Biology subjects

Mentzelopoulou, A.

Publications and source records attributed to Mentzelopoulou, A..

6 recordsLinked to original sources

bioRxiv2024

H+ drives ultra-fast root-to-root responses to wounding

The plant-to-plant communication of damage is vital for plants to mount pre-emptive defensive responses in the face of threats. A variety of threats to the well-being of plants are found below ground; yet how plant roots activate inter-plant communication is largely unclear. Here we demonstrate that a wounded root rapidly releases protons (H+), that travel faster than any other "known" soluble biochemical signal due to a specialised diffusion mechanism. Within seconds after damage, cells in neighbouring unwounded roots sense the acidification and activate tissue-specific Ca2+ damage signalling. In turn, this triggers a differential growth response allowing the unwounded root to avoid the site of a potential threat. Our results reveal a non-canonical rapid response mechanism for inter-plant communication based on ultrafast proton diffusion.

plant biology↗

bioRxiv2023

A Proxitome-RNA-capture Approach Reveals that Processing Bodies Repress Co-Regulated Hubs

Cellular condensates are usually ribonucleoprotein assemblies with liquid- or solid-like properties. Because they lack a delineating membrane, the compositional determination of condensates is laborious. Here we set up a pipeline for proximity-biotinylation-dependent capture of RNA to investigate the RNA composition of the condensate in Arabidopsis known as the processing bodies (PBs). Using this pipeline together with in situ protein-protein interaction and RNA detection, in silico, and high-resolution imaging approaches, we studied PBs under normal and heat stress conditions. The composition of PBs in RNAs is much more dynamic than that of the total transcriptome. RNAs involved in cell wall development and regeneration, hormonal signaling, secondary metabolism/defense, and RNA metabolism were enriched in PBs. RNA binding proteins and liquid-to-solid phase transitions modulated specificity of RNA recruitment in PBs. Surprisingly, RNAs were sometimes recruited together with their encoded proteins. In PBs RNAs follow distinct fates, with small liquid-like PBs modulating RNA decay while larger ones storage. The size and properties of PBs are regulated by the actin polymerization cAMP receptor (SCAR)-WASP family verprolin homologous (WAVE) complex. SCAR/WAVE modulates signaling by shuttling RNAs between PBs and the translational machinery adjusting the ethylene signaling pathway. Heat stress leads to the storage of immunity-related RNAs in PBs by reducing PBs dynamics, suggesting why processes such as immunity malfunction under heat stress. In summary, we provide a method to identify RNAs in condensates which allowed us to reveal a mechanism for RNA fate regulation.

plant biology↗

bioRxiv2022

The Proxitome of Arabidopsis Processing Bodies Reveals a Condensate-Membrane Interface Instructing Actin-Driven Directional Growth

Cellular condensates can comprise membrane-less ribonucleoprotein assemblies with liquid-like properties. These cellular condensates influence various biological outcomes, but their liquidity hampers their isolation and characterization. Here, we investigated the composition of the condensates known as processing bodies (PBs) in the model plant Arabidopsis through a proximity-biotinylation pipeline. Using in situ protein-protein interaction approaches, genetics and high-resolution imaging, we show that PBs comprise networks that interface with membranes. Surprisingly, the conserved component of PBs, DECAPPING PROTEIN 1 (DCP1), can interface with unique plasma membrane subdomains that include cell edges and vertices. We characterized these plasma membrane interfaces and discovered a developmental module that can control cell shape. This module is modulated by the liquid-like properties of DCP1 and the actin-nucleating SCAR-WAVE complex, whereby the DCP1-SCAR-WAVE interaction confines actin nucleation. This study reveals an unexpected repertoire for a conserved condensate at unique membrane-condensate interfaces.

cell biology↗

bioRxiv2022

Phase Separation of a Nodulin Sec14-like protein Maintains Auxin Efflux Carrier Polarity at Arabidopsis Plasma Membranes

Protein function can be modulated by phase transitions in their material properties, which can range from liquid-to solid-like; yet the mechanisms that drive these transitions and whether they are important for physiology are still unknown. Using the model plant Arabidopsis, we show that developmental robustness is reinforced by phase transitions of the plasma membrane-bound lipid-binding protein SEC14-like. Using imaging, genetics, and in vitro reconstitution experiments, we show that SEC14-like undergoes liquid-like phase separation in the root stem cells. Outside the stem cell niche, SEC14-like associates with the caspase-like protease separase and conserved microtubule motors at unique polar plasma membrane interfaces. In these interfaces, SEC14-like undergoes abrupt processing by separase, which promotes its liquid-to-solid transition. The SEC14-like liquid-to-solid transition is important for root developmental robustness, as lines expressing an uncleavable SEC14-like variant or mutants of separase, and associated microtubule motors show similar developmental phenotypes. Furthermore, the processed and solidified but not the liquid form of SEC14-like interacts with the polar protein PINFORMED2 at the plasma membrane and perhaps other polar proteins of the PINFORMED family. This work demonstrates that robust development can involve abrupt liquid-to-solid transitions mediated by proteolysis at unique plasma membrane interfaces.

cell biology↗

bioRxiv2021

Assassination Tango: An NLR/NLR-ID immune receptors pair of rapeseed co-operates inside the nucleus to activate cell death

Plant immunity relies on cell-surface receptors and intracellular NLR immune receptors. Some plant NLRs carry integrated domains (IDs) that that mimic authentic pathogens effector targets. We report here the identification in Brassica napus of the genetically linked NLR/NLR-ID pair, BnRPR1 and BnRPR2. The NLR-ID carries two ID fusions and their mode of action conforms to the proposed "integrated sensor/decoy" model. The two NLRs interact and the heterocomplex localizes in the plant-cell nucleus and nucleolus. However, the BnRPRs pair does not operate through a negative regulation as it was previously reported for other NLR-IDs. Cell death is induced only upon co-expression of the two proteins and it is dependent on the helper genes EDS1 and NRG1. Truncations of the IDs of BnRPR1 results in cytoplasmic localization and compromises cell death activation. Expression, using the native promoter in Nicotiana species, led to a conditional cell death induction. However, this was not the case for the transgenic Arabidopsis, where no cell death was observed. In summary, we describe a new pair of NLR-IDs with interesting features in relation to its regulation and the cell death activation.

immunology↗

bioRxiv2020

Protein Detection and Localization in Plant Cells Using Spot-Tagging

Fluorescent labelling of proteins without compromising their activity is crucial for determining their spatiotemporal localization while retaining their functionality. Spot-tag is a 12-amino acid peptide recognized by a single-domain nanobody. Here we introduce the spot-tag as a labelling strategy for proteins in fixed and living plant cells, using as an example the microtubule motor centromeric protein E-related Kinesin 7.3. Spot-tagging of ectopically introduced Kinesin 7.3 does not interfere with microtubules and spot staining results in a close-grained fluorophore labelling revealing a localization pattern that resembles "beads-on-a-string". We anticipate that our protocol will apply to many more demanding protein cellular targets, offsetting activity perturbations and low photon quantum yields imposed by other protein-tagging approaches.

plant biology↗