Dataset Information

Multiple C2 domains and Transmembrane region Proteins (MCTPs) tether membranes at plasmodesmata

ABSTRACT: In eukaryotes, membrane contact sites (MCS) allow direct communication between organelles. Plants have evolved unique MCS, the plasmodesmata intercellular pores, which combine organelle tethering with regulation of cell-to-cell signalling, the molecular mechanisms of which remains unknown. Here, we identify Multiple C2 domains and Transmembrane region Proteins (MCTPs) as tethers that link the endoplasmic reticulum (ER) to the plasma membrane (PM) within plasmodesmata. We report that MCTPs, including MCTP3 and 4 recently identified as modulators of SHOOTMERISTEMLESS trafficking, are ER-anchored proteins that cluster at plasmodesmata. MCTPs insert into the ER via their transmembrane region whilst their C2 domains dock to the PM through interaction with anionic phospholipids. A mctp3/4 loss-of function mutant induces plant developmental defects while MCTP4 expression in a yeast .tether mutant partially restores ER-PM tethering. Our data suggest that MCTPs are unique membrane tethers controlling both ER-PM contacts and cell-cell signalling.

INSTRUMENT(S): Orbitrap Fusion

ORGANISM(S): Arabidopsis Thaliana (mouse-ear Cress)

TISSUE(S): Plant Cell, Leaf

SUBMITTER: Max Kraner

LAB HEAD: Max Edmund Kraner

PROVIDER: PXD013999 | Pride | 2019-07-08

REPOSITORIES: Pride

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Publications

Multiple C2 domains and transmembrane region proteins (MCTPs) tether membranes at plasmodesmata.

Brault Marie L ML Petit Jules D JD Immel Françoise F Nicolas William J WJ Glavier Marie M Brocard Lysiane L Gaston Amèlia A Fouché Mathieu M Hawkins Timothy J TJ Crowet Jean-Marc JM Grison Magali S MS Germain Véronique V Rocher Marion M Kraner Max M Alva Vikram V Claverol Stéphane S Paterlini Andrea A Helariutta Ykä Y Deleu Magali M Lins Laurence L Tilsner Jens J Bayer Emmanuelle M EM

EMBO reports 20190709 8

In eukaryotes, membrane contact sites (MCS) allow direct communication between organelles. Plants have evolved a unique type of MCS, inside intercellular pores, the plasmodesmata, where endoplasmic reticulum (ER)-plasma membrane (PM) contacts coincide with regulation of cell-to-cell signalling. The molecular mechanism and function of membrane tethering within plasmodesmata remain unknown. Here, we show that the multiple C2 domains and transmembrane region protein (MCTP) family, key regulators of ...[more]

PMID: 31286648

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Project description:The bundle sheath cells (BSCs) layer – a presumed control point for radial transport of water and solutes between the vasculature and the leaf mesophyll cells (MCs) – is still largely understudied. Using isolated protoplasts, we found that 45% of the 90 genes differentially expressed in BSCs vs. MCs are membrane related and 20% are transport related, suggesting unique functionality of membrane transport in the BSCs, supported also by functional assays (electrophysiology and fluorescence imaging). A tight control of long distance transport is required for the optimization of the hydro-mineral homeostasis of organs in plants under fluctuating ambient conditions. The mechanism of ion selectivity and absorption from the xylem to the leaf is still poorly understood. The bundle sheath (BS), tightly enwrapping the leaf vasculature, has been suggested as a part of this mechanism, acting as a selective barrier which regulates the radial transport of water and solutes from the xylem to leaf cells. This suggestion relies on the anatomy, as well as on the recent physiological transport assays of the BS and its cells (BSCs). We hypothesized that the unique transport functionality of the BSCs is manifested in its transcriptome. To test this, we compared the transcriptomes of individually hand-picked protoplasts of GFP-labeled BSCs and non-labeled mesophyll cells (MCs) of Arabidopsis thaliana leaves. Indeed, in conformation of our hypothesis, 45% of the 90 genes differentially expressed in BSCs vs. MCs are membrane related and 20% are transport related, with the proton-pump AHA2 as a prominent example. Moreover, fluorescence imaging using the potentiometric dye (di-8 ANEPPS) revealed a more negative membrane potential of the BSCs protoplasts compared to those of MCs, and electrophysiological assays (patch-clamp) showed that the major, AKT2-like, membrane K+ conductances of BSCs and MCs had different voltage dependency ranges. Combined, these differences are compatible with an expected possibility of simultaneous but oppositely directed transmembrane K+ fluxes in BSCs and MCs in otherwise similar conditions.

Dataset Information

Multiple C2 domains and Transmembrane region Proteins (MCTPs) tether membranes at plasmodesmata

Publications

Multiple C2 domains and transmembrane region proteins (MCTPs) tether membranes at plasmodesmata.

Similar Datasets

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