Multiple C2 domains and transmembrane region proteins (MCTPs) tether membranes at plasmodesmata.
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ABSTRACT:
SUBMITTER: Brault ML
PROVIDER: S-EPMC6680132 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description: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.
2019-07-08 | PXD013999 | Pride
Project description:BACKGROUND:Multiple C2 domains and transmembrane region proteins (MCTPs) may act as transport mediators of other regulators. Although increased number of MCTPs in higher plants implies their diverse and specific functions in plant growth and development, only a few plant MCTPs have been studied and no study on the MCTPs in cotton has been reported. RESULTS:In this study, we identified 31 MCTPs in G. hirsutum, which were classified into five subfamilies according to the phylogenetic analysis. GhMCTPs from subfamily V exhibited isoelectric points (pIs) less than 7, whereas GhMCTPs from subfamily I, II, III and IV exhibited pIs more than 7.5, implying their distinct biological functions. In addition, GhMCTPs within subfamily III, IV and V exhibited more diverse physicochemical properties, domain architectures and expression patterns than GhMCTPs within subfamily I and II, suggesting that GhMCTPs within subfamily III, IV and V diverged to perform more diverse and specific functions. Analyses of conserved motifs and pIs indicated that the N-terminus was more divergent than the C-terminus and GhMCTPs' functional divergence might be mainly contributed by the N-terminus. Furthermore, yeast two-hybrid assay indicated that the N-terminus was responsible to interact with target proteins. Phylogenetic analysis classified multiple N-terminal C2 domains into four subclades, suggesting that these C2 domains performed different molecular functions in mediating the transport of target proteins. CONCLUSIONS:Our systematic characterization of MCTPs in G. hirsutum will provide helpful information to further research GhMCTPs' molecular roles in mediating other regulators' transport to coordinate growth and development of various cotton tissues.
| S-EPMC7325108 | biostudies-literature
Project description:Background Multiple C2 domain and transmembrane region proteins (MCTPs) are evolutionarily conserved and important signaling molecules. However, the MCTP gene family has not been comprehensively analyzed in maize. Results In this study, 385 MCTP genes were identified in all surveyed 38 species. Moreover, gene duplication mode exploration showed that whole genome duplication (WGD) mainly contributed to the expansion of MCTP genes in angiosperms. Phylogeny reconstruction with all surveyed species by the maximum-likelihood (ML) method showed five clades of MCTPs, Clades I to V. Each clade of MCTPs had conservative structures and motifs. Focusing on maize, 17 MCTPs were identified, and a neighborjoining (NJ) phylogenetic tree with only ZmMCTPs was also constructed. As expected, 17 MCTPs showed similar phylogenetic relationships in the neighbor-joining (NJ) tree with those in the maximum-likelihood (ML) tree and could also be divided into five subclades. Moreover, ZmMCTP members in different clades showed specific gene structure, conserved motif, and domain structure compositions. Intriguingly, most ZmMCTP genes were intronless. Analyses of isoelectric points (pIs) and grand averages of hydropathicity (GRAVYs) indicated that the N-terminus was more dispersive than the C-terminus. Further tissue-specific expression analysis indicated that duplicated ZmMCTP pairs involved in whole genome duplication (WGD) had similar expression trends. Finally, ZmMCTPs were transcriptionally altered under diverse abiotic stresses and hormone treatments. Conclusions Our results contribute to deciphering the evolutionary history of MCTPs in maize and other plants, facilitating further functional analysis of these factors, and provide a basis for further clarification of the molecular mechanism of stress responses. Supplementary Information The online version contains supplementary material available at 10.1186/s12870-022-03771-x.
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Project description:C(2) domains are autonomously folded protein modules that generally act as Ca(2+)- and phospholipid-binding domains and/or as protein-protein interaction domains. We now report the primary structures and biochemical properties of a family of evolutionarily conserved mammalian proteins, referred to as E-Syts, for extended synaptotagmin-like proteins. E-Syts contain an N-terminal transmembrane region, a central juxtamembranous domain that is conserved from yeast to human, and five (E-Syt1) or three (E-Syt2 and E-Syt3) C-terminal C(2) domains. Only the first E-Syt C(2) domain, the C(2)A domain, includes the complete sequence motif that is required for Ca(2+) binding in C(2) domains. Recombinant protein fragments of E-Syt2 that include the first C(2) domain are capable of Ca(2+)-dependent phospholipid binding at micromolar concentrations of free Ca(2+), suggesting that E-Syts bind Ca(2+) through their first C(2) domain in a phospholipid complex. E-Syts are ubiquitously expressed, but enriched in brain. Expression of myc-tagged E-Syt proteins in transfected cells demonstrated localization to intracellular membranes for E-Syt1 and to plasma membranes for E-Syt2 and E-Syt3. Structure/function studies showed that the plasma-membrane localization of E-Syt2 and E-Syt3 was directed by their C-terminal C(2)C domains. This result reveals an unexpected mechanism by which the C(2)C domains of E-Syt2 and E-Syt3 functions as a targeting motif that localizes these proteins into the plasma membrane independent of their transmembrane region. Viewed together, our findings suggest that E-Syts function as Ca(2+)-regulated intrinsic membrane proteins with multiple C(2) domains, expanding the repertoire of such proteins to a fourth class beyond synaptotagmins, ferlins, and MCTPs (multiple C(2) domain and transmembrane region proteins).
| S-EPMC1820668 | biostudies-literature
Project description:Multiple C2 domain and transmembrane region proteins (MCTPs) are a group of evolutionarily conserved proteins and show emerging roles in mediating protein trafficking and signaling transduction. Although, several studies showed that MCTPs play important roles during plant growth and development, their biological functions in cotton remain largely unknown. Here, we identify and characterize 33 GhMCTP genes from upland cotton (Gossypium hirsutum) and reveal the diverse expression patterns of GhMCTPs in various tissues. We also find that GhMCTP7, GhMCTP12, and GhMCTP17 are highly expressed in the main stem apex, suggesting their possible roles in shoot development. Through analyzing different cotton species, we discover plant heights are closely related to the expression levels of GhMCTP7, GhMCTP12, and GhMCTP17. Furthermore, we silence the expression of GhMCTP genes using virus-induced gene silencing (VIGS) system in cotton and find that GhMCTP7, GhMCTP12, and GhMCTP17 play an essential role in shoot meristem development. GhMCTPs interact with GhKNAT1 and GhKNAT2 and regulate meristem development through integrating multiple signal pathways. Taken together, our results demonstrate functional redundancy of GhMCTPs in cotton shoot meristem development and provide a valuable resource to further study various functions of GhMCTPs in plant growth and development.
| S-EPMC8573151 | biostudies-literature
Project description:Lipid droplets (LDs) are neutral lipid-containing organelles enclosed in a single monolayer of phospholipids. LD formation begins with the accumulation of neutral lipids within the bilayer of the endoplasmic reticulum (ER) membrane. It is not known how the sites of formation of nascent LDs in the ER membrane are determined. Here we show that multiple C2 domain-containing transmembrane proteins, MCTP1 and MCTP2, are at sites of LD formation in specialized ER subdomains. We show that the transmembrane domain (TMD) of these proteins is similar to a reticulon homology domain. Like reticulons, these proteins tubulate the ER membrane and favor highly curved regions of the ER. Our data indicate that the MCTP TMDs promote LD biogenesis, increasing LD number. MCTPs colocalize with seipin, a protein involved in LD biogenesis, but form more stable microdomains in the ER. The MCTP C2 domains bind charged lipids and regulate LD size, likely by mediating ER-LD contact sites. Together, our data indicate that MCTPs form microdomains within ER tubules that regulate LD biogenesis, size, and ER-LD contacts. Interestingly, MCTP punctae colocalized with other organelles as well, suggesting that these proteins may play a general role in linking tubular ER to organelle contact sites.
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Project description:Lipids and proteins, as essential components of biological cell membranes, exhibit a significant degree of freedom for different kinds of motions including lateral long-range mobility. Due to their interactions, they not only preserve the cellular membrane but also contribute to many important cellular functions as e.g., signal transport or molecular exchange of the cell with its surrounding. Many of these processes take place on a short time (up to some nanoseconds) and length scale (up to some nanometers) which is perfectly accessible by quasielastic neutron scattering (QENS) experiments and molecular dynamics (MD) simulations. In order to probe the influence of a peptide, a transmembrane sequence of the transferrin receptor (TFRC) protein, on the dynamics of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) large unilamellar vesicles (LUVs) on a nanosecond time scale, high-resolution QENS experiments and complementary MD simulations have been utilized. By using different scattering contrasts in the experiment (chain-deuterated lipids and protonated lipids, respectively), a model could be developed which allows to examine the lipid and peptide dynamics separately. The experimental results revealed a restricted lipid lateral mobility in the presence of the TFRC transmembrane peptides. Also the apparent self-diffusion coefficient of the lateral movement of the peptide molecules could be determined quantitatively for the probed short-time regime. The findings could be confirmed very precisely by MD simulations. Furthermore, the article presents an estimation for the radius of influence of the peptides on the lipid long-range dynamics which could be determined by consistently combining results from experiment and simulation.
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Project description:An enigmatic step in de novo formation of the autophagosome membrane compartment is the expansion of the precursor membrane phagophore, which requires the acquisition of lipids to serve as building blocks. Autophagy-related 2 (ATG2), the rod-shaped protein that tethers phosphatidylinositol 3-phosphate (PI3P)-enriched phagophores to the endoplasmic reticulum (ER), is suggested to be essential for phagophore expansion, but the underlying mechanism remains unclear. Here, we demonstrate that human ATG2A is a lipid transfer protein. ATG2A can extract lipids from membrane vesicles and unload them to other vesicles. Lipid transfer by ATG2A is more efficient between tethered vesicles than between untethered vesicles. The PI3P effectors WIPI4 and WIPI1 associate ATG2A stably to PI3P-containing vesicles, thereby facilitating ATG2A-mediated tethering and lipid transfer between PI3P-containing vesicles and PI3P-free vesicles. Based on these results, we propose that ATG2-mediated transfer of lipids from the ER to the phagophore enables phagophore expansion.
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