[en] Intercellular communication is critical for multicellularity. It coordinates the activities within individual cells to support the function of an organism as a whole. Plants have developed remarkable cellular machines –the plasmodesmata (PD) pores- which interconnect every single cell within the plant body, establishing direct membrane and cytoplasmic continuity, a situation unique to plants. A striking feature of PD organisation, setting them apart from animal cell junctions, is a strand of tightly constricted ER called the desmotubule forming the center of plasmodesmata and connected to the PM by tethering elements which appear like spokes by electron microscopy and are assumed to be proteinaceous 1,2 . The close proximity (~10 nm) of the PM and ER within the pores, and the presence of tethers qualifies plasmodesmata as a specialized type of ER-to-PM membrane contact sites (MCS) 3,4 . Due to their importance for plant intercellular transport, and their emerging role as sensing and signalling ‘hubs’, a better understanding of the structure-function relationship of plasmodesmata is crucial for plant biology. Based on the biophysical properties of the plasmodesmata membranes and their distinct composition in lipid species, it can be assumed that both the ER and PM domains within PD differ from their surrounding bulk membranes and have a unique protein population. Very recently, it was shown by the team of E. Bayer that highly plasmodesmata-enriched proteins, members of the Multiple C2 domains and Transmembrane region Proteins (MCTPs) were significantly more abundant in PD with tight membrane connections, and exhibit the domain architecture expected of membrane tethering proteins 5,6 , with multiple lipid-binding C2 domains in the N-terminal, and an ER-anchored transmembrane region in the C-terminal region.
Our work is focused on investigating the potential docking of C2 domains of MCTPs on the plant plasma membrane at a molecular level. We first performed sequence analysis to accurately define the C2 domains from the MCTP and to obtain good 3D models by homology modelling. Then, molecular dynamics is carried out to predict the docking of the different C2 domains onto biomimetic plant plasma membrane and eventually lipid specificity. Based on those results and sequence analysis, specific binding sites in the C2 domains could be predicted.
Our preliminary results suggest that the different C2 domains of MCTP proteins could have different roles in lipid tethering, depending or not of calcium.
Research Center/Unit :
Agronomie, Bioingénierie et Chimie - AgroBioChem; CNRS
Crowet, Jean-Marc ; Université de Reims Champagne Ardenne > UFR Sciences exactes et naturelles > UMR 7369
Deleu, Magali ; Université de Liège - ULiège > Agronomie, Bio-ingénierie et Chimie (AgroBioChem) > Chimie des agro-biosystèmes
Bayer, Emmanuelle; Université Bordeaux Segalen > Laboratoire de Biogenèse Membranaire (LBM) - CNRS UMR 5200
Lins, Laurence ; Université de Liège - ULiège > Agronomie, Bio-ingénierie et Chimie (AgroBioChem) > Chimie des agro-biosystèmes
Language :
English
Title :
Sequence analysis & molecular dynamics to decipher the role of C2 domains from plant plasmodesmata MCTP proteins for membrane tethering
Alternative titles :
[fr] Analyse de séquence et dynamique moléculaire pour révéler le rôle des domaines C2 des protéines MCTPs impliquées dans la connexion membranaire des plasmodesmes chez les plantes
Publication date :
November 2017
Event name :
GEM XIX: International Conference of "Groupe d'Etude des Membranes"
Event organizer :
Groupe d'Etude des Membranes
Event place :
Roscoff, France
Event date :
du 5 au 8 novembre 2017
Audience :
International
Funders :
F.R.S.-FNRS - Fonds de la Recherche Scientifique [BE] FRIA - Fonds pour la Formation à la Recherche dans l'Industrie et dans l'Agriculture [BE]
Commentary :
References
1. Ding, B., Turgeon, R. & Parthasarathy, M. V. Substructure of freeze-substituted plasmodesmata. Protoplasma 169, 28–41 (1992).
2. Nicolas, W. et al. Architecture and permeability of post-cytokinesis plasmodesmata lacking cytoplasmic sleeve. Nat. Plants 3, 17082 (2017).
3. Pérez-Sancho, J. et al. Stitching organelles: organization and function of specialized membrane contact sites in plants. Trends Cell Biol. 26, 705–717 (2016).
4. Tilsner, J., Nicolas, W., Rosado, A. & Bayer, E. M. Staying Tight: Plasmodesmal Membrane Contact Sites and the Control of Cell-to-Cell Connectivity in Plants. Annu. Rev. Plant Biol. 67, 1–28 (2016).
5. Giordano, F. et al. PI(4,5)P(2)-dependent and Ca(2+)-regulated ER-PM interactions mediated by the extended synaptotagmins. Cell 153, 1494–509 (2013).
6. Pérez-Sancho, J. et al. The Arabidopsis synaptotagmin1 is enriched in endoplasmic reticulum-plasma membrane contact sites and confers cellular resistance to mechanical stresses. Plant Physiol. 168, 132–43 (2015).