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Li H, Bai M, Jiang X, Shen R, Wang H, Wang H, Wu H. Cytological evidence of BSD2 functioning in both chloroplast division and dimorphic chloroplast formation in maize leaves. BMC PLANT BIOLOGY 2020; 20:17. [PMID: 31918680 PMCID: PMC6953307 DOI: 10.1186/s12870-019-2219-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 12/26/2019] [Indexed: 05/07/2023]
Abstract
BACKGROUND Maize bsd2 (bundle sheath defective2) is a classical C4 mutant with defective C4 photosynthesis, accompanied with reduced accumulation of Rubisco (ribulose bisphosphate carboxylase oxygenase) and aberrant mature chloroplast morphology in the bundle sheath (BS) cells. However, as a hypothetical chloroplast chaperone, the effects of BSD2 on C4 chloroplast development have not been fully examined yet, which precludes a full appreciation of BSD2 function in C4 photosynthesis. The aims of our study are to find out the role ofBSD2 in regulating chloroplasts development in maize leaves, and to add new insights into our understanding of C4 biology. RESULTS We found that at the chloroplast maturation stage, the thylakoid membranes of chloroplasts in the BS and mesophyll (M) cells became significantly looser, and the granaof chloroplasts in the M cells became thinner stacking in the bsd2 mutant when compared with the wildtype plant. Moreover, at the early chloroplast development stage, the number of dividing chloroplasts and the chloroplast division rate are both reduced in the bsd2 mutant, compared with wild type. Quantitative reverse transcriptase-PCR analysis revealed that the expression of both thylakoid formation-related genesand chloroplast division-related genes is significantly reduced in the bsd2 mutants. Further, we showed that BSD2 interacts physically with the large submit of Rubisco (LS) in Bimolecular Fluorescence Complementation assay. CONCLUSIONS Our combined results suggest that BSD2 plays an essential role in regulating the division and differentiation of the dimorphic BS and M chloroplasts, and that it acts at a post-transcriptional level to regulate LS stability or assembly of Rubisco.
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Affiliation(s)
- Heying Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, 510642 China
| | - Mei Bai
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, 510642 China
| | - Xingshan Jiang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, 510642 China
| | - Rongxin Shen
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, 510642 China
| | - Huina Wang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, 510642 China
| | - Haiyang Wang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, 510642 China
| | - Hong Wu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, South China Agricultural University, Guangzhou, 510642 China
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Jilly R, Khan NZ, Aronsson H, Schneider D. Dynamin-Like Proteins Are Potentially Involved in Membrane Dynamics within Chloroplasts and Cyanobacteria. FRONTIERS IN PLANT SCIENCE 2018; 9:206. [PMID: 29520287 PMCID: PMC5827413 DOI: 10.3389/fpls.2018.00206] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 02/02/2018] [Indexed: 05/24/2023]
Abstract
Dynamin-like proteins (DLPs) are a family of membrane-active proteins with low sequence identity. The proteins operate in different organelles in eukaryotic cells, where they trigger vesicle formation, membrane fusion, or organelle division. As discussed here, representatives of this protein family have also been identified in chloroplasts and DLPs are very common in cyanobacteria. Since cyanobacteria and chloroplasts, an organelle of bacterial origin, have similar internal membrane systems, we suggest that DLPs are involved in membrane dynamics in cyanobacteria and chloroplasts. Here, we discuss the features and activities of DLPs with a focus on their potential presence and activity in chloroplasts and cyanobacteria.
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Affiliation(s)
- Ruven Jilly
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Nadir Zaman Khan
- Department of Biotechnology, University of Malakand, Malakand, Pakistan
| | - Henrik Aronsson
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Dirk Schneider
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg University Mainz, Mainz, Germany
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Heidrich J, Thurotte A, Schneider D. Specific interaction of IM30/Vipp1 with cyanobacterial and chloroplast membranes results in membrane remodeling and eventually in membrane fusion. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:537-549. [PMID: 27693914 DOI: 10.1016/j.bbamem.2016.09.025] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 09/19/2016] [Accepted: 09/21/2016] [Indexed: 12/22/2022]
Abstract
The photosynthetic light reaction takes place within the thylakoid membrane system in cyanobacteria and chloroplasts. Besides its global importance, the biogenesis, maintenance and dynamics of this membrane system are still a mystery. In the last two decades, strong evidence supported the idea that these processes involve IM30, the inner membrane-associated protein of 30kDa, a protein also known as the vesicle-inducing protein in plastids 1 (Vipp1). Even though we just only begin to understand the precise physiological function of this protein, it is clear that interaction of IM30 with membranes is crucial for biogenesis of thylakoid membranes. Here we summarize and discuss forces guiding IM30-membrane interactions, as the membrane properties as well as the oligomeric state of IM30 appear to affect proper interaction of IM30 with membrane surfaces. Interaction of IM30 with membranes results in an altered membrane structure and can finally trigger fusion of adjacent membranes, when Mg2+ is present. Based on recent results, we finally present a model summarizing individual steps involved in IM30-mediated membrane fusion. This article is part of a Special Issue entitled: Lipid order/lipid defects and lipid-control of protein activity edited by Dirk Schneider.
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Affiliation(s)
- Jennifer Heidrich
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg-University Mainz, Johann-Joachim-Becher-Weg 30, 55128 Mainz, Germany
| | - Adrien Thurotte
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg-University Mainz, Johann-Joachim-Becher-Weg 30, 55128 Mainz, Germany
| | - Dirk Schneider
- Institute of Pharmacy and Biochemistry, Johannes Gutenberg-University Mainz, Johann-Joachim-Becher-Weg 30, 55128 Mainz, Germany.
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Karim S, Aronsson H. The puzzle of chloroplast vesicle transport - involvement of GTPases. FRONTIERS IN PLANT SCIENCE 2014; 5:472. [PMID: 25295043 PMCID: PMC4171996 DOI: 10.3389/fpls.2014.00472] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2014] [Accepted: 08/28/2014] [Indexed: 05/04/2023]
Abstract
In the cytosol of plant cells vesicle transport occurs via secretory pathways among the endoplasmic reticulum network, Golgi bodies, secretory granules, endosome, and plasma membrane. Three systems transfer lipids, proteins and other important molecules through aqueous spaces to membrane-enclosed compartments, via vesicles that bud from donor membranes, being coated and uncoated before tethered and fused with acceptor membranes. In addition, molecular, biochemical and ultrastructural evidence indicates presence of a vesicle transport system in chloroplasts. Little is known about the protein components of this system. However, as chloroplasts harbor the photosynthetic apparatus that ultimately supports most organisms on the planet, close attention to their pathways is warranted. This may also reveal novel diversification and/or distinct solutions to the problems posed by the targeted intra-cellular trafficking of important molecules. To date two homologs to well-known yeast cytosolic vesicle transport proteins, CPSAR1 and CPRabA5e (CP, chloroplast localized), have been shown to have roles in chloroplast vesicle transport, both being GTPases. Bioinformatic data indicate that several homologs of cytosolic vesicle transport system components are putatively chloroplast-localized and in addition other proteins have been implicated to participate in chloroplast vesicle transport, including vesicle-inducing protein in plastids 1, thylakoid formation 1, snowy cotyledon 2/cotyledon chloroplast biogenesis factor, curvature thylakoid 1 proteins, and a dynamin like GTPase FZO-like protein. Several putative potential cargo proteins have also been identified, including building blocks of the photosynthetic apparatus. Here we discuss details of the largely unknown putative chloroplast vesicle transport system, focusing on GTPase-related components.
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Affiliation(s)
| | - Henrik Aronsson
- *Correspondence: Henrik Aronsson, Department of Biological and Environmental Sciences, University of Gothenburg, Box 461, 405 30 Gothenburg, Sweden e-mail:
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New putative chloroplast vesicle transport components and cargo proteins revealed using a bioinformatics approach: an Arabidopsis model. PLoS One 2013; 8:e59898. [PMID: 23573218 PMCID: PMC3613420 DOI: 10.1371/journal.pone.0059898] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 02/19/2013] [Indexed: 11/23/2022] Open
Abstract
Proteins and lipids are known to be transported to targeted cytosolic compartments in vesicles. A similar system in chloroplasts is suggested to transfer lipids from the inner envelope to the thylakoids. However, little is known about both possible cargo proteins and the proteins required to build a functional vesicle transport system in chloroplasts. A few components have been suggested, but only one (CPSAR1) has a verified location in chloroplast vesicles. This protein is localized in the donor membrane (envelope) and vesicles, but not in the target membrane (thylakoids) suggesting it plays a similar role to a cytosolic homologue, Sar1, in the secretory pathway. Thus, we hypothesized that there may be more similarities, in addition to lipid transport, between the vesicle transport systems in the cytosol and chloroplast, i.e. similar vesicle transport components, possible cargo proteins and receptors. Therefore, using a bioinformatics approach we searched for putative chloroplast components in the model plant Arabidopsis thaliana, corresponding mainly to components of the cytosolic vesicle transport system that may act in coordination with previously proposed COPII chloroplast homologues. We found several additional possible components, supporting the notion of a fully functional vesicle transport system in chloroplasts. Moreover, we found motifs in thylakoid-located proteins similar to those of COPII vesicle cargo proteins, supporting the hypothesis that chloroplast vesicles may transport thylakoid proteins from the envelope to the thylakoid membrane. Several putative cargo proteins are involved in photosynthesis, thus we propose the existence of a novel thylakoid protein pathway that is important for construction and maintenance of the photosynthetic machinery.
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Abstract
Two separate families of Arabidopsis dynamin-related proteins, DRP1 and DRP2, have been implicated in clathrin-mediated endocytosis and cell plate maturation during cytokinesis. The present review summarizes the current genetic, biochemical and cell biological knowledge about these two protein families, and suggests key directions for more fully understanding their roles and untangling their function in membrane trafficking. We focus particularly on comparing and contrasting these two protein families, which have very distinct domain structures and are independently essential for Arabidopsis development, yet which have been implicated in very similar cellular processes during cytokinesis and cell expansion.
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Garcia C, Khan NZ, Nannmark U, Aronsson H. The chloroplast protein CPSAR1, dually localized in the stroma and the inner envelope membrane, is involved in thylakoid biogenesis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 63:73-85. [PMID: 20408996 DOI: 10.1111/j.1365-313x.2010.04225.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Thylakoid biogenesis is a crucial step for plant development involving the combined action of many cellular actors. CPSAR1 is shown here to be required for the normal organization of mature thylakoid stacks, and ultimately for embryo development. CPSAR1 is a chloroplast protein that has a dual localization in the stroma and the inner envelope membrane, according to microscopy studies and subfractionation analysis. CPSAR1 is close to the Obg nucleotide binding protein subfamily and displays GTPase activity, as demonstrated by in vitro assays. Disruption of the CPSAR1 gene via T-DNA insertion results in the arrest of embryo development. In addition, transmission electron microscopy analysis indicates that mutant embryos are unable to develop thylakoid membranes, and remain white. Unstacked membrane structures resembling single lamellae accumulate in the stroma, and do not assemble into mature thylakoid stacks. CPSAR1 RNA interference induces partially developed thylakoids leading to pale-green embryos. Altogether, the presented data demonstrate that CPSAR1 is a protein essential for the formation of normal thylakoid membranes, and suggest a possible involvement in the initiation of vesicles from the inner envelope membrane for the transfer of lipids to the thylakoids.
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Affiliation(s)
- Christel Garcia
- Department of Plant and Environmental Sciences, University of Gothenburg, Box 461, SE-405 30 Gothenburg, Sweden
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8
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Andersson MX, Dörmann P. Chloroplast Membrane Lipid Biosynthesis and Transport. PLANT CELL MONOGRAPHS 2008. [DOI: 10.1007/978-3-540-68696-5_4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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9
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El-Kafafi ES, Karamoko M, Pignot-Paintrand I, Grunwald D, Mandaron P, Lerbs-Mache S, Falconet D. Developmentally regulated association of plastid division protein FtsZ1 with thylakoid membranes in Arabidopsis thaliana. Biochem J 2008; 409:87-94. [PMID: 17725544 DOI: 10.1042/bj20070543] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
FtsZ is a key protein involved in bacterial and organellar division. Bacteria have only one ftsZ gene, while chlorophytes (higher plants and green alga) have two distinct FtsZ gene families, named FtsZ1 and FtsZ2. This raises the question of why chloroplasts in these organisms need distinct FtsZ proteins to divide. In order to unravel new functions associated with FtsZ proteins, we have identified and characterized an Arabidopsis thaliana FtsZ1 loss-of-function mutant. ftsZ1-knockout mutants are impeded in chloroplast division, and division is restored when FtsZ1 is expressed at a low level. FtsZ1-overexpressing plants show a drastic inhibition of chloroplast division. Chloroplast morphology is altered in ftsZ1, with chloroplasts having abnormalities in the thylakoid membrane network. Overexpression of FtsZ1 also induced defects in thylakoid organization with an increased network of twisting thylakoids and larger grana. We show that FtsZ1, in addition to being present in the stroma, is tightly associated with the thylakoid fraction. This association is developmentally regulated since FtsZ1 is found in the thylakoid fraction of young developing plant leaves but not in mature and old plant leaves. Our results suggest that plastid division protein FtsZ1 may have a function during leaf development in thylakoid organization, thus highlighting new functions for green plastid FtsZ.
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Affiliation(s)
- El-Sayed El-Kafafi
- Laboratoire Plastes et Différenciation Cellulaire, Université Joseph Fourier and CNRS, BP 53, F-38041 Grenoble Cedex 9, France
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10
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Andersson MX, Dörmann P. Chloroplast Membrane Lipid Biosynthesis and Transport. PLANT CELL MONOGRAPHS 2008. [DOI: 10.1007/7089_2008_18] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
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11
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Pyke K. Plastid biogenesis and differentiation. CELL AND MOLECULAR BIOLOGY OF PLASTIDS 2007. [DOI: 10.1007/4735_2007_0226] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Jouhet J, Maréchal E, Block MA. Glycerolipid transfer for the building of membranes in plant cells. Prog Lipid Res 2007; 46:37-55. [PMID: 16970991 DOI: 10.1016/j.plipres.2006.06.002] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2006] [Revised: 06/14/2006] [Accepted: 06/20/2006] [Indexed: 01/05/2023]
Abstract
Membranes of plant organelles have specific glycerolipid compositions. Selective distribution of lipids at the levels of subcellular organelles, membrane leaflets and membrane domains reflects a complex and finely tuned lipid homeostasis. Glycerolipid neosynthesis occurs mainly in plastid envelope and endoplasmic reticulum membranes. Since most lipids are not only present in the membranes where they are synthesized, one cannot explain membrane specific lipid distribution by metabolic processes confined in each membrane compartment. In this review, we present our current understanding of glycerolipid trafficking in plant cells. We examine the potential mechanisms involved in lipid transport inside bilayers and from one membrane to another. We survey lipid transfers going through vesicular membrane flow and those dependent on lipid transfer proteins at membrane contact sites. By introducing recently described membrane lipid reorganization during phosphate deprivation and recent developments issued from mutant analyses, we detail the specific lipid transfers towards or outwards the chloroplast envelope.
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Affiliation(s)
- Juliette Jouhet
- Laboratoire de Physiologie, Cellulaire Végétale, UMR 5168 (CNRS/CEA/Université Joseph Fourier/INRA), DRDC/PCV, CEA-Grenoble, 17 rue des Martyrs, F-38054 Grenoble-cedex 9, France
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13
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Rochaix JD. The Role of Nucleus- and Chloroplast-Encoded Factors in the Synthesis of the Photosynthetic Apparatus. ACTA ACUST UNITED AC 2007. [DOI: 10.1007/978-1-4020-4061-0_7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
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Sulmon C, Gouesbet G, Couée I, Cabello-Hurtado F, Cavalier A, Penno C, Zaka R, Bechtold N, Thomas D, El Amrani A. The pleiotropic Arabidopsis frd mutation with altered coordination of chloroplast biogenesis, cell size and differentiation, organ size and number. Gene 2006; 382:88-99. [PMID: 16973304 DOI: 10.1016/j.gene.2006.06.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2006] [Revised: 06/26/2006] [Accepted: 06/27/2006] [Indexed: 10/24/2022]
Abstract
In higher plants, plastid development must be tightly coordinated with cell and organ development. In this paper, a novel T-DNA-mutagenized Arabidopsis line showing chlorotic leaves and minute stature was identified in a genetic screen for altered chloroplast development. The mutation corresponded to a single locus on chromosome IV and was associated with insertion of the T-DNA. This locus was named FARFADET and resulted in pleiotropic effects on chloroplast biogenesis, cell size and differentiation, organ size and number. Thus, in contrast with previously described chlorotic mutants, frd mutants were affected not only in chloroplast development and chlorophyll accumulation, but also in cell and organ development. Alteration of differentiation affected different cell types such as leaf epidermal cells, trichomes, mesophyll cells, and columella cells. A major effect on mesophyll cell differentiation was the lack of palisadic parenchyma and absence of grana stacks. Moreover, meristem size and lateral meristem initiation were affected. Genetic and molecular characterisation showed that the T-DNA insertion generated 41 bp deletion in a potential miRNA precursor. The predicted miRNA target genes were involved in plant development and stress. It is therefore hypothesized that the frd mutation had affected coordination of cell developmental span and the control of the division-differentiation balance.
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Affiliation(s)
- Cécile Sulmon
- Centre National de la Recherche Scientifique, Université de Rennes 1, UMR 6553 Fonctionnement des écosystèmes, Campus de Beaulieu, bâtiment 14A, F-35042 Rennes Cedex, France
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Huang F, Fulda S, Hagemann M, Norling B. Proteomic screening of salt-stress-induced changes in plasma membranes of Synechocystis sp. strain PCC 6803. Proteomics 2006; 6:910-20. [PMID: 16400685 DOI: 10.1002/pmic.200500114] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The plasma membrane of a cyanobacterial cell is crucial as barrier against the outer medium. It is also an energy-transducing membrane as well as essential for biogenesis of cyanobacterial photosystems and the endo-membrane system. Previously we have identified 57 different proteins in the plasma membrane of control cells from Synechocystis sp. strain PCC6803. In the present work, proteomic screening of salt-stress proteins in the plasma membrane resulted in identification of 109 proteins corresponding to 66 different gene products. Differential and quantitative analyses of 2-DE profiles of plasma membranes isolated from both control and salt-acclimated cells revealed that twenty proteins were enhanced/induced and five reduced during salt stress. More than half of the enhanced/induced proteins were periplasmic binding proteins of ABC-transporters or hypothetical proteins. Proteins that exhibited the highest enhancement during salt stress include FutA1 (Slr1295) and Vipp1 (Sll0617), which have been suggested to be involved in protection of photosystem II under iron deficiency and in thylakoid membrane formation, respectively. Other salt-stress proteins were regulatory proteins such as PII protein, LrtA, and a protein that belongs to CheY subfamily. The physiological significance of the identified salt-stress proteins in the plasma membrane is discussed integrating our current knowledge on cyanobacterial stress physiology.
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Affiliation(s)
- Fang Huang
- Department of Biochemistry and Biophysics, Arrhenius Laboratories for Natural Sciences, Stockholm University, Stockholm, Sweden
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Wang Q, Sullivan RW, Kight A, Henry RL, Huang J, Jones AM, Korth KL. Deletion of the chloroplast-localized Thylakoid formation1 gene product in Arabidopsis leads to deficient thylakoid formation and variegated leaves. PLANT PHYSIOLOGY 2004; 136:3594-604. [PMID: 15516501 PMCID: PMC527158 DOI: 10.1104/pp.104.049841] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2004] [Revised: 09/01/2004] [Accepted: 09/07/2004] [Indexed: 05/18/2023]
Abstract
Development of thylakoid membranes depends upon the transport of membrane vesicles from the chloroplast inner envelope and subsequent fusion of vesicles within the interior of the plastid. The Arabidopsis (Arabidopsis thaliana) Thylakoid formation1 (Thf1) gene product is shown here to control an important step required for the normal organization of these vesicles into mature thylakoid stacks and ultimately for leaf development. The Arabidopsis Thf1 gene encodes an imported chloroplast protein, as shown by in vitro import and localization of a Thf1-green fluorescent protein fusion product in transgenic plants. This gene is conserved in oxygenic photoautotrophs ranging from cyanobacteria to flowering land plants. Transcript levels for Thf1 are induced in the light and decrease under dark conditions, paralleling profiles of light-regulated nuclear genes involved in chloroplast function. Disruption of the Thf1 gene via T-DNA insertion results in plants that are severely stunted with variegated leaf patterns. Nongreen sectors of variegated leaves lacking Thf1 expression contain plastids that accumulate membrane vesicles on the interior and lack organized thylakoid structures. Green sectors of Thf1-disrupted leaves contain some chloroplasts that form organized thylakoid membranes, indicating that an inefficient compensatory mechanism supports thylakoid formation in the absence of Thf1. Genetic complementation of a Thf1 knockout line confirms the role of this gene in chloroplast and leaf development. Transgenic plants expressing the Thf1 gene in antisense orientation are stunted with altered thylakoid organization, especially in young seedlings. The data indicate that the Thf1 gene product plays a crucial role in a dynamic process of vesicle-mediated thylakoid membrane biogenesis.
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Affiliation(s)
- Qin Wang
- Department of Plant Pathology , University of Arkansas, Fayetteville, Arkansas 72701, USA
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Andersson MX, Sandelius AS. A chloroplast-localized vesicular transport system: a bio-informatics approach. BMC Genomics 2004; 5:40. [PMID: 15236667 PMCID: PMC481061 DOI: 10.1186/1471-2164-5-40] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2004] [Accepted: 07/05/2004] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The thylakoid membrane of higher plant chloroplasts is made of membrane lipids synthesized in the chloroplast envelope. As the inner envelope membrane and the thylakoid are separated by the aqueous stroma, a system for transporting newly synthesized lipids from the inner envelope membrane to the thylakoid is required. Ultrastructural as well as biochemical studies have indicated that lipid transport inside the chloroplast could be mediated by a system similar in characteristics to vesicular trafficking in the cytosol. If indeed the chloroplast system is related to cytosolic vesicular trafficking systems, a certain degree of sequence conservation between components of the chloroplast and the cytosolic systems could be expected. We used the Arabidopsis thaliana genome and web-based subcellular localization prediction tools to search for chloroplast-localized homologues of cytosolic vesicular trafficking components. RESULTS Out of the 28952 hypothetical proteins in the A. thaliana genome sequence, 1947 were predicted to be chloroplast-localized by two different subcellular localization predictors. In this chloroplast protein dataset, strong homologues for the main coat proteins of COPII coated cytosolic vesicles were found. Homologues of the small GTPases ARF1 and Sar1 were also found in the chloroplast protein dataset. CONCLUSION Our database search approach gives further support to that a system similar to cytosolic vesicular trafficking is operational inside the chloroplast. However, solid biochemical data is needed to support the chloroplast localization of the identified proteins as well as their involvement in intra-chloroplast lipid trafficking.
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Affiliation(s)
- Mats X Andersson
- Department of Botany, Göteborg University, Box 461, SE-405 30 Göteborg, Sweden
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Mano S, Nakamori C, Kondo M, Hayashi M, Nishimura M. An Arabidopsis dynamin-related protein, DRP3A, controls both peroxisomal and mitochondrial division. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2004; 38:487-98. [PMID: 15086806 DOI: 10.1111/j.1365-313x.2004.02063.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Peroxisomes undergo dramatic changes in size, shape, number, and position within the cell, but the division process of peroxisomes has not been characterized. We screened a number of Arabidopsis mutants with aberrant peroxisome morphology (apm mutants). In one of these mutants, apm1, the peroxisomes are long and reduced in number, apparently as a result of inhibition of division. We showed that APM1 encodes dynamin-related protein 3A (DRP3A), and that mutations in APM1/DRP3A also caused aberrant morphology of mitochondria. The transient expression analysis showed that DRP3A is associated with the cytosolic side of peroxisomes. These findings indicate that the same dynamin molecule is involved in peroxisomal and mitochondrial division in higher plants. We also report that the growth of Arabidopsis, which requires the cooperation of various organelles, including peroxisomes and mitochondria, is repressed in apm1, indicating that the changes of morphology of peroxisomes and mitochondria reduce the efficiency of metabolism in these organelles.
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Affiliation(s)
- Shoji Mano
- Department of Cell Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan
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Praefcke GJK, McMahon HT. The dynamin superfamily: universal membrane tubulation and fission molecules? Nat Rev Mol Cell Biol 2004; 5:133-47. [PMID: 15040446 DOI: 10.1038/nrm1313] [Citation(s) in RCA: 1042] [Impact Index Per Article: 52.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Dynamins are large GTPases that belong to a protein superfamily that, in eukaryotic cells, includes classical dynamins, dynamin-like proteins, OPA1, Mx proteins, mitofusins and guanylate-binding proteins/atlastins. They are involved in many processes including budding of transport vesicles, division of organelles, cytokinesis and pathogen resistance. With sequenced genomes from Homo sapiens, Drosophila melanogaster, Caenorhabditis elegans, yeast species and Arabidopsis thaliana, we now have a complete picture of the members of the dynamin superfamily from different organisms. Here, we review the superfamily of dynamins and their related proteins, and propose that a common mechanism leading to membrane tubulation and/or fission could encompass their many varied functions.
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Affiliation(s)
- Gerrit J K Praefcke
- Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK.
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Arimura SI, Aida GP, Fujimoto M, Nakazono M, Tsutsumi N. Arabidopsis dynamin-like protein 2a (ADL2a), like ADL2b, is involved in plant mitochondrial division. PLANT & CELL PHYSIOLOGY 2004; 45:236-42. [PMID: 14988495 DOI: 10.1093/pcp/pch024] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The Arabidopsis genome has two similar dynamin-like proteins, ADL2a and ADL2b (76.7% identity). ADL2a is reported to be localized in chloroplasts [Kang et al. (1998) Plant Mol. Biol. 38: 437], while ADL2b functions in mitochondrial division [Arimura and Tsutsumi (2002) PROC: Natl. Acad. Sci. USA 99: 5727]. Using GFP fusion proteins, we observed both ADL2a and ADL2b in portions of mitochondria but not in chloroplasts. Furthermore, cells transformed with ADL2a and ADL2b with a defective GTPase domain had normal chloroplasts but elongated mitochondria. These results imply that both ADL2b and ADL2a are involved in the division of plant mitochondria.
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Affiliation(s)
- Shin-ichi Arimura
- Laboratory of Plant Molecular Genetics, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657 Japan.
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Abstract
Mitochondria cannot be created de novo but instead must arise from the fission (division) of a parental organelle. In addition to fission, mitochondria also fuse with one another and it is thought that a co-ordinated balance of these two processes controls mitochondrial shape, size and number. In the past 5-7 yr, molecular genetics coupled to state-of-the-art cell biology, in particular the use of mitochondrial-targeted green fluorescent protein (GFP), has enabled identification of proteins controlling mitochondrial shape, size and number in yeast and mammalian cells. Little is known about higher plant mitochondrial dynamics. Recently, however, several genes involved in the control of plant mitochondrial dynamics have been identified. The aim of this article is to bring together what is known about mitochondrial dynamics in any organisms and to relate this to our recent knowledge of the underlying processes in higher plants. Contents Summary 463 I. Introduction 464 II. Mitochondrial evolution 464 III. Mitochondria and the cytoskeleton 465 IV. Mitochondrial morphology, biogenesis, proliferation and inheritance 466 V. Mitochondrial fission and fusion 468 VI. Mitochondrial distribution 470 VII. Plant specific proteins playing a role in mitochondrial dynamics 470 VIII. Conclusions 471 Acknowledgements 475 References 475.
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Affiliation(s)
- David C Logan
- School of Biology, Sir Harold Mitchell Building, University of St Andrews, St Andrews, KY16 9TH, UK
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Hong Z, Bednarek SY, Blumwald E, Hwang I, Jurgens G, Menzel D, Osteryoung KW, Raikhel NV, Shinozaki K, Tsutsumi N, Verma DPS. A unified nomenclature for Arabidopsis dynamin-related large GTPases based on homology and possible functions. PLANT MOLECULAR BIOLOGY 2003; 53:261-5. [PMID: 14750516 DOI: 10.1023/b:plan.0000007000.29697.81] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
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Jeong SY, Rose A, Meier I. MFP1 is a thylakoid-associated, nucleoid-binding protein with a coiled-coil structure. Nucleic Acids Res 2003; 31:5175-85. [PMID: 12930969 PMCID: PMC212795 DOI: 10.1093/nar/gkg693] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Plastid DNA, like bacterial and mitochondrial DNA, is organized into protein-DNA complexes called nucleoids. Plastid nucleoids are believed to be associated with the inner envelope in developing plastids and the thylakoid membranes in mature chloroplasts, but the mechanism for this re-localization is unknown. Here, we present the further characterization of the coiled-coil DNA-binding protein MFP1 as a protein associated with nucleoids and with the thylakoid membranes in mature chloroplasts. MFP1 is located in plastids in both suspension culture cells and leaves and is attached to the thylakoid membranes with its C-terminal DNA-binding domain oriented towards the stroma. It has a major DNA-binding activity in mature Arabidopsis chloroplasts and binds to all tested chloroplast DNA fragments without detectable sequence specificity. Its expression is tightly correlated with the accumulation of thylakoid membranes. Importantly, it is associated in vivo with nucleoids, suggesting a function for MFP1 at the interface between chloroplast nucleoids and the developing thylakoid membrane system.
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Affiliation(s)
- Sun Yong Jeong
- Department of Plant Biology and Plant Biotechnology Center, Ohio State University, 244 Rightmire Hall, 1060 Carmack Road, Columbus, OH 43210, USA
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Lam BCH, Sage TL, Bianchi F, Blumwald E. Regulation of ADL6 activity by its associated molecular network. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2002; 31:565-576. [PMID: 12207647 DOI: 10.1046/j.1365-313x.2002.01377.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Plant dynamin-like proteins consist of a group of high molecular weight GTPase with diverse structural arrangements and cellular localizations. In addition, unlike animal dynamins, there was no evidence for the involvement of any plant dynamin-like protein in clathrin-mediated vesicle trafficking. In this study we demonstrate that ADL6 (Arabidopsis dynamin-like protein 6), due to its domain arrangement, behaves similarly to the animal dynamins. The association of ADL6 with clathrin-coated vesicles was demonstrated by co-fractionation and immunocytochemical studies. ADL6 also interacted via its C-terminus with gamma-adaptin, an adaptor protein of clathrin-coated vesicles. Our results suggest that ADL6 participates in clathrin-mediated vesicle trafficking originating from the Golgi. In addition, our studies demonstrate that ADL6 intrinsic GTPase activity is regulated by its association with acidic phospholipids and an SH3 (Src homology 3)-containing protein.
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Affiliation(s)
- Bernard C-H Lam
- Department of Botany, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada M5S 3B2
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Lee SH, Jin JB, Song J, Min MK, Park DS, Kim YW, Hwang I. The intermolecular interaction between the PH domain and the C-terminal domain of Arabidopsis dynamin-like 6 determines lipid binding specificity. J Biol Chem 2002; 277:31842-9. [PMID: 12105222 DOI: 10.1074/jbc.m204770200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dynamin and its related proteins are a group of mechanochemical proteins involved in the modulation of lipid membranes in various biological processes. Here we investigate the nature of membrane binding of the Arabidopsis dynamin-like 6 (ADL6) involved in vesicle trafficking from the trans-Golgi network to the central vacuole. Fractionation experiments by continuous sucrose gradients and gel filtration revealed that the majority of ADL6 is associated with membranes in vivo. Amino acid sequence analysis revealed that ADL6 has a putative pleckstrin homology (PH) domain. In vitro lipid binding assays demonstrated that ADL6 showed high affinity binding to phosphatidylinositol 3-phosphate (PtdIns-3-P) and that the PH domain was responsible for this interaction. However, the PH domain alone binds equally well to both PtdIns-3-P and phosphatidylinositol 4-phosphate (PtdIns-4-P). Interestingly, the high affinity binding of the PH domain to PtdIns-3-P was restored by a protein-protein interaction between the PH domain and the C-terminal region. In addition, deletion of the inserted regions within the PH domain results in high affinity binding of the PH domain to PtdIns-3-P. These results suggest that ADL6 binds specifically to PtdIns-3-P and that the lipid binding specificity is determined by the interaction between the PH domain and the C-terminal domain of ADL6.
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Affiliation(s)
- Sung Hoon Lee
- Center for Plant Intracellular Trafficking and the Division of Molecular and Life Sciences, Pohang University of Science and Technology, 790-784, Korea
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Kochs G, Haener M, Aebi U, Haller O. Self-assembly of human MxA GTPase into highly ordered dynamin-like oligomers. J Biol Chem 2002; 277:14172-6. [PMID: 11847228 DOI: 10.1074/jbc.m200244200] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human MxA protein is a member of the interferon-induced Mx protein family and an important component of the innate host defense against RNA viruses. The Mx family belongs to a superfamily of large GTPases that also includes the dynamins and the interferon-regulated guanylate-binding proteins. A common feature of these large GTPases is their ability to form high molecular weight oligomers. Here we determined the capacity of MxA to self-assemble into homo-oligomers in vitro. We show that recombinant MxA protein assembles into long filamentous structures with a diameter of about 20 nm at physiological salt concentration as demonstrated by sedimentation assays and electron microscopy. In the presence of guanosine nucleotides the filaments rearranged into rings and more compact helical arrays. Our data indicate that binding and hydrolysis of GTP induce conformational changes in MxA that may be essential for viral target recognition and antiviral activity.
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Affiliation(s)
- Georg Kochs
- Abteilung Virologie, Institut für Medizinische Mikrobiologie und Hygiene, Universität Freiburg, D-79008 Freiburg, Germany.
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Lam BC, Sage TL, Bianchi F, Blumwald E. Role of SH3 domain-containing proteins in clathrin-mediated vesicle trafficking in Arabidopsis. THE PLANT CELL 2001. [PMID: 11701884 DOI: 10.1105/tpc.13.11.2499] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
A group of plant AtSH3Ps (Arabidopsis thaliana SH3-containing proteins) involved in trafficking of clathrin-coated vesicles was identified from the GenBank database. These proteins contained predicted coiled-coil and Src homology 3 (SH3) domains that are similar to animal and yeast proteins involved in the formation, fission, and uncoating of clathrin-coated vesicles. Subcellular fractionation and immunolocalization studies confirmed the presence of AtSH3P1 in the endomembrane system. In particular, AtSH3P1 was localized on or adjacent to the plasma membrane and its associated vesicles, vesicles of the trans-Golgi network, and the partially coated reticulum. At all of these locations, AtSH3P1 colocalized with clathrin. Functionally, in vitro lipid binding assay demonstrated that AtSH3P1 bound to specific lipid groups known to accumulate at invaginated coated pits or coated vesicles. In addition, immunohistochemical studies and actin binding assays indicated that AtSH3P1 also may regulate vesicle trafficking along the actin cytoskeleton. Yeast complementation studies suggested that AtSH3Ps have similar functions to the yeast Rvs167p protein involved in endocytosis and actin arrangement. A novel interaction between AtSH3P1 and an auxilin-like protein was identified by yeast two-hybrid screening, immunolocalization, and an in vitro binding assay. The interaction was mediated through the SH3 domain of AtSH3P1 and a proline-rich domain of auxilin. The auxilin-like protein stimulated the uncoating of clathrin-coated vesicles by Hsc70, a reaction that appeared to be inhibited in the presence of AtSH3P1. Hence, AtSH3P1 may perform regulatory and/or scaffolding roles during the transition of fission and the uncoating of clathrin-coated vesicles.
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Affiliation(s)
- B C Lam
- Department of Botany, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada
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Lam BC, Sage TL, Bianchi F, Blumwald E. Role of SH3 domain-containing proteins in clathrin-mediated vesicle trafficking in Arabidopsis. THE PLANT CELL 2001; 13:2499-512. [PMID: 11701884 PMCID: PMC139467 DOI: 10.1105/tpc.010279] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2001] [Accepted: 08/24/2001] [Indexed: 05/18/2023]
Abstract
A group of plant AtSH3Ps (Arabidopsis thaliana SH3-containing proteins) involved in trafficking of clathrin-coated vesicles was identified from the GenBank database. These proteins contained predicted coiled-coil and Src homology 3 (SH3) domains that are similar to animal and yeast proteins involved in the formation, fission, and uncoating of clathrin-coated vesicles. Subcellular fractionation and immunolocalization studies confirmed the presence of AtSH3P1 in the endomembrane system. In particular, AtSH3P1 was localized on or adjacent to the plasma membrane and its associated vesicles, vesicles of the trans-Golgi network, and the partially coated reticulum. At all of these locations, AtSH3P1 colocalized with clathrin. Functionally, in vitro lipid binding assay demonstrated that AtSH3P1 bound to specific lipid groups known to accumulate at invaginated coated pits or coated vesicles. In addition, immunohistochemical studies and actin binding assays indicated that AtSH3P1 also may regulate vesicle trafficking along the actin cytoskeleton. Yeast complementation studies suggested that AtSH3Ps have similar functions to the yeast Rvs167p protein involved in endocytosis and actin arrangement. A novel interaction between AtSH3P1 and an auxilin-like protein was identified by yeast two-hybrid screening, immunolocalization, and an in vitro binding assay. The interaction was mediated through the SH3 domain of AtSH3P1 and a proline-rich domain of auxilin. The auxilin-like protein stimulated the uncoating of clathrin-coated vesicles by Hsc70, a reaction that appeared to be inhibited in the presence of AtSH3P1. Hence, AtSH3P1 may perform regulatory and/or scaffolding roles during the transition of fission and the uncoating of clathrin-coated vesicles.
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Affiliation(s)
- B C Lam
- Department of Botany, University of Toronto, 25 Willcocks Street, Toronto, Ontario, Canada
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Kim YW, Park DS, Park SC, Kim SH, Cheong GW, Hwang I. Arabidopsis dynamin-like 2 that binds specifically to phosphatidylinositol 4-phosphate assembles into a high-molecular weight complex in vivo and in vitro. PLANT PHYSIOLOGY 2001; 127:1243-1255. [PMID: 11706203 PMCID: PMC129292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 05/17/2001] [Revised: 08/02/2001] [Accepted: 08/28/2001] [Indexed: 05/23/2023]
Abstract
Arabadopsis dynamin-like (ADL) 2, a member of the high-molecular weight (M(r)) dynamin family found in Arabidopsis, has been shown to be targeted to the plastid. In the chloroplast, most of the ADL2 was present in the fraction containing the envelope membranes when analyzed by suborganellar fractionation. Sucrose gradient and gel filtration experiments showed that when associated with membranes, ADL2 existed as a high-M(r) complex, whereas the soluble form existed as a monomer. The recombinant ADL2 expressed in Escherichia coli was present as a high-M(r) form and showed higher GTPase activity at a low NaCl concentration, whereas ADL2 existed as a low-M(r) form with a low level of GTPase activity at a high NaCl concentration. Electron microscopy studies revealed that the purified recombinant ADL2 formed spiral-coiled structures or rings. In the presence of guanosine-5'-O-(3-thio)triphosphate, these structures were transformed into a long rod structure. In contrast, in the presence of GDP, these structures disassembled into oligomers that were shown to be tetramer with 4-fold symmetry. Finally, a lipid-binding assay revealed that recombinant ADL2 purified from E. coli bound specifically to phosphatidylinositol 4-phosphate. Together, these results demonstrated that the biochemical properties of ADL2 were very similar to those of dynamin and other related proteins. Based on this similarity, we propose that ADL2 may be involved in vesicle formation at the chloroplast envelope membrane.
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Affiliation(s)
- Y W Kim
- Department of Life Science and Center for Plant Intracellular Trafficking, Pohang University of Science and Technology, Pohang, 790-784, Korea
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Lee YJ, Kim DH, Kim YW, Hwang I. Identification of a signal that distinguishes between the chloroplast outer envelope membrane and the endomembrane system in vivo. THE PLANT CELL 2001; 13:2175-2190. [PMID: 11595795 DOI: 10.1105/tpc.13.10.2175] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Certain small outer envelope membrane proteins of chloroplasts are encoded by the nuclear genome without a cleavable N-terminal transit peptide. We investigated in vivo the targeting mechanism of AtOEP7, an Arabidopsis homolog of the small outer envelope membrane protein. AtOEP7 was expressed as a fusion protein with the green fluorescent protein (GFP) either transiently in protoplasts or stably in transgenic plants. In either case, fluorescence microscopy of transformed cells and protein gel blot analysis of fractionated proteins confirmed that the AtOEP7:GFP fusion protein was targeted to the chloroplast outer envelope membrane. In vivo targeting experiments revealed that two regions, the transmembrane domain (TMD) and its C-terminal neighboring seven-amino acid region, were necessary and sufficient for targeting to the chloroplast outer membrane. Substitution of aspartic acid or lysine residues with glycine residues or scrambling of the amino acid sequence of the seven-amino acid region caused mistargeting to the plasma membrane. Although the amino acid sequence of the TMD is not important for targeting, amino acid residues with large side chains inhibited targeting to the chloroplasts and resulted in the formation of large aggregates in the protoplasts. In addition, introduction of a proline residue within the TMD resulted in inhibition of targeting. Finally, a fusion protein, AtOEP7:NLS:GFP, was targeted efficiently to the chloroplast envelope membranes despite the presence of a nuclear localization signal. On the basis of these results, we conclude that the seven-amino acid region and the TMD are determinants for targeting to the chloroplast outer envelope membrane. The seven-amino acid region plays a critical role in AtOEP7 evading the endomembrane system and entering the chloroplast pathway, and the TMD plays critical roles in migration to the chloroplasts and/or subsequent insertion into the membrane.
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Affiliation(s)
- Y J Lee
- Division of Molecular and Life Science, Pohang University of Science and Technology, Pohang 790-784, Korea
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Lee YJ, Kim DH, Kim YW, Hwang I. Identification of a signal that distinguishes between the chloroplast outer envelope membrane and the endomembrane system in vivo. THE PLANT CELL 2001. [PMID: 11595795 DOI: 10.2307/3871501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Certain small outer envelope membrane proteins of chloroplasts are encoded by the nuclear genome without a cleavable N-terminal transit peptide. We investigated in vivo the targeting mechanism of AtOEP7, an Arabidopsis homolog of the small outer envelope membrane protein. AtOEP7 was expressed as a fusion protein with the green fluorescent protein (GFP) either transiently in protoplasts or stably in transgenic plants. In either case, fluorescence microscopy of transformed cells and protein gel blot analysis of fractionated proteins confirmed that the AtOEP7:GFP fusion protein was targeted to the chloroplast outer envelope membrane. In vivo targeting experiments revealed that two regions, the transmembrane domain (TMD) and its C-terminal neighboring seven-amino acid region, were necessary and sufficient for targeting to the chloroplast outer membrane. Substitution of aspartic acid or lysine residues with glycine residues or scrambling of the amino acid sequence of the seven-amino acid region caused mistargeting to the plasma membrane. Although the amino acid sequence of the TMD is not important for targeting, amino acid residues with large side chains inhibited targeting to the chloroplasts and resulted in the formation of large aggregates in the protoplasts. In addition, introduction of a proline residue within the TMD resulted in inhibition of targeting. Finally, a fusion protein, AtOEP7:NLS:GFP, was targeted efficiently to the chloroplast envelope membranes despite the presence of a nuclear localization signal. On the basis of these results, we conclude that the seven-amino acid region and the TMD are determinants for targeting to the chloroplast outer envelope membrane. The seven-amino acid region plays a critical role in AtOEP7 evading the endomembrane system and entering the chloroplast pathway, and the TMD plays critical roles in migration to the chloroplasts and/or subsequent insertion into the membrane.
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Affiliation(s)
- Y J Lee
- Division of Molecular and Life Science, Pohang University of Science and Technology, Pohang 790-784, Korea
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Lee YJ, Kim DH, Kim YW, Hwang I. Identification of a signal that distinguishes between the chloroplast outer envelope membrane and the endomembrane system in vivo. THE PLANT CELL 2001; 13:2175-90. [PMID: 11595795 PMCID: PMC139152 DOI: 10.1105/tpc.010232] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2001] [Accepted: 08/03/2001] [Indexed: 05/18/2023]
Abstract
Certain small outer envelope membrane proteins of chloroplasts are encoded by the nuclear genome without a cleavable N-terminal transit peptide. We investigated in vivo the targeting mechanism of AtOEP7, an Arabidopsis homolog of the small outer envelope membrane protein. AtOEP7 was expressed as a fusion protein with the green fluorescent protein (GFP) either transiently in protoplasts or stably in transgenic plants. In either case, fluorescence microscopy of transformed cells and protein gel blot analysis of fractionated proteins confirmed that the AtOEP7:GFP fusion protein was targeted to the chloroplast outer envelope membrane. In vivo targeting experiments revealed that two regions, the transmembrane domain (TMD) and its C-terminal neighboring seven-amino acid region, were necessary and sufficient for targeting to the chloroplast outer membrane. Substitution of aspartic acid or lysine residues with glycine residues or scrambling of the amino acid sequence of the seven-amino acid region caused mistargeting to the plasma membrane. Although the amino acid sequence of the TMD is not important for targeting, amino acid residues with large side chains inhibited targeting to the chloroplasts and resulted in the formation of large aggregates in the protoplasts. In addition, introduction of a proline residue within the TMD resulted in inhibition of targeting. Finally, a fusion protein, AtOEP7:NLS:GFP, was targeted efficiently to the chloroplast envelope membranes despite the presence of a nuclear localization signal. On the basis of these results, we conclude that the seven-amino acid region and the TMD are determinants for targeting to the chloroplast outer envelope membrane. The seven-amino acid region plays a critical role in AtOEP7 evading the endomembrane system and entering the chloroplast pathway, and the TMD plays critical roles in migration to the chloroplasts and/or subsequent insertion into the membrane.
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Affiliation(s)
- Y J Lee
- Division of Molecular and Life Science, Pohang University of Science and Technology, Pohang 790-784, Korea
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Abstract
The dynamin family of proteins is continually growing, and in recent years members have been localized to areas of mitochondrial fission, plant phragmoplasts and chloroplasts, and viral ribonucleoprotein complexes. All the dynamin-like proteins examined to-date appear to assemble into oligomers, such as rings or spirals; however, it remains to be determined if a global mechanism of action exists. Even the role of dynamin in vesicle formation remains controversial as to whether it behaves as a molecular switch or as a mechanochemical enzyme.
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Affiliation(s)
- D Danino
- Laboratory of Cell Biochemistry and Biology, Building 8, Room 419, MSC 0851, 8 Center Drive, National Institute of Health, Bethesda, Maryland 20892, USA.
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Jin JB, Kim YA, Kim SJ, Lee SH, Kim DH, Cheong GW, Hwang I. A new dynamin-like protein, ADL6, is involved in trafficking from the trans-Golgi network to the central vacuole in Arabidopsis. THE PLANT CELL 2001; 13:1511-26. [PMID: 11449048 PMCID: PMC139540 DOI: 10.1105/tpc.000534] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Dynamin, a high-molecular-weight GTPase, plays a critical role in vesicle formation at the plasma membrane during endocytosis in animal cells. Here we report the identification of a new dynamin homolog in Arabidopsis named Arabidopsis dynamin-like 6 (ADL6). ADL6 is quite similar to dynamin I in its structural organization: a conserved GTPase domain at the N terminus, a pleckstrin homology domain at the center, and a Pro-rich motif at the C terminus. In the cell, a majority of ADL6 is associated with membranes. Immunohistochemistry and in vivo targeting experiments revealed that ADL6 is localized to the Golgi apparatus. Expression of the dominant negative mutant ADL6[K51E] in Arabidopsis protoplasts inhibited trafficking of cargo proteins destined for the lytic vacuole and caused them to accumulate at the trans-Golgi network. In contrast, expression of ADL6[K51E] did not affect trafficking of a cargo protein, H(+)-ATPase:green fluorescent protein, destined for the plasma membrane. These results suggest that ADL6 is involved in vesicle formation for vacuolar trafficking at the trans-Golgi network but not for trafficking to the plasma membrane in plant cells.
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Affiliation(s)
- J B Jin
- Department of Molecular Biology, Gyeongsang National University, Chinju 660-701, Korea
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Jin JB, Kim YA, Kim SJ, Lee SH, Kim DH, Cheong GW, Hwang I. A new dynamin-like protein, ADL6, is involved in trafficking from the trans-Golgi network to the central vacuole in Arabidopsis. THE PLANT CELL 2001. [PMID: 11449048 DOI: 10.1105/tpc.13.7.1511] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Dynamin, a high-molecular-weight GTPase, plays a critical role in vesicle formation at the plasma membrane during endocytosis in animal cells. Here we report the identification of a new dynamin homolog in Arabidopsis named Arabidopsis dynamin-like 6 (ADL6). ADL6 is quite similar to dynamin I in its structural organization: a conserved GTPase domain at the N terminus, a pleckstrin homology domain at the center, and a Pro-rich motif at the C terminus. In the cell, a majority of ADL6 is associated with membranes. Immunohistochemistry and in vivo targeting experiments revealed that ADL6 is localized to the Golgi apparatus. Expression of the dominant negative mutant ADL6[K51E] in Arabidopsis protoplasts inhibited trafficking of cargo proteins destined for the lytic vacuole and caused them to accumulate at the trans-Golgi network. In contrast, expression of ADL6[K51E] did not affect trafficking of a cargo protein, H(+)-ATPase:green fluorescent protein, destined for the plasma membrane. These results suggest that ADL6 is involved in vesicle formation for vacuolar trafficking at the trans-Golgi network but not for trafficking to the plasma membrane in plant cells.
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Affiliation(s)
- J B Jin
- Department of Molecular Biology, Gyeongsang National University, Chinju 660-701, Korea
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Jin JB, Kim YA, Kim SJ, Lee SH, Kim DH, Cheong GW, Hwang I. A new dynamin-like protein, ADL6, is involved in trafficking from the trans-Golgi network to the central vacuole in Arabidopsis. THE PLANT CELL 2001. [PMID: 11449048 DOI: 10.2307/3871383] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Dynamin, a high-molecular-weight GTPase, plays a critical role in vesicle formation at the plasma membrane during endocytosis in animal cells. Here we report the identification of a new dynamin homolog in Arabidopsis named Arabidopsis dynamin-like 6 (ADL6). ADL6 is quite similar to dynamin I in its structural organization: a conserved GTPase domain at the N terminus, a pleckstrin homology domain at the center, and a Pro-rich motif at the C terminus. In the cell, a majority of ADL6 is associated with membranes. Immunohistochemistry and in vivo targeting experiments revealed that ADL6 is localized to the Golgi apparatus. Expression of the dominant negative mutant ADL6[K51E] in Arabidopsis protoplasts inhibited trafficking of cargo proteins destined for the lytic vacuole and caused them to accumulate at the trans-Golgi network. In contrast, expression of ADL6[K51E] did not affect trafficking of a cargo protein, H(+)-ATPase:green fluorescent protein, destined for the plasma membrane. These results suggest that ADL6 is involved in vesicle formation for vacuolar trafficking at the trans-Golgi network but not for trafficking to the plasma membrane in plant cells.
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Affiliation(s)
- J B Jin
- Department of Molecular Biology, Gyeongsang National University, Chinju 660-701, Korea
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39
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Kang BH, Busse JS, Dickey C, Rancour DM, Bednarek SY. The arabidopsis cell plate-associated dynamin-like protein, ADL1Ap, is required for multiple stages of plant growth and development. PLANT PHYSIOLOGY 2001; 126:47-68. [PMID: 11351070 PMCID: PMC102281 DOI: 10.1104/pp.126.1.47] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Dynamin and dynamin-like proteins are GTP-binding proteins involved in vesicle trafficking. In soybean, a 68-kD dynamin-like protein called phragmoplastin has been shown to be associated with the cell plate in dividing cells (Gu and Verma, 1996). Five ADL1 genes encoding dynamin-like proteins related to phragmoplastin have been identified in the completed Arabidopsis genome. Here we report that ADL1Ap is associated with punctate subcellular structures and with the cell plate in dividing cells. To assess the function of ADL1Ap we utilized a reverse genetic approach to isolate three separate Arabidopsis mutant lines containing T-DNA insertions in ADL1A. Homozygous adl1A seeds were shriveled and mutant seedlings arrested soon after germination, producing only two leaf primordia and severely stunted roots. Immunoblotting revealed that ADL1Ap expression was not detectable in the mutants. Despite the loss of ADL1Ap, the mutants did not display any defects in cytokinesis, and growth of the mutant seedlings could be rescued in tissue culture by the addition of sucrose. Although these sucrose-rescued plants displayed normal vegetative growth and flowered, they set very few seeds. Thus, ADL1Ap is critical for several stages of plant development, including embryogenesis, seedling development, and reproduction. We discuss the putative role of ADL1Ap in vesicular trafficking, cytokinesis, and other aspects of plant growth.
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Affiliation(s)
- B H Kang
- Department of Biochemistry, University of Wisconsin, 433 Babcock Drive, Madison, Wisconsin 53706, USA
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40
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Kroll D, Meierhoff K, Bechtold N, Kinoshita M, Westphal S, Vothknecht UC, Soll J, Westhoff P. VIPP1, a nuclear gene of Arabidopsis thaliana essential for thylakoid membrane formation. Proc Natl Acad Sci U S A 2001; 98:4238-42. [PMID: 11274447 PMCID: PMC31209 DOI: 10.1073/pnas.061500998] [Citation(s) in RCA: 262] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2000] [Indexed: 11/18/2022] Open
Abstract
The conversion of light to chemical energy by the process of photosynthesis is localized to the thylakoid membrane network in plant chloroplasts. Although several pathways have been described that target proteins into and across the thylakoids, little is known about the origin of this membrane system or how the lipid backbone of the thylakoids is transported and fused with the target membrane. Thylakoid biogenesis and maintenance seem to involve the flow of membrane elements via vesicular transport. Here we show by mutational analysis that deletion of a single gene called VIPP1 (vesicle-inducing protein in plastids 1) is deleterious to thylakoid membrane formation. Although VIPP1 is a hydrophilic protein it is found in both the inner envelope and the thylakoid membranes. In VIPP1 deletion mutants vesicle formation is abolished. We propose that VIPP1 is essential for the maintenance of thylakoids by a transport pathway not previously recognized.
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Affiliation(s)
- D Kroll
- Institut für Entwicklungs- und Molekularbiologie der Pflanzen, Heinrich-Heine-Universität, Universitätsstrasse 1, 40225 Düsseldorf, Germany
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41
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Proteins Involved in Biogenesis of the Thylakoid Membrane. REGULATION OF PHOTOSYNTHESIS 2001. [DOI: 10.1007/0-306-48148-0_9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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42
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Jan van Wijk K. Proteomics of the chloroplast: experimentation and prediction. TRENDS IN PLANT SCIENCE 2000; 5:420-425. [PMID: 11044718 DOI: 10.1016/s1360-1385(00)01737-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
New technologies, in combination with increasing amounts of plant genome sequence data, have opened up incredible experimental possibilities to identify the total set of chloroplast proteins (the chloroplast proteome) as well as their expression levels and post-translational modifications in a global manner. This is summarized under the term 'proteomics' and typically involves two-dimensional electrophoresis or chromatography, mass spectrometry and bioinformatics. Complemented with nucleotide-based global techniques, proteomics is expected to provide many new insights into chloroplast biogenesis, adaptation and function.
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Affiliation(s)
- K Jan van Wijk
- Dept of Biochemistry, Arrhenius Laboratories, Stockholm University, S-10691 Stockholm, Sweden
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43
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Abstract
The discovery that chloroplasts have semi-autonomous genetic systems has led to many insights into the biogenesis of these organelles and their evolution from free-living photosynthetic bacteria. Recent developments of our understanding of the molecular mechanisms of translation in chloroplasts suggest selective pressures that have maintained the 100-200 genes of the ancestral endosymbiont in chloroplast genomes. The ability to introduce modified genes into chloroplast genomes by homologous recombination and the recent development of an in vitro chloroplast translation system have been exploited for analyses of the cis-acting requirements for chloroplast translation. Trans-acting translational factors have been identified by genetic and biochemical approaches. Several studies have suggested that chloroplast mRNAs are translated in association with membranes.
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Affiliation(s)
- W Zerges
- Concordia University, 1455 de Maisonneuve W., H3G 1M8, Quebec, Montreal, Canada.
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44
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Zhang Z, Hong Z, Verma DP. Phragmoplastin polymerizes into spiral coiled structures via intermolecular interaction of two self-assembly domains. J Biol Chem 2000; 275:8779-84. [PMID: 10722722 DOI: 10.1074/jbc.275.12.8779] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phragmoplastin, a high molecular weight GTPase belonging to the dynamin superfamily of proteins, becomes associated with the cell plate during cytokinesis in plants. Growth of the cell plate requires continuous fusion of vesicles, and phragmoplastin appears to play a role in the formation of vesicle-tubule-vesicle structures at the cell plate. In this study, we have demonstrated that two self-assembly domains (SA1 and SA2) are involved in polymerization of phragmoplastin. SA1 is about 42 amino acids long and is located near the N terminus overlapping with the GTP-binding region. SA2, containing at least 24 amino acids, is located in the middle of the molecule outside the GTP-binding domain. Peptides containing either SA1 or SA2 interact efficiently with the full-length phragmoplastin. The SA1 domain of one phragmoplastin molecule also binds to SA2 of another as confirmed in vitro by using radiolabeled peptides. This interaction leads to the formation of polymers with a staggered contoured spiral structure. Electron microscopy studies revealed that helical arrays of phragmoplastin can be induced by reducing salt concentration. Our results suggest that phragmoplastin may assemble into helical arrays that wrap around and squeeze vesicles into vesicle-tubule-vesicle structures observed on the forming cell plate.
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Affiliation(s)
- Z Zhang
- Department of Molecular Genetics and Plant Biotechnology Center, The Ohio State University, Columbus, Ohio 43210-1002, USA
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45
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Mikami K, Iuchi S, Yamaguchi-Shinozaki K, Shinozaki K. A novel Arabidopsis thaliana dynamin-like protein containing the pleckstrin homology domain. JOURNAL OF EXPERIMENTAL BOTANY 2000; 51:317-318. [PMID: 10938838 DOI: 10.1093/jexbot/51.343.317] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A full-length cDNA encoding a novel type of plant dynamin-like protein, ADL3, was isolated from Arabidopsis thaliana. ADL3 is a high molecular weight GTPase whose GTP-binding domain shows a low homology to those of other plant dynamin-like proteins. ADL3 contains the pleckstrin homology domain as is in mammalian dynamins, although other plant dynamin-like proteins reported lack this domain. The ADL3 gene was expressed weakly in various tissues, except for siliques with high level expression, which is distinct from the case for other plant dynamin-like protein genes. Taken together, it is predicted that the mode of activation of ADL3 is different from those of other plant homologues.
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Affiliation(s)
- K Mikami
- Laboratory of Plant Molecular Biology, Institute of Physical and Chemical Research (RIKEN), Tsukuba Life Science Center, Ibaraki, Japan.
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46
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Abstract
Dynamin, a 100-kDa GTPase, is an essential component of vesicle formation in receptor-mediated endocytosis, synaptic vesicle recycling, caveolae internalization, and possibly vesicle trafficking in and out of the Golgi. In addition to the GTPase domain, dynamin also contains a pleckstrin homology domain (PH) implicated in membrane binding, a GTPase effector domain (GED) shown to be essential for self-assembly and stimulated GTPase activity, and a C-terminal proline-rich domain (PRD), which contains several SH3-binding sites. Dynamin partners bind to the PRD and may either stimulate dynamin's GTPase activity or target dynamin to the plasma membrane. Purified dynamin readily self-assembles into rings or spirals. This striking structural property supports the hypothesis that dynamin wraps around the necks of budding vesicles where it plays a key role in membrane fission. The focus of this review is on the relationship between the GTPase and self-assembly properties of dynamin and its cellular function.
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Affiliation(s)
- J E Hinshaw
- Laboratory of Cell Biochemistry and Biology, National Institutes of Health, Bethesda, Maryland 20892, USA.
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47
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Pelloquin L, Belenguer P, Menon Y, Gas N, Ducommun B. Fission yeast Msp1 is a mitochondrial dynamin-related protein. J Cell Sci 1999; 112 ( Pt 22):4151-61. [PMID: 10547374 DOI: 10.1242/jcs.112.22.4151] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We recently identified Msp1p, a fission yeast Schizosaccharomyces pombe dynamin-related protein, which is essential for the maintenance of mitochondrial DNA. The Msp1p sequence displays typical features of a mitochondrial protein. Here we report in vitro and in vivo data that validate that prediction. We demonstrate that the targeting sequence of Msp1p is processed by recombinant mitochondrial processing peptidase and that Msp1p is imported into S. pombe mitochondria in vitro in the presence of cellular extracts. We show that the first 109 residues of Msp1p encompass a functional peptide signal that is sufficient to direct chimera to mitochondria. Immunofluorescence studies indicate that Msp1p staining colocalises with a mitochondrial marker and electron microscopy shows that the protein is located inside the mitochondria. Mitochondrial enrichment and fractionation further confirm that localisation and show that Msp1p is anchored to the matrix side of the mitochondrial inner membrane. Finally, we report that overexpression of the Msp1 protein results in gross alteration of the mitochondrial structure and function. All together our results suggest that Msp1p is an essential component for mitochondrial maintenance.
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Affiliation(s)
- L Pelloquin
- Laboratoire de Biologie Cellulaire et Moléculaire du Contrôle de la Prolifération, Université Paul Sabatier, CNRS EP2079, 31062 Toulouse cedex, France
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48
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Amin P, Sy DA, Pilgrim ML, Parry DH, Nussaume L, Hoffman NE. Arabidopsis mutants lacking the 43- and 54-kilodalton subunits of the chloroplast signal recognition particle have distinct phenotypes. PLANT PHYSIOLOGY 1999; 121:61-70. [PMID: 10482661 PMCID: PMC59390 DOI: 10.1104/pp.121.1.61] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/1999] [Accepted: 05/24/1999] [Indexed: 05/21/2023]
Abstract
The chloroplast signal recognition particle (cpSRP) is a protein complex consisting of 54- and 43-kD subunits encoded by the fifty-four chloroplast, which encodes cpSRP54 (ffc), and chaos (cao) loci, respectively. Two new null alleles in the ffc locus have been identified. ffc1-1 is caused by a stop codon in exon 10, while ffc1-2 has a large DNA insertion in intron 8. ffc mutants have yellow first true leaves that subsequently become green. The reaction center proteins D1, D2, and psaA/B, as well as seven different light-harvesting chlorophyll proteins (LHCPs), were found at reduced levels in the young ffc leaves but at wild-type levels in the older leaves. The abundance of the two types of LHCP was unaffected by the mutation, while two others were increased in the absence of cpSRP54. Null mutants in the cao locus contain reduced levels of the same subset of LHCP proteins as ffc mutants, but are distinguishable in four ways: young leaves are greener, the chlorophyll a/b ratio is elevated, levels of reaction center proteins are normal, and there is no recovery in the level of LHCPs in the adult plant. The data suggest that cpSRP54 and cpSRP43 have some nonoverlapping roles and that alternative transport pathways can compensate for the absence of a functional cpSRP.
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Affiliation(s)
- P Amin
- Department of Plant Biology, Carnegie Institution of Washington, 260 Panama Street, Stanford, California 94305, USA
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49
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Abstract
The function of the GTPase dynamin has been discussed for several years. It clearly plays a role in vesicle budding, but, despite recent insights, precisely how it functions in this process is still a matter of debate. In addition, it is now clear that dynamin is a member of a large protein family, present in a variety of cellular locations where members apparently perform a range of functions. This article describes current understanding of the structure and function of the various dynamin family members.
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Affiliation(s)
- A M van der Bliek
- Dept of Biological Chemistry, UCLA School of Medicine 90095-1737, USA.
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50
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Wienke DC, Knetsch ML, Neuhaus EM, Reedy MC, Manstein DJ. Disruption of a dynamin homologue affects endocytosis, organelle morphology, and cytokinesis in Dictyostelium discoideum. Mol Biol Cell 1999; 10:225-43. [PMID: 9880338 PMCID: PMC25165 DOI: 10.1091/mbc.10.1.225] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The identification and functional characterization of Dictyostelium discoideum dynamin A, a protein composed of 853 amino acids that shares up to 44% sequence identity with other dynamin-related proteins, is described. Dynamin A is present during all stages of D. discoideum development and is found predominantly in the cytosolic fraction and in association with endosomal and postlysosomal vacuoles. Overexpression of the protein has no adverse effect on the cells, whereas depletion of dynamin A by gene-targeting techniques leads to multiple and complex phenotypic changes. Cells lacking a functional copy of dymA show alterations of mitochondrial, nuclear, and endosomal morphology and a defect in fluid-phase uptake. They also become multinucleated due to a failure to complete normal cytokinesis. These pleiotropic effects of dynamin A depletion can be rescued by complementation with the cloned gene. Morphological studies using cells producing green fluorescent protein-dynamin A revealed that dynamin A associates with punctate cytoplasmic vesicles. Double labeling with vacuolin, a marker of a postlysosomal compartment in D. discoideum, showed an almost complete colocalization of vacuolin and dynamin A. Our results suggest that that dynamin A is likely to function in membrane trafficking processes along the endo-lysosomal pathway of D. discoideum but not at the plasma membrane.
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Affiliation(s)
- D C Wienke
- Abteilung Biophysik, Max-Planck-Institut für Medizinische Forschung, D-69120 Heidelberg, Germany
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