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Preiser AL, Banerjee A, Weise SE, Renna L, Brandizzi F, Sharkey TD. Phosphoglucoisomerase Is an Important Regulatory Enzyme in Partitioning Carbon out of the Calvin-Benson Cycle. FRONTIERS IN PLANT SCIENCE 2020; 11:580726. [PMID: 33362810 PMCID: PMC7758399 DOI: 10.3389/fpls.2020.580726] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 11/18/2020] [Indexed: 05/04/2023]
Abstract
Phosphoglucoisomerase (PGI) isomerizes fructose 6-phosphate (F6P) and glucose 6-phosphate (G6P) in starch and sucrose biosynthesis. Both plastidic and cytosolic isoforms are found in plant leaves. Using recombinant enzymes and isolated chloroplasts, we have characterized the plastidic and cytosolic isoforms of PGI. We have found that the Arabidopsis plastidic PGI K m for G6P is three-fold greater compared to that for F6P and that erythrose 4-phosphate is a key regulator of PGI activity. Additionally, the K m of spinach plastidic PGI can be dynamically regulated in the dark compared to the light and increases by 200% in the dark. We also found that targeting Arabidopsis cytosolic PGI into plastids of Nicotiana tabacum disrupts starch accumulation and degradation. Our results, in combination with the observation that plastidic PGI is not in equilibrium, indicates that PGI is an important regulatory enzyme that restricts flow and acts as a one-way valve preventing backflow of G6P into the Calvin-Benson cycle. We propose the PGI may be manipulated to improve flow of carbon to desired targets of biotechnology.
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Affiliation(s)
- Alyssa L. Preiser
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, United States
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, United States
| | - Aparajita Banerjee
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, United States
| | - Sean E. Weise
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, United States
| | - Luciana Renna
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, United States
| | - Federica Brandizzi
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, United States
- Department of Plant Biology, Michigan State University, East Lansing, MI, United States
| | - Thomas D. Sharkey
- MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI, United States
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, United States
- Plant Resilience Institute, Michigan State University, East Lansing, MI, United States
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2
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Lawson T, Lycett GW, Mayes S, Ho WK, Chin CF. Transcriptome-wide identification and characterization of the Rab GTPase family in mango. Mol Biol Rep 2020; 47:4183-4197. [PMID: 32444976 DOI: 10.1007/s11033-020-05519-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 05/14/2020] [Indexed: 10/24/2022]
Abstract
The Rab GTPase family plays a vital role in several plant physiological processes including fruit ripening. Fruit softening during ripening involves trafficking of cell wall polymers and enzymes between cellular compartments. Mango, an economically important fruit crop, is known for its delicious taste, exotic flavour and nutritional value. So far, there is a paucity of information on the mango Rab GTPase family. In this study, 23 genes encoding Rab proteins were identified in mango by a comprehensive in silico approach. Sequence alignment and similarity tree analysis with the model plant Arabidopsis as a reference enabled the bona fide assignment of the deduced mango proteins to classify into eight subfamilies. Expression analysis by RNA-Sequencing (RNA-Seq) showed that the Rab genes were differentially expressed in ripe and unripe mangoes suggesting the involvement of vesicle trafficking during ripening. Interaction analysis showed that the proteins involved in vesicle trafficking and cell wall softening were interconnected providing further evidence of the involvement of the Rab GTPases in fruit softening. Correlation analyses showed a significant relationship between the expression level of the RabA3 and RabA4 genes and fruit firmness at the unripe stage of the mango varieties suggesting that the differences in gene expression level might be associated with the contrasting firmness of these varieties. This study will not only provide new insights into the complexity of the ripening-regulated molecular mechanism but also facilitate the identification of potential Rab GTPases to address excessive fruit softening.
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Affiliation(s)
- Tamunonengiyeofori Lawson
- School of Biosciences, Faculty of Science, The University of Nottingham, Jalan Broga, 43500, Semenyih, Selangor Darul Ehsan, Malaysia.,Division of Plant and Crop Sciences, School of Biosciences, The University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK.,Crops for the Future (CFF) Jalan Broga, 43500, Semenyih, Selangor Darul Ehsan, Malaysia
| | - Grantley W Lycett
- Division of Plant and Crop Sciences, School of Biosciences, The University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK
| | - Sean Mayes
- Division of Plant and Crop Sciences, School of Biosciences, The University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK.,Crops for the Future (CFF) Jalan Broga, 43500, Semenyih, Selangor Darul Ehsan, Malaysia
| | - Wai Kuan Ho
- School of Biosciences, Faculty of Science, The University of Nottingham, Jalan Broga, 43500, Semenyih, Selangor Darul Ehsan, Malaysia.,Crops for the Future (CFF) Jalan Broga, 43500, Semenyih, Selangor Darul Ehsan, Malaysia
| | - Chiew Foan Chin
- School of Biosciences, Faculty of Science, The University of Nottingham, Jalan Broga, 43500, Semenyih, Selangor Darul Ehsan, Malaysia.
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3
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Larskaya I, Gorshkov O, Mokshina N, Trofimova O, Mikshina P, Klepikova A, Gogoleva N, Gorshkova T. Stimulation of adventitious root formation by the oligosaccharin OSRG at the transcriptome level. PLANT SIGNALING & BEHAVIOR 2019; 15:1703503. [PMID: 31851577 PMCID: PMC7012187 DOI: 10.1080/15592324.2019.1703503] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/06/2019] [Accepted: 12/09/2019] [Indexed: 05/26/2023]
Abstract
Oligosaccharins, which are biologically active oligosaccharide fragments of cell wall polysaccharides, may regulate the processes of growth and development as well as the response to stress factors. We characterized the effect of the oligosaccharin that stimulates rhizogenesis (OSRG) on the gene expression profile in the course of IAA-induced formation of adventitious roots in hypocotyl explants of buckwheat (Fagopyrum esculentum Moench.). The transcriptomes at two stages of IAA-induced root primordium formation (6 h and 24 h after induction) were compared after either treatment with auxin alone or joint treatment with auxin and OSRG. The set of differentially expressed genes indicated the special importance of oligosaccharin at the early stage of auxin-induced adventitious root formation. The list of genes with altered mRNA abundance in the presence of oligosaccharin included those, which Arabidopsis homologs encode proteins directly involved in the response to auxin as well as proteins that contribute to redox regulation, detoxification of various compounds, vesicle trafficking, and cell wall modification. The obtained results contribute to understanding the mechanism of adventitious root formation and demonstrate that OSRG is involved in fine-tuning of ROS and auxin regulatory modes involved in root development.
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Affiliation(s)
- Irina Larskaya
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, Kazan, Russia
| | - Oleg Gorshkov
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, Kazan, Russia
| | - Natalia Mokshina
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, Kazan, Russia
| | - Oksana Trofimova
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, Kazan, Russia
| | - Polina Mikshina
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, Kazan, Russia
| | - Anna Klepikova
- Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, Russia
- Skolkovo Institute of Science and Technology, Moscow, Russia
| | - Natalia Gogoleva
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, Kazan, Russia
- Laboratory of Extreme Biology, Institute of Fundamental Medicine and Biology, Kazan (Volga Region) Federal University, Kazan, Russia
| | - Tatyana Gorshkova
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, Kazan, Russia
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Zwiewka M, Friml J. Fluorescence imaging-based forward genetic screens to identify trafficking regulators in plants. FRONTIERS IN PLANT SCIENCE 2012; 3:97. [PMID: 22654887 PMCID: PMC3359526 DOI: 10.3389/fpls.2012.00097] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Accepted: 04/25/2012] [Indexed: 05/25/2023]
Abstract
Coordinated, subcellular trafficking of proteins is one of the fundamental properties of the multicellular eukaryotic organisms. Trafficking involves a large diversity of compartments, pathways, cargo molecules, and vesicle-sorting events. It is also crucial in regulating the localization and, thus, the activity of various proteins, but the process is still poorly genetically defined in plants. In the past, forward genetics screens had been used to determine the function of genes by searching for a specific morphological phenotype in the organism population in which mutations had been induced chemically or by irradiation. Unfortunately, these straightforward genetic screens turned out to be limited in identifying new regulators of intracellular protein transport, because mutations affecting essential trafficking pathways often lead to lethality. In addition, the use of these approaches has been restricted by functional redundancy among trafficking regulators. Screens for mutants that rely on the observation of changes in the cellular localization or dynamics of fluorescent subcellular markers enable, at least partially, to circumvent these issues. Hence, such image-based screens provide the possibility to identify either alleles with weak effects or components of the subcellular trafficking machinery that have no strong impact on the plant growth.
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Affiliation(s)
- Marta Zwiewka
- Department of Plant Systems Biology, VIB Life Sciences Research InstituteGent, Belgium
- Department of Plant Biotechnology and Genetics, Ghent UniversityGent, Belgium
| | - Jiří Friml
- Department of Plant Systems Biology, VIB Life Sciences Research InstituteGent, Belgium
- Department of Plant Biotechnology and Genetics, Ghent UniversityGent, Belgium
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Breuers FKH, Bräutigam A, Geimer S, Welzel UY, Stefano G, Renna L, Brandizzi F, Weber APM. Dynamic Remodeling of the Plastid Envelope Membranes - A Tool for Chloroplast Envelope in vivo Localizations. FRONTIERS IN PLANT SCIENCE 2012; 3:7. [PMID: 22645566 PMCID: PMC3355811 DOI: 10.3389/fpls.2012.00007] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 01/05/2012] [Indexed: 05/20/2023]
Abstract
Two envelope membranes delimit plastids, the defining organelles of plant cells. The inner and outer envelope membranes are unique in their protein and lipid composition. Several studies have attempted to establish the proteome of these two membranes; however, differentiating between them is difficult due to their close proximity. Here, we describe a novel approach to distinguish the localization of proteins between the two membranes using a straightforward approach based on live cell imaging coupled with transient expression. We base our approach on analyses of the distribution of GFP-fusions, which were aimed to verify outer envelope membrane proteomics data. To distinguish between outer envelope and inner envelope protein localization, we used AtTOC64-GFP and AtTIC40-GFP, as respective controls. During our analyses, we observed membrane proliferations and loss of chloroplast shape in conditions of protein over-expression. The morphology of the proliferations varied in correlation with the suborganellar distribution of the over-expressed proteins. In particular, while layers of membranes built up in the inner envelope membrane, the outer envelope formed long extensions into the cytosol. Using electron microscopy, we showed that these extensions were stromules, a dynamic feature of plastids. Since the behavior of the membranes is different and is related to the protein localization, we propose that in vivo studies based on the analysis of morphological differences of the membranes can be used to distinguish between inner and outer envelope localizations of proteins. To demonstrate the applicability of this approach, we demonstrated the localization of AtLACS9 to the outer envelope membrane. We also discuss protein impact on membrane behavior and regulation of protein insertion into membranes, and provide new hypotheses on the formation of stromules.
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Affiliation(s)
| | - Andrea Bräutigam
- Institute for Plant Biochemistry, Heinrich Heine University DüsseldorfDüsseldorf, Germany
| | - Stefan Geimer
- Electron Microscopy Laboratory, Institute for Cell Biology, University of BayreuthBayreuth, Germany
| | - Ulla Y. Welzel
- Electron Microscopy Laboratory, Institute for Cell Biology, University of BayreuthBayreuth, Germany
| | - Giovanni Stefano
- Plant Research Laboratory, Department of Energy, Michigan State UniversityEast Lansing, MI, USA
| | - Luciana Renna
- Plant Research Laboratory, Department of Energy, Michigan State UniversityEast Lansing, MI, USA
| | - Federica Brandizzi
- Plant Research Laboratory, Department of Energy, Michigan State UniversityEast Lansing, MI, USA
| | - Andreas P. M. Weber
- Institute for Plant Biochemistry, Heinrich Heine University DüsseldorfDüsseldorf, Germany
- *Correspondence: Andreas P. M. Weber, Institute for Plant Biochemistry, Heinrich Heine University, Geb. 26.03.01, Universitätsstrasse 1, D-40225 Düsseldorf, Germany. e-mail:
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6
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Xu Y, Zhou X. Role of Rice Stripe Virus NSvc4 in Cell-to-Cell Movement and Symptom Development in Nicotiana benthamiana. FRONTIERS IN PLANT SCIENCE 2012; 3:269. [PMID: 23233857 PMCID: PMC3516811 DOI: 10.3389/fpls.2012.00269] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 11/19/2012] [Indexed: 05/19/2023]
Abstract
Our previous work has demonstrated that the NSvc4 protein of Rice stripe virus (RSV) functions as a cell-to-cell movement protein. However, the mechanisms whereby RSV traffics through plasmodesmata (PD) are unknown. Here we provide evidence that the NSvc4 moves on the actin filament and endoplasmic reticulum network, but not microtubules, to reach cell wall PD. Disruption of cytoskeleton using different inhibitors altered NSvc4 localization to PD, thus impeding RSV infection of Nicotiana benthamiana. Sequence analyses and deletion mutagenesis experiment revealed that the N-terminal 125 amino acids (AAs) of the NSvc4 determine PD targeting and that a transmembrane domain spanning AAs 106-125 is critical for PD localization. We also found that the NSvc4 protein can localize to chloroplasts in infected cells. Analyses using deletion mutants revealed that the N-terminal 73 AAs are essential for chloroplast localization. Furthermore, expression of NSvc4 from a Potato virus X (PVX) vector resulted in more severe disease symptoms than PVX alone in systemically infected N. benthamiana leaves. Expression of NSvc4 in Spodoptera frugiperda 9 cells did not elicit tubule formation, but instead resulted in punctate foci at the plasma membrane. These findings shed new light on our understanding of the movement mechanisms whereby RSV infects host plants.
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Affiliation(s)
- Yi Xu
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang UniversityHangzhou, China
| | - Xueping Zhou
- State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang UniversityHangzhou, China
- *Correspondence: Xueping Zhou, State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, Zhejiang 310058, China. e-mail:
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7
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Ruiz-May E, Kim SJ, Brandizzi F, Rose JKC. The secreted plant N-glycoproteome and associated secretory pathways. FRONTIERS IN PLANT SCIENCE 2012; 3:117. [PMID: 22685447 PMCID: PMC3368311 DOI: 10.3389/fpls.2012.00117] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Accepted: 05/15/2012] [Indexed: 05/14/2023]
Abstract
N-Glycosylation is a common form of eukaryotic protein post-translational modification, and one that is particularly prevalent in plant cell wall proteins. Large scale and detailed characterization of N-glycoproteins therefore has considerable potential in better understanding the composition and functions of the cell wall proteome, as well as those proteins that reside in other compartments of the secretory pathway. While there have been numerous studies of mammalian and yeast N-glycoproteins, less is known about the population complexity, biosynthesis, structural variation, and trafficking of their plant counterparts. However, technical developments in the analysis of glycoproteins and the structures the glycans that they bear, as well as valuable comparative analyses with non-plant systems, are providing new insights into features that are common among eukaryotes and those that are specific to plants, some of which may reflect the unique nature of the plant cell wall. In this review we present an overview of the current knowledge of plant N-glycoprotein synthesis and trafficking, with particular reference to those that are cell wall localized.
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Affiliation(s)
- Eliel Ruiz-May
- Department of Plant Biology, Cornell UniversityIthaca, NY, USA
| | - Sang-Jin Kim
- Great Lakes Bioenergy Research Center, Michigan State UniversityEast Lansing, MI, USA
- DOE Plant Research Laboratory, Michigan State UniversityEast Lansing, MI, USA
| | - Federica Brandizzi
- Great Lakes Bioenergy Research Center, Michigan State UniversityEast Lansing, MI, USA
- DOE Plant Research Laboratory, Michigan State UniversityEast Lansing, MI, USA
| | - Jocelyn K. C. Rose
- Department of Plant Biology, Cornell UniversityIthaca, NY, USA
- *Correspondence: Jocelyn K. C. Rose, Department of Plant Biology, Cornell University, 412 Mann Library Building, Ithaca, NY 14853 USA. e-mail:
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8
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Chen Z, Grefen C, Donald N, Hills A, Blatt MR. A bicistronic, Ubiquitin-10 promoter-based vector cassette for transient transformation and functional analysis of membrane transport demonstrates the utility of quantitative voltage clamp studies on intact Arabidopsis root epidermis. PLANT, CELL & ENVIRONMENT 2011; 34:554-64. [PMID: 21251017 DOI: 10.1111/j.1365-3040.2010.02262.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
To date the use of fluorescent reporter constructs in analysing membrane transport has been limited primarily to cell lines expressing stably either the tagged transporter protein(s) or markers to identify lineages of interest. Strategies for transient expression have yet to be exploited in transport analysis, despite their wide application in cellular imaging studies. Here we describe a Gateway-compatible, bicistronic vector, incorporating the constitutive Ubiqutin-10 gene promoter of Arabidopsis that gives prolonged expression after transient transformation and enables fluorescence marking of cells without a fusion construct. We show that Arabidopsis root epidermal cells are readily transformed by co-cultivation with Agrobacterium and are tractable for quantitative electrophysiological analysis. As a proof of principle, we transiently transformed Arabidopsis with the bicistronic vector carrying GFP as the fluorescent marker and, separately, the integral plasma membrane protein SYP121 essential for the inward K+ channel current. We demonstrate that transient expression of SYP121 in syp121 mutant plants is sufficient to rescue the K+ current in vivo. The combination of transient expression and use of the bicistronic vector promises significant advantages for studies of membrane transport and nutrient acquisition in roots.
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Affiliation(s)
- Zhonghua Chen
- Laboratory of Plant Physiology and Biophysics, MCSB-Plant Sciences, Bower Building, University of Glasgow, Glasgow G128QQ, UK
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9
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Park M, Jürgens G. Membrane traffic and fusion at post-Golgi compartments. FRONTIERS IN PLANT SCIENCE 2011; 2:111. [PMID: 22645561 PMCID: PMC3355779 DOI: 10.3389/fpls.2011.00111] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 12/19/2011] [Indexed: 05/18/2023]
Abstract
Complete sequencing of the Arabidopsis genome a decade ago has facilitated the functional analysis of various biological processes including membrane traffic by which many proteins are delivered to their sites of action and turnover. In particular, membrane traffic between post-Golgi compartments plays an important role in cell signaling, taking care of receptor-ligand interaction and inactivation, which requires secretion, endocytosis, and recycling or targeting to the vacuole for degradation. Here, we discuss recent studies that address the identity of post-Golgi compartments, the machinery involved in traffic and fusion or functionally characterized cargo proteins that are delivered to or pass through post-Golgi compartments. We also provide an outlook on future challenges in this area of research.
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Affiliation(s)
- Misoon Park
- Entwicklungsgenetik, Zentrum für Molekularbiologie der Pflanzen, University of TübingenTübingen, Germany
| | - Gerd Jürgens
- Entwicklungsgenetik, Zentrum für Molekularbiologie der Pflanzen, University of TübingenTübingen, Germany
- *Correspondence: Gerd Jürgens, Entwicklungsgenetik, Zentrum für Molekularbiologie der Pflanzen, University of Tübingen, Auf der Morgenstelle 3, 72076 Tübingen, Germany. e-mail:
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10
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Sparkes IA, Hawes C, Baker A. AtPEX2 and AtPEX10 are targeted to peroxisomes independently of known endoplasmic reticulum trafficking routes. PLANT PHYSIOLOGY 2005; 139:690-700. [PMID: 16169966 PMCID: PMC1255988 DOI: 10.1104/pp.105.065094] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Controversy exists in the literature over the involvement of the endoplasmic reticulum (ER) in the delivery of membrane proteins to peroxisomes. In this study, the involvement of the ER in the trafficking of two Arabidopsis (Arabidopsis thaliana) peroxisomal membrane proteins was investigated using confocal laser scanning microscopy of living cells expressing fusions between enhanced yellow fluorescent protein (eYFP) and AtPEX2 and AtPEX10. The fusion proteins were always detected in peroxisomes and cytosol irrespective of the location of the eYFP tag or the level of expression. The cytosolic fluorescence was not due to cleavage of the eYFP reporter from the C-terminal fusion proteins. Blocking known ER transport routes using the fungal metabolite Brefeldin A or expressing dominant negative mutants of Sar1 or RabD2a had no effect on the trafficking of AtPEX2 and AtPEX10 to peroxisomes. We conclude that AtPEX2 and AtPEX10 are inserted into peroxisome membranes directly from the cytosol.
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11
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Sawers RJH, Linley PJ, Gutierrez-Marcos JF, Delli-Bovi T, Farmer PR, Kohchi T, Terry MJ, Brutnell TP. The Elm1 (ZmHy2) gene of maize encodes a phytochromobilin synthase. PLANT PHYSIOLOGY 2004; 136:2771-81. [PMID: 15347785 PMCID: PMC523340 DOI: 10.1104/pp.104.046417] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2004] [Revised: 07/06/2004] [Accepted: 07/13/2004] [Indexed: 05/22/2023]
Abstract
The light insensitive maize (Zea mays) mutant elongated mesocotyl1 (elm1) has previously been shown to be deficient in the synthesis of the phytochrome chromophore 3E-phytochromobilin (PPhiB). To identify the Elm1 gene, a maize homolog of the Arabidopsis PPhiB synthase gene AtHY2 was isolated and designated ZmHy2. ZmHy2 encodes a 297-amino acid protein of 34 kD that is 50% identical to AtHY2. ZmHY2 was predicted to be plastid localized and was targeted to chloroplasts following transient expression in tobacco (Nicotiana plumbaginifolia) leaves. Molecular mapping indicated that ZmHy2 is a single copy gene in maize that is genetically linked to the Elm1 locus. Sequence analysis revealed that the ZmHy2 gene of elm1 mutants contains a single G to A transition at the 3' splice junction of intron III resulting in missplicing and premature translational termination. However, flexibility in the splicing machinery allowed a small pool of in-frame ZmHy2 transcripts to accumulate in elm1 plants. In addition, multiple ZmHy2 transcript forms accumulated in both wild-type and elm1 mutant plants. ZmHy2 splice variants were expressed in Escherichia coli and products examined for activity using a coupled apophytochrome assembly assay. Only full-length ZmHY2 (as defined by homology to AtHY2) was found to exhibit PPhiB synthase activity. Thus, the elm1 mutant of maize is deficient in phytochrome response due to a lesion in a gene encoding phytochromobilin synthase that severely compromises the PPhiB pool.
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12
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Bhatt AM, Zhang Q, Harris SA, White-Cooper H, Dickinson H. Gene structure and molecular analysis of Arabidopsis thaliana ALWAYS EARLY homologs. Gene 2004; 336:219-29. [PMID: 15246533 DOI: 10.1016/j.gene.2004.03.033] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2003] [Revised: 03/11/2004] [Accepted: 03/29/2004] [Indexed: 10/26/2022]
Abstract
Drosophila always early (aly) is essential for spermatogenesis, and is related to the LIN-9 protein of Caenorhabditis elegans; lin-9 is a class B Synthetic Multivulva gene (synMuvB) required for gonadal sheath development. Aly/LIN-9 have two conserved regions, called domains 1 and 2, which have been identified in homologous proteins from several multicellular eukaryotes, including the model plant Arabidopsis thaliana. We cloned and sequenced cDNAs of three different A. thaliana ALWAYS EARLY homologs (AtALY1, AtALY2 and AtALY3), analysed the expression pattern of these three genes and show that AtALY1, like Aly, is nuclear localised. We also demonstrate that the plant homologs of aly/lin-9 contain an additional N-terminal myb domain not present in the animal Aly/LIN-9 proteins, and that part of the ALY/LIN-9 conserved domain 1 in the predicted plant proteins is related to the TUDOR domain.
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Affiliation(s)
- Anuj M Bhatt
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
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13
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Bhatt AM, Etchells JP, Canales C, Lagodienko A, Dickinson H. VAAMANA--a BEL1-like homeodomain protein, interacts with KNOX proteins BP and STM and regulates inflorescence stem growth in Arabidopsis. Gene 2004; 328:103-11. [PMID: 15019989 DOI: 10.1016/j.gene.2003.12.033] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2003] [Revised: 11/14/2003] [Accepted: 12/02/2003] [Indexed: 11/26/2022]
Abstract
Plant shoot growth depends on the activity of the shoot apical meristem (SAM), where organ primordia are initiated. In turn, the function of the SAM depends on the activities of homeodomain (HD) proteins of the knotted1-like homeobox (KNOX) class [Long et al., Nature 379 (1996) 66; Vollbrecht et al., Development 127 (2000) 3161]. In plants, KNOX proteins have been shown to interact specifically with the BEL1-like (BELL) class of homeodomain proteins [Bellaoui et al., Plant Cell 13 (2001) 2455; Muller et al., Plant 27 (2001) 13; Smith et al., Proc. Natl. Acad. Sci. USA 99 (2002) 9579], through a domain conserved between plants and animals. We have isolated a mutation in a BELL homeobox gene VAAMANA (VAN) that causes a dwarf phenotype. In addition, van inflorescence stems have clusters of cauline leaves; typically three are produced at each node. VAN interacts specifically with the class I KNOX proteins SHOOTMERISTEMLESS (STM), BREVIPEDICELLUS (BP), and KNAT6 (K6), and nuclear localisation of a VAN-GFP fusion depends on co-expression of STM or BP in tobacco leaves. This suggests that localisation of VAN, like that of the animal PBC homeodomain protein [Rieckhof et al., Cell 91 (1997) 171; Berthelsen et al., Genes Dev. 13 (1999) 946], is also regulated by interaction with a partner homeodomain protein.
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MESH Headings
- Amino Acid Sequence
- Arabidopsis/genetics
- Arabidopsis/growth & development
- Arabidopsis Proteins/genetics
- Arabidopsis Proteins/metabolism
- Base Sequence
- Blotting, Northern
- Cell Nucleus/metabolism
- Cloning, Molecular
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- Flowers/genetics
- Flowers/growth & development
- Gene Expression Regulation, Developmental
- Gene Expression Regulation, Plant
- Green Fluorescent Proteins
- Homeodomain Proteins/genetics
- Homeodomain Proteins/metabolism
- Luminescent Proteins/genetics
- Luminescent Proteins/metabolism
- Microscopy, Confocal
- Molecular Sequence Data
- Mutation
- Phenotype
- Phylogeny
- Plant Proteins/genetics
- Plant Proteins/metabolism
- Protein Binding
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Saccharomyces cerevisiae/genetics
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Two-Hybrid System Techniques
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Affiliation(s)
- Anuj M Bhatt
- Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
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Park M, Kim SJ, Vitale A, Hwang I. Identification of the protein storage vacuole and protein targeting to the vacuole in leaf cells of three plant species. PLANT PHYSIOLOGY 2004; 134:625-39. [PMID: 14730078 PMCID: PMC344539 DOI: 10.1104/pp.103.030635] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2003] [Revised: 10/08/2003] [Accepted: 11/04/2003] [Indexed: 05/17/2023]
Abstract
Protein storage vacuoles (PSVs) are specialized vacuoles devoted to the accumulation of large amounts of protein in the storage tissues of plants. In this study, we investigated the presence of the storage vacuole and protein trafficking to the compartment in cells of tobacco (Nicotiana tabacum), common bean (Phaseolus vulgaris), and Arabidopsis leaf tissue. When we expressed phaseolin, the major storage protein of common bean, or an epitope-tagged version of alpha-tonoplast intrinsic protein (alpha-TIP, a tonoplast aquaporin of PSV), in protoplasts derived from leaf tissues, these proteins were targeted to a compartment ranging in size from 2 to 5 microm in all three plant species. Most Arabidopsis leaf cells have one of these organelles. In contrast, from one to five these organelles occurred in bean and tobacco leaf cells. Also, endogenous alpha-TIP is localized in a similar compartment in untransformed leaf cells of common bean and is colocalized with transiently expressed epitope-tagged alpha-TIP. In Arabidopsis, phaseolin contained N-glycans modified by Golgi enzymes and its traffic was sensitive to brefeldin A. However, trafficking of alpha-TIP was insensitive to brefeldin A treatment and was not affected by the dominant-negative mutant of AtRab1. In addition, a modified alpha-TIP with an insertion of an N-glycosylation site has the endoplasmic reticulum-type glycans. Finally, the early step of phaseolin traffic, from the endoplasmic reticulum to the Golgi complex, required the activity of the small GTPase Sar1p, a key component of coat protein complex II-coated vesicles, independent of the presence of the vacuolar sorting signal in phaseolin. Based on these results, we propose that the proteins we analyzed are targeted to the PSV or equivalent organelle in leaf cells and that proteins can be transported to the PSV by two different pathways, the Golgi-dependent and Golgi-independent pathways, depending on the individual cargo proteins.
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Affiliation(s)
- Misoon Park
- Center for Plant Intracellular Trafficking, Pohang University of Science and Technology, Pohang, 790-784, Korea
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