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1.
Nat Commun ; 12(1): 4194, 2021 07 07.
Artigo em Inglês | MEDLINE | ID: mdl-34234144

RESUMO

Photomorphogenesis, light-mediated development, is an essential feature of all terrestrial plants. While chloroplast development and brassinosteroid (BR) signaling are known players in photomorphogenesis, proteins that regulate both pathways have yet to be identified. Here we report that DE-ETIOLATION IN THE DARK AND YELLOWING IN THE LIGHT (DAY), a membrane protein containing DnaJ-like domain, plays a dual-role in photomorphogenesis by stabilizing the BR receptor, BRI1, as well as a key enzyme in chlorophyll biosynthesis, POR. DAY localizes to both the endomembrane and chloroplasts via its first transmembrane domain and chloroplast transit peptide, respectively, and interacts with BRI1 and POR in their respective subcellular compartments. Using genetic analysis, we show that DAY acts independently on BR signaling and chlorophyll biogenesis. Collectively, this work uncovers DAY as a factor that simultaneously regulates BR signaling and chloroplast development, revealing a key regulator of photomorphogenesis that acts across cell compartments.


Assuntos
Proteínas de Arabidopsis/metabolismo , Proteínas de Choque Térmico HSP40/metabolismo , Proteínas de Membrana/metabolismo , Morfogênese/fisiologia , Proteínas Quinases/metabolismo , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Brassinosteroides/metabolismo , Clorofila/biossíntese , Cloroplastos/metabolismo , Estiolamento/fisiologia , Regulação da Expressão Gênica de Plantas/fisiologia , Técnicas de Silenciamento de Genes , Proteínas de Choque Térmico HSP40/genética , Proteínas de Choque Térmico HSP40/isolamento & purificação , Luz , Proteínas de Membrana/genética , Proteínas de Membrana/isolamento & purificação , Proteínas Associadas aos Microtúbulos/genética , Proteínas Associadas aos Microtúbulos/metabolismo , Morfogênese/efeitos da radiação , Mutação , Plantas Geneticamente Modificadas , Proteínas Quinases/genética , RNA-Seq , Proteínas Recombinantes/genética , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Plântula/crescimento & desenvolvimento , Transdução de Sinais/fisiologia
2.
Curr Opin Plant Biol ; 62: 102044, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33979769

RESUMO

The detection of molecular signals derived from other organisms is central to the evolutionary success of plants in the colonization of Earth. The sensory coding of these signals is critical for marshaling local and systemic immune responses that keep most invading organisms at bay. Plants detect immune signals inside and outside their cells using receptors. Here, we focus on receptors that function at the cell surface. We present recent work that expands our understanding of the repertoire of immune signals sensed by this family of receptors.


Assuntos
Plantas , Receptores de Reconhecimento de Padrão , Imunidade Vegetal/genética , Plantas/genética
3.
Nat Plants ; 7(5): 587-597, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-34007035

RESUMO

Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is a low-abundance membrane lipid essential for plasma membrane function1,2. In plants, mutations in phosphatidylinositol 4-phosphate (PI4P) 5-kinases (PIP5K) suggest that PI(4,5)P2 production is involved in development, immunity and reproduction3-5. However, phospholipid synthesis is highly intricate6. It is thus likely that steady-state depletion of PI(4,5)P2 triggers confounding indirect effects. Furthermore, inducible tools available in plants allow PI(4,5)P2 to increase7-9 but not decrease, and no PIP5K inhibitors are available. Here, we introduce iDePP (inducible depletion of PI(4,5)P2 in plants), a system for the inducible and tunable depletion of PI(4,5)P2 in plants in less than three hours. Using this strategy, we confirm that PI(4,5)P2 is critical for various aspects of plant development, including root growth, root-hair elongation and organ initiation. We show that PI(4,5)P2 is required to recruit various endocytic proteins, including AP2-µ, to the plasma membrane, and thus to regulate clathrin-mediated endocytosis. Finally, we find that inducible PI(4,5)P2 perturbation impacts the dynamics of the actin cytoskeleton as well as microtubule anisotropy. Together, we propose that iDePP is a simple and efficient genetic tool to test the importance of PI(4,5)P2 in given cellular or developmental responses, and also to evaluate the importance of this lipid in protein localization.


Assuntos
Arabidopsis/metabolismo , Fosfatidilinositol 4,5-Difosfato/metabolismo , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Membrana Celular/metabolismo , Citoesqueleto/metabolismo , Proteínas de Drosophila/genética , Inositol Polifosfato 5-Fosfatases/genética , Fosfatidilinositol 4,5-Difosfato/fisiologia , Fosfolipídeos/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Plantas Geneticamente Modificadas
4.
Cell Host Microbe ; 29(4): 620-634.e9, 2021 04 14.
Artigo em Inglês | MEDLINE | ID: mdl-33713601

RESUMO

Immune systems respond to "non-self" molecules termed microbe-associated molecular patterns (MAMPs). Microbial genes encoding MAMPs have adaptive functions and are thus evolutionarily conserved. In the presence of a host, these genes are maladaptive and drive antagonistic pleiotropy (AP) because they promote microbe elimination by activating immune responses. The role AP plays in balancing the functionality of MAMP-coding genes against their immunogenicity is unknown. To address this, we focused on an epitope of flagellin that triggers antibacterial immunity in plants. Flagellin is conserved because it enables motility. Here, we decode the immunogenic and motility profiles of this flagellin epitope and determine the spectrum of amino acid mutations that drives AP. We discover two synthetic mutational tracks that undermine the detection activities of a plant flagellin receptor. These tracks generate epitopes with either antagonist or weaker agonist activities. Finally, we find signatures of these tracks layered atop each other in natural Pseudomonads.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/imunologia , Epitopos/genética , Flagelina/genética , Imunidade , Doenças das Plantas
5.
Cell Host Microbe ; 29(4): 635-649.e9, 2021 04 14.
Artigo em Inglês | MEDLINE | ID: mdl-33713602

RESUMO

Immune systems restrict microbial pathogens by identifying "non-self" molecules called microbe-associated molecular patterns (MAMPs). It is unclear how immune responses are tuned to or by MAMP diversity present in commensal microbiota. We systematically studied the variability of commensal peptide derivatives of flagellin (flg22), a MAMP detected by plants. We define substantial functional diversity. Most flg22 peptides evade recognition, while others contribute to evasion by manipulating immunity through antagonism and signal modulation. We establish a paradigm of signal integration, wherein the sequential signaling outputs of the flagellin receptor are separable and allow for reprogramming by commensal-derived flg22 epitope variants. Plant-associated communities are enriched for immune evading flg22 epitopes, but upon physiological stress that represses the immune system, immune-activating flg22 epitopes become enriched. The existence of immune-manipulating epitopes suggests that they evolved to either communicate or utilize the immune system for host colonization and thus can influence commensal microbiota community composition.


Assuntos
Epitopos/imunologia , Flagelina/imunologia , Interações entre Hospedeiro e Microrganismos/imunologia , Imunidade Vegetal , Bactérias/genética , Imunidade , Microbiota , Peptídeos , Ralstonia , Simbiose
6.
Science ; 370(6516): 550-557, 2020 10 30.
Artigo em Inglês | MEDLINE | ID: mdl-33122378

RESUMO

Spontaneously arising channels that transport the phytohormone auxin provide positional cues for self-organizing aspects of plant development such as flexible vasculature regeneration or its patterning during leaf venation. The auxin canalization hypothesis proposes a feedback between auxin signaling and transport as the underlying mechanism, but molecular players await discovery. We identified part of the machinery that routes auxin transport. The auxin-regulated receptor CAMEL (Canalization-related Auxin-regulated Malectin-type RLK) together with CANAR (Canalization-related Receptor-like kinase) interact with and phosphorylate PIN auxin transporters. camel and canar mutants are impaired in PIN1 subcellular trafficking and auxin-mediated PIN polarization, which macroscopically manifests as defects in leaf venation and vasculature regeneration after wounding. The CAMEL-CANAR receptor complex is part of the auxin feedback that coordinates polarization of individual cells during auxin canalization.


Assuntos
Arabidopsis/enzimologia , Ácidos Indolacéticos/metabolismo , Proteínas Quinases/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Transporte Biológico , Proteínas de Membrana Transportadoras/metabolismo , Mapeamento de Interação de Proteínas , Proteínas Quinases/genética , Fatores de Transcrição/metabolismo
7.
Cell Host Microbe ; 27(3): 308-310, 2020 03 11.
Artigo em Inglês | MEDLINE | ID: mdl-32164838

RESUMO

The organizational principles of the root immune system are largely uncharacterized. In the February 6, 2020 issue of Cell, Zhou et al. showed roots are built entirely by immunocompetent cells that require distinct instructions to unlock cell-autonomous immune programs. A root cell's developmental identity combined with its spatial distribution fine-tunes immune signal sensitivity, enabling sector-specific immune responses.


Assuntos
Imunidade Celular
8.
Nature ; 572(7768): 270-274, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31291642

RESUMO

Receptor kinases of the Catharanthus roseus RLK1-like (CrRLK1L) family have emerged as important regulators of plant reproduction, growth and responses to the environment1. Endogenous RAPID ALKALINIZATION FACTOR (RALF) peptides2 have previously been proposed as ligands for several members of the CrRLK1L family1. However, the mechanistic basis of this perception is unknown. Here we report that RALF23 induces a complex between the CrRLK1L FERONIA (FER) and LORELEI (LRE)-LIKE GLYCOSYLPHOSPHATIDYLINOSITOL (GPI)-ANCHORED PROTEIN 1 (LLG1) to regulate immune signalling. Structural and biochemical data indicate that LLG1 (which is genetically important for RALF23 responses) and the related LLG2 directly bind RALF23 to nucleate the assembly of RALF23-LLG1-FER and RALF23-LLG2-FER heterocomplexes, respectively. A conserved N-terminal region of RALF23 is sufficient for the biochemical recognition of RALF23 by LLG1, LLG2 or LLG3, and binding assays suggest that other RALF peptides that share this conserved N-terminal region may be perceived by LLG proteins in a similar manner. Structural data also show that RALF23 recognition is governed by the conformationally flexible C-terminal sides of LLG1, LLG2 and LLG3. Our work reveals a mechanism of peptide perception in plants by GPI-anchored proteins that act together with a phylogenetically unrelated receptor kinase. This provides a molecular framework for understanding how diverse RALF peptides may regulate multiple processes, through perception by distinct heterocomplexes of CrRLK1L receptor kinases and GPI-anchored proteins of the LRE and LLG family.


Assuntos
Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/metabolismo , Arabidopsis/imunologia , Arabidopsis/metabolismo , Proteínas Ligadas por GPI/metabolismo , Peptídeos e Proteínas de Sinalização Intercelular/química , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Fragmentos de Peptídeos/metabolismo , Fosfotransferases/metabolismo , Proteínas de Arabidopsis/genética , Peptídeos e Proteínas de Sinalização Intercelular/genética , Modelos Moleculares , Mutagênese , Proteínas Mutantes/química , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Mutação , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/genética , Fosfotransferases/genética , Maleabilidade , Ligação Proteica/genética , Conformação Proteica , Multimerização Proteica
9.
Proc Natl Acad Sci U S A ; 116(17): 8525-8534, 2019 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-30948631

RESUMO

The rice immune receptor XA21 is activated by the sulfated microbial peptide required for activation of XA21-mediated immunity X (RaxX) produced by Xanthomonas oryzae pv. oryzae (Xoo). Mutational studies and targeted proteomics revealed that the RaxX precursor peptide (proRaxX) is processed and secreted by the protease/transporter RaxB, the function of which can be partially fulfilled by a noncognate peptidase-containing transporter component B (PctB). proRaxX is cleaved at a Gly-Gly motif, yielding a mature peptide that retains the necessary elements for RaxX function as an immunogen and host peptide hormone mimic. These results indicate that RaxX is a prokaryotic member of a previously unclassified and understudied group of eukaryotic tyrosine sulfated ribosomally synthesized, posttranslationally modified peptides (RiPPs). We further demonstrate that sulfated RaxX directly binds XA21 with high affinity. This work reveals a complete, previously uncharacterized biological process: bacterial RiPP biosynthesis, secretion, binding to a eukaryotic receptor, and triggering of a robust host immune response.


Assuntos
Proteínas de Bactérias/metabolismo , Peptídeo Hidrolases/metabolismo , Peptídeos/metabolismo , Proteínas de Plantas/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Transportadores de Cassetes de Ligação de ATP/química , Transportadores de Cassetes de Ligação de ATP/genética , Transportadores de Cassetes de Ligação de ATP/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Genes Bacterianos/genética , Interações Hospedeiro-Patógeno/genética , Interações Hospedeiro-Patógeno/imunologia , Redes e Vias Metabólicas/genética , Oryza/imunologia , Oryza/metabolismo , Oryza/microbiologia , Peptídeo Hidrolases/química , Peptídeo Hidrolases/genética , Peptídeos/química , Peptídeos/genética , Proteínas de Plantas/química , Proteínas de Plantas/imunologia , Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/imunologia , Xanthomonas/genética , Xanthomonas/metabolismo , Xanthomonas/patogenicidade
10.
Science ; 364(6436): 178-181, 2019 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-30975887

RESUMO

In plants, cell-surface immune receptors sense molecular non-self-signatures. Lipid A of Gram-negative bacterial lipopolysaccharide is considered such a non-self-signature. The receptor kinase LIPOOLIGOSACCHARIDE-SPECIFIC REDUCED ELICITATION (LORE) mediates plant immune responses to Pseudomonas and Xanthomonas but not enterobacterial lipid A or lipopolysaccharide preparations. Here, we demonstrate that synthetic and bacterial lipopolysaccharide-copurified medium-chain 3-hydroxy fatty acid (mc-3-OH-FA) metabolites elicit LORE-dependent immunity. The mc-3-OH-FAs are sensed in a chain length- and hydroxylation-specific manner, with free (R)-3-hydroxydecanoic acid [(R)-3-OH-C10:0] representing the strongest immune elicitor. By contrast, bacterial compounds comprising mc-3-OH-acyl building blocks but devoid of free mc-3-OH-FAs-including lipid A or lipopolysaccharide, rhamnolipids, lipopeptides, and acyl-homoserine-lactones-do not trigger LORE-dependent responses. Hence, plants sense low-complexity bacterial metabolites to trigger immune responses.


Assuntos
Arabidopsis/imunologia , Arabidopsis/microbiologia , Ácidos Decanoicos/metabolismo , Pseudomonas aeruginosa/metabolismo , Acil-Butirolactonas/metabolismo , Ácidos Decanoicos/química , Glicolipídeos/metabolismo , Lipídeo A/metabolismo , Lipopeptídeos/metabolismo
11.
Sci Data ; 6: 190025, 2019 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-30806640

RESUMO

Plants use surface receptors to perceive information about many aspects of their local environment. These receptors physically interact to form both steady state and signalling competent complexes. The signalling events downstream of receptor activation impact both plant developmental and immune responses. Here, we present a comprehensive study of the physical interactions between the extracellular domains of leucine-rich repeat receptor kinases (LRR-RKs) in Arabidopsis. Using a sensitized assay, we tested reciprocal interactions among 200 of the 225 Arabidopsis LRR-RKs for a total search space of 40,000 interactions. Applying a stringent statistical cut-off and requiring that interactions performed well in both bait-prey and prey-bait orientations resulted in a high-confidence set of 567 bidirectional interactions. Additionally, we identified a total of 2,586 unidirectional interactions, which passed our stringent statistical cut-off in only one orientation. These datasets will guide further investigation into the regulatory roles of LRR-RKs in plant developmental and immune signalling decisions.


Assuntos
Proteínas de Arabidopsis , Mapeamento de Interação de Proteínas , Proteínas Quinases/química , Proteínas , Proteínas de Arabidopsis/química , Domínios Proteicos , Mapeamento de Interação de Proteínas/métodos , Proteínas Quinases/fisiologia
12.
Nature ; 561(7722): E8, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29973716

RESUMO

In this Letter, an incorrect version of the Supplementary Information file was inadvertently used, which contained several errors. The details of references 59-65 were missing from the end of the Supplementary Discussion section on page 4. In addition, the section 'Text 3. Y2H on ICD interactions' incorrectly referred to 'Extended Data Fig. 4d' instead of 'Extended Data Fig. 3d' on page 3. Finally, the section 'Text 4. Interaction network analysis' incorrectly referred to 'Fig. 1b and Extended Data Fig. 6' instead of 'Fig. 2b and Extended Data Fig. 7' on page 3. These errors have all been corrected in the Supplementary Information.

13.
Nat Commun ; 9(1): 2312, 2018 06 13.
Artigo em Inglês | MEDLINE | ID: mdl-29899369

RESUMO

In all organisms, major biological processes are controlled by complex protein-protein interactions networks (interactomes), yet their structural complexity presents major analytical challenges. Here, we integrate a compendium of over 4300 phenotypes with Arabidopsis interactome (AI-1MAIN). We show that nodes with high connectivity and betweenness are enriched and depleted in conditional and essential phenotypes, respectively. Such nodes are located in the innermost layers of AI-1MAIN and are preferential targets of pathogen effectors. We extend these network-centric analyses to Cell Surface Interactome (CSILRR) and predict its 35 most influential nodes. To determine their biological relevance, we show that these proteins physically interact with pathogen effectors and modulate plant immunity. Overall, our findings contrast with centrality-lethality rule, discover fast information spreading nodes, and highlight the structural properties of pathogen targets in two different interactomes. Finally, this theoretical framework could possibly be applicable to other inter-species interactomes to reveal pathogen contact points.


Assuntos
Arabidopsis/metabolismo , Mapas de Interação de Proteínas , Arabidopsis/genética , Arabidopsis/imunologia , Proteínas de Arabidopsis/imunologia , Proteínas de Arabidopsis/metabolismo , Interações Hospedeiro-Patógeno , Modelos Biológicos , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Imunidade Vegetal , Mapeamento de Interação de Proteínas , Proteínas Quinases/imunologia , Proteínas Quinases/metabolismo , Pseudomonas syringae/patogenicidade , Biologia de Sistemas
14.
Nature ; 553(7688): 342-346, 2018 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-29320478

RESUMO

The cells of multicellular organisms receive extracellular signals using surface receptors. The extracellular domains (ECDs) of cell surface receptors function as interaction platforms, and as regulatory modules of receptor activation. Understanding how interactions between ECDs produce signal-competent receptor complexes is challenging because of their low biochemical tractability. In plants, the discovery of ECD interactions is complicated by the massive expansion of receptor families, which creates tremendous potential for changeover in receptor interactions. The largest of these families in Arabidopsis thaliana consists of 225 evolutionarily related leucine-rich repeat receptor kinases (LRR-RKs), which function in the sensing of microorganisms, cell expansion, stomata development and stem-cell maintenance. Although the principles that govern LRR-RK signalling activation are emerging, the systems-level organization of this family of proteins is unknown. Here, to address this, we investigated 40,000 potential ECD interactions using a sensitized high-throughput interaction assay, and produced an LRR-based cell surface interaction network (CSILRR) that consists of 567 interactions. To demonstrate the power of CSILRR for detecting biologically relevant interactions, we predicted and validated the functions of uncharacterized LRR-RKs in plant growth and immunity. In addition, we show that CSILRR operates as a unified regulatory network in which the LRR-RKs most crucial for its overall structure are required to prevent the aberrant signalling of receptors that are several network-steps away. Thus, plants have evolved LRR-RK networks to process extracellular signals into carefully balanced responses.


Assuntos
Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimologia , Leucina/metabolismo , Proteínas Quinases/química , Proteínas Quinases/metabolismo , Arabidopsis/citologia , Arabidopsis/imunologia , Arabidopsis/microbiologia , Ligação Proteica , Domínios Proteicos , Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/metabolismo , Receptores de Superfície Celular/química , Receptores de Superfície Celular/metabolismo , Reprodutibilidade dos Testes , Transdução de Sinais
15.
Science ; 355(6322): 280-284, 2017 01 20.
Artigo em Inglês | MEDLINE | ID: mdl-28104888

RESUMO

The root endodermis forms its extracellular diffusion barrier by developing ringlike impregnations called Casparian strips. A factor responsible for their establishment is the SCHENGEN3/GASSHO1 (SGN3/GSO1) receptor-like kinase. Its loss of function causes discontinuous Casparian strips. SGN3 also mediates endodermal overlignification of other Casparian strip mutants. Yet, without ligand, SGN3 function remained elusive. Here we report that schengen2 (sgn2) is defective in an enzyme sulfating peptide ligands. On the basis of this observation, we identified two stele-expressed peptides (CASPARIAN STRIP INTEGRITY FACTORS, CIF1/2) that complement sgn2 at nanomolar concentrations and induce Casparian strip mislocalization as well as overlignification-all of which depend on SGN3. Direct peptide binding to recombinant SGN3 identifies these peptides as SGN3 ligands. We speculate that CIF1/2-SGN3 is part of a barrier surveillance system, evolved to guarantee effective sealing of the supracellular Casparian strip network.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Raízes de Plantas/metabolismo , Proteínas Quinases/metabolismo , Sulfotransferases/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Difusão , Ligantes , Peptídeos/metabolismo , Raízes de Plantas/genética , Ligação Proteica , Proteínas Quinases/genética , Sulfotransferases/genética
16.
Science ; 355(6322): 287-289, 2017 01 20.
Artigo em Inglês | MEDLINE | ID: mdl-28104890

RESUMO

In plants, perception of invading pathogens involves cell-surface immune receptor kinases. Here, we report that the Arabidopsis SITE-1 PROTEASE (S1P) cleaves endogenous RAPID ALKALINIZATION FACTOR (RALF) propeptides to inhibit plant immunity. This inhibition is mediated by the malectin-like receptor kinase FERONIA (FER), which otherwise facilitates the ligand-induced complex formation of the immune receptor kinases EF-TU RECEPTOR (EFR) and FLAGELLIN-SENSING 2 (FLS2) with their co-receptor BRASSINOSTEROID INSENSITIVE 1-ASSOCIATED KINASE 1 (BAK1) to initiate immune signaling. We show that FER acts as a RALF-regulated scaffold that modulates receptor kinase complex assembly. A similar scaffolding mechanism may underlie FER function in other signaling pathways.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/imunologia , Hormônios Peptídicos/metabolismo , Fosfotransferases/metabolismo , Imunidade Vegetal , Pró-Proteína Convertases/metabolismo , Proteínas Quinases/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteólise , Receptores de Reconhecimento de Padrão/metabolismo , Serina Endopeptidases/metabolismo , Transdução de Sinais
17.
Methods Mol Biol ; 1564: 49-61, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28124246

RESUMO

Pathway cross-communication cannot be simply tackled by studying isolated signaling systems. Yet understanding how signal transduction pathways attenuate or reinforce each other in vivo is a challenging task. In plants, biosynthesis and signaling of brassinosteroids (BRs) finely regulate growth and defense programs through a complex array of mechanistic and physiological interactions. Conversely, induction of defenses also impacts on the BR biosynthesis at the transcriptional level. In this chapter, we present an experimental framework to study the physiological connection between BR-controlled growth and defenses. We focus on the signaling pathways regulated by the two archetypal cell surface receptors, BRASSINOSTEROID INSENSITIVE1 (BRI1) and FLAGELLIN-SENSITIVE2 (FLS2), to illustrate the signaling nexus of BRs and plant immunity. In Arabidopsis thaliana, these pathways provide one of the very few systems in which the tools and mechanistic details exist to study cross talk at the molecular level.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Brassinosteroides/farmacologia , Regulação da Expressão Gênica de Plantas , Reguladores de Crescimento de Plantas/farmacologia , Imunidade Vegetal/genética , Proteínas Quinases/genética , Esteroides Heterocíclicos/farmacologia , Arabidopsis/efeitos dos fármacos , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/imunologia , Proteínas de Arabidopsis/imunologia , Bioensaio , Proteínas Quinases Ativadas por Mitógeno/genética , Proteínas Quinases Ativadas por Mitógeno/imunologia , Proteínas Quinases/imunologia , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/imunologia , Espécies Reativas de Oxigênio/imunologia , Espécies Reativas de Oxigênio/metabolismo , Receptor Cross-Talk/imunologia , Plântula/efeitos dos fármacos , Plântula/genética , Plântula/crescimento & desenvolvimento , Plântula/imunologia , Transdução de Sinais
18.
Sci Signal ; 9(435): rs5, 2016 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-27382028

RESUMO

Extracellular matrices (ECMs) are central to the advent of multicellular life, and their mechanical properties are modulated by and impinge on intracellular signaling pathways that regulate vital cellular functions. High spatial-resolution mapping of mechanical properties in live cells is, however, extremely challenging. Thus, our understanding of how signaling pathways process physiological signals to generate appropriate mechanical responses is limited. We introduce fluorescence emission-Brillouin scattering imaging (FBi), a method for the parallel and all-optical measurements of mechanical properties and fluorescence at the submicrometer scale in living organisms. Using FBi, we showed that changes in cellular hydrostatic pressure and cytoplasm viscoelasticity modulate the mechanical signatures of plant ECMs. We further established that the measured "stiffness" of plant ECMs is symmetrically patterned in hypocotyl cells undergoing directional growth. Finally, application of this method to Arabidopsis thaliana with photoreceptor mutants revealed that red and far-red light signals are essential modulators of ECM viscoelasticity. By mapping the viscoelastic signatures of a complex ECM, we provide proof of principle for the organism-wide applicability of FBi for measuring the mechanical outputs of intracellular signaling pathways. As such, our work has implications for investigations of mechanosignaling pathways and developmental biology.


Assuntos
Arabidopsis/citologia , Arabidopsis/metabolismo , Matriz Extracelular/metabolismo , Arabidopsis/genética , Microscopia de Fluorescência , Mutação
19.
Genome Biol ; 17: 98, 2016 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-27160854

RESUMO

BACKGROUND: The recognition of microbe-associated molecular patterns during infection is central to the mounting of an effective immune response. In spite of their importance, it remains difficult to identify these molecules and the host receptors required for their perception, ultimately limiting our understanding of the role of these molecules in the evolution of host-pathogen relationships. RESULTS: We employ a comparative genomics screen to identify six new immune eliciting peptides from the phytopathogenic bacterium Pseudomonas syringae. We then perform a reverse genetic screen to identify Arabidopsis thaliana leucine-rich repeat receptor-like kinases required for the recognition of these elicitors. We test the six elicitors on 187 receptor-like kinase knock-down insertion lines using a high-throughput peroxidase-based immune assay and identify multiple lines that show decreased immune responses to specific peptides. From this primary screen data, we focused on the interaction between the xup25 peptide from a bacterial xanthine/uracil permease and the Arabidopsis receptor-like kinase xanthine/uracil permease sensing 1; a family XII protein closely related to two well-characterized receptor-like kinases. We show that xup25 treatment increases pathogenesis-related gene induction, callose deposition, seedling growth inhibition, and resistance to virulent bacteria, all in a xanthine/uracil permease sensing 1-dependent manner. Finally, we show that this kinase-like receptor can bind the xup25 peptide directly. These results identify xup25 as a P. syringae microbe-associated molecular pattern and xanthine/uracil permease sensing 1 as a receptor-like kinase that detects the xup25 epitope to activate immune responses. CONCLUSIONS: The present study demonstrates an efficient method to identify immune elicitors and the plant receptors responsible for their perception. Further exploration of these molecules will increase our understanding of plant-pathogen interactions and the basis for host specificity.


Assuntos
Arabidopsis/genética , Genoma de Planta , Interações Hospedeiro-Patógeno/genética , Imunidade Vegetal/genética , Proteínas Quinases/genética , Receptores de Superfície Celular/genética , Arabidopsis/imunologia , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Perfilação da Expressão Gênica/métodos , Proteínas Quinases/metabolismo , Pseudomonas syringae/genética , Pseudomonas syringae/patogenicidade , Receptores de Superfície Celular/metabolismo
20.
Proc Natl Acad Sci U S A ; 113(12): 3389-94, 2016 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-26944079

RESUMO

Plants use receptor kinases (RKs) and receptor-like proteins (RLPs) as pattern recognition receptors (PRRs) to sense pathogen-associated molecular patterns (PAMPs) that are typical of whole classes of microbes. After ligand perception, many leucine-rich repeat (LRR)-containing PRRs interact with the LRR-RK BRI1-ASSOCIATED KINASE 1 (BAK1). BAK1 is thus expected to interact with unknown PRRs. Here, we used BAK1 as molecular bait to identify a previously unknown LRR-RLP required for the recognition of the csp22 peptide derived from bacterial cold shock protein. We established a method to identify proteins that interact with BAK1 only after csp22 treatment. BAK1 was expressed transiently in Nicotiana benthamiana and immunopurified after treatment with csp22. BAK1-associated proteins were identified by mass spectrometry. We identified several proteins including known BAK1 interactors and a previously uncharacterized LRR-RLP that we termed RECEPTOR-LIKE PROTEIN REQUIRED FOR CSP22 RESPONSIVENESS (NbCSPR). This RLP associates with BAK1 upon csp22 treatment, and NbCSPR-silenced plants are impaired in csp22-induced defense responses. NbCSPR confers resistance to bacteria in an age-dependent and flagellin-induced manner. As such, it limits bacterial growth and Agrobacterium-mediated transformation of flowering N. benthamiana plants. Transgenic expression of NbCSPR into Arabidopsis thaliana conferred responsiveness to csp22 and antibacterial resistance. Our method may be used to identify LRR-type RKs and RLPs required for PAMP perception/responsiveness, even when the active purified PAMP has not been defined.


Assuntos
Proteínas de Bactérias/imunologia , Proteínas e Peptídeos de Choque Frio/fisiologia , Tabaco/imunologia , Tabaco/microbiologia
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