Biology subjects

Gutierrez-Beltran, E.

Publications and source records attributed to Gutierrez-Beltran, E..

4 recordsLinked to original sources

bioRxiv2023

Phosphorylation Promotes Liquid-Liquid Phase Separation of GRP8 and Its Assembly into Stress Granules Upon Salinity Stress in Arabidopsis

Drought and salinity are major environmental stresses affecting plant development and growth. SNF1-related protein kinases type 2 (SnRK2s) are key regulators of the plant responses to water deficit and salt stress. Here, we show that Arabidopsis thaliana Glycine-Rich RNA-Binding Protein 8 (GRP8) is a target of abscisic acid (ABA)-non-activated SnRK2s and negatively regulates root growth and seed germination under salt stress. In response to salinity, GRP8 assembles into stress granules (SGs). We show that in addition to the GRP8 C-terminal glycine-rich intrinsically disordered region (IRD), the N-terminal RNA recognition motif (RRM) plays a key role in this process. Phosphorylation of S27 in the RRM by SnRK2s significantly affects the structural dynamics of GRP8, facilitates its dimerization and subsequent liquid-liquid phase separation. Thus, we show that in addition to the known role of IDRs in recruitment into SGs, the RRM plays a decisive role.

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↗

bioRxiv2020

Tudor staphylococcal nuclease acts as a docking platform for stress granule components in Arabidopsis thaliana

Adaptation to stress depends on the modulation of gene expression. Regulation of mRNA stability and degradation in stress granules (SGs), - cytoplasmic membraneless organelles composed of messenger ribonucleoprotein (mRNP) complexes, - plays an important role in fine-tuning of gene expression. In addition, SG formation can modulate stress signaling pathways by protein sequestration. Molecular composition, structure, and function of SGs in plants remain obscure. Recently, we established Tudor Staphylococcal Nuclease (TSN or Tudor-SN; also known as SND1) as integral component of SGs in Arabidopsis thaliana. Here, we combined purification of TSN interactome with cell biology, reverse genetics and bioinformatics to study composition and function of SGs in plants. We found that under both normal (in the absence of stress) and stress conditions TSN interactome is enriched in the homologues of known mammalian and yeast SG proteins, in addition to novel or plant-specific SG components. We estimate that upon stress perception, approximately half of TSN interactors are recruited to SGs de novo, in a stress-dependent manner, while another half represent a dense protein-protein interaction network pre-formed before onset of stress. Almost all TSN-interacting proteins are moderately or highly disordered and approximately 20% of them are predisposed for liquid-liquid phase separation (LLPS). This suggests that plant SGs, similarly to mammalian and yeast counterparts, are multicomponent viscous liquid droplets. Finally, we have discovered that evolutionary conserved SNF1-related protein kinase 1 (SnRK1) interacts with TSN in heat-induced SGs and that SnRK1 activation critically depends on the presence of TSN and formation of SGs. Altogether, our results establish TSN as a docking platform for SG-associated proteins and important stress signal mediator in plants.

plant biology↗