of Tic56, a unique component of the recently identified 1-MD translocon at the inner envelope membrane of chloroplasts (TIC) in Arabidopsis (Arabidopsis thaliana) comprising Tic20, Tic100, and Tic214. We isolated Tic56 by copurification with Tandem Affinity Purification-tagged Toc159 in the absence of precursor protein, indicating spontaneous and translocation-independent formation of the translocon at the outer envelope membrane of chloroplasts (TOC) and TIC supercomplexes. Tic56 mutant plants have an albino phenotype and are unable to grow without an external carbon source. Using specific enrichment of protein amino termini, we analyzed the tic56-1 and plastid protein import2 (toc159) mutants to assess the in vivo import capacity of plastids in mutants of an outer and inner envelope component of the anticipated TOC-TIC supercomplex. Inboth mutants, we observed processing of several import substrates belonging to various pathways. Our results suggest that despite the severe developmental defects, protein import into Tic56-deficient plastids is functional to a considerable degree, indicating the existence of alternative translocases at the inner envelope membrane.
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181
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The TIC complex uncovered: The alternative view on the molecular mechanism of protein translocation across the inner envelope membrane of chloroplasts. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:957-67. [PMID: 25689609 DOI: 10.1016/j.bbabio.2015.02.011] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 01/19/2015] [Accepted: 02/07/2015] [Indexed: 12/29/2022]
Abstract
Chloroplasts must import thousands of nuclear-encoded preproteins synthesized in the cytosol through two successive protein translocons at the outer and inner envelope membranes, termed TOC and TIC, respectively, to fulfill their complex physiological roles. The molecular identity of the TIC translocon had long remained controversial; two proteins, namely Tic20 and Tic110, had been proposed to be central to protein translocation across the inner envelope membrane. Tic40 also had long been considered to be another central player in this process. However, recently, a novel 1-megadalton complex consisting of Tic20, Tic56, Tic100, and Tic214 was identified at the chloroplast inner membrane of Arabidopsis and was demonstrated to constitute a general TIC translocon which functions in concert with the well-characterized TOC translocon. On the other hand, direct interaction between this novel TIC transport system and Tic110 or Tic40 was hardly observed. Consequently, the molecular model for protein translocation across the inner envelope membrane of chloroplasts might need to be extensively revised. In this review article, I intend to propose such alternative view regarding the TIC transport system in contradistinction to the classical view. I also would emphasize importance of reevaluation of previous works in terms of with what methods these classical Tic proteins such as Tic110 or Tic40 were picked up as TIC constituents at the very beginning as well as what actual evidence there were to support their direct and specific involvement in chloroplast protein import. This article is part of a Special Issue entitled: Chloroplast Biogenesis.
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182
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Hochmal AK, Schulze S, Trompelt K, Hippler M. Calcium-dependent regulation of photosynthesis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:993-1003. [PMID: 25687895 DOI: 10.1016/j.bbabio.2015.02.010] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 02/05/2015] [Accepted: 02/07/2015] [Indexed: 01/03/2023]
Abstract
The understanding of calcium as a second messenger in plants has been growing intensively over the last decades. Recently, attention has been drawn to the organelles, especially the chloroplast but focused on the stromal Ca2+ transients in response to environmental stresses. Herein we will expand this view and discuss the role of Ca2+ in photosynthesis. Moreover we address of how Ca2+ is delivered to chloroplast stroma and thylakoids. Thereby, new light is shed on the regulation of photosynthetic electron flow and light-dependent metabolism by the interplay of Ca2+, thylakoid acidification and redox status. This article is part of a Special Issue entitled: Chloroplast biogenesis.
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Affiliation(s)
- Ana Karina Hochmal
- Institute of Plant Biology and Biotechnology, University of Münster, Münster 48143, Germany
| | - Stefan Schulze
- Institute of Plant Biology and Biotechnology, University of Münster, Münster 48143, Germany
| | - Kerstin Trompelt
- Institute of Plant Biology and Biotechnology, University of Münster, Münster 48143, Germany
| | - Michael Hippler
- Institute of Plant Biology and Biotechnology, University of Münster, Münster 48143, Germany.
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183
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Dong W, Xu C, Li C, Sun J, Zuo Y, Shi S, Cheng T, Guo J, Zhou S. ycf1, the most promising plastid DNA barcode of land plants. Sci Rep 2015; 5:8348. [PMID: 25672218 PMCID: PMC4325322 DOI: 10.1038/srep08348] [Citation(s) in RCA: 251] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 01/15/2015] [Indexed: 11/09/2022] Open
Abstract
A DNA barcode is a DNA fragment used to identify species. For land plants, DNA fragments of plastid genome could be the primary consideration. Unfortunately, most of the plastid candidate barcodes lack species-level resolution. The identification of DNA barcodes of high resolution at species level is critical to the success of DNA barcoding in plants. We searched the available plastid genomes for the most variable regions and tested the best candidates using both a large number of tree species and seven well-sampled plant groups. Two regions of the plastid gene ycf1, ycf1a and ycf1b, were the most variable loci that were better than existing plastid candidate barcodes and can serve as a barcode of land plants. Primers were designed for the amplification of these regions, and the PCR success of these primers ranged from 82.80% to 98.17%. Of 420 tree species, 357 species could be distinguished using ycf1b, which was slightly better than the combination of matK and rbcL. For the well-sampled representative plant groups, ycf1b generally performed better than any of the matK, rbcL and trnH-psbA. We concluded that ycf1a or ycf1b is the most variable plastid genome region and can serve as a core barcode of land plants.
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Affiliation(s)
- Wenpan Dong
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Chao Xu
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Changhao Li
- 1] State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China [2] University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jiahui Sun
- 1] State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China [2] University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yunjuan Zuo
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Shuo Shi
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Tao Cheng
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Junjie Guo
- Research Institute of Tropical Forestry, the Chinese Academy of Forestry, Gongdong, Guangzhou 510520, China
| | - Shiliang Zhou
- State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
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184
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Bölter B, Soll J, Schwenkert S. Redox meets protein trafficking. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:949-56. [PMID: 25626173 DOI: 10.1016/j.bbabio.2015.01.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 01/16/2015] [Accepted: 01/19/2015] [Indexed: 11/15/2022]
Abstract
After the engulfment of two prokaryotic organisms, the thus emerged eukaryotic cell needed to establish means of communication and signaling to properly integrate the acquired organelles into its metabolism. Regulatory mechanisms had to evolve to ensure that chloroplasts and mitochondria smoothly function in accordance with all other cellular processes. One essential process is the post-translational import of nuclear encoded organellar proteins, which needs to be adapted according to the requirements of the plant. The demand for protein import is constantly changing depending on varying environmental conditions, as well as external and internal stimuli or different developmental stages. Apart from long-term regulatory mechanisms such as transcriptional/translation control, possibilities for short-term acclimation are mandatory. To this end, protein import is integrated into the cellular redox network, utilizing the recognition of signals from within the organelles and modifying the efficiency of the translocon complexes. Thereby, cellular requirements can be communicated throughout the whole organism. This article is part of a Special Issue entitled: Chloroplast Biogenesis.
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Affiliation(s)
- Bettina Bölter
- Department Biologie I-Botanik, Ludwig-Maximilians-Universität, Großhadernerstr. 2-4, D-82152 Planegg-Martinsried, Germany; Munich Center for Integrated Protein Science CiPSM, Ludwig-Maximilians-Universität, Feodor-Lynen-Strasse 25, D-81377 Munich, Germany
| | - Jürgen Soll
- Department Biologie I-Botanik, Ludwig-Maximilians-Universität, Großhadernerstr. 2-4, D-82152 Planegg-Martinsried, Germany; Munich Center for Integrated Protein Science CiPSM, Ludwig-Maximilians-Universität, Feodor-Lynen-Strasse 25, D-81377 Munich, Germany.
| | - Serena Schwenkert
- Department Biologie I-Botanik, Ludwig-Maximilians-Universität, Großhadernerstr. 2-4, D-82152 Planegg-Martinsried, Germany; Munich Center for Integrated Protein Science CiPSM, Ludwig-Maximilians-Universität, Feodor-Lynen-Strasse 25, D-81377 Munich, Germany
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185
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Chu CC, Li HM. Protein import into isolated pea root leucoplasts. FRONTIERS IN PLANT SCIENCE 2015; 6:690. [PMID: 26388889 PMCID: PMC4560022 DOI: 10.3389/fpls.2015.00690] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 08/20/2015] [Indexed: 05/06/2023]
Abstract
Leucoplasts are important organelles for the synthesis and storage of starch, lipids and proteins. However, molecular mechanism of protein import into leucoplasts and how it differs from that of import into chloroplasts remain unknown. We used pea seedlings for both chloroplast and leucoplast isolations to compare within the same species. We further optimized the isolation and import conditions to improve import efficiency and to permit a quantitative comparison between the two plastid types. The authenticity of the import was verified using a mitochondrial precursor protein. Our results show that, when normalized to Toc75, most translocon proteins are less abundant in leucoplasts than in chloroplasts. A precursor shown to prefer the receptor Toc132 indeed had relatively more similar import efficiencies between chloroplasts and leucoplasts compared to precursors that prefer Toc159. Furthermore we found two precursors that exhibited very high import efficiency into leucoplasts. Their transit peptides may be candidates for delivering transgenic proteins into leucoplasts and for analyzing motifs important for leucoplast import.
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Affiliation(s)
| | - Hsou-min Li
- *Correspondence: Hsou-min Li, Institute of Molecular Biology, Academia Sinica, Nankang, Taipei 11529, Taiwan,
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186
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Abstract
Eukaryotic cells contain a multitude of membrane structures that are connected through a highly dynamic and complex exchange of their constituents. The vibrant instability of these structures challenges the classical view of defined, static compartments that are connected by different types of vesicles. Despite this astonishing complexity, proteins and lipids are accurately transported into the different intracellular membrane systems. Over the past few decades many factors have been identified that either mediate or regulate intracellular membrane trafficking. Like in a modern parcel sorting system of a logistics center, the cargo typically passes through several sequential sorting stations until it finally reaches the location that is specified by its individual address label. While each membrane system employs specific sets of factors, the transport processes typically operate on common principles. With the advent of genome- and proteome-wide screens, the availability of mutant collections, exciting new developments in microscope technology and sophisticated methods to study their dynamics, the future promises a broad and comprehensive picture of the processes by which eukaryotic cells sort their proteins.
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187
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Campbell JH, Hoang T, Jelokhani-Niaraki M, Smith MD. Folding and self-association of atTic20 in lipid membranes: implications for understanding protein transport across the inner envelope membrane of chloroplasts. BMC BIOCHEMISTRY 2014; 15:29. [PMID: 25551276 PMCID: PMC4307631 DOI: 10.1186/s12858-014-0029-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 12/12/2014] [Indexed: 11/24/2022]
Abstract
Background The Arabidopsis thaliana protein atTic20 is a key component of the protein import machinery at the inner envelope membrane of chloroplasts. As a component of the TIC complex, it is believed to form a preprotein-conducting channel across the inner membrane. Results We report a method for producing large amounts of recombinant atTic20 using a codon-optimized strain of E. coli coupled with an autoinduction method of protein expression. This method resulted in the recombinant protein being directed to the bacterial membrane without the addition of a bacterial targeting sequence. Using biochemical and biophysical approaches, we were able to demonstrate that atTic20 homo-oligomerizes in vitro when solubilized in detergents or reconstituted into liposomes. Furthermore, we present evidence that the extramembranous N-terminus of the mature protein displays characteristics that are consistent with it being an intrinsically disordered protein domain. Conclusion Our work strengthens the hypothesis that atTic20 functions similarly to other small α-helical integral membrane proteins, such as Tim23, that are involved in protein transport across membranes. Electronic supplementary material The online version of this article (doi:10.1186/s12858-014-0029-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- James H Campbell
- Department of Biology, Wilfrid Laurier University, 75 University Avenue West, Waterloo, ON, N2L 3C5, Canada. .,Current address: Department of Biology, University of Waterloo, Waterloo, ON, Canada.
| | - Tuan Hoang
- Department of Chemistry & Biochemistry, Wilfrid Laurier University, Waterloo, ON, Canada. .,Biophysics Interdepartmental Group, University of Guelph, Guelph, ON, Canada.
| | - Masoud Jelokhani-Niaraki
- Department of Chemistry & Biochemistry, Wilfrid Laurier University, Waterloo, ON, Canada. .,Biophysics Interdepartmental Group, University of Guelph, Guelph, ON, Canada.
| | - Matthew D Smith
- Department of Biology, Wilfrid Laurier University, 75 University Avenue West, Waterloo, ON, N2L 3C5, Canada. .,Biophysics Interdepartmental Group, University of Guelph, Guelph, ON, Canada.
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188
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Correlation between sequence divergence and polymorphism reveals similar evolutionary mechanisms acting across multiple timescales in a rapidly evolving plastid genome. BMC Evol Biol 2014; 14:268. [PMID: 25539645 PMCID: PMC4300152 DOI: 10.1186/s12862-014-0268-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2014] [Accepted: 12/11/2014] [Indexed: 11/25/2022] Open
Abstract
Background Although the plastid genome is highly conserved across most angiosperms, multiple lineages have increased rates of structural rearrangement and nucleotide substitution. These lineages exhibit an excess of nonsynonymous substitutions (i.e., elevated dN/dS ratios) in similar subsets of plastid genes, suggesting that similar mechanisms may be leading to relaxed and/or positive selection on these genes. However, little is known regarding whether these mechanisms continue to shape sequence diversity at the intraspecific level. Results We examined patterns of interspecific divergence and intraspecific polymorphism in the plastid genome of Campanulastrum americanum, and across plastid genes found a significant correlation between dN/dS and pN/pS (i.e., the within-species equivalent of dN/dS). A number of genes including ycf1, ycf2, clpP, and ribosomal protein genes exhibited high dN/dS ratios. McDonald-Kreitman tests detected little evidence for positive selection acting on these genes, likely due to the presence of substantial intraspecific divergence. Conclusions These results suggest that mechanisms leading to increased nucleotide substitution rates in the plastid genome are continuing to act at the intraspecific level. Accelerated plastid genome evolution may increase the likelihood of intraspecific cytonuclear genetic incompatibilities, and thereby contribute to the early stages of the speciation process. Electronic supplementary material The online version of this article (doi:10.1186/s12862-014-0268-y) contains supplementary material, which is available to authorized users.
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189
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Organization, function and substrates of the essential Clp protease system in plastids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1847:915-30. [PMID: 25482260 DOI: 10.1016/j.bbabio.2014.11.012] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 11/20/2014] [Indexed: 01/21/2023]
Abstract
Intra-plastid proteolysis is essential in plastid biogenesis, differentiation and plastid protein homeostasis (proteostasis). We provide a comprehensive review of the Clp protease system present in all plastid types and we draw lessons from structural and functional information of bacterial Clp systems. The Clp system plays a central role in plastid development and function, through selective removal of miss-folded, aggregated, or otherwise unwanted proteins. The Clp system consists of a tetradecameric proteolytic core with catalytically active ClpP and inactive ClpR subunits, hexameric ATP-dependent chaperones (ClpC,D) and adaptor protein(s) (ClpS1) enhancing delivery of subsets of substrates. Many structural and functional features of the plastid Clp system are now understood though extensive reverse genetics analysis combined with biochemical analysis, as well as large scale quantitative proteomics for loss-of-function mutants of Clp core, chaperone and ClpS1 subunits. Evolutionary diversification of Clp system across non-photosynthetic and photosynthetic prokaryotes and organelles is illustrated. Multiple substrates have been suggested based on their direct interaction with the ClpS1 adaptor or screening of different loss-of-function protease mutants. The main challenge is now to determine degradation signals (degrons) in Clp substrates and substrate delivery mechanisms, as well as functional interactions of Clp with other plastid proteases. This article is part of a Special Issue entitled: Chloroplast Biogenesis.
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190
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Parker N, Wang Y, Meinke D. Natural variation in sensitivity to a loss of chloroplast translation in Arabidopsis. PLANT PHYSIOLOGY 2014; 166:2013-27. [PMID: 25336520 PMCID: PMC4256881 DOI: 10.1104/pp.114.249052] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Mutations that eliminate chloroplast translation in Arabidopsis (Arabidopsis thaliana) result in embryo lethality. The stage of embryo arrest, however, can be influenced by genetic background. To identify genes responsible for improved growth in the absence of chloroplast translation, we examined seedling responses of different Arabidopsis accessions on spectinomycin, an inhibitor of chloroplast translation, and crossed the most tolerant accessions with embryo-defective mutants disrupted in chloroplast ribosomal proteins generated in a sensitive background. The results indicate that tolerance is mediated by ACC2, a duplicated nuclear gene that targets homomeric acetyl-coenzyme A carboxylase to plastids, where the multidomain protein can participate in fatty acid biosynthesis. In the presence of functional ACC2, tolerance is enhanced by a second locus that maps to chromosome 5 and heightened by additional genetic modifiers present in the most tolerant accessions. Notably, some of the most sensitive accessions contain nonsense mutations in ACC2, including the "Nossen" line used to generate several of the mutants studied here. Functional ACC2 protein is therefore not required for survival in natural environments, where heteromeric acetyl-coenzyme A carboxylase encoded in part by the chloroplast genome can function instead. This work highlights an interesting example of a tandem gene duplication in Arabidopsis, helps to explain the range of embryo phenotypes found in Arabidopsis mutants disrupted in essential chloroplast functions, addresses the nature of essential proteins encoded by the chloroplast genome, and underscores the value of using natural variation to study the relationship between chloroplast translation, plant metabolism, protein import, and plant development.
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Affiliation(s)
- Nicole Parker
- Department of Botany, Oklahoma State University, Stillwater, Oklahoma 74078
| | - Yixing Wang
- Department of Botany, Oklahoma State University, Stillwater, Oklahoma 74078
| | - David Meinke
- Department of Botany, Oklahoma State University, Stillwater, Oklahoma 74078
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191
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Demarsy E, Lakshmanan AM, Kessler F. Border control: selectivity of chloroplast protein import and regulation at the TOC-complex. FRONTIERS IN PLANT SCIENCE 2014; 5:483. [PMID: 25278954 PMCID: PMC4166117 DOI: 10.3389/fpls.2014.00483] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 09/01/2014] [Indexed: 05/25/2023]
Abstract
Plants have evolved complex and sophisticated molecular mechanisms to regulate their development and adapt to their surrounding environment. Particularly the development of their specific organelles, chloroplasts and other plastid-types, is finely tuned in accordance with the metabolic needs of the cell. The normal development and functioning of plastids require import of particular subsets of nuclear encoded proteins. Most preproteins contain a cleavable sequence at their N terminal (transit peptide) serving as a signal for targeting to the organelle and recognition by the translocation machinery TOC-TIC (translocon of outer membrane complex-translocon of inner membrane complex) spanning the dual membrane envelope. The plastid proteome needs constant remodeling in response to developmental and environmental factors. Therefore selective regulation of preprotein import plays a crucial role in plant development. In this review we describe the diversity of transit peptides and TOC receptor complexes, and summarize the current knowledge and potential directions for future research concerning regulation of the different Toc isoforms.
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Affiliation(s)
| | | | - Felix Kessler
- *Correspondence: Felix Kessler, Laboratory of Plant Physiology, Université de Neuchâtel, UniMail, Rue Emile Argand 11, 2000 Neuchâtel, Switzerland e-mail:
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192
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Paila YD, Richardson LGL, Schnell DJ. New insights into the mechanism of chloroplast protein import and its integration with protein quality control, organelle biogenesis and development. J Mol Biol 2014; 427:1038-1060. [PMID: 25174336 DOI: 10.1016/j.jmb.2014.08.016] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 08/20/2014] [Accepted: 08/23/2014] [Indexed: 01/04/2023]
Abstract
The translocons at the outer (TOC) and the inner (TIC) envelope membranes of chloroplasts mediate the targeting and import of several thousand nucleus-encoded preproteins that are required for organelle biogenesis and homeostasis. The cytosolic events in preprotein targeting remain largely unknown, although cytoplasmic chaperones have been proposed to facilitate delivery to the TOC complex. Preprotein recognition is mediated by the TOC GTPase receptors Toc159 and Toc34. The receptors constitute a GTP-regulated switch, which initiates membrane translocation via Toc75, a member of the Omp85 (outer membrane protein 85)/TpsB (two-partner secretion system B) family of bacterial, plastid and mitochondrial β-barrel outer membrane proteins. The TOC receptor systems have diversified to recognize distinct sets of preproteins, thereby maximizing the efficiency of targeting in response to changes in gene expression during developmental and physiological events that impact organelle function. The TOC complex interacts with the TIC translocon to allow simultaneous translocation of preproteins across the envelope. Both the two inner membrane complexes, the Tic110 and 1 MDa complexes, have been implicated as constituents of the TIC translocon, and it remains to be determined how they interact to form the TIC channel and assemble the import-associated chaperone network in the stroma that drives import across the envelope membranes. This review will focus on recent developments in our understanding of the mechanisms and diversity of the TOC-TIC systems. Our goal is to incorporate these recent studies with previous work and present updated or revised models for the function of TOC-TIC in protein import.
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Affiliation(s)
- Yamuna D Paila
- Department of Biochemistry and Molecular Biology, Life Sciences Laboratories Room N431, 240 Thatcher Rd, University of Massachusetts, Amherst MA 01003-9364, USA
| | - Lynn G L Richardson
- Department of Biochemistry and Molecular Biology, Life Sciences Laboratories Room N431, 240 Thatcher Rd, University of Massachusetts, Amherst MA 01003-9364, USA
| | - Danny J Schnell
- Department of Biochemistry and Molecular Biology, Life Sciences Laboratories Room N431, 240 Thatcher Rd, University of Massachusetts, Amherst MA 01003-9364, USA
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193
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Sherman-Broyles S, Bombarely A, Grimwood J, Schmutz J, Doyle J. Complete plastome sequences from Glycine syndetika and six additional perennial wild relatives of soybean. G3 (BETHESDA, MD.) 2014; 4:2023-33. [PMID: 25155272 PMCID: PMC4199708 DOI: 10.1534/g3.114.012690] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 08/19/2014] [Indexed: 12/03/2022]
Abstract
Organelle sequences have a long history of utility in phylogenetic analyses. Chloroplast sequences when combined with nuclear data can help resolve relationships among flowering plant genera, and within genera incongruence can point to reticulate evolution. Plastome sequences are becoming plentiful because they are increasingly easier to obtain. Complete plastome sequences allow us to detect rare rearrangements and test the tempo of sequence evolution. Chloroplast sequences are generally considered a nuisance to be kept to a minimum in bacterial artificial chromosome libraries. Here, we sequenced two bacterial artificial chromosomes per species to generate complete plastome sequences from seven species. The plastome sequences from Glycine syndetika and six other perennial Glycine species are similar in arrangement and gene content to the previously published soybean plastome. Repetitive sequences were detected in high frequencies as in soybean, but further analysis showed that repeat sequence numbers are inflated. Previous chloroplast-based phylogenetic trees for perennial Glycine were incongruent with nuclear gene-based phylogenetic trees. We tested whether the hypothesis of introgression was supported by the complete plastomes. Alignment of complete plastome sequences and Bayesian analysis allowed us to date putative hybridization events supporting the hypothesis of introgression and chloroplast "capture."
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Affiliation(s)
| | | | - Jane Grimwood
- Hudson Alpha Institute for Biotechnology, Huntsville, Alabama 35806
| | - Jeremy Schmutz
- Hudson Alpha Institute for Biotechnology, Huntsville, Alabama 35806
| | - Jeff Doyle
- Cornell University, Department of Plant Biology, Ithaca, New York 14853
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194
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Sabir J, Schwarz E, Ellison N, Zhang J, Baeshen NA, Mutwakil M, Jansen R, Ruhlman T. Evolutionary and biotechnology implications of plastid genome variation in the inverted-repeat-lacking clade of legumes. PLANT BIOTECHNOLOGY JOURNAL 2014; 12:743-54. [PMID: 24618204 DOI: 10.1111/pbi.12179] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 01/22/2014] [Accepted: 01/24/2014] [Indexed: 05/21/2023]
Abstract
Land plant plastid genomes (plastomes) provide a tractable model for evolutionary study in that they are relatively compact and gene dense. Among the groups that display an appropriate level of variation for structural features, the inverted-repeat-lacking clade (IRLC) of papilionoid legumes presents the potential to advance general understanding of the mechanisms of genomic evolution. Here, are presented six complete plastome sequences from economically important species of the IRLC, a lineage previously represented by only five completed plastomes. A number of characters are compared across the IRLC including gene retention and divergence, synteny, repeat structure and functional gene transfer to the nucleus. The loss of clpP intron 2 was identified in one newly sequenced member of IRLC, Glycyrrhiza glabra. Using deeply sequenced nuclear transcriptomes from two species helped clarify the nature of the functional transfer of accD to the nucleus in Trifolium, which likely occurred in the lineage leading to subgenus Trifolium. Legumes are second only to cereal crops in agricultural importance based on area harvested and total production. Genetic improvement via plastid transformation of IRLC crop species is an appealing proposition. Comparative analyses of intergenic spacer regions emphasize the need for complete genome sequences for developing transformation vectors for plastid genetic engineering of legume crops.
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Affiliation(s)
- Jamal Sabir
- Department of Biological Sciences, Faculty of Science, King Abdulaziz University (KAU), Jeddah, Saudi Arabia
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195
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The dynamic history of plastid genomes in the Campanulaceae sensu lato is unique among angiosperms. Proc Natl Acad Sci U S A 2014; 111:11097-102. [PMID: 25024223 DOI: 10.1073/pnas.1403363111] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Why have some plants lost the organizational stability in plastid genomes (plastomes) that evolved in their algal ancestors? During the endosymbiotic transformation of a cyanobacterium into the eukaryotic plastid, most cyanobacterial genes were transferred to the nucleus or otherwise lost from the plastome, and the resulting plastome architecture in land plants confers organizational stability, as evidenced by the conserved gene order among bryophytes and lycophytes, whereas ferns, gymnosperms, and angiosperms share a single, 30-kb inversion. Although some additional gene losses have occurred, gene additions to angiosperm plastomes were previously unknown. Plastomes in the Campanulaceae sensu lato have incorporated dozens of large ORFs (putative protein-coding genes). These insertions apparently caused many of the 125+ large inversions now known in this small eudicot clade. This phylogenetically restricted phenomenon is not biogeographically localized, which indicates that these ORFs came from the nucleus or (less likely) a cryptic endosymbiont.
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196
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Gutierrez-Carbonell E, Takahashi D, Lattanzio G, Rodríguez-Celma J, Kehr J, Soll J, Philippar K, Uemura M, Abadía J, López-Millán AF. The distinct functional roles of the inner and outer chloroplast envelope of Pea (Pisum sativum) as revealed by proteomic approaches. J Proteome Res 2014; 13:2941-53. [PMID: 24792535 DOI: 10.1021/pr500106s] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Protein profiles of inner (IE) and outer (OE) chloroplast envelope membrane preparations from pea were studied using shotgun nLC-MS/MS and two-dimensional electrophoresis, and 589 protein species (NCBI entries) were identified. The relative enrichment of each protein in the IE/OE pair of membranes was used to provide an integrated picture of the chloroplast envelope. From the 546 proteins identified with shotgun, 321 showed a significant differential distribution, with 180 being enriched in IE and 141 in OE. To avoid redundancy and facilitate in silico localization, Arabidopsis homologues were used to obtain a nonredundant list of 409 envelope proteins, with many showing significant OE or IE enrichment. Functional classification reveals that IE is a selective barrier for transport of many metabolites and plays a major role in controlling protein homeostasis, whereas proteins in OE are more heterogeneous and participate in a wide range of processes. Data support that metabolic processes previously described to occur in the envelope such as chlorophyll and tocopherol biosynthesis can be ascribed to the IE, whereas others such as carotenoid or lipid biosynthesis occur in both membranes. Furthermore, results allow empirical assignation to the IE and/or OE of many proteins previously assigned to the bulk chloroplast envelope proteome.
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Affiliation(s)
- Elain Gutierrez-Carbonell
- Plant Nutrition Department, Aula Dei Experimental Station, CSIC , P.O. Box 13034, 50080 Zaragoza, Spain
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197
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Abstract
In this review, we consider a selection of recent advances in chloroplast biology. These include new findings concerning chloroplast evolution, such as the identification of Chlamydiae as a third partner in primary endosymbiosis, a second instance of primary endosymbiosis represented by the chromatophores found in amoebae of the genus Paulinella, and a new explanation for the longevity of captured chloroplasts (kleptoplasts) in sacoglossan sea slugs. The controversy surrounding the three-dimensional structure of grana, its recent resolution by tomographic analyses, and the role of the CURVATURE THYLAKOID1 (CURT1) proteins in supporting grana formation are also discussed. We also present an updated inventory of photosynthetic proteins and the factors involved in the assembly of thylakoid multiprotein complexes, and evaluate findings that reveal that cyclic electron flow involves NADPH dehydrogenase (NDH)- and PGRL1/PGR5-dependent pathways, both of which receive electrons from ferredoxin. Other topics covered in this review include new protein components of nucleoids, an updated inventory of the chloroplast proteome, new enzymes in chlorophyll biosynthesis and new candidate messengers in retrograde signaling. Finally, we discuss the first successful synthetic biology approaches that resulted in chloroplasts in which electrons from the photosynthetic light reactions are fed to enzymes derived from secondary metabolism.
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Affiliation(s)
- Poul Erik Jensen
- Copenhagen Plant Science Center (CPSC), Department of Plant and Environmental Sciences, University of CopenhagenThorvaldsensvej 40, DK-1871 Frederiksberg CDenmark
| | - Dario Leister
- Copenhagen Plant Science Center (CPSC), Department of Plant and Environmental Sciences, University of CopenhagenThorvaldsensvej 40, DK-1871 Frederiksberg CDenmark
- Plant Molecular Biology, Department of Biology I, Ludwig-Maximilians-University MunichGroßhaderner Str. 2, D-82152 Planegg-MartinsriedGermany
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198
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Scharff LB, Bock R. Synthetic biology in plastids. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 78:783-98. [PMID: 24147738 DOI: 10.1111/tpj.12356] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 10/08/2013] [Accepted: 10/16/2013] [Indexed: 05/21/2023]
Abstract
Plastids (chloroplasts) harbor a small gene-dense genome that is amenable to genetic manipulation by transformation. During 1 billion years of evolution from the cyanobacterial endosymbiont to present-day chloroplasts, the plastid genome has undergone a dramatic size reduction, mainly as a result of gene losses and the large-scale transfer of genes to the nuclear genome. Thus the plastid genome can be regarded as a naturally evolved miniature genome, the gradual size reduction and compaction of which has provided a blueprint for the design of minimum genomes. Furthermore, because of the largely prokaryotic genome structure and gene expression machinery, the high transgene expression levels attainable in transgenic chloroplasts and the very low production costs in plant systems, the chloroplast lends itself to synthetic biology applications that are directed towards the efficient synthesis of green chemicals, biopharmaceuticals and other metabolites of commercial interest. This review describes recent progress with the engineering of plastid genomes with large constructs of foreign or synthetic DNA, and highlights the potential of the chloroplast as a model system in bottom-up and top-down synthetic biology approaches.
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Affiliation(s)
- Lars B Scharff
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476, Potsdam-Golm, Germany
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199
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Dutta S, Teresinski HJ, Smith MD. A split-ubiquitin yeast two-hybrid screen to examine the substrate specificity of atToc159 and atToc132, two Arabidopsis chloroplast preprotein import receptors. PLoS One 2014; 9:e95026. [PMID: 24736607 PMCID: PMC3988174 DOI: 10.1371/journal.pone.0095026] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 03/22/2014] [Indexed: 11/18/2022] Open
Abstract
Post-translational import of nucleus-encoded chloroplast pre-proteins is critical for chloroplast biogenesis, and the Toc159 family of proteins serve as receptors for the process. Toc159 shares with other members of the family (e.g. Toc132), homologous GTPase (G−) and Membrane (M−) domains, but a highly dissimilar N-terminal acidic (A−) domain. Although there is good evidence that atToc159 and atToc132 from Arabidopsis mediate the initial sorting step, preferentially recognizing photosynthetic and non-photosynthetic preproteins, respectively, relatively few chloroplast preproteins have been assigned as substrates for particular members of the Toc159 family, which has limited the proof for the hypothesis. The current study expands the number of known preprotein substrates for members of the Arabidopsis Toc159 receptor family using a split-ubiquitin membrane-based yeast two-hybrid system using the atToc159 G-domain (Toc159G), atToc132 G-domain (Toc132G) and atToc132 A- plus G-domains (Toc132AG) as baits. cDNA library screening with all three baits followed by pairwise interaction assays involving the 81 chloroplast preproteins identified show that although G-domains of the Toc159 family are sufficient for preprotein recognition, they alone do not confer specificity for preprotein subclasses. The presence of the A-domain fused to atToc132G (Toc132AG) not only positively influences its specificity for non-photosynthetic preproteins, but also negatively regulates the ability of this receptor to interact with a subset of photosynthetic preproteins. Our study not only substantiates the fact that atToc132 can serve as a receptor by directly binding to chloroplast preproteins but also proposes the existence of subsets of preproteins with different but overlapping affinities for more than one member of the Toc159 receptor family.
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Affiliation(s)
- Siddhartha Dutta
- Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - Howard J Teresinski
- Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - Matthew D Smith
- Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada
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200
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McFadden GI. Origin and evolution of plastids and photosynthesis in eukaryotes. Cold Spring Harb Perspect Biol 2014; 6:a016105. [PMID: 24691960 DOI: 10.1101/cshperspect.a016105] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Recent progress in understanding the origins of plastids from endosymbiotic cyanobacteria is reviewed. Establishing when during geological time the endosymbiosis occurred remains elusive, but progress has been made in defining the cyanobacterial lineage most closely related to plastids, and some mechanistic insight into the possible existence of cryptic endosymbioses perhaps involving Chlamydia-like infections of the host have also been presented. The phylogenetic affinities of the host remain obscure. The existence of a second lineage of primary plastids in euglyphid amoebae has now been confirmed, but the quasipermanent acquisition of plastids by animals has been shown to be more ephemeral than initially suspected. A new understanding of how plastids have been integrated into their hosts by transfer of photosynthate, by endosymbiotic gene transfer and repatriation of gene products back to the endosymbiont, and by regulation of endosymbiont division is presented in context.
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