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Accueil > Départements > Biologie Cellulaire > Anciennes équipes du département > Grégory VERT : Signalisation Cellulaire et Ubiquitination chez les Plantes

Publications de l’équipe

Principales publications


  • G. Dubeaux, J. Neveu, E. Zelazny, et G. Vert, « Metal Sensing by the IRT1 Transporter-Receptor Orchestrates Its Own Degradation and Plant Metal Nutrition », Molecular Cell, vol. 69, nᵒ 6, p. 953-964.e5, mars 2018.
    Résumé : Plant roots forage the soil for iron, the concentration of which can be dramatically lower than those needed for growth. Soil iron uptake uses the broad metal spectrum IRT1 transporter that also transports zinc, manganese, cobalt, and cadmium. Sophisticated iron-dependent transcriptional regulatory mechanisms allow plants to tightly control the abundance of IRT1, ensuring optimal absorption of iron. Here, we uncover that IRT1 acts as a transporter and receptor (transceptor), directly sensing excess of its non-iron metal substrates in the cytoplasm, to regulate its own degradation. Direct metal binding to a histidine-rich stretch in IRT1 triggers its phosphorylation by the CIPK23 kinase and facilitates the subsequent recruitment of the IDF1 E3 ligase. CIPK23-driven phosphorylation and IDF1-mediated lysine-63 polyubiquitination are jointly required for efficient endosomal sorting and vacuolar degradation of IRT1. Thus, IRT1 directly senses elevated non-iron metal concentrations and integrates multiple substrate-dependent regulations to optimize iron uptake and protect plants from highly reactive metals.
    Mots-clés : Arabidopsis, BIOCELL, degradation, metal homeostasis, phosphorylation, plant, receptor, sensing, transceptor, transporter, UBINET, ubiquitin.

  • P. Junková, M. Daněk, D. Kocourková, J. Brouzdová, K. Kroumanová, E. Zelazny, M. Janda, R. Hynek, J. Martinec, et O. Valentová, « Mapping of Plasma Membrane Proteins Interacting With Arabidopsis thaliana Flotillin 2 », Frontiers in Plant Science, vol. 9, p. 991, 2018.
    Résumé : Arabidopsis flotillin 2 (At5g25260) belongs to the group of plant flotillins, which are not well characterized. In contrast, metazoan flotillins are well known as plasma membrane proteins associated with membrane microdomains that act as a signaling hub. The similarity of plant and metazoan flotillins, whose functions most likely consist of affecting other proteins via protein-protein interactions, determines the necessity of detecting their interacting partners in plants. Nevertheless, identifying the proteins that form complexes on the plasma membrane is a challenging task due to their low abundance and hydrophobic character. Here we present an approach for mapping Arabidopsis thaliana flotillin 2 plasma membrane interactors, based on the immunoaffinity purification of crosslinked and enriched plasma membrane proteins with mass spectrometry detection. Using this approach, 61 proteins were enriched in the AtFlot-GFP plasma membrane fraction, and 19 of them were proposed to be flotillin 2 interaction partners. Among our proposed partners of Flot2, proteins playing a role in the plant response to various biotic and abiotic stresses were detected. Additionally, the use of the split-ubiquitin yeast system helped us to confirm that plasma-membrane ATPase 1, early-responsive to dehydration stress protein 4, syntaxin-71, harpin-induced protein-like 3, hypersensitive-induced response protein 2 and two aquaporin isoforms interact with flotillin 2 directly. Based on the results of our study and the reported properties of Flot2 interactors, we propose that Flot2 complexes may be involved in plant-pathogen interactions, water transport and intracellular trafficking.
    Mots-clés : Arabidopsis flotillin 2, BIOCELL, immunopurification, intracellular trafficking, mass spectrometry, plant–pathogen interaction, protein–protein interactions, split-ubiquitin yeast system, UBINET, water transport.

  • K. Mishev, Q. Lu, B. Denoo, F. Peurois, W. Dejonghe, J. Hullaert, R. De Rycke, S. Boeren, M. Bretou, S. De Munck, I. Sharma, K. Goodman, K. Kalinowska, V. Storme, L. S. L. Nguyen, A. Drozdzecki, S. Martins, W. Nerinckx, D. Audenaert, G. Vert, A. Madder, M. S. Otegui, E. Isono, S. N. Savvides, W. Annaert, S. De Vries, J. Cherfils, J. Winne, et E. Russinova, « Nonselective Chemical Inhibition of Sec7 Domain-Containing ARF GTPase Exchange Factors », Plant Cell, vol. 30, nᵒ 10, p. 2573-2593, oct. 2018.
    Résumé : Small GTP-binding proteins from the ADP-ribosylation factor (ARF) family are important regulators of vesicle formation and cellular trafficking in all eukaryotes. ARF activation is accomplished by a protein family of guanine nucleotide exchange factors (GEFs) that contain a conserved catalytic Sec7 domain. Here, we identified and characterized Secdin, a small-molecule inhibitor of Arabidopsis thaliana ARF-GEFs. Secdin application caused aberrant retention of plasma membrane (PM) proteins in late endosomal compartments, enhanced vacuolar degradation, impaired protein recycling, and delayed secretion and endocytosis. Combined treatments with Secdin and the known ARF-GEF inhibitor Brefeldin A (BFA) prevented the BFA-induced PM stabilization of the ARF-GEF GNOM, impaired its translocation from the Golgi to the trans-Golgi network/early endosomes, and led to the formation of hybrid endomembrane compartments reminiscent of those in ARF-GEF-deficient mutants. Drug affinity-responsive target stability assays revealed that Secdin, unlike BFA, targeted all examined Arabidopsis ARF-GEFs, but that the interaction was probably not mediated by the Sec7 domain because Secdin did not interfere with the Sec7 domain-mediated ARF activation. These results show that Secdin and BFA affect their protein targets through distinct mechanisms, in turn showing the usefulness of Secdin in studies in which ARF-GEF-dependent endomembrane transport cannot be manipulated with BFA.
    Mots-clés : arabidopsis-thaliana, BIOCELL, brefeldin-a, endomembrane trafficking, golgi network/early endosome, plant-cells, plasma-membrane, protein complexes, receptor kinase bri1, small molecules, UBINET, wide analysis.

  • N. Romero-Barrios et G. Vert, « Proteasome-independent functions of lysine-63 polyubiquitination in plants », The New Phytologist, vol. 217, nᵒ 3, p. 995-1011, févr. 2018.
    Résumé : Contents Summary 995 I. Introduction 995 II. The plant Ub machinery 996 III. From Ub to Ub linkage types in plants 997 IV. Increasing analytical resolution for K63 polyUb in plants 998 V. How to build K63 polyUb chains? 998 VI. Cellular roles of K63 polyUb in plants 999 VII. Physiological roles of K63 polyUb in plants 1004 VIII. Future perspectives: towards the next level of the Ub code 1006 Acknowledgements 1006 References 1007 SUMMARY: Ubiquitination is a post-translational modification essential for the regulation of eukaryotic proteins, having an impact on protein fate, function, localization or activity. What originally appeared to be a simple system to regulate protein turnover by the 26S proteasome is now known to be the most intricate regulatory process cells have evolved. Ubiquitin can be arranged in countless chain assemblies, triggering various cellular outcomes. Polyubiquitin chains using lysine-63 from ubiquitin represent the second most abundant type of ubiquitin modification. Recent studies have exposed their common function in proteasome-independent functions in non-plant model organisms. The existence of lysine-63 polyubiquitination in plants is, however, only just emerging. In this review, we discuss the recent advances on the characterization of ubiquitin chains and the molecular mechanisms driving the formation of lysine-63-linked ubiquitin modifications. We provide an overview of the roles associated with lysine-63 polyubiquitination in plant cells in the light of what is known in non-plant models. Finally, we review the crucial roles of lysine-63 polyubiquitin-dependent processes in plant growth, development and responses to environmental conditions.
    Mots-clés : Autophagy, BIOCELL, UBINET.


  • G. Dubeaux et G. Vert, « Zooming into plant ubiquitin-mediated endocytosis », Current Opinion in Plant Biology, vol. 40, p. 56-62, juill. 2017.
    Résumé : Endocytosis in plants plays an essential role, not only for basic cellular functions but also for growth, development, and environmental responses. Over the past few years, ubiquitin emerged as a major signal triggering the removal of plasma membrane proteins from the cell surface and promoting their vacuolar targeting. Detailed genetic, biochemical and imaging studies have provided initial insights into the precise mechanisms and roles of ubiquitin-mediated endocytosis in plants. Here, we summarize the present state of knowledge about the machinery involved in plant ubiquitin-mediated endocytosis and how this is coordinated in time and space to control the internalization and the endosomal sorting of endocytosed proteins.
    Mots-clés : BIOCELL, UBINET.

  • A. Johnson et G. Vert, « Single Event Resolution of Plant Plasma Membrane Protein Endocytosis by TIRF Microscopy », Frontiers in Plant Science, vol. 8, p. 612, 2017.
    Résumé : Endocytosis is a key process in the internalization of extracellular materials and plasma membrane proteins, such as receptors and transporters, thereby controlling many aspects of cell signaling and cellular homeostasis. Endocytosis in plants has an essential role not only for basic cellular functions but also for growth and development, nutrient delivery, toxin avoidance, and pathogen defense. The precise mechanisms of endocytosis in plants remain quite elusive. The lack of direct visualization and examination of single events of endocytosis has greatly hampered our ability to precisely monitor the cell surface lifetime and the recruitment profile of proteins driving endocytosis or endocytosed cargos in plants. Here, we discuss the necessity to systematically implement total internal reflection fluorescence microcopy (TIRF) in the Plant Cell Biology community and present reliable protocols for high spatial and temporal imaging of endocytosis in plants using clathrin-mediated endocytosis as a test case, since it represents the major route for internalization of cell-surface proteins in plants. We developed a robust method to directly visualize cell surface proteins using TIRF microscopy combined to a high throughput, automated and unbiased analysis pipeline to determine the temporal recruitment profile of proteins to single sites of endocytosis, using the departure of clathrin as a physiological reference for scission. Using this 'departure assay', we assessed the recruitment of two different AP-2 subunits, alpha and mu, to the sites of endocytosis and found that AP2A1 was recruited in concert with clathrin, while AP2M was not. This validated approach therefore offers a powerful solution to better characterize the plant endocytic machinery and the dynamics of one's favorite cargo protein.
    Mots-clés : Arabidopsis, BIOCELL, endocytosis, imaging techniques, plants, TIRF microscopy, trafficking, UBINET.

  • S. Martins, A. Montiel-Jorda, A. Cayrel, S. Huguet, C. P. - L. Roux, K. Ljung, et G. Vert, « Brassinosteroid signaling-dependent root responses to prolonged elevated ambient temperature », Nature Communications, vol. 8, nᵒ 1, p. 309, août 2017.
    Résumé : Due to their sessile nature, plants have to cope with and adjust to their fluctuating environment. Temperature elevation stimulates the growth of Arabidopsis aerial parts. This process is mediated by increased biosynthesis of the growth-promoting hormone auxin. How plant roots respond to elevated ambient temperature is however still elusive. Here we present strong evidence that temperature elevation impinges on brassinosteroid hormone signaling to alter root growth. We show that elevated temperature leads to increased root elongation, independently of auxin or factors known to drive temperature-mediated shoot growth. We further demonstrate that brassinosteroid signaling regulates root responses to elevated ambient temperature. Increased growth temperature specifically impacts on the level of the brassinosteroid receptor BRI1 to downregulate brassinosteroid signaling and mediate root elongation. Our results establish that BRI1 integrates temperature and brassinosteroid signaling to regulate root growth upon long-term changes in environmental conditions associated with global warming.Moderate heat stimulates the growth of Arabidopsis shoots in an auxin-dependent manner. Here, Martins et al. show that elevated ambient temperature modifies root growth by reducing the BRI1 brassinosteroid-receptor protein level and downregulating brassinosteroid signaling.
    Mots-clés : BIOCELL, UBINET.

  • S. Martins, G. Vert, et Y. Jaillais, « Probing Activation and Deactivation of the BRASSINOSTEROID INSENSITIVE1 Receptor Kinase by Immunoprecipitation », Methods in Molecular Biology (Clifton, N.J.), vol. 1564, p. 169-180, 2017.
    Résumé : Brassinosteroids (BRs) are sterol-derived hormones that control plant growth and development. The BR receptor complex is encoded by the BRASSINOSTEROID INSENSITIVE1 (BRI1) and members of the SOMATIC EMBRYOGENESIS RECEPTOR KINASE family. For activation and deactivation, the BR receptor complex uses different posttranslational modifications and recruits various partner proteins. Here, we describe optimized immunoprecipitation protocols and variants for biochemical analyses of posttranslational modifications of BRI1 and of protein-protein interactions.
    Mots-clés : BIOCELL, Brassinosteroids, BRI1, Immunoprecipitation, Phosphorylation, Protein–protein interaction, UBINET, Ubiquitination.



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Principales publications avant 2015

  • Barberon, M., Dubeaux, G., Kolb, C., Isono, E., Zelazny, E., and Vert, G. (2014). Polarization of IRON-REGULATED TRANSPORTER 1 (IRT1) at the plant-soil interface plays crucial role in metal homeostasis. PNAS 111, 8293-8298.
  • Zelazny, E. and Vert, G. (2014). Plant nutrition : root transporters on the move. Plant Physiology 166, 500-508.
  • Luschnig, C., and Vert, G. (2014). The dynamics of plant membrane proteins : PINs and beyond. Development 141, 2924-2938.
  • Thomine, S., and Vert, G. (2013). Iron transport in plants : better be safe than sorry ! Current Opinion in Plant Biology 16, 322-327.
  • Jaillais, Y. and Vert, G. (2012). Brassinosteroids, gibberellins and light-mediated signalling are the three-way controls of plant sprouting. Nature Cell Biology 14, 788-790.
  • Vert, G., and chory, J. (2011). Crosstalk in Cellular Signaling : Background noise or the Real Thing ? Developmental Cell 6, 985-991.
  • Barberon, M., Zelazny, E., Robert, S., Conejero, G., Curie, C., Friml, J., and Vert, G. (2011). Monoubiquitin-dependent endocytosis of the root transporter IRT1 controls iron uptake in plants. PNAS 108, E450-E458.
    [Pubmed] [F1000]
  • Sivitz, A., Grinvalds, C. Barberon, M., Curie, C. and Vert, G. (2011). Proteasome-Mediated Turnover of the Transcriptional Activator FIT is Required for Plant Iron Deficiency Responses. Plant Journal 66, 1044-1052.
  • Vert, G. and Chory, J. (2009). A Toggle Switch in Plant Nitrate Uptake. Cell 138, 1064-1066.
  • Vert, G. (2008). Plant signaling : brassinosteroids, immunity and effectors are BAK ! Current Biology 18, 963-965.
  • Vert, G., Walcher, C., Chory, J., and Nemhauser, J. (2008). Integration of auxin and brassinosteroid pathways by Auxin Response Factor 2. PNAS 105, 9829-9834.
    [Pubmed] [F1000]
  • Vert, G. and Chory, J. (2006). Downstream nuclear events in brassinosteroid signaling. Nature 441, 96-100.
    [Pubmed] [F1000]

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