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Du X, Weng X, Lyu B, Zhao L, Wang H. Localized calcium transients in phragmoplast regulate cytokinesis of tobacco BY-2 cells. PLANT CELL REPORTS 2024; 43:97. [PMID: 38488911 DOI: 10.1007/s00299-024-03181-3] [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: 12/03/2023] [Accepted: 02/22/2024] [Indexed: 03/17/2024]
Abstract
KEY MESSAGE Plants exhibit a unique pattern of cytosolic Ca2+ dynamics to correlate with microtubules to regulate cytokinesis, which significantly differs from those observed in animal and yeast cells. Calcium (Ca2+) transients mediated signaling is known to be essential in cytokinesis across eukaryotic cells. However, the detailed spatiotemporal dynamics of Ca2+ during plant cytokinesis remain largely unexplored. In this study, we employed GCaMP5, a genetically encoded Ca2+ sensor, to investigate cytokinetic Ca2+ transients during cytokinesis in Nicotiana tabacum Bright Yellow-2 (BY-2) cells. We validated the effectiveness of GCaMP5 to capture fluctuations in intracellular free Ca2+ in transgenic BY-2 cells. Our results reveal that Ca2+ dynamics during BY-2 cell cytokinesis are distinctly different from those observed in embryonic and yeast cells. It is characterized by an initial significant Ca2+ spike within the phragmoplast region. This spike is followed by a decrease in Ca2+ concentration at the onset of cytokinesis in phragmoplast, which then remains elevated in comparison to the cytosolic Ca2+ until the completion of cell plate formation. At the end of cytokinesis, Ca2+ becomes uniformly distributed in the cytosol. This pattern contrasts with the typical dual waves of Ca2+ spikes observed during cytokinesis in animal embryonic cells and fission yeasts. Furthermore, applications of pharmaceutical inhibitors for either Ca2+ or microtubules revealed a close correlation between Ca2+ transients and microtubule organization in the regulation of cytokinesis. Collectively, our findings highlight the unique dynamics and crucial role of Ca2+ transients during plant cell cytokinesis, and provides new insights into plant cell division mechanisms.
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Affiliation(s)
- Xiaojuan Du
- Department of Cell and Developmental Biology, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Xun Weng
- Department of Cell and Developmental Biology, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Binyang Lyu
- Department of Cell and Developmental Biology, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Lifeng Zhao
- Department of Cell and Developmental Biology, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China
| | - Hao Wang
- Department of Cell and Developmental Biology, College of Life Sciences, South China Agricultural University, Guangzhou, 510642, China.
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2
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Zhao S, Chen J, Cao S, Wang H, Chen H, Wei Y, Chen Y, Shao X, Xu F. The regulation of Cytochrome f by mannose treatment in broccoli and its relationship with programmed cell death in tobacco BY-2 cells. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2024; 208:108480. [PMID: 38437751 DOI: 10.1016/j.plaphy.2024.108480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 02/25/2024] [Accepted: 02/28/2024] [Indexed: 03/06/2024]
Abstract
It is well established that programmed cell death (PCD) occurred in broccoli during postharvest senescence, but no studies have been conducted on the regulation of broccoli cytochrome f by mannose treatment and its relationship with PCD. In this study, we treated broccoli buds with mannose to investigate the changes in color, total chlorophyll content, gene expression related to chlorophyll metabolism, chloroplast structure, and cytochrome f determination during postharvest storage. In addition, to investigate the effect of cytochrome f on PCD, we extracted cytochrome f from broccoli and treated Nicotiana tabacum L. cv Bright Yellow 2 (BY-2) cells with extracted cytochrome f from broccoli at various concentrations. The results showed that cytochrome f can induce PCD in tobacco BY-2 cells, as evidenced by altered cell morphology, nuclear chromatin disintegration, DNA degradation, decreased cell viability, and increased caspase-3-like protease production. Taken together, our study indicated that mannose could effectively delay senescence of postharvest broccoli by inhibiting the expression of gene encoding cytochrome f which could induce PCD.
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Affiliation(s)
- Shiyi Zhao
- College of Food Science and Engineering, Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, Ningbo University, Ningbo, 315800, China
| | - Jiahui Chen
- College of Food Science and Engineering, Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, Ningbo University, Ningbo, 315800, China
| | - Shifeng Cao
- College of Biological and Environmental Sciences, Zhejiang Wanli University, Ningbo, 315100, China
| | - Hongfei Wang
- College of Food Science and Engineering, Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, Ningbo University, Ningbo, 315800, China
| | - Hangjun Chen
- Food Science Institute, Zhejiang Academy of Agricultural Sciences, Key Laboratory of Postharvest Preservation and Processing of Vegetables (Co-construction By Ministry and Province), Ministry of Agriculture and Rural Affairs, Key Laboratory of Post-Harvest Handling of Fruits, Ministry of Agriculture and Rural Affairs, Key Laboratory of Fruits and Vegetables Postharvest and Processing Technology Research of Zhejiang Province, Hangzhou, 310021, China
| | - Yingying Wei
- College of Food Science and Engineering, Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, Ningbo University, Ningbo, 315800, China
| | - Yi Chen
- College of Food Science and Engineering, Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, Ningbo University, Ningbo, 315800, China
| | - Xingfeng Shao
- College of Food Science and Engineering, Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, Ningbo University, Ningbo, 315800, China
| | - Feng Xu
- College of Food Science and Engineering, Zhejiang-Malaysia Joint Research Laboratory for Agricultural Product Processing and Nutrition, Ningbo University, Ningbo, 315800, China.
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Palmieri F, Monné M, Fiermonte G, Palmieri L. Mitochondrial transport and metabolism of the vitamin B-derived cofactors thiamine pyrophosphate, coenzyme A, FAD and NAD + , and related diseases: A review. IUBMB Life 2022; 74:592-617. [PMID: 35304818 PMCID: PMC9311062 DOI: 10.1002/iub.2612] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 02/17/2022] [Accepted: 02/18/2022] [Indexed: 01/19/2023]
Abstract
Multiple mitochondrial matrix enzymes playing key roles in metabolism require cofactors for their action. Due to the high impermeability of the mitochondrial inner membrane, these cofactors need to be synthesized within the mitochondria or be imported, themselves or one of their precursors, into the organelles. Transporters belonging to the protein family of mitochondrial carriers have been identified to transport the coenzymes: thiamine pyrophosphate, coenzyme A, FAD and NAD+ , which are all structurally similar to nucleotides and derived from different B-vitamins. These mitochondrial cofactors bind more or less tightly to their enzymes and, after having been involved in a specific reaction step, are regenerated, spontaneously or by other enzymes, to return to their active form, ready for the next catalysis round. Disease-causing mutations in the mitochondrial cofactor carrier genes compromise not only the transport reaction but also the activity of all mitochondrial enzymes using that particular cofactor and the metabolic pathways in which the cofactor-dependent enzymes are involved. The mitochondrial transport, metabolism and diseases of the cofactors thiamine pyrophosphate, coenzyme A, FAD and NAD+ are the focus of this review.
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Affiliation(s)
- Ferdinando Palmieri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy.,CNR Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), Bari, Italy
| | - Magnus Monné
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy.,Department of Sciences, University of Basilicata, Potenza, Italy
| | - Giuseppe Fiermonte
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy.,CNR Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), Bari, Italy
| | - Luigi Palmieri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy.,CNR Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies (IBIOM), Bari, Italy
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4
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de Moliner F, Knox K, Gordon D, Lee M, Tipping WJ, Geddis A, Reinders A, Ward JM, Oparka K, Vendrell M. A Palette of Minimally Tagged Sucrose Analogues for Real-Time Raman Imaging of Intracellular Plant Metabolism. ANGEWANDTE CHEMIE (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2021; 133:7715-7720. [PMID: 38505234 PMCID: PMC10946860 DOI: 10.1002/ange.202016802] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Indexed: 12/19/2022]
Abstract
Sucrose is the main saccharide used for long-distance transport in plants and plays an essential role in energy metabolism; however, there are no analogues for real-time imaging in live cells. We have optimised a synthetic approach to prepare sucrose analogues including very small (≈50 Da or less) Raman tags in the fructose moiety. Spectroscopic analysis identified the alkyne-tagged compound 6 as a sucrose analogue recognised by endogenous transporters in live cells and with higher Raman intensity than other sucrose derivatives. Herein, we demonstrate the application of compound 6 as the first optical probe to visualise real-time uptake and intracellular localisation of sucrose in live plant cells using Raman microscopy.
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Affiliation(s)
| | - Kirsten Knox
- Institute of Molecular Plant SciencesThe University of EdinburghUK
| | - Doireann Gordon
- Centre for Inflammation ResearchThe University ofEdinburghUK
| | - Martin Lee
- Cancer Research (UK) Edinburgh CentreThe University of EdinburghUK
| | - William J. Tipping
- EaStCHEM School of ChemistryThe University of EdinburghUK
- Centre for Molecular NanometrologyUniversity of StrathclydeUK
| | - Ailsa Geddis
- Centre for Inflammation ResearchThe University ofEdinburghUK
- EaStCHEM School of ChemistryThe University of EdinburghUK
| | - Anke Reinders
- Department of Plant and Microbial BiologyUniversity of MinnesotaUSA
| | - John M. Ward
- Department of Plant and Microbial BiologyUniversity of MinnesotaUSA
| | - Karl Oparka
- Institute of Molecular Plant SciencesThe University of EdinburghUK
| | - Marc Vendrell
- Centre for Inflammation ResearchThe University ofEdinburghUK
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5
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de Moliner F, Knox K, Gordon D, Lee M, Tipping WJ, Geddis A, Reinders A, Ward JM, Oparka K, Vendrell M. A Palette of Minimally Tagged Sucrose Analogues for Real-Time Raman Imaging of Intracellular Plant Metabolism. Angew Chem Int Ed Engl 2021; 60:7637-7642. [PMID: 33491852 PMCID: PMC8048481 DOI: 10.1002/anie.202016802] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Indexed: 12/20/2022]
Abstract
Sucrose is the main saccharide used for long-distance transport in plants and plays an essential role in energy metabolism; however, there are no analogues for real-time imaging in live cells. We have optimised a synthetic approach to prepare sucrose analogues including very small (≈50 Da or less) Raman tags in the fructose moiety. Spectroscopic analysis identified the alkyne-tagged compound 6 as a sucrose analogue recognised by endogenous transporters in live cells and with higher Raman intensity than other sucrose derivatives. Herein, we demonstrate the application of compound 6 as the first optical probe to visualise real-time uptake and intracellular localisation of sucrose in live plant cells using Raman microscopy.
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Affiliation(s)
| | - Kirsten Knox
- Institute of Molecular Plant SciencesThe University of EdinburghUK
| | - Doireann Gordon
- Centre for Inflammation ResearchThe University ofEdinburghUK
| | - Martin Lee
- Cancer Research (UK) Edinburgh CentreThe University of EdinburghUK
| | - William J. Tipping
- EaStCHEM School of ChemistryThe University of EdinburghUK
- Centre for Molecular NanometrologyUniversity of StrathclydeUK
| | - Ailsa Geddis
- Centre for Inflammation ResearchThe University ofEdinburghUK
- EaStCHEM School of ChemistryThe University of EdinburghUK
| | - Anke Reinders
- Department of Plant and Microbial BiologyUniversity of MinnesotaUSA
| | - John M. Ward
- Department of Plant and Microbial BiologyUniversity of MinnesotaUSA
| | - Karl Oparka
- Institute of Molecular Plant SciencesThe University of EdinburghUK
| | - Marc Vendrell
- Centre for Inflammation ResearchThe University ofEdinburghUK
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6
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Jasieniecka-Gazarkiewicz K, Demski K, Gidda SK, Klińska S, Niedojadło J, Lager I, Carlsson AS, Minina EA, Mullen RT, Bozhkov PV, Stymne S, Banaś A. Subcellular Localization of Acyl-CoA: Lysophosphatidylethanolamine Acyltransferases (LPEATs) and the Effects of Knocking-Out and Overexpression of Their Genes on Autophagy Markers Level and Life Span of A. thaliana. Int J Mol Sci 2021; 22:ijms22063006. [PMID: 33809440 PMCID: PMC8000221 DOI: 10.3390/ijms22063006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 03/10/2021] [Accepted: 03/12/2021] [Indexed: 12/14/2022] Open
Abstract
Arabidopsis thaliana possesses two acyl-CoA:lysophosphatidylethanolamine acyltransferases, LPEAT1 and LPEAT2, which are encoded by At1g80950 and At2g45670 genes, respectively. Both single lpeat2 mutant and double lpeat1 lpeat2 mutant plants exhibit a variety of conspicuous phenotypes, including dwarfed growth. Confocal microscopic analysis of tobacco suspension-cultured cells transiently transformed with green fluorescent protein-tagged versions of LPEAT1 or LPEAT2 revealed that LPEAT1 is localized to the endoplasmic reticulum (ER), whereas LPEAT2 is localized to both Golgi and late endosomes. Considering that the primary product of the reaction catalyzed by LPEATs is phosphatidylethanolamine, which is known to be covalently conjugated with autophagy-related protein ATG8 during a key step of the formation of autophagosomes, we investigated the requirements for LPEATs to engage in autophagic activity in Arabidopsis. Knocking out of either or both LPEAT genes led to enhanced accumulation of the autophagic adaptor protein NBR1 and decreased levels of both ATG8a mRNA and total ATG8 protein. Moreover, we detected significantly fewer membrane objects in the vacuoles of lpeat1 lpeat2 double mutant mesophyll cells than in vacuoles of control plants. However, contrary to what has been reported on autophagy deficient plants, the lpeat mutants displayed a prolonged life span compared to wild type, including delayed senescence.
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Affiliation(s)
- Katarzyna Jasieniecka-Gazarkiewicz
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, 80-307 Gdansk, Poland; (K.D.); (S.K.); (A.B.)
- Correspondence:
| | - Kamil Demski
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, 80-307 Gdansk, Poland; (K.D.); (S.K.); (A.B.)
| | - Satinder K. Gidda
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada; (S.K.G.); (R.T.M.)
| | - Sylwia Klińska
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, 80-307 Gdansk, Poland; (K.D.); (S.K.); (A.B.)
| | - Janusz Niedojadło
- Department of Cell Biology, Department of Cellular and Molecular Biology, Nicolaus Copernicus University, 87-100 Torun, Poland;
| | - Ida Lager
- Department of Plant Breeding, Swedish University of Agricultural Sciences, 230-53 Alnarp, Sweden; (I.L.); (A.S.C.); (S.S.)
| | - Anders S. Carlsson
- Department of Plant Breeding, Swedish University of Agricultural Sciences, 230-53 Alnarp, Sweden; (I.L.); (A.S.C.); (S.S.)
| | - Elena A. Minina
- Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 750-07 Uppsala, Sweden; (E.A.M.); (P.V.B.)
| | - Robert T. Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON N1G 2W1, Canada; (S.K.G.); (R.T.M.)
| | - Peter V. Bozhkov
- Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences and Linnean Center for Plant Biology, 750-07 Uppsala, Sweden; (E.A.M.); (P.V.B.)
| | - Sten Stymne
- Department of Plant Breeding, Swedish University of Agricultural Sciences, 230-53 Alnarp, Sweden; (I.L.); (A.S.C.); (S.S.)
| | - Antoni Banaś
- Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, 80-307 Gdansk, Poland; (K.D.); (S.K.); (A.B.)
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7
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Teresinski HJ, Gidda SK, Nguyen TND, Howard NJM, Porter BK, Grimberg N, Smith MD, Andrews DW, Dyer JM, Mullen RT. An RK/ST C-Terminal Motif is Required for Targeting of OEP7.2 and a Subset of Other Arabidopsis Tail-Anchored Proteins to the Plastid Outer Envelope Membrane. PLANT & CELL PHYSIOLOGY 2019; 60:516-537. [PMID: 30521026 DOI: 10.1093/pcp/pcy234] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 12/03/2018] [Indexed: 06/09/2023]
Abstract
Tail-anchored (TA) proteins are a unique class of integral membrane proteins that possess a single C-terminal transmembrane domain and target post-translationally to the specific organelles at which they function. While significant advances have been made in recent years in elucidating the mechanisms and molecular targeting signals involved in the proper sorting of TA proteins, particularly to the endoplasmic reticulum and mitochondria, relatively little is known about the targeting of TA proteins to the plastid outer envelope. Here we show that several known or predicted plastid TA outer envelope proteins (OEPs) in Arabidopsis possess a C-terminal RK/ST sequence motif that serves as a conserved element of their plastid targeting signal. Evidence for this conclusion comes primarily from experiments with OEP7.2, which is a member of the Arabidopsis 7 kDa OEP family. We confirmed that OEP7.2 is localized to the plastid outer envelope and possesses a TA topology, and its C-terminal sequence (CTS), which includes the RK/ST motif, is essential for proper targeting to plastids. The CTS of OEP7.2 is functionally interchangeable with the CTSs of other TA OEPs that possess similar RK/ST motifs, but not with those that lack the motif. Further, a bioinformatics search based on a consensus sequence led to the identification of several new OEP TA proteins. Collectively, this study provides new insight into the mechanisms of TA protein sorting in plant cells, defines a new targeting signal element for a subset of TA OEPs and expands the number and repertoire of TA proteins at the plastid outer envelope.
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Affiliation(s)
- Howard J Teresinski
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Satinder K Gidda
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Thuy N D Nguyen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Naomi J Marty Howard
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Brittany K Porter
- Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - Nicholas Grimberg
- Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - Matthew D Smith
- Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - David W Andrews
- Sunnybrook Research Institute and Departments of Biochemistry and Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - John M Dyer
- United States Department of Agriculture, Agricultural Research Service, US Arid-Land Agricultural Research Center, Maricopa, USA
| | - Robert T Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
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8
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The metabolite repair enzyme Nit1 is a dual-targeted amidase that disposes of damaged glutathione in Arabidopsis. Biochem J 2019; 476:683-697. [PMID: 30692244 DOI: 10.1042/bcj20180931] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 01/16/2019] [Accepted: 01/28/2019] [Indexed: 12/19/2022]
Abstract
The tripeptide glutathione (GSH) is implicated in various crucial physiological processes including redox buffering and protection against heavy metal toxicity. GSH is abundant in plants, with reported intracellular concentrations typically in the 1-10 mM range. Various aminotransferases can inadvertently transaminate the amino group of the γ-glutamyl moiety of GSH to produce deaminated glutathione (dGSH), a metabolite damage product. It was recently reported that an amidase known as Nit1 participates in dGSH breakdown in mammals and yeast. Plants have a hitherto uncharacterized homolog of the Nit1 amidase. We show that recombinant Arabidopsis Nit1 (At4g08790) has high and specific amidase activity towards dGSH. Ablating the Arabidopsis Nit1 gene causes a massive accumulation of dGSH and other marked changes to the metabolome. All plant Nit1 sequences examined had predicted plastidial targeting peptides with a potential second start codon whose use would eliminate the targeting peptide. In vitro transcription/translation assays show that both potential translation start codons in Arabidopsis Nit1 were used and confocal microscopy of Nit1-GFP fusions in plant cells confirmed both cytoplasmic and plastidial localization. Furthermore, we show that Arabidopsis enzymes present in leaf extracts convert GSH to dGSH at a rate of 2.8 pmol min-1 mg-1 in the presence of glyoxalate as an amino acceptor. Our data demonstrate that plants have a dGSH repair system that is directed to at least two cellular compartments via the use of alternative translation start sites.
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9
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Aznar-Moreno JA, Sánchez R, Gidda SK, Martínez-Force E, Moreno-Pérez AJ, Venegas Calerón M, Garcés R, Mullen RT, Salas JJ. New Insights Into Sunflower ( Helianthus annuus L.) FatA and FatB Thioesterases, Their Regulation, Structure and Distribution. FRONTIERS IN PLANT SCIENCE 2018; 9:1496. [PMID: 30459777 PMCID: PMC6232763 DOI: 10.3389/fpls.2018.01496] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 09/25/2018] [Indexed: 05/13/2023]
Abstract
Sunflower seeds (Helianthus annuus L.) accumulate large quantities of triacylglycerols (TAG) between 12 and 28 days after flowering (DAF). This is the period of maximal acyl-acyl carrier protein (acyl-ACP) thioesterase activity in vitro, the enzymes that terminate the process of de novo fatty acid synthesis by catalyzing the hydrolysis of the acyl-ACPs synthesized by fatty acid synthase. Fatty acid thioesterases can be classified into two families with distinct substrate specificities, namely FatA and FatB. Here, some new aspects of these enzymes have been studied, assessing how both enzymes contribute to the acyl composition of sunflower oil, not least through the changes in their expression during the process of seed filling. Moreover, the binding pockets of these enzymes were modeled based on new data from plant thioesterases, revealing important differences in their volume and geometry. Finally, the subcellular location of the two enzymes was evaluated and while both possess an N-terminal plastid transit peptide, only in FatB contains a hydrophobic sequence that could potentially serve as a transmembrane domain. Indeed, using in vivo imaging and organelle fractionation, H. annuus thioesterases, HaFatA and HaFatB, appear to be differentially localized in the plastid stroma and membrane envelope, respectively. The divergent roles fulfilled by HaFatA and HaFatB in oil biosynthesis are discussed in the light of our data.
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Affiliation(s)
- Jose A. Aznar-Moreno
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS, United States
| | - Rosario Sánchez
- Instituto de la Grasa (CSIC), Campus Universitario Pablo de Olavide, Seville, Spain
| | - Satinder K. Gidda
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | | | | | - Mónica Venegas Calerón
- Instituto de la Grasa (CSIC), Campus Universitario Pablo de Olavide, Seville, Spain
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Seville, Spain
| | - Rafael Garcés
- Instituto de la Grasa (CSIC), Campus Universitario Pablo de Olavide, Seville, Spain
| | - Robert T. Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Joaquín J. Salas
- Instituto de la Grasa (CSIC), Campus Universitario Pablo de Olavide, Seville, Spain
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10
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A plastidial pantoate transporter with a potential role in pantothenate synthesis. Biochem J 2018; 475:813-825. [DOI: 10.1042/bcj20170883] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 01/26/2018] [Accepted: 01/30/2018] [Indexed: 11/17/2022]
Abstract
The pantothenate (vitamin B5) synthesis pathway in plants is not fully defined because the subcellular site of its ketopantoate → pantoate reduction step is unclear. However, the pathway is known to be split between cytosol, mitochondria, and potentially plastids, and inferred to involve mitochondrial or plastidial transport of ketopantoate or pantoate. No proteins that mediate these transport steps have been identified. Comparative genomic and transcriptomic analyses identified Arabidopsis thaliana BASS1 (At1g78560) and its maize (Zea mays) ortholog as candidates for such a transport role. BASS1 proteins belong to the bile acid : sodium symporter family and share similarity with the Salmonella enterica PanS pantoate/ketopantoate transporter and with predicted bacterial transporters whose genes cluster on the chromosome with pantothenate synthesis genes. Furthermore, Arabidopsis BASS1 is co-expressed with genes related to metabolism of coenzyme A, the cofactor derived from pantothenate. Expression of Arabidopsis or maize BASS1 promoted the growth of a S. enterica panB panS mutant strain when pantoate, but not ketopantoate, was supplied, and increased the rate of [3H]pantoate uptake. Subcellular localization of green fluorescent protein fusions in Nicotiana tabacum BY-2 cells demonstrated that Arabidopsis BASS1 is targeted solely to the plastid inner envelope. Two independent Arabidopsis BASS1 knockout mutants accumulated pantoate ∼10-fold in leaves and had smaller seeds. Taken together, these data indicate that BASS1 is a physiologically significant plastidial pantoate transporter and that the pantoate reduction step in pantothenate biosynthesis could be at least partly localized in plastids.
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11
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Brikis CJ, Zarei A, Trobacher CP, DeEll JR, Akama K, Mullen RT, Bozzo GG, Shelp BJ. Ancient Plant Glyoxylate/Succinic Semialdehyde Reductases: GLYR1s Are Cytosolic, Whereas GLYR2s Are Localized to Both Mitochondria and Plastids. FRONTIERS IN PLANT SCIENCE 2017; 8:601. [PMID: 28484477 PMCID: PMC5399074 DOI: 10.3389/fpls.2017.00601] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 04/03/2017] [Indexed: 05/18/2023]
Abstract
Plant NADPH-dependent glyoxylate/succinic semialdehyde reductases 1 and 2 (GLYR1 and GLYR2) are considered to be involved in detoxifying harmful aldehydes, thereby preserving plant health during exposure to various abiotic stresses. Phylogenetic analysis revealed that the two GLYR isoforms appeared in the plant lineage prior to the divergence of the Chlorophyta and Streptophyta, which occurred approximately 750 million years ago. Green fluorescent protein fusions of apple (Malus x domestica Borkh.), rice (Oryza sativa L.) and Arabidopsis thaliana [L.] Heynh GLYRs were transiently expressed in tobacco (Nicotiana tabaccum L.) suspension cells or Arabidopsis protoplasts, as well in methoxyfenozide-induced, stably transformed Arabidopsis seedlings. The localization of apple GLYR1 confirmed that this isoform is cytosolic, whereas apple, rice and Arabidopsis GLYR2s were localized to both mitochondria and plastids. These findings highlight the potential involvement of GLYRs within distinct compartments of the plant cell.
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Affiliation(s)
| | - Adel Zarei
- Department of Plant Agriculture, University of Guelph, GuelphON, Canada
| | | | - Jennifer R. DeEll
- Ontario Ministry of Agriculture Food and Rural Affairs, SimcoeON, Canada
| | - Kazuhito Akama
- Department of Biological Science, Shimane UniversityMatsue, Japan
| | - Robert T. Mullen
- Department of Molecular and Cellular Biology, University of Guelph, GuelphON, Canada
| | - Gale G. Bozzo
- Department of Plant Agriculture, University of Guelph, GuelphON, Canada
| | - Barry J. Shelp
- Department of Plant Agriculture, University of Guelph, GuelphON, Canada
- *Correspondence: Barry J. Shelp,
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12
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Sabetta W, Vannini C, Sgobba A, Marsoni M, Paradiso A, Ortolani F, Bracale M, Viggiano L, Blanco E, de Pinto MC. Cyclic AMP deficiency negatively affects cell growth and enhances stress-related responses in tobacco Bright Yellow-2 cells. PLANT MOLECULAR BIOLOGY 2016; 90:467-83. [PMID: 26786166 DOI: 10.1007/s11103-016-0431-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 01/05/2016] [Indexed: 05/24/2023]
Abstract
Cyclic adenosine 3',5'-monophosphate (cAMP) is a recognized second messenger; however, knowledge of cAMP involvement in plant physiological processes originates primarily from pharmacological studies. To obtain direct evidence for cAMP function in plants, tobacco Bright Yellow-2 (BY-2) cells were transformed with the cAMP sponge, which is a genetically encoded tool that reduces cAMP availability. BY-2 cells expressing the cAMP sponge (cAS cells), showed low levels of free cAMP and exhibited growth inhibition that was not proportional to the cAMP sponge transcript level. Growth inhibition in cAS cells was closely related to the precocious inhibition of mitosis due to a delay in cell cycle progression. The cAMP deficiency also enhanced antioxidant systems. Remarkable changes occurred in the cAS proteomic profile compared with that of wild-type (WT) cells. Proteins involved in translation, cytoskeletal organization, and cell proliferation were down-regulated, whereas stress-related proteins were up-regulated in cAS cells. These results support the hypothesis that BY-2 cells sense cAMP deficiency as a stress condition. Finally, many proteasome subunits were differentially expressed in cAS cells compared with WT cells, indicating that cAMP signaling broadly affects protein degradation via the ubiquitin/proteasome pathway.
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Affiliation(s)
- Wilma Sabetta
- Istituto di Bioscienze e Biorisorse, CNR, Via G. Amendola 165/A, 70126, Bari, Italy
| | - Candida Vannini
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, Via H. J. Dunant 3, 21100, Varese, Italy
| | - Alessandra Sgobba
- Dipartimento di Biologia, Università degli Studi di Bari "Aldo Moro", via E. Orabona 4, 70125, Bari, Italy
| | - Milena Marsoni
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, Via H. J. Dunant 3, 21100, Varese, Italy
| | - Annalisa Paradiso
- Dipartimento di Biologia, Università degli Studi di Bari "Aldo Moro", via E. Orabona 4, 70125, Bari, Italy
| | - Francesca Ortolani
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, Via H. J. Dunant 3, 21100, Varese, Italy
| | - Marcella Bracale
- Dipartimento di Biotecnologie e Scienze della Vita, Università degli Studi dell'Insubria, Via H. J. Dunant 3, 21100, Varese, Italy
| | - Luigi Viggiano
- Dipartimento di Biologia, Università degli Studi di Bari "Aldo Moro", via E. Orabona 4, 70125, Bari, Italy
| | - Emanuela Blanco
- Istituto di Bioscienze e Biorisorse, CNR, Via G. Amendola 165/A, 70126, Bari, Italy
| | - Maria Concetta de Pinto
- Dipartimento di Biologia, Università degli Studi di Bari "Aldo Moro", via E. Orabona 4, 70125, Bari, Italy.
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13
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Sugiyama A, Fukuda S, Takanashi K, Yoshioka M, Yoshioka H, Narusaka Y, Narusaka M, Kojima M, Sakakibara H, Shitan N, Sato S, Tabata S, Kawaguchi M, Yazaki K. Molecular Characterization of LjABCG1, an ATP-Binding Cassette Protein in Lotus japonicus. PLoS One 2015; 10:e0139127. [PMID: 26418593 PMCID: PMC4587964 DOI: 10.1371/journal.pone.0139127] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 09/08/2015] [Indexed: 11/18/2022] Open
Abstract
LjABCG1, a full-size ABCG subfamily of ATP-binding cassette proteins of a model legume, Lotus japonicus, was reported as a gene highly expressed during the early stages of nodulation, but have not been characterized in detail. In this study we showed that the induction of LjABCG1 expression was remarkable by methyl jasmonate treatment, and reporter gene experiments indicated that LjABCG1 was strongly expressed in the nodule parenchyma and cell layers adjacent to the root vascular tissue toward the nodule. LjABCG1 was suggested to be localized at the plasma membrane based on the fractionation of microsomal membranes as well as separation via aqueous two-phase partitioning. The physiological functions of LjABCG1 in symbiosis and pathogenesis were analyzed in homologous and heterologous systems. LjABCG1 knock-down L. japonicus plants did not show clear phenotypic differences in nodule formation, and not in defense against Pseudomonas syringae, either. In contrast, when LjABCG1 was expressed in the Arabidopsis pdr8-1 mutant, the penetration frequency of Phytophthora infestans, a potato late blight pathogen, was significantly reduced in LjABCG1/pdr8-1 than in pdr8-1 plants. This finding indicated that LjABCG1, at least partially, complemented the phenotype of pdr8 in Arabidopsis, suggesting the multiple roles of this protein in plant-microbe interactions.
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Affiliation(s)
- Akifumi Sugiyama
- Laboratory of Plant Gene Expression, Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji, 611-0011, Japan
| | - Shoju Fukuda
- Laboratory of Plant Gene Expression, Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji, 611-0011, Japan
| | - Kojiro Takanashi
- Laboratory of Plant Gene Expression, Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji, 611-0011, Japan
| | - Miki Yoshioka
- Laboratory of Defense in Plant-Pathogen Interactions, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601, Japan
| | - Hirofumi Yoshioka
- Laboratory of Defense in Plant-Pathogen Interactions, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601, Japan
| | - Yoshihiro Narusaka
- Research Institute for Biological Sciences, Okayama, 7549-1, Yoshikawa, Kaga-gun, Okayama, 716-1241, Japan
| | - Mari Narusaka
- Research Institute for Biological Sciences, Okayama, 7549-1, Yoshikawa, Kaga-gun, Okayama, 716-1241, Japan
| | - Mikiko Kojima
- RIKEN Center for Sustainable Resource Science, 1-7-22, Suehiro, Tsurumi, Yokohama, 230-0045, Japan
| | - Hitoshi Sakakibara
- RIKEN Center for Sustainable Resource Science, 1-7-22, Suehiro, Tsurumi, Yokohama, 230-0045, Japan
| | - Nobukazu Shitan
- Laboratory of Natural Medicinal Chemistry, Kobe Pharmaceutical University, Kobe, 658-8558, Japan
| | - Shusei Sato
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan; Kazusa DNA Research Institute, 2-6-7, Kazusa-Kamatari, Kisarazu, Chiba, 292-0812, Japan
| | - Satoshi Tabata
- Kazusa DNA Research Institute, 2-6-7, Kazusa-Kamatari, Kisarazu, Chiba, 292-0812, Japan
| | - Masayoshi Kawaguchi
- National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki, 444-8585, Japan
| | - Kazufumi Yazaki
- Laboratory of Plant Gene Expression, Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji, 611-0011, Japan
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14
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Goodin MM, Zaitlin D, Naidu RA, Lommel SA. Nicotiana benthamiana: Its History and Future as a Model for Plant-Pathogen Interactions. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 2015:28-39. [PMID: 27839076 DOI: 10.1094/mpmi-00-00-1015-rev.testissue] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Nicotiana benthamiana is the most widely used experimental host in plant virology, due mainly to the large number of diverse plant viruses that can successfully infect it. Addi- tionally, N. benthamiana is susceptible to a wide variety of other plant-pathogenic agents (such as bacteria, oomycetes, fungi, and so on), making this species a cornerstone of host-pathogen research, particularly in the context of innate immunity and defense signaling. Moreover, because it can be genetically transformed and regenerated with good efficiency and is amenable to facile methods for virus- induced gene silencing or transient protein expression, N. benthamiana is rapidly gaining popularity in plant biology, particularly in studies requiring protein localization, inter- action, or plant-based systems for protein expression and purification. Paradoxically, despite being an indispensable research model, little is known about the origins, genetic variation, or ecology of the N. benthamiana accessions cur- rently used by the research community. In addition to ad- dressing these latter topics, the purpose of this review is to provide information regarding sources for tools and reagents that can be used to support research in N. benthamiana. Finally, we propose that N. benthamiana is well situated to become a premier plant cell biology model, particularly for the virology community, who as a group were the first to recognize the potential of this unique Australian native.
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Affiliation(s)
| | - David Zaitlin
- 2 Kentucky Tobacco Research and Development Center (KTRDC), University of Kentucky, Lexington 40546, U.S.A
| | - Rayapati A Naidu
- 3 Department of Plant Pathology, Irrigated Agriculture Research & Extension Center, Washington State University, Prosser 99350, U.S.A
| | - Steven A Lommel
- 4 Department of Plant Pathology, North Carolina State University, Raleigh 27695, U.S.A
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15
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Noirot E, Der C, Lherminier J, Robert F, Moricova P, Kiêu K, Leborgne-Castel N, Simon-Plas F, Bouhidel K. Dynamic changes in the subcellular distribution of the tobacco ROS-producing enzyme RBOHD in response to the oomycete elicitor cryptogein. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:5011-22. [PMID: 24987013 PMCID: PMC4144778 DOI: 10.1093/jxb/eru265] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Plant NADPH oxidases, also known as respiratory burst oxidase homologues (RBOHs), have been identified as a major source of reactive oxygen species (ROS) during plant-microbe interactions. The subcellular localization of the tobacco (Nicotiana tabacum) ROS-producing enzyme RBOHD was examined in Bright Yellow-2 cells before and after elicitation with the oomycete protein cryptogein using electron and confocal microscopy. The plasma membrane (PM) localization of RBOHD was confirmed and immuno-electron microscopy on purified PM vesicles revealed its distribution in clusters. The presence of the protein fused to GFP was also seen in intracellular compartments, mainly Golgi cisternae. Cryptogein induced, within 1h, a 1.5-fold increase in RBOHD abundance at the PM and a concomitant decrease in the internal compartments. Use of cycloheximide revealed that most of the proteins targeted to the PM upon elicitation were not newly synthesized but may originate from the Golgi pool. ROS accumulation preceded RBOHD transcript- and protein-upregulation, indicating that ROS resulted from the activation of a PM-resident pool of enzymes, and that enzymes newly addressed to the PM were inactive. Taken together, the results indicate that control of RBOH abundance and subcellular localization may play a fundamental role in the mechanism of ROS production.
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Affiliation(s)
- Elodie Noirot
- INRA, UMR1347 Agroécologie, ERL CNRS 6300, Plateforme DImaCell, Centre de Microscopie INRA/Université de Bourgogne, BP 86510, F-21065 Dijon Cedex, France
| | - Christophe Der
- Université de Bourgogne, UMR1347 Agroécologie, ERL CNRS 6300, BP 86510, F-21065 Dijon Cedex, France
| | - Jeannine Lherminier
- INRA, UMR1347 Agroécologie, ERL CNRS 6300, Plateforme DImaCell, Centre de Microscopie INRA/Université de Bourgogne, BP 86510, F-21065 Dijon Cedex, France
| | - Franck Robert
- INRA, UMR1347 Agroécologie, ERL CNRS 6300, BP 86510, F-21065 Dijon Cedex, France
| | - Pavla Moricova
- INRA, UMR1347 Agroécologie, ERL CNRS 6300, BP 86510, F-21065 Dijon Cedex, France Present address: Department of Biochemistry, Faculty of Science, Palacký University in Olomouc, Šlechtitelů 11, CZ-783 71 Olomouc, Czech Republic
| | - Kiên Kiêu
- INRA, UR341 Mathématiques et Informatique Appliquées, F-78352 Jouy-en-Josas Cedex, France
| | - Nathalie Leborgne-Castel
- Université de Bourgogne, UMR1347 Agroécologie, ERL CNRS 6300, BP 86510, F-21065 Dijon Cedex, France
| | - Françoise Simon-Plas
- INRA, UMR1347 Agroécologie, ERL CNRS 6300, BP 86510, F-21065 Dijon Cedex, France
| | - Karim Bouhidel
- Université de Bourgogne, UMR1347 Agroécologie, ERL CNRS 6300, BP 86510, F-21065 Dijon Cedex, France
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16
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Richardson LGL, Clendening EA, Sheen H, Gidda SK, White KA, Mullen RT. A unique N-terminal sequence in the Carnation Italian ringspot virus p36 replicase-associated protein interacts with the host cell ESCRT-I component Vps23. J Virol 2014; 88:6329-44. [PMID: 24672030 PMCID: PMC4093892 DOI: 10.1128/jvi.03840-13] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Accepted: 03/18/2014] [Indexed: 01/24/2023] Open
Abstract
UNLABELLED Like most positive-strand RNA viruses, infection by plant tombusviruses results in extensive rearrangement of specific host cell organelle membranes that serve as the sites of viral replication. The tombusvirus Tomato bushy stunt virus (TBSV) replicates within spherules derived from the peroxisomal boundary membrane, a process that involves the coordinated action of various viral and cellular factors, including constituents of the endosomal sorting complex required for transport (ESCRT). ESCRT is comprised of a series of protein subcomplexes (i.e., ESCRT-0 -I, -II, and -III) that normally participate in late endosome biogenesis and some of which are also hijacked by certain enveloped retroviruses (e.g., HIV) for viral budding from the plasma membrane. Here we show that the replication of Carnation Italian ringspot virus (CIRV), a tombusvirus that replicates at mitochondrial membranes also relies on ESCRT. In plant cells, CIRV recruits the ESCRT-I protein, Vps23, to mitochondria through an interaction that involves a unique region in the N terminus of the p36 replicase-associated protein that is not conserved in TBSV or other peroxisome-targeted tombusviruses. The interaction between p36 and Vps23 also involves the Vps23 C-terminal steadiness box domain and not its N-terminal ubiquitin E2 variant domain, which in the case of TBSV (and enveloped retroviruses) mediates the interaction with ESCRT. Overall, these results provide evidence that CIRV uses a unique N-terminal sequence for the recruitment of Vps23 that is distinct from those used by TBSV and certain mammalian viruses for ESCRT recruitment. Characterization of this novel interaction with Vps23 contributes to our understanding of how CIRV may have evolved to exploit key differences in the plant ESCRT machinery. IMPORTANCE Positive-strand RNA viruses replicate their genomes in association with specific host cell membranes. To accomplish this, cellular components responsible for membrane biogenesis and modeling are appropriated by viral proteins and redirected to assemble membrane-bound viral replicase complexes. The diverse pathways leading to the formation of these replication structures are poorly understood. We have determined that the cellular ESCRT system that is normally responsible for mediating late endosome biogenesis is also involved in the replication of the tombusvirus Carnation Italian ringspot virus (CIRV) at mitochondria. Notably, CIRV recruits ESCRT to the mitochondrial outer membrane via an interaction between a unique motif in the viral protein p36 and the ESCRT component Vps23. Our findings provide new insights into tombusvirus replication and the virus-induced remodeling of plant intracellular membranes, as well as normal ESCRT assembly in plants.
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Affiliation(s)
- Lynn G. L. Richardson
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Eric A. Clendening
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Hyukho Sheen
- Department of Biology, York University, Toronto, Ontario, Canada
| | - Satinder K. Gidda
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - K. Andrew White
- Department of Biology, York University, Toronto, Ontario, Canada
| | - Robert T. Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
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17
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Hanson MR, Sattarzadeh A. Fluorescent labeling and confocal microscopic imaging of chloroplasts and non-green plastids. Methods Mol Biol 2014; 1132:125-43. [PMID: 24599850 DOI: 10.1007/978-1-62703-995-6_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
While chlorophyll has served as an excellent label for plastids in green tissue, the development of fluorescent proteins has allowed their ready visualization in all tissues of the plants, revealing new features of their morphology and motility. Gene regulatory sequences in plastid transgenes can be optimized through the use of fluorescent protein reporters. Fluorescent labeling of plastids simultaneously with other subcellular locations reveals dynamic interactions and mutant phenotypes. Transient expression of fluorescent protein fusions is particularly valuable to determine whether or not a protein of unknown function is targeted to the plastid. Particle bombardment and agroinfiltration methods described here are convenient for imaging fluorescent proteins in plant organelles. With proper selection of fluorophores for labeling the components of the plant cell, confocal microscopy can produce extremely informative images at high resolution at depths not feasible by standard epifluorescence microscopy.
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Affiliation(s)
- Maureen R Hanson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
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18
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Bender KW, Dobney S, Ogunrinde A, Chiasson D, Mullen RT, Teresinski HJ, Singh P, Munro K, Smith SP, Snedden WA. The calmodulin-like protein CML43 functions as a salicylic-acid-inducible root-specific Ca(2+) sensor in Arabidopsis. Biochem J 2014; 457:127-36. [PMID: 24102643 DOI: 10.1042/bj20131080] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Many signalling pathways in plants are regulated by the second messenger calcium (Ca(2+)). In the standard model, Ca(2+)-sensor proteins, such as CaM (calmodulin), detect Ca(2+) signals and subsequently regulate downstream targets to advance the signal transduction cascade. In addition to CaM, plants possess many CMLs (CaM-like proteins) that are predicted to function as Ca(2+) sensors, but which remain largely uncharacterized. In the present study, we examined the biochemical properties, subcellular localization and tissue-specific distribution of Arabidopsis CML43. Our data indicate that CML43 displays characteristics typical of Ca(2+) sensors, including high-affinity Ca(2+) binding, conformational changes upon Ca(2+) binding that expose hydrophobic regions and stabilization of structure in the presence of Mg(2+) or Ca(2+). In vivo localization analysis demonstrates that CML43 resides in cytosolic and nuclear compartments. Transgenic plants expressing a CML43:GUS (β-glucoronidase) promoter reporter gene revealed that CML43 promoter activity is restricted almost exclusively to root tips under normal growth conditions. GUS reporter activity in these transgenic plants was strongly increased when exposed to the defence compound SA (salicylic acid). Furthermore, immunoblot analysis revealed that the CML43 protein accumulates following treatment with SA. Collectively, our findings suggest that CML43 functions as a Ca(2+) sensor in root tips during both normal growth and plant immune response.
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Affiliation(s)
- Kyle W Bender
- *Department of Biology, Queen's University, Kingston, ON, Canada, K7L 3N6
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19
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Marty NJ, Teresinski HJ, Hwang YT, Clendening EA, Gidda SK, Sliwinska E, Zhang D, Miernyk JA, Brito GC, Andrews DW, Dyer JM, Mullen RT. New insights into the targeting of a subset of tail-anchored proteins to the outer mitochondrial membrane. FRONTIERS IN PLANT SCIENCE 2014; 5:426. [PMID: 25237314 PMCID: PMC4154396 DOI: 10.3389/fpls.2014.00426] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Accepted: 08/12/2014] [Indexed: 05/21/2023]
Abstract
Tail-anchored (TA) proteins are a unique class of functionally diverse membrane proteins defined by their single C-terminal membrane-spanning domain and their ability to insert post-translationally into specific organelles with an Ncytoplasm-Corganelle interior orientation. The molecular mechanisms by which TA proteins are sorted to the proper organelles are not well-understood. Herein we present results indicating that a dibasic targeting motif (i.e., -R-R/K/H-X({X≠E})) identified previously in the C terminus of the mitochondrial isoform of the TA protein cytochrome b 5, also exists in many other A. thaliana outer mitochondrial membrane (OMM)-TA proteins. This motif is conspicuously absent, however, in all but one of the TA protein subunits of the translocon at the outer membrane of mitochondria (TOM), suggesting that these two groups of proteins utilize distinct biogenetic pathways. Consistent with this premise, we show that the TA sequences of the dibasic-containing proteins are both necessary and sufficient for targeting to mitochondria, and are interchangeable, while the TA regions of TOM proteins lacking a dibasic motif are necessary, but not sufficient for localization, and cannot be functionally exchanged. We also present results from a comprehensive mutational analysis of the dibasic motif and surrounding sequences that not only greatly expands the functional definition and context-dependent properties of this targeting signal, but also led to the identification of other novel putative OMM-TA proteins. Collectively, these results provide important insight to the complexity of the targeting pathways involved in the biogenesis of OMM-TA proteins and help define a consensus targeting motif that is utilized by at least a subset of these proteins.
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Affiliation(s)
- Naomi J. Marty
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Howard J. Teresinski
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Yeen Ting Hwang
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Eric A. Clendening
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Satinder K. Gidda
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
| | - Elwira Sliwinska
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
- Department of Plant Genetics, Physiology and Biotechnology, University of Technology and Life Sciences in BydgoszczBydgoszcz, Poland
| | - Daiyuan Zhang
- United States Department of Agriculture, Agricultural Research Service, US Arid-Land Agricultural Research CenterMaricopa, AZ, USA
| | - Ján A. Miernyk
- United States Department of Agriculture, Agricultural Research Service, Plant Genetics Research Unit, University of MissouriColumbia, MO, USA
| | - Glauber C. Brito
- Instituto do Cancer do Estado de Sao Paulo, Fundacao Faculdade de Medicina, Universidade de Sao PauloSao Paulo, Brazil
| | - David W. Andrews
- Sunnybrook Research Institute and Department of Biochemistry, University of TorontoToronto, ON, Canada
| | - John M. Dyer
- United States Department of Agriculture, Agricultural Research Service, US Arid-Land Agricultural Research CenterMaricopa, AZ, USA
| | - Robert T. Mullen
- Department of Molecular and Cellular Biology, University of GuelphGuelph, ON, Canada
- *Correspondence: Robert T. Mullen, Department of Molecular and Cellular, Biology, University of Guelph, Room 4470 Science Complex, 488 Gordon Street, Guelph, ON N1G 2W1, Canada e-mail:
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20
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Mitchell CA, Kalies S, Cizmár T, Heisterkamp A, Torrance L, Roberts AG, Gunn-Moore FJ, Dholakia K. Femtosecond optoinjection of intact tobacco BY-2 cells using a reconfigurable photoporation platform. PLoS One 2013; 8:e79235. [PMID: 24244456 PMCID: PMC3828288 DOI: 10.1371/journal.pone.0079235] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 09/20/2013] [Indexed: 01/06/2023] Open
Abstract
A tightly-focused ultrashort pulsed laser beam incident upon a cell membrane has previously been shown to transiently increase cell membrane permeability while maintaining the viability of the cell, a technique known as photoporation. This permeability can be used to aid the passage of membrane-impermeable biologically-relevant substances such as dyes, proteins and nucleic acids into the cell. Ultrashort-pulsed lasers have proven to be indispensable for photoporating mammalian cells but they have rarely been applied to plant cells due to their larger sizes and rigid and thick cell walls, which significantly hinders the intracellular delivery of exogenous substances. Here we demonstrate and quantify femtosecond optical injection of membrane impermeable dyes into intact BY-2 tobacco plant cells growing in culture, investigating both optical and biological parameters. Specifically, we show that the long axial extent of a propagation invariant ("diffraction-free") Bessel beam, which relaxes the requirements for tight focusing on the cell membrane, outperforms a standard Gaussian photoporation beam, achieving up to 70% optoinjection efficiency. Studies on the osmotic effects of culture media show that a hypertonic extracellular medium was found to be necessary to reduce turgor pressure and facilitate molecular entry into the cells.
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Affiliation(s)
- Claire A. Mitchell
- School of Physics and Astronomy, University of St. Andrews, St. Andrews, Fife, United Kingdom
| | - Stefan Kalies
- Biomedical Optics Department, Laser Zentrum Hannover e.V., Hannover, Germany
| | - Tomás Cizmár
- School of Medicine, University of St. Andrews, St. Andrews, Fife, United Kingdom
| | | | - Lesley Torrance
- Cell and Molecular Sciences, James Hutton Institute, Invergowrie, Dundee, United Kingdom
- School of Biology, University of St. Andrews, St. Andrews, Fife, United Kingdom
| | - Alison G. Roberts
- Cell and Molecular Sciences, James Hutton Institute, Invergowrie, Dundee, United Kingdom
| | - Frank J. Gunn-Moore
- School of Biology, University of St. Andrews, St. Andrews, Fife, United Kingdom
| | - Kishan Dholakia
- School of Physics and Astronomy, University of St. Andrews, St. Andrews, Fife, United Kingdom
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21
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Gidda SK, Watt SC, Collins-Silva J, Kilaru A, Arondel V, Yurchenko O, Horn PJ, James CN, Shintani D, Ohlrogge JB, Chapman KD, Mullen RT, Dyer JM. Lipid droplet-associated proteins (LDAPs) are involved in the compartmentalization of lipophilic compounds in plant cells. PLANT SIGNALING & BEHAVIOR 2013; 8:e27141. [PMID: 24305619 PMCID: PMC4091607 DOI: 10.4161/psb.27141] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 11/10/2013] [Indexed: 05/20/2023]
Abstract
While lipid droplets have traditionally been considered as inert sites for the storage of triacylglycerols and sterol esters, they are now recognized as dynamic and functionally diverse organelles involved in energy homeostasis, lipid signaling, and stress responses. Unlike most other organelles, lipid droplets are delineated by a half-unit membrane whose protein constituents are poorly understood, except in the specialized case of oleosins, which are associated with seed lipid droplets. Recently, we identified a new class of lipid-droplet associated proteins called LDAPs that localize specifically to the lipid droplet surface within plant cells and share extensive sequence similarity with the small rubber particle proteins (SRPPs) found in rubber-accumulating plants. Here, we provide additional evidence for a role of LDAPs in lipid accumulation in oil-rich fruit tissues, and further explore the functional relationships between LDAPs and SRPPs. In addition, we propose that the larger LDAP/SRPP protein family plays important roles in the compartmentalization of lipophilic compounds, including triacylglycerols and polyisoprenoids, into lipid droplets within plant cells. Potential roles in lipid droplet biogenesis and function of these proteins also are discussed.
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Affiliation(s)
- Satinder K Gidda
- Department of Molecular and Cellular Biology; University of Guelph; Guelph, ON Canada
| | | | - Jillian Collins-Silva
- Department of Biochemistry and Molecular Biology; University of Nevada; Reno, NV USA
| | - Aruna Kilaru
- Department of Biological Sciences; East Tennessee State University; Johnson City, TN USA
| | - Vincent Arondel
- CNRS and University of Bordeaux; UMR5200 LBM; BP81; Villenave d’Ornon cedex, France
| | - Olga Yurchenko
- USDA-ARS; US Arid-Land Agricultural Research Center; Maricopa, AZ USA
| | - Patrick J Horn
- Department of Biological Sciences; Center for Plant Lipid Research; University of North Texas; Denton, TX USA
| | - Christopher N James
- Department of Biological Sciences; Center for Plant Lipid Research; University of North Texas; Denton, TX USA
| | | | - John B Ohlrogge
- Department of Plant Biology; Michigan State University; East Lansing, MI USA
| | - Kent D Chapman
- Department of Biological Sciences; Center for Plant Lipid Research; University of North Texas; Denton, TX USA
| | - Robert T Mullen
- Department of Molecular and Cellular Biology; University of Guelph; Guelph, ON Canada
| | - John M Dyer
- USDA-ARS; US Arid-Land Agricultural Research Center; Maricopa, AZ USA
- Correspondence to: John M Dyer,
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Frelin O, Agrimi G, Laera VL, Castegna A, Richardson LGL, Mullen RT, Lerma-Ortiz C, Palmieri F, Hanson AD. Identification of mitochondrial thiamin diphosphate carriers from Arabidopsis and maize. Funct Integr Genomics 2012; 12:317-26. [DOI: 10.1007/s10142-012-0273-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Revised: 02/17/2012] [Accepted: 03/02/2012] [Indexed: 10/28/2022]
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Graumann K, Evans DE. Nuclear envelope dynamics during plant cell division suggest common mechanisms between kingdoms. Biochem J 2011; 435:661-7. [PMID: 21323637 DOI: 10.1042/bj20101769] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Behaviour of the NE (nuclear envelope) during open mitosis has been explored extensively in metazoans, but lack of native markers has limited similar investigations in plants. In the present study, carried out using living synchronized tobacco BY-2 suspension cultures, the non-functional NE marker LBR (lamin B receptor)-GFP (green fluorescent protein) and two native, functional NE proteins, AtSUN1 [Arapidopsis thaliana SUN (Sad1/UNC84) 1] and AtSUN2, we provide evidence that the ER (endoplasmic reticulum)-retention theory for NE membranes is applicable in plants. We also observe two apparently unique plant features: location of the NE-membrane components in close proximity to chromatin throughout division, and spatially distinct reformation of the NE commencing at the chromatin surface facing the spindle poles and concluding at the surface facing the cell plate. Mobility of the proteins was investigated in the interphase NE, during NE breakdown and reformation, in the spindle membranes and the cell plate. A role for AtSUN2 in nuclear envelope breakdown is suggested.
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Affiliation(s)
- Katja Graumann
- School of Life Sciences, Oxford Brookes University, Oxford OX3 0BP, UK
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Dhanoa PK, Richardson LGL, Smith MD, Gidda SK, Henderson MPA, Andrews DW, Mullen RT. Distinct pathways mediate the sorting of tail-anchored proteins to the plastid outer envelope. PLoS One 2010; 5:e10098. [PMID: 20418952 PMCID: PMC2854689 DOI: 10.1371/journal.pone.0010098] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2009] [Accepted: 03/11/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Tail-anchored (TA) proteins are a distinct class of membrane proteins that are sorted post-translationally to various organelles and function in a number of important cellular processes, including redox reactions, vesicular trafficking and protein translocation. While the molecular targeting signals and pathways responsible for sorting TA proteins to their correct intracellular destinations in yeasts and mammals have begun to be characterized, relatively little is known about TA protein biogenesis in plant cells, especially for those sorted to the plastid outer envelope. METHODOLOGY/PRINCIPAL FINDINGS Here we investigated the biogenesis of three plastid TA proteins, including the 33-kDa and 34-kDa GTPases of the translocon at the outer envelope of chloroplasts (Toc33 and Toc34) and a novel 9-kDa protein of unknown function that we define here as an outer envelope TA protein (OEP9). Using a combination of in vivo and in vitro assays we show that OEP9 utilizes a different sorting pathway than that used by Toc33 and Toc34. For instance, while all three TA proteins interact with the cytosolic OEP chaperone/receptor, AKR2A, the plastid targeting information within OEP9 is distinct from that within Toc33 and Toc34. Toc33 and Toc34 also appear to differ from OEP9 in that their insertion is dependent on themselves and the unique lipid composition of the plastid outer envelope. By contrast, the insertion of OEP9 into the plastid outer envelope occurs in a proteinaceous-dependent, but Toc33/34-independent manner and membrane lipids appear to serve primarily to facilitate normal thermodynamic integration of this TA protein. CONCLUSIONS/SIGNIFICANCE Collectively, the results provide evidence in support of at least two sorting pathways for plastid TA outer envelope proteins and shed light on not only the complex diversity of pathways involved in the targeting and insertion of proteins into plastids, but also the molecular mechanisms that underlie the delivery of TA proteins to their proper intracellular locations in general.
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Affiliation(s)
- Preetinder K. Dhanoa
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Lynn G. L. Richardson
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Matthew D. Smith
- Department of Biology, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - Satinder K. Gidda
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Matthew P. A. Henderson
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - David W. Andrews
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Robert T. Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
- * E-mail:
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Chong YT, Gidda SK, Sanford C, Parkinson J, Mullen RT, Goring DR. Characterization of the Arabidopsis thaliana exocyst complex gene families by phylogenetic, expression profiling, and subcellular localization studies. THE NEW PHYTOLOGIST 2010; 185:401-19. [PMID: 19895414 DOI: 10.1111/j.1469-8137.2009.03070.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
*The exocyst is a complex of eight proteins (Sec3p, Sec5p, Sec6p, Sec8p, Sec10p, Sec15p, Exo70p and Exo84p) involved in tethering vesicles to the plasma membrane during regulated or polarized secretion. Here, the plant exocyst complex was explored in phylogenetic, expression, and subcellular localization studies. *Evolutionary relationships of predicted exocyst subunits were examined in the complete genomes of Arabidopsis thaliana, Oryza sativa, Populus trichocarpa and Physcomitrella patens. Furthermore, detailed expression profiling of the A. thaliana microarray databases was performed and subcellular localization patterns were studied. *Several plant exocyst subunit genes appear to have undergone gene expansion in a common ancestor and subsequent duplication events in independent plant lineages. Expression profiling revealed that the A. thaliana Exo70 gene family exhibits dynamic expression patterns, while the remaining exocyst subunit genes displayed more static profiles. Subcellular localization patterns for A. thaliana exocyst subunits ranged from cytosolic to endosomal compartments (with enrichment in the early endosomes and the trans-Golgi network). Interestingly, two endosomal-localized AtExo70 proteins also recruited other exocyst subunits to these compartments. *Overall subcellular localization patterns were observed that were also found in yeast and animal cells, and this, coupled with the evolutionary relationships, suggests that the exocyst may perform similar conserved functions in plants.
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Affiliation(s)
- Yolanda T Chong
- Department of Cell & Systems Biology and the Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario, Canada M5S 3B2
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Gidda SK, Shockey JM, Rothstein SJ, Dyer JM, Mullen RT. Arabidopsis thaliana GPAT8 and GPAT9 are localized to the ER and possess distinct ER retrieval signals: functional divergence of the dilysine ER retrieval motif in plant cells. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2009; 47:867-79. [PMID: 19539490 DOI: 10.1016/j.plaphy.2009.05.008] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Revised: 05/14/2009] [Accepted: 05/27/2009] [Indexed: 05/03/2023]
Abstract
Glycerol-3-phosphate acyltransferase (GPAT; EC 2.3.1.15) catalyzes the committed step in the production of glycerolipids, which are major components of cellular membranes, seed storage oils, and epicuticular wax coatings. While the biochemical activities of GPATs have been characterized in detail, the cellular features of these enzymes are only beginning to emerge. Here we characterized the phylogenetic relationships and cellular properties of two GPAT enzymes from the relatively large Arabidopsis thaliana GPAT family, including GPAT8, which is involved in cutin biosynthesis, and GPAT9, which is a new putative GPAT that has extensive homology with a GPAT from mammalian cells involved in storage oil formation and, thus, may have a similar role in plants. Immunofluorescence microscopy of transiently-expressed myc-epitope-tagged GPAT8 and GPAT9 revealed that both proteins were localized to the endoplasmic reticulum (ER), and differential permeabilization experiments indicated that their N- and C-termini were oriented towards the cytosol. However, these two proteins contained distinct types of ER retrieval signals, with GPAT8 possessing a divergent type of dilysine motif (-KK-COOH rather than the prototypic -KKXX-COOH or -KXKXX-COOH motif) and GPAT9 possessing a hydrophobic pentapeptide motif (-phi-X-X-K/R/D/E-phi-; where phi are large hydrophobic amino acid residues). Notably, the divergent dilysine motif in GPAT8 only functioned effectively when additional upstream residues were included to provide the proper protein context. Extensive mutational analyses of the divergent dilysine motif, based upon sequences present in the C-termini of other GPAT8s from various plant species, further expanded the functional definition of this molecular targeting signal, thereby providing insight to the targeting signals in other GPAT family members as well as other ER-resident membrane proteins within plant cells.
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Affiliation(s)
- Satinder K Gidda
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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Clark SM, Di Leo R, Van Cauwenberghe OR, Mullen RT, Shelp BJ. Subcellular localization and expression of multiple tomato gamma-aminobutyrate transaminases that utilize both pyruvate and glyoxylate. JOURNAL OF EXPERIMENTAL BOTANY 2009; 60:3255-67. [PMID: 19470656 PMCID: PMC2718222 DOI: 10.1093/jxb/erp161] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Revised: 04/24/2009] [Accepted: 04/27/2009] [Indexed: 05/20/2023]
Abstract
Gamma-aminobutyric acid transaminase (GABA-T) catalyses the breakdown of GABA to succinic semialdehyde. In this report, three GABA-T isoforms were identified in the tomato (Solanum lycopersicum L.) plant. The deduced amino acid sequences of the three isoforms are highly similar over most of their coding regions with the exception of their N-terminal regions. Transient expression of the individual full-length GABA-T isoforms fused to the green fluorescent protein in tobacco suspension-cultured cells revealed their distinct subcellular localizations to the mitochondrion, plastid or cytosol, and that the specific targeting of the mitochondrion- and plastid-localized isoforms is mediated by their predicted N-terminal presequences. Removal of the N-terminal targeting presequences from the mitochondrion and plastid GABA-T isoforms yielded good recovery of the soluble recombinant proteins in Escherichia coli when they were co-expressed with the GroES/EL molecular chaperone complex. Activity assays indicated that all three recombinant isoforms possess both pyruvate- and glyoxylate-dependent GABA-T activities, although the mitochondrial enzyme has a specific activity that is significantly higher than that of its plastid and cytosolic counterparts. Finally, differential expression patterns of the three GABA-T isoforms in reproductive tissues, but not vegetative tissues, suggest unique roles for each enzyme in developmental processes. Overall, these findings, together with recent information about rice and pepper GABA-Ts, indicate that the subcellular distribution of GABA-T in the plant kingdom is highly variable.
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Affiliation(s)
- Shawn M. Clark
- Department of Plant Agriculture, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Rosa Di Leo
- Department of Plant Agriculture, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | | | - Robert T. Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Barry J. Shelp
- Department of Plant Agriculture, University of Guelph, Guelph, Ontario, Canada N1G 2W1
- To whom correspondence should be addressed. E-mail:
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Hwang YT, McCartney AW, Gidda SK, Mullen RT. Localization of the Carnation Italian ringspot virus replication protein p36 to the mitochondrial outer membrane is mediated by an internal targeting signal and the TOM complex. BMC Cell Biol 2008; 9:54. [PMID: 18811953 PMCID: PMC2573885 DOI: 10.1186/1471-2121-9-54] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2008] [Accepted: 09/23/2008] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Carnation Italian ringspot virus (CIRV) is a positive-strand RNA virus that causes massive structural alterations of mitochondria in infected host cells, the most conspicuous being the formation of numerous internal vesicles/spherules that are derived from the mitochondrial outer membrane and serve as the sites for viral RNA replication. While the membrane-bound components of the CIRV replication complex, including a 36-kD RNA-binding protein (p36), are known to be essential for these changes in mitochondrial morphology and are relatively well characterized in terms of their roles in nascent viral RNA synthesis, how these proteins are specifically targeted and inserted into mitochondria is poorly defined. RESULTS Here we report on the molecular signal responsible for sorting p36 to the mitochondrial outer membrane. Using a combination of gain-of-function assays with portions of p36 fused to reporter proteins and domain-swapping assays with p36 and another closely-related viral RNA-binding protein, p33, that sorts specifically to the peroxisomal boundary membrane, we show that the mitochondrial targeting information in p36 resides within its two transmembrane domains (TMDs) and intervening hydrophilic loop sequence. Comprehensive mutational analysis of these regions in p36 revealed that the primary targeting determinants are the moderate hydrophobicity of both TMDs and the positively-charged face of an amphipathic helix within the intervening loop sequence. We show also using bimolecular fluorescence complementation (BiFC) that p36 interacts with certain components of the translocase complex in the mitochondrial outer membrane (TOM), but not with the sorting and assembly machinery (SAM). CONCLUSION Our results provide insight to how viruses, such as CIRV, exploit specific host-cell protein sorting pathways to facilitate their replication. The characterization of the targeting and insertion of p36 into the mitochondrial outer membrane also sheds light on the mechanisms involved in sorting of host-cell membrane proteins to mitochondria, a process that has been largely unexplored in plants.
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Affiliation(s)
- Yeen Ting Hwang
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Andrew W McCartney
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
- JD Irving, Limited, Woodlands Division, 1350 Regent Street, Fredericton, New Brunswick, E3C 2G6, Canada
| | - Satinder K Gidda
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Robert T Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
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Goodin MM, Zaitlin D, Naidu RA, Lommel SA. Nicotiana benthamiana: its history and future as a model for plant-pathogen interactions. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2008; 21:1015-26. [PMID: 18616398 DOI: 10.1094/mpmi-21-8-1015] [Citation(s) in RCA: 377] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Nicotiana benthamiana is the most widely used experimental host in plant virology, due mainly to the large number of diverse plant viruses that can successfully infect it. Additionally, N. benthamiana is susceptible to a wide variety of other plant-pathogenic agents (such as bacteria, oomycetes, fungi, and so on), making this species a cornerstone of host-pathogen research, particularly in the context of innate immunity and defense signaling. Moreover, because it can be genetically transformed and regenerated with good efficiency and is amenable to facile methods for virus-induced gene silencing or transient protein expression, N. benthamiana is rapidly gaining popularity in plant biology, particularly in studies requiring protein localization, interaction, or plant-based systems for protein expression and purification. Paradoxically, despite being an indispensable research model, little is known about the origins, genetic variation, or ecology of the N. benthamiana accessions currently used by the research community. In addition to addressing these latter topics, the purpose of this review is to provide information regarding sources for tools and reagents that can be used to support research in N. benthamiana. Finally, we propose that N. benthamiana is well situated to become a premier plant cell biology model, particularly for the virology community, who as a group were the first to recognize the potential of this unique Australian native.
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Affiliation(s)
- Michael M Goodin
- Department of Plant Pathology, University of Kentucky, Lexington 40546, USA.
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