RESUMEN
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 thaliana through a proximity-biotinylation proteomics approach. Using in situ protein-protein interaction approaches, genetics and high-resolution dynamic imaging, we show that processing bodies comprise networks that interface with membranes. Surprisingly, the conserved component of PBs, DECAPPING PROTEIN 1 (DCP1), can localize to unique plasma membrane subdomains including cell edges and vertices. We characterized these plasma membrane interfaces and discovered a developmental module that can control cell shape. This module is regulated by DCP1, independently from its role in decapping, and the actin-nucleating SCAR-WAVE complex, whereby the DCP1-SCAR-WAVE interaction confines and enhances actin nucleation. This study reveals an unexpected function for a conserved condensate at unique membrane interfaces.
Asunto(s)
Actinas , Proteínas de Arabidopsis , Arabidopsis , Complejo 2-3 Proteico Relacionado con la Actina/metabolismo , Actinas/metabolismo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Cuerpos de ProcesamientoRESUMEN
Cellular condensates are usually ribonucleoprotein assemblies with liquid- or solid-like properties. Because these subcellular structures lack a delineating membrane, determining their compositions is difficult. Here we describe a proximity-biotinylation approach for capturing the RNAs of the condensates known as processing bodies (PBs) in Arabidopsis (Arabidopsis thaliana). By combining this approach with RNA detection, in silico, and high-resolution imaging approaches, we studied PBs under normal conditions and heat stress. PBs showed a much more dynamic RNA composition than the total transcriptome. RNAs involved in cell wall development and regeneration, plant hormonal signaling, secondary metabolism/defense, and RNA metabolism were enriched in PBs. RNA-binding proteins and the liquidity of PBs modulated RNA recruitment, while RNAs were frequently recruited together with their encoded proteins. In PBs, RNAs follow distinct fates: in small liquid-like PBs, RNAs get degraded while in more solid-like larger ones, they are stored. PB properties can be regulated by the actin-polymerizing SCAR (suppressor of the cyclic AMP)-WAVE (WASP family verprolin homologous) complex. SCAR/WAVE modulates the shuttling of RNAs between PBs and the translational machinery, thereby adjusting ethylene signaling. In summary, we provide an approach to identify RNAs in condensates that allowed us to reveal a mechanism for regulating RNA fate.
Asunto(s)
Arabidopsis , ARN , Cuerpos de Procesamiento , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo , Respuesta al Choque Térmico , Arabidopsis/genética , Arabidopsis/metabolismoRESUMEN
Biomolecular condensates are membraneless organelle-like structures that can concentrate molecules and often form through liquid-liquid phase separation. Biomolecular condensate assembly is tightly regulated by developmental and environmental cues. Although research on biomolecular condensates has intensified in the past 10 years, our current understanding of the molecular mechanisms and components underlying their formation remains in its infancy, especially in plants. However, recent studies have shown that the formation of biomolecular condensates may be central to plant acclimation to stress conditions. Here, we describe the mechanism, regulation, and properties of stress-related condensates in plants, focusing on stress granules and processing bodies, 2 of the most well-characterized biomolecular condensates. In this regard, we showcase the proteomes of stress granules and processing bodies in an attempt to suggest methods for elucidating the composition and function of biomolecular condensates. Finally, we discuss how biomolecular condensates modulate stress responses and how they might be used as targets for biotechnological efforts to improve stress tolerance.
Asunto(s)
Condensados Biomoleculares , ProteomaRESUMEN
Stress granules (SGs) are highly conserved cytoplasmic condensates that assemble in response to stress and contribute to maintaining protein homeostasis. These membraneless organelles are dynamic, disassembling once the stress is no longer present. Persistence of SGs due to mutations or chronic stress has been often related to age-dependent protein-misfolding diseases in animals. Here, we find that the metacaspase MC1 is dynamically recruited into SGs upon proteotoxic stress in Arabidopsis (Arabidopsis thaliana). Two predicted disordered regions, the prodomain and the 360 loop, mediate MC1 recruitment to and release from SGs. Importantly, we show that MC1 has the capacity to clear toxic protein aggregates in vivo and in vitro, acting as a disaggregase. Finally, we demonstrate that overexpressing MC1 delays senescence and this phenotype is dependent on the presence of the 360 loop and an intact catalytic domain. Together, our data indicate that MC1 regulates senescence through its recruitment into SGs and this function could potentially be linked to its remarkable protein aggregate-clearing activity.
Asunto(s)
Arabidopsis , Animales , Arabidopsis/genética , Arabidopsis/metabolismo , Agregado de Proteínas , Gránulos de Estrés , Gránulos Citoplasmáticos/metabolismo , Estrés FisiológicoRESUMEN
Tudor staphylococcal nuclease (TSN; also known as Tudor-SN, p100, or SND1) is a multifunctional, evolutionarily conserved regulator of gene expression, exhibiting cytoprotective activity in animals and plants and oncogenic activity in mammals. During stress, TSN stably associates with stress granules (SGs), in a poorly understood process. Here, we show that in the model plant Arabidopsis thaliana, TSN is an intrinsically disordered protein (IDP) acting as a scaffold for a large pool of other IDPs, enriched for conserved stress granule components as well as novel or plant-specific SG-localized proteins. While approximately 30% of TSN interactors are recruited to stress granules de novo upon stress perception, 70% form a protein-protein interaction network present before the onset of stress. Finally, we demonstrate that TSN and stress granule formation promote heat-induced activation of the evolutionarily conserved energy-sensing SNF1-related protein kinase 1 (SnRK1), the plant orthologue of mammalian AMP-activated protein kinase (AMPK). Our results establish TSN as a docking platform for stress granule proteins, with an important role in stress signalling.
Asunto(s)
Gránulos Citoplasmáticos/metabolismo , Proteínas Intrínsecamente Desordenadas/metabolismo , Mapas de Interacción de Proteínas , Arabidopsis , Proteínas de Arabidopsis/metabolismo , Sitios de Unión , Respuesta al Choque Térmico , Proteínas Intrínsecamente Desordenadas/química , Unión Proteica , Proteínas Serina-Treonina Quinasas/metabolismoAsunto(s)
Caspasas/clasificación , Proteína 1 de la Translocación del Linfoma del Tejido Linfático Asociado a Mucosas/clasificación , Proteínas de Plantas/clasificación , Terminología como Asunto , Animales , Caspasas/química , Caspasas/metabolismo , Consenso , Humanos , Proteína 1 de la Translocación del Linfoma del Tejido Linfático Asociado a Mucosas/química , Proteína 1 de la Translocación del Linfoma del Tejido Linfático Asociado a Mucosas/metabolismo , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Conformación Proteica , Relación Estructura-ActividadRESUMEN
Autophagy is a catabolic pathway capable of degrading cellular components ranging from individual molecules to organelles. Autophagy helps cells cope with stress by removing superfluous or hazardous material. In a previous work, we demonstrated that transcriptional upregulation of two autophagy-related genes, ATG5 and ATG7, in Arabidopsis thaliana positively affected agronomically important traits: biomass, seed yield, tolerance to pathogens and oxidative stress. Although the occurrence of these traits correlated with enhanced autophagic activity, it is possible that autophagy-independent roles of ATG5 and ATG7 also contributed to the phenotypes. In this study, we employed affinity purification and LC-MS/MS to identify the interactome of wild-type ATG5 and its autophagy-inactive substitution mutant, ATG5K128R Here we present the first interactome of plant ATG5, encompassing not only known autophagy regulators but also stress-response factors, components of the ubiquitin-proteasome system, proteins involved in endomembrane trafficking, and potential partners of the nuclear fraction of ATG5. Furthermore, we discovered post-translational modifications, such as phosphorylation and acetylation present on ATG5 complex components that are likely to play regulatory functions. These results strongly indicate that plant ATG5 complex proteins have roles beyond autophagy itself, opening avenues for further investigations on the complex roles of autophagy in plant growth and stress responses.
Asunto(s)
Arabidopsis , Proteína 5 Relacionada con la Autofagia , Arabidopsis/metabolismo , Autofagia/genética , Proteína 5 Relacionada con la Autofagia/genética , Proteína 5 Relacionada con la Autofagia/metabolismo , Cromatografía Liquida , Espectrometría de Masas en TándemRESUMEN
SNF1-related protein kinase 1 (SnRK1), the plant ortholog of mammalian AMP-activated protein kinase/fungal (yeast) Sucrose Non-Fermenting 1 (AMPK/SNF1), plays a central role in metabolic responses to reduced energy levels in response to nutritional and environmental stresses. SnRK1 functions as a heterotrimeric complex composed of a catalytic α- and regulatory ß- and ßγ-subunits. SnRK1 is a multitasking protein involved in regulating various cellular functions, including growth, autophagy, stress response, stomatal development, pollen maturation, hormone signaling, and gene expression. However, little is known about the mechanism whereby SnRK1 ensures differential execution of downstream functions. Compartmentalization has been recently proposed as a new key mechanism for regulating SnRK1 signaling in response to stimuli. In this review, we discuss the multitasking role of SnRK1 signaling associated with different subcellular compartments.
Asunto(s)
Proteínas Quinasas Activadas por AMP , Proteínas de Arabidopsis , Animales , Proteínas Quinasas Activadas por AMP/metabolismo , Estrés Fisiológico , Transducción de Señal , Saccharomyces cerevisiae/metabolismo , Plantas/genética , Plantas/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Mamíferos/metabolismoRESUMEN
Factors regulating dynamics of chromatin structure have direct impact on expression of genetic information. Cohesin is a multi-subunit protein complex that is crucial for pairing sister chromatids during cell division, DNA repair and regulation of gene transcription and silencing. In non-plant species, cohesin is loaded on chromatin by the Scc2-Scc4 complex (also known as the NIBPL-MAU2 complex). Here, we identify the Arabidopsis homolog of Scc4, which we denote Arabidopsis thaliana (At)SCC4, and show that it forms a functional complex with AtSCC2, the homolog of Scc2. We demonstrate that AtSCC2 and AtSCC4 act in the same pathway, and that both proteins are indispensable for cell fate determination during early stages of embryo development. Mutant embryos lacking either of these proteins develop only up to the globular stage, and show the suspensor overproliferation phenotype preceded by ectopic auxin maxima distribution. We further establish a new assay to reveal the AtSCC4-dependent dynamics of cohesin loading on chromatin in vivo Our findings define the Scc2-Scc4 complex as an evolutionary conserved machinery controlling cohesin loading and chromatin structure maintenance, and provide new insight into the plant-specific role of this complex in controlling cell fate during embryogenesis.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/embriología , Arabidopsis/metabolismo , Proteínas Portadoras/metabolismo , Homología de Secuencia de Aminoácido , Secuencia de Aminoácidos , Arabidopsis/citología , Arabidopsis/genética , Proteínas de Arabidopsis/química , Proteínas Portadoras/química , Proteínas de Ciclo Celular/metabolismo , Linaje de la Célula , Núcleo Celular/metabolismo , Proliferación Celular , Cromatina/metabolismo , Proteínas Cromosómicas no Histona/metabolismo , ADN Bacteriano/genética , Fase G1 , Proteínas Fluorescentes Verdes/metabolismo , Mutación/genética , Fenotipo , Raíces de Plantas/citología , Raíces de Plantas/metabolismo , Unión Proteica , Dominios Proteicos , Semillas/embriología , Semillas/metabolismo , CohesinasRESUMEN
2',3'-cAMP is an intriguing small molecule that is conserved among different kingdoms. 2',3'-cAMP is presumably produced during RNA degradation, with increased cellular levels observed especially under stress conditions. Previously, we observed the presence of 2',3'-cAMP in Arabidopsis (Arabidopsis thaliana) protein complexes isolated from native lysate, suggesting that 2',3'-cAMP has potential protein partners in plants. Here, affinity purification experiments revealed that 2',3'-cAMP associates with the stress granule (SG) proteome. SGs are aggregates composed of protein and mRNA, which enable cells to selectively store mRNA for use in response to stress such as heat whereby translation initiation is impaired. Using size-exclusion chromatography and affinity purification analyses, we identified Rbp47b, the key component of SGs, as a potential interacting partner of 2',3'-cAMP. Furthermore, SG formation was promoted in 2',3'-cAMP-treated Arabidopsis seedlings, and interactions between 2',3'-cAMP and RNA-binding domains of Rbp47b, RRM2 and RRM3, were confirmed in vitro using microscale thermophoresis. Taken together, these results (1) describe novel small-molecule regulation of SG formation, (2) provide evidence for the biological role of 2',3'-cAMP, and (3) demonstrate an original biochemical pipeline for the identification of protein-metabolite interactors.
Asunto(s)
Nucleótidos de Adenina/metabolismo , Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Gránulos Citoplasmáticos/metabolismo , Proteínas de Unión a Poli(A)/metabolismo , Estrés Fisiológico , Proteínas de Arabidopsis/química , Cromatografía de Afinidad , Modelos Biológicos , Proteínas de Unión a Poli(A)/química , Unión Proteica , Dominios ProteicosRESUMEN
Calcineurin B-like interacting protein kinases (CIPKs) decode calcium signals upon interaction with the calcium sensors calcineurin B like proteins into phosphorylation events that result into adaptation to environmental stresses. Few phosphorylation targets of CIPKs are known and therefore the molecular mechanisms underlying their downstream output responses are not fully understood. Tomato (Solanum lycopersicum) Cipk6 regulates immune and susceptible Programmed cell death in immunity transforming Ca2+ signals into reactive oxygen species (ROS) signaling. To investigate SlCipk6-induced molecular mechanisms and identify putative substrates, a yeast two-hybrid approach was carried on and a protein was identified that contained a Universal stress protein (Usp) domain present in bacteria, protozoa and plants, which we named "SlRd2". SlRd2 was an ATP-binding protein that formed homodimers in planta. SlCipk6 and SlRd2 interacted using coimmunoprecipitation and bimolecular fluorescence complementation (BiFC) assays in Nicotiana benthamiana leaves and the complex localized in the cytosol. SlCipk6 phosphorylated SlRd2 in vitro, thus defining, to our knowledge, a novel target for CIPKs. Heterologous SlRd2 overexpression in yeast conferred resistance to highly toxic LiCl, whereas SlRd2 expression in Escherichia coli UspA mutant restored bacterial viability in response to H2O2 treatment. Finally, transient expression of SlCipk6 in transgenic N benthamiana SlRd2 overexpressors resulted in reduced ROS accumulation as compared to wild-type plants. Taken together, our results establish that SlRd2, a tomato UspA, is, to our knowledge, a novel interactor and phosphorylation target of a member of the CIPK family, SlCipk6, and functionally regulates SlCipk6-mediated ROS generation.
Asunto(s)
Proteínas de Plantas/metabolismo , Proteínas Quinasas/metabolismo , Solanum lycopersicum/fisiología , Adenosina Trifosfato/metabolismo , Escherichia coli/genética , Regulación de la Expresión Génica de las Plantas , Cloruro de Litio/farmacología , Solanum lycopersicum/efectos de los fármacos , Solanum lycopersicum/metabolismo , Estrés Oxidativo/fisiología , Fosforilación , Proteínas de Plantas/genética , Plantas Modificadas Genéticamente , Mapeo de Interacción de Proteínas , Proteínas Quinasas/genética , Especies Reactivas de Oxígeno/metabolismo , Estrés Fisiológico/fisiología , Nicotiana/genética , Nicotiana/metabolismo , Técnicas del Sistema de Dos HíbridosRESUMEN
Tudor Staphylococcal Nuclease (TSN or Tudor-SN; also known as SND1) is an evolutionarily conserved protein involved in the transcriptional and posttranscriptional regulation of gene expression in animals. Although TSN was found to be indispensable for normal plant development and stress tolerance, the molecular mechanisms underlying these functions remain elusive. Here, we show that Arabidopsis thaliana TSN is essential for the integrity and function of cytoplasmic messenger ribonucleoprotein (mRNP) complexes called stress granules (SGs) and processing bodies (PBs), sites of posttranscriptional gene regulation during stress. TSN associates with SGs following their microtubule-dependent assembly and plays a scaffolding role in both SGs and PBs. The enzymatically active tandem repeat of four SN domains is crucial for targeting TSN to the cytoplasmic mRNA complexes and is sufficient for the cytoprotective function of TSN during stress. Furthermore, our work connects the cytoprotective function of TSN with its positive role in stress-induced mRNA decapping. While stress led to a pronounced increase in the accumulation of uncapped mRNAs in wild-type plants, this increase was abrogated in TSN knockout plants. Taken together, our results establish TSN as a key enzymatic component of the catabolic machinery responsible for the processing of mRNAs in the cytoplasmic mRNP complexes during stress.
Asunto(s)
Arabidopsis/metabolismo , Gránulos Citoplasmáticos/metabolismo , Nucleasa Microcócica/metabolismo , Procesamiento Postranscripcional del ARN , Estrés Fisiológico , Adaptación Fisiológica , Proteínas de Arabidopsis/metabolismo , Respuesta al Choque Térmico , Cinética , Meristema/citología , Meristema/metabolismo , Nucleasa Microcócica/química , Microtúbulos/metabolismo , Estructura Terciaria de Proteína , Transporte de Proteínas , Caperuzas de ARN/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Estrés Fisiológico/genéticaRESUMEN
The caspase-related protease separase (EXTRA SPINDLE POLES, ESP) plays a major role in chromatid disjunction and cell expansion in Arabidopsis thaliana. Whether the expansion phenotypes are linked to defects in cell division in Arabidopsis ESP mutants remains elusive. Here we present the identification, cloning and characterization of the gymnosperm Norway spruce (Picea abies, Pa) ESP. We used the P. abies somatic embryo system and a combination of reverse genetics and microscopy to explore the roles of Pa ESP during embryogenesis. Pa ESP was expressed in the proliferating embryonal mass, while it was absent in the suspensor cells. Pa ESP associated with kinetochore microtubules in metaphase and then with anaphase spindle midzone. During cytokinesis, it localized on the phragmoplast microtubules and on the cell plate. Pa ESP deficiency perturbed anisotropic expansion and reduced mitotic divisions in cotyledonary embryos. Furthermore, whilst Pa ESP can rescue the chromatid nondisjunction phenotype of Arabidopsis ESP mutants, it cannot rescue anisotropic cell expansion. Our data demonstrate that the roles of ESP in daughter chromatid separation and cell expansion are conserved between gymnosperms and angiosperms. However, the mechanisms of ESP-mediated regulation of cell expansion seem to be lineage-specific.
Asunto(s)
Anafase , Picea/citología , Picea/enzimología , Proteínas de Plantas/metabolismo , Semillas/citología , Semillas/enzimología , Separasa/metabolismo , Secuencia de Aminoácidos , Anisotropía , Proliferación Celular , Cromosomas de las Plantas/genética , Clonación Molecular , Citocinesis , Regulación del Desarrollo de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Técnicas de Silenciamiento del Gen , Microtúbulos/metabolismo , Filogenia , Picea/embriología , Transporte de Proteínas , Semillas/embriología , Análisis de Secuencia de ProteínaRESUMEN
Ca(2+) signaling is an early and necessary event in plant immunity. The tomato (Solanum lycopersicum) kinase Pto triggers localized programmed cell death (PCD) upon recognition of Pseudomonas syringae effectors AvrPto or AvrPtoB. In a virus-induced gene silencing screen in Nicotiana benthamiana, we independently identified two components of a Ca(2+)-signaling system, Cbl10 (for calcineurin B-like protein) and Cipk6 (for calcineurin B-like interacting protein kinase), as their silencing inhibited Pto/AvrPto-elicited PCD. N. benthamiana Cbl10 and Cipk6 are also required for PCD triggered by other plant resistance genes and virus, oomycete, and nematode effectors and for host susceptibility to two P. syringae pathogens. Tomato Cipk6 interacts with Cbl10 and its in vitro kinase activity is enhanced in the presence of Cbl10 and Ca(2+), suggesting that tomato Cbl10 and Cipk6 constitute a Ca(2+)-regulated signaling module. Overexpression of tomato Cipk6 in N. benthamiana leaves causes accumulation of reactive oxygen species (ROS), which requires the respiratory burst homolog RbohB. Tomato Cbl10 and Cipk6 interact with RbohB at the plasma membrane. Finally, Cbl10 and Cipk6 contribute to ROS generated during effector-triggered immunity in the interaction of P. syringae pv tomato DC3000 and N. benthamiana. We identify a role for the Cbl/Cipk signaling module in PCD, establishing a mechanistic link between Ca(2+) and ROS signaling in plant immunity.
Asunto(s)
Inmunidad de la Planta/fisiología , Proteínas de Plantas/metabolismo , Transducción de Señal/fisiología , Solanum lycopersicum/metabolismo , Secuencia de Aminoácidos , Apoptosis/genética , Apoptosis/fisiología , Calcio/metabolismo , Calcio/farmacología , Membrana Celular/metabolismo , Técnicas de Silenciamiento del Gen , Interacciones Huésped-Patógeno , Immunoblotting , Solanum lycopersicum/genética , Solanum lycopersicum/microbiología , Microscopía Confocal , Datos de Secuencia Molecular , Filogenia , Inmunidad de la Planta/efectos de los fármacos , Inmunidad de la Planta/genética , Proteínas de Plantas/clasificación , Proteínas de Plantas/genética , Plantas Modificadas Genéticamente , Unión Proteica/efectos de los fármacos , Pseudomonas syringae/fisiología , Especies Reactivas de Oxígeno/metabolismo , Homología de Secuencia de Aminoácido , Transducción de Señal/efectos de los fármacos , Transducción de Señal/genética , Nicotiana/genética , Nicotiana/metabolismo , Nicotiana/microbiologíaRESUMEN
Stress granules (SGs) are conserved cytoplasmic biomolecular condensates mainly formed by proteins and RNA molecules assembled by liquid-liquid phase separation. Isolation of SGs components has been a major challenge in the field due to the dynamic and transient nature of stress granule shells. Here, we describe the methodology for the isolation and visualization of SGs proteins from Arabidopsis thaliana plants using a scaffold component as the target. The protocol consists of the first immunoprecipitation of GFP-tagged scaffold protein, followed by an on-beads enzymatic digestion and previous mass spectrometry identification. Finally, the localization of selected SGs candidates is visualized in Nicotiana benthamiana mesophyll protoplasts.
Asunto(s)
Arabidopsis , Gránulos Citoplasmáticos , Estrés Fisiológico , Arabidopsis/metabolismo , Gránulos Citoplasmáticos/metabolismo , Gránulos Citoplasmáticos/química , Proteínas de Arabidopsis/metabolismo , Protoplastos/metabolismo , Nicotiana/metabolismo , Inmunoprecipitación/métodos , Espectrometría de Masas/métodosRESUMEN
To survive extreme desiccation, seeds enter a period of quiescence that can last millennia. Seed quiescence involves the accumulation of protective storage proteins and lipids through unknown adjustments in protein homeostasis (proteostasis). Here, we show that mutation of all six type-II metacaspase (MCA-II) proteases in Arabidopsis thaliana disturbs proteostasis in seeds. MCA-II mutant seeds fail to restrict the AAA ATPase CELL DIVISION CYCLE 48 (CDC48) at the endoplasmic reticulum to discard misfolded proteins, compromising seed storability. Endoplasmic reticulum (ER) localization of CDC48 relies on the MCA-IIs-dependent cleavage of PUX10 (ubiquitination regulatory X domain-containing 10), the adaptor protein responsible for titrating CDC48 to lipid droplets. PUX10 cleavage enables the shuttling of CDC48 between lipid droplets and the ER, providing an important regulatory mechanism sustaining spatiotemporal proteolysis, lipid droplet dynamics, and protein homeostasis. In turn, the removal of the PUX10 adaptor in MCA-II mutant seeds partially restores proteostasis, CDC48 localization, and lipid droplet dynamics prolonging seed lifespan. Taken together, we uncover a proteolytic module conferring seed longevity.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Retículo Endoplásmico , Gotas Lipídicas , Mutación , Semillas , Proteína que Contiene Valosina , Arabidopsis/genética , Arabidopsis/metabolismo , Semillas/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Retículo Endoplásmico/metabolismo , Proteína que Contiene Valosina/metabolismo , Proteína que Contiene Valosina/genética , Gotas Lipídicas/metabolismo , Proteostasis , Proteolisis , Regulación de la Expresión Génica de las Plantas , Longevidad/fisiología , Longevidad/genéticaRESUMEN
Phenolic acids (PAs) secreted by donor plants suppress the growth of their susceptible plant neighbours. However, how structurally diverse ensembles of PAs are perceived by plants to mediate interspecific competition remains a mystery. Here we show that a plant stress granule (SG) marker, RNA-BINDING PROTEIN 47B (RBP47B), is a sensor of PAs in Arabidopsis. PAs, including salicylic acid, 4-hydroxybenzoic acid, protocatechuic acid and so on, directly bind RBP47B, promote its phase separation and trigger SG formation accompanied by global translation inhibition. Salicylic acid-induced global translation inhibition depends on RBP47 family members. RBP47s regulate the proteome rather than the absolute quantity of SG. The rbp47 quadruple mutant shows a reduced sensitivity to the inhibitory effect of the PA mixture as well as to that of PA-rich rice when tested in a co-culturing ecosystem. In this Article, we identified the long sought-after PA sensor as RBP47B and illustrated that PA-induced SG-mediated translational inhibition was one of the PA perception mechanisms.
Asunto(s)
Arabidopsis , Ecosistema , Arabidopsis/genética , Ecología , SalicilatosRESUMEN
Microtubules play an essential role in breaking cellular symmetry. We have previously shown that separase associates with microtubules and regulates microtubule-dependent establishment of cell polarity in Arabidopsis. However, separase lacks microtubule-binding activity, raising questions about mechanisms underlying this phenomenon. Here we report that the N-terminal non-catalytic domain of separase binds to the C-terminal tail domain of three homologs of the centromeric protein CENP-E Kinesin 7 (Kin7). Conformational changes of Kin7 induced upon binding to separase facilitate recruitment of Kin7/separase complex (KISC) onto microtubules. KISC operates independently of proteolytic activity of separase in promoting microtubule rescue and pauses, as well as in suppressing catastrophes. Genetic complementation experiments in conditional separase mutant rsw4 background demonstrate the importance of KISC for the establishment of cell polarity and for plant development. Our study establishes a mechanism governing microtubule dynamics via the separase-dependent activation of CENP-E-related kinesins.