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1.
Plant J ; 116(6): 1633-1651, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37659090

RESUMO

The final step in secretion is membrane fusion facilitated by SNARE proteins that reside in opposite membranes. The formation of a trans-SNARE complex between one R and three Q coiled-coiled SNARE domains drives the final approach of the membranes providing the mechanical energy for fusion. Biological control of this mechanism is exerted by additional domains within some SNAREs. For example, the N-terminal Longin domain (LD) of R-SNAREs (also called Vesicle-associated membrane proteins, VAMPs) can fold back onto the SNARE domain blocking interaction with other cognate SNAREs. The LD may also determine the subcellular localization via interaction with other trafficking-related proteins. Here, we provide cell-biological and genetic evidence that phosphorylation of the Tyrosine57 residue regulates the functionality of VAMP721. We found that an aspartate mutation mimics phosphorylation, leading to protein instability and subsequent degradation in lytic vacuoles. The mutant SNARE also fails to rescue the defects of vamp721vamp722 loss-of-function lines in spite of its wildtype-like localization within the secretory pathway and the ability to interact with cognate SNARE partners. Most importantly, it imposes a dominant negative phenotype interfering with root growth, normal secretion and cytokinesis in wildtype plants generating large aggregates that mainly contain secretory vesicles. Non-phosphorylatable VAMP721Y57F needs higher gene dosage to rescue double mutants in comparison to native VAMP721 underpinning that phosphorylation modulates SNARE function. We propose a model where short-lived phosphorylation of Y57 serves as a regulatory step to control VAMP721 activity, favoring its open state and interaction with cognate partners to ultimately drive membrane fusion.


Assuntos
Arabidopsis , Proteínas SNARE , Membrana Celular/metabolismo , Fusão de Membrana , Proteínas R-SNARE/genética , Proteínas R-SNARE/metabolismo , Proteínas SNARE/genética , Proteínas SNARE/metabolismo , Tirosina/metabolismo , Arabidopsis/citologia , Arabidopsis/metabolismo
2.
Plant Biotechnol J ; 22(3): 602-616, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37870975

RESUMO

Ralstonia solanacearum, a species complex of bacterial plant pathogens that causes bacterial wilt, comprises four phylotypes that evolved when a founder population was split during the continental drift ~180 million years ago. Each phylotype contains strains with RipTAL proteins structurally related to transcription activator-like (TAL) effectors from the bacterial pathogen Xanthomonas. RipTALs have evolved in geographically separated phylotypes and therefore differ in sequence and potentially functionality. Earlier work has shown that phylotype I RipTAL Brg11 targets a 17-nucleotide effector binding element (EBE) and transcriptionally activates the downstream arginine decarboxylase (ADC) gene. The predicted DNA binding preferences of Brg11 and RipTALs from other phylotypes are similar, suggesting that most, if not all, RipTALs target the Brg11-EBE motif and activate downstream ADC genes. Here we show that not only phylotype I RipTAL Brg11 but also RipTALs from other phylotypes activate host genes when preceded by the Brg11-EBE motif. Furthermore, we show that Brg11 and RipTALs from other phylotypes induce the same quantitative changes of ADC-dependent plant metabolites, suggesting that most, if not all, RipTALs induce functionally equivalent changes in host cells. Finally, we report transgenic tobacco lines in which the RipTAL-binding motif Brg11-EBE mediates RipTAL-dependent transcription of the executor-type resistance (R) gene Bs4C from pepper, thereby conferring resistance to RipTAL-delivering R. solanacearum strains. Our results suggest that cell death-inducing executor-type R genes, preceded by the RipTAL-binding motif Brg11-EBE, could be used to genetically engineer broad-spectrum bacterial wilt resistance in crop plants without any apparent fitness penalty.


Assuntos
Ralstonia solanacearum , Ralstonia solanacearum/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Regiões Promotoras Genéticas/genética , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Plantas/genética , Doenças das Plantas/genética , Doenças das Plantas/microbiologia
3.
Environ Microbiol ; 20(4): 1330-1349, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29215193

RESUMO

Ralstonia solanacearum thrives in plant xylem vessels and causes bacterial wilt disease despite the low nutrient content of xylem sap. We found that R. solanacearum manipulates its host to increase nutrients in tomato xylem sap, enabling it to grow better in sap from infected plants than in sap from healthy plants. Untargeted GC/MS metabolomics identified 22 metabolites enriched in R. solanacearum-infected sap. Eight of these could serve as sole carbon or nitrogen sources for R. solanacearum. Putrescine, a polyamine that is not a sole carbon or nitrogen source for R. solanacearum, was enriched 76-fold to 37 µM in R. solanacearum-infected sap. R. solanacearum synthesized putrescine via a SpeC ornithine decarboxylase. A ΔspeC mutant required ≥ 15 µM exogenous putrescine to grow and could not grow alone in xylem even when plants were treated with putrescine. However, co-inoculation with wildtype rescued ΔspeC growth, indicating R. solanacearum produced and exported putrescine to xylem sap. Intriguingly, treating plants with putrescine before inoculation accelerated wilt symptom development and R. solanacearum growth and systemic spread. Xylem putrescine concentration was unchanged in putrescine-treated plants, so the exogenous putrescine likely accelerated disease indirectly by affecting host physiology. These results indicate that putrescine is a pathogen-produced virulence metabolite.


Assuntos
Doenças das Plantas/microbiologia , Putrescina/metabolismo , Ralstonia solanacearum/metabolismo , Ralstonia solanacearum/patogenicidade , Solanum lycopersicum/microbiologia , Xilema/metabolismo , Metabolômica , Virulência , Fatores de Virulência/metabolismo , Xilema/microbiologia
4.
Plant Physiol ; 169(3): 1766-86, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-26338951

RESUMO

Two different thiol redox systems exist in plant chloroplasts, the ferredoxin-thioredoxin (Trx) system, which depends on ferredoxin reduced by the photosynthetic electron transport chain and, thus, on light, and the NADPH-dependent Trx reductase C (NTRC) system, which relies on NADPH and thus may be linked to sugar metabolism in the dark. Previous studies suggested, therefore, that the two different systems may have different functions in plants. We now report that there is a previously unrecognized functional redundancy of Trx f1 and NTRC in regulating photosynthetic metabolism and growth. In Arabidopsis (Arabidopsis thaliana) mutants, combined, but not single, deficiencies of Trx f1 and NTRC led to severe growth inhibition and perturbed light acclimation, accompanied by strong impairments of Calvin-Benson cycle activity and starch accumulation. Light activation of key enzymes of these pathways, fructose-1,6-bisphosphatase and ADP-glucose pyrophosphorylase, was almost completely abolished. The subsequent increase in NADPH-NADP(+) and ATP-ADP ratios led to increased nitrogen assimilation, NADP-malate dehydrogenase activation, and light vulnerability of photosystem I core proteins. In an additional approach, reporter studies show that Trx f1 and NTRC proteins are both colocalized in the same chloroplast substructure. Results provide genetic evidence that light- and NADPH-dependent thiol redox systems interact at the level of Trx f1 and NTRC to coordinately participate in the regulation of the Calvin-Benson cycle, starch metabolism, and growth in response to varying light conditions.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimologia , Tiorredoxina Dissulfeto Redutase/metabolismo , Tiorredoxinas/metabolismo , Arabidopsis/genética , Arabidopsis/fisiologia , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , Cloroplastos/metabolismo , Glucose-1-Fosfato Adenililtransferase/genética , Glucose-1-Fosfato Adenililtransferase/metabolismo , Malato Desidrogenase (NADP+)/genética , Malato Desidrogenase (NADP+)/metabolismo , Metaboloma , Oxirredução , Fenótipo , Fotossíntese/efeitos da radiação , Complexo de Proteína do Fotossistema I/metabolismo , Folhas de Planta/enzimologia , Folhas de Planta/genética , Folhas de Planta/fisiologia , Folhas de Planta/efeitos da radiação , Transpiração Vegetal/efeitos da radiação , Amido/metabolismo , Tiorredoxina Dissulfeto Redutase/genética
5.
Plant Cell Environ ; 38(2): 280-98, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24329537

RESUMO

The enzyme ferrochelatase catalyses the formation of protoheme by inserting Fe(2+) into protoporphyrin IX. Although most organisms express only one ferrochelatase, all land plants analysed so far possess at least two ferrochelatase proteins. Analysis of publicly available expression data suggests that the two Arabidopsis thaliana ferrochelatases, FC1 and FC2, serve different functions, corroborating previous assumptions. Co-expression analysis of FC1 and FC2, together with microarray analyses, implies that fc1 and fc2 trigger different modes of plastid signalling in roots and leaves, respectively, and indicates that FC2 might be involved in stress responses. Thus, loss of FC2 increases resistance to salt and flagellin treatment. Whereas fc1 plants showed no obvious mutant phenotype, fc2 mutants formed abnormally small, pale green rosette leaves; were low in chlorophylls, carotenoids and several photosynthetic proteins; and their photosynthetic performance was impaired. These phenotypes are attenuated by growth in continuous light, in agreement with the finding that fc2 plants accumulate protochlorophyllide and display a fluorescent (flu) phenotype in the dark. In consequence we show that, contrary to earlier suggestions, FC2 produces heme not only for photosynthetic cytochromes, but also for proteins involved in stress responses, whereas the impairment of FC1 apparently interferes only marginally with stress responses.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimologia , Arabidopsis/metabolismo , Ferroquelatase/metabolismo , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , DNA Bacteriano/genética , Ferroquelatase/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Técnicas de Silenciamento de Genes , Luz , Mutagênese Insercional/genética , Mutação/genética , Fenótipo , Fotossíntese/efeitos dos fármacos , Fotossíntese/efeitos da radiação , Protoclorifilida/metabolismo , Protoporfirinas/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Cloreto de Sódio/farmacologia , Estresse Fisiológico/efeitos dos fármacos , Estresse Fisiológico/genética , Estresse Fisiológico/efeitos da radiação , Transcriptoma/genética , Transcriptoma/efeitos da radiação
6.
Plant Cell Environ ; 36(1): 16-29, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22646759

RESUMO

Chloroplast thioredoxin f (Trx f) is an important regulator of primary metabolic enzymes. However, genetic evidence for its physiological importance is largely lacking. To test the functional significance of Trx f in vivo, Arabidopsis mutants with insertions in the trx f1 gene were studied, showing a drastic decrease in Trx f leaf content. Knockout of Trx f1 led to strong attenuation in reductive light activation of ADP-glucose pyrophosphorylase (AGPase), the key enzyme of starch synthesis, in leaves during the day and in isolated chloroplasts, while sucrose-dependent redox activation of AGPase in darkened leaves was not affected. The decrease in light-activation of AGPase in leaves was accompanied by a decrease in starch accumulation, an increase in sucrose levels and a decrease in starch-to-sucrose ratio. Analysis of metabolite levels at the end of day shows that inhibition of starch synthesis was unlikely due to shortage of substrates or changes in allosteric effectors. Metabolite profiling by gas chromatography-mass spectrometry pinpoints only a small number of metabolites affected, including sugars, organic acids and ethanolamine. Interestingly, metabolite data indicate carbon shortage in trx f1 mutant leaves at the end of night. Overall, results provide in planta evidence for the role played by Trx f in the light activation of AGPase and photosynthetic carbon partitioning in plants.


Assuntos
Arabidopsis/enzimologia , Tiorredoxinas de Cloroplastos/metabolismo , Glucose-1-Fosfato Adenililtransferase/metabolismo , Folhas de Planta/metabolismo , Amido/biossíntese , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Tiorredoxinas de Cloroplastos/genética , Cloroplastos/enzimologia , Ritmo Circadiano , Ativação Enzimática , Cromatografia Gasosa-Espectrometria de Massas , Técnicas de Inativação de Genes , Luz , Oxirredução , Fotossíntese , Sacarose/metabolismo
7.
Nat Plants ; 9(1): 128-141, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36550363

RESUMO

Bacteria inject effector proteins into host cells to manipulate cellular processes that promote disease. Since bacteria deliver minuscule amounts of effectors only into targeted host cells, it is technically challenging to capture effector-dependent cellular changes from bulk-infected host tissues. Here, we report a new technique called effector-inducible isolation of nuclei tagged in specific cell types (eINTACT), which facilitates affinity-based purification of nuclei from Arabidopsis plant cells that have received Xanthomonas bacterial effectors. Analysis of purified nuclei reveals that the Xanthomonas effector XopD manipulates the expression of Arabidopsis abscisic acid signalling-related genes and activates OSCA1.1, a gene encoding a calcium-permeable channel required for stomatal closure in response to osmotic stress. The loss of OSCA1.1 causes leaf wilting and reduced bacterial growth in infected leaves, suggesting that OSCA1.1 promotes host susceptibility. eINTACT allows us to uncover that XopD exploits host OSCA1.1/abscisic acid osmosignalling-mediated stomatal closure to create a humid habitat that favours bacterial growth and opens up a new avenue for accurately elucidating functions of effectors from numerous gram-negative plant bacteria in native infection contexts.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Xanthomonas , Arabidopsis/metabolismo , Virulência , Ácido Abscísico/metabolismo , Xanthomonas/fisiologia , Proteínas de Arabidopsis/metabolismo , Canais de Cálcio/metabolismo , Doenças das Plantas/microbiologia , Proteínas de Bactérias/genética
8.
Plant Physiol ; 155(3): 1127-45, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21248075

RESUMO

Sinapine (O-sinapoylcholine) is the predominant phenolic compound in a complex group of sinapate esters in seeds of oilseed rape (Brassica napus). Sinapine has antinutritive activity and prevents the use of seed protein for food and feed. A strategy was developed to lower its content in seeds by expressing an enzyme that hydrolyzes sinapine in developing rape seeds. During early stages of seedling development, a sinapine esterase (BnSCE3) hydrolyzes sinapine, releasing choline and sinapate. A portion of choline enters the phospholipid metabolism, and sinapate is routed via 1-O-sinapoyl-ß-glucose into sinapoylmalate. Transgenic oilseed rape lines were generated expressing BnSCE3 under the control of a seed-specific promoter. Two distinct single-copy transgene insertion lines were isolated and propagated to generate homozygous lines, which were subjected to comprehensive phenotyping. Sinapine levels of transgenic seeds were less than 5% of wild-type levels, whereas choline levels were increased. Weight, size, and water content of transgenic seeds were significantly higher than those of wild-type seeds. Seed quality parameters, such as fiber and glucosinolate levels, and agronomically important traits, such as oil and protein contents, differed only slightly, except that amounts of hemicellulose and cellulose were about 30% higher in transgenic compared with wild-type seeds. Electron microscopic examination revealed that a fraction of the transgenic seeds had morphological alterations, characterized by large cavities near the embryonic tissue. Transgenic seedlings were larger than wild-type seedlings, and young seedlings exhibited longer hypocotyls. Examination of metabolic profiles of transgenic seeds indicated that besides suppression of sinapine accumulation, there were other dramatic differences in primary and secondary metabolism. Mapping of these changes onto metabolic pathways revealed global effects of the transgenic BnSCE3 expression on seed metabolism.


Assuntos
Brassica napus/enzimologia , Colina/análogos & derivados , Esterases/metabolismo , Proteínas de Plantas/metabolismo , Sementes/metabolismo , Brassica napus/genética , Brassica napus/ultraestrutura , Colina/química , Colina/metabolismo , Segregação de Cromossomos/genética , Esterases/genética , Cromatografia Gasosa-Espectrometria de Massas , Regulação da Expressão Gênica de Plantas , Lipídeos/análise , Redes e Vias Metabólicas , Metaboloma , Dados de Sequência Molecular , Fenóis/química , Fenóis/metabolismo , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas , Plântula/metabolismo , Sementes/ultraestrutura , Espectroscopia de Luz Próxima ao Infravermelho
9.
Nat Commun ; 13(1): 1656, 2022 03 29.
Artigo em Inglês | MEDLINE | ID: mdl-35351902

RESUMO

Seed germination is a critical step in the life cycle of plants controlled by the phytohormones abscisic acid (ABA) and gibberellin (GA), and by phytochromes, an important class of photoreceptors in plants. Here we show that light-dependent germination is enhanced in mutants deficient in the AP2/ERF transcription factors ERF55 and ERF58. Light-activated phytochromes repress ERF55/ERF58 expression and directly bind ERF55/ERF58 to displace them from the promoter of PIF1 and SOM, genes encoding transcriptional regulators that prevent the completion of germination. The same mechanism controls the expression of genes that encode ABA or GA metabolic enzymes to decrease levels of ABA and possibly increase levels of GA. Interestingly, ERF55 and ERF58 are themselves under transcriptional control of ABA and GA, suggesting that they are part of a self-reinforcing signalling loop which controls the completion of germination. Overall, we identified a role of ERF55/ERF58 in phytochrome-mediated regulation of germination completion.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Fitocromo , Ácido Abscísico/metabolismo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , Germinação/genética , Giberelinas/metabolismo , Luz , Fitocromo/genética , Fitocromo/metabolismo , Sementes/metabolismo
10.
PLoS One ; 17(3): e0254741, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35333873

RESUMO

In annual plants, tight coordination of successive developmental events is of primary importance to optimize performance under fluctuating environmental conditions. The recent finding of the genetic interaction of WRKY53, a key senescence-related gene with REVOLUTA, a master regulator of early leaf patterning, raises the question of how early and late developmental events are connected. Here, we investigated the developmental and metabolic consequences of an alteration of the REVOLUTA and WRKY53 gene expression, from seedling to fruiting. Our results show that REVOLUTA critically controls late developmental phases and reproduction while inversely WRKY53 determines vegetative growth at early developmental stages. We further show that these regulators of distinct developmental phases frequently, but not continuously, interact throughout ontogeny and demonstrated that their genetic interaction is mediated by the salicylic acid (SA). Moreover, we showed that REVOLUTA and WRKY53 are keys regulatory nodes of development and plant immunity thought their role in SA metabolic pathways, which also highlights the role of REV in pathogen defence. Together, our findings demonstrate how late and early developmental events are tightly intertwined by molecular hubs. These hubs interact with each other throughout ontogeny, and participate in the interplay between plant development and immunity.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Ligação a DNA/genética , Regulação da Expressão Gênica de Plantas , Imunidade , Desenvolvimento Vegetal , Folhas de Planta/metabolismo , Plantas Geneticamente Modificadas/metabolismo , Ácido Salicílico/metabolismo
11.
J Biol Chem ; 285(33): 25654-65, 2010 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-20538606

RESUMO

An intricate network of hormone signals regulates plant development and responses to biotic and abiotic stress. Salicylic acid (SA), derived from the shikimate/isochorismate pathway, is a key hormone in resistance to biotrophic pathogens. Several SA derivatives and associated modifying enzymes have been identified and implicated in the storage and channeling of benzoic acid intermediates or as bioactive molecules. However, the range and modes of action of SA-related metabolites remain elusive. In Arabidopsis, Enhanced Disease Susceptibility 1 (EDS1) promotes SA-dependent and SA-independent responses in resistance against pathogens. Here, we used metabolite profiling of Arabidopsis wild type and eds1 mutant leaf extracts to identify molecules, other than SA, whose accumulation requires EDS1 signaling. Nuclear magnetic resonance and mass spectrometry of isolated and purified compounds revealed 2,3-dihydroxybenzoic acid (2,3-DHBA) as an isochorismate-derived secondary metabolite whose accumulation depends on EDS1 in resistance responses and during ageing of plants. 2,3-DHBA exists predominantly as a xylose-conjugated form (2-hydroxy-3-beta-O-D-xylopyranosyloxy benzoic acid) that is structurally distinct from known SA-glucose conjugates. Analysis of DHBA accumulation profiles in various Arabidopsis mutants suggests an enzymatic route to 2,3-DHBA synthesis that is under the control of EDS1. We propose that components of the EDS1 pathway direct the generation or stabilization of 2,3-DHBA, which as a potentially bioactive molecule is sequestered as a xylose conjugate.


Assuntos
Arabidopsis/metabolismo , Arabidopsis/parasitologia , Ácido Corísmico/metabolismo , Glicosídeos/metabolismo , Folhas de Planta/metabolismo , Folhas de Planta/parasitologia , Plantas Geneticamente Modificadas/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Cromatografia Líquida de Alta Pressão , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Hidroxibenzoatos/metabolismo , Espectroscopia de Ressonância Magnética , Oomicetos/patogenicidade , Folhas de Planta/genética , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/parasitologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Ácido Salicílico/metabolismo , Espectrometria de Massas por Ionização por Electrospray
12.
Cell Host Microbe ; 26(5): 638-649.e5, 2019 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-31628081

RESUMO

Pathogenic bacteria inject effector proteins into host cells to manipulate cellular processes and facilitate the infection. Transcription-activator-like effectors (TALEs), an effector class in plant pathogenic bacteria, transcriptionally activate host genes to promote disease. We identify arginine decarboxylase (ADC) genes as the host targets of Brg11, a TALE-like effector from the plant pathogen Ralstonia solanacearum. Brg11 targets a 17-bp sequence that was found to be part of a conserved 50-bp motif, termed the ADC-box, upstream of ADC genes involved in polyamine biosynthesis. The transcribed ADC-box attenuates translation from native ADC mRNAs; however, Brg11 induces truncated ADC mRNAs lacking the ADC-box, thus bypassing this translational control. As a result, Brg11 induces elevated polyamine levels that trigger a defense reaction and likely inhibits bacterial niche competitors but not R. solanacearum. Our findings suggest that Brg11 may give R. solanacearum a competitive advantage and uncover a role for bacterial effectors in regulating ternary microbe-host-microbe interactions.


Assuntos
Proteínas de Bactérias/metabolismo , Carboxiliases/metabolismo , Poliaminas/metabolismo , Ralstonia solanacearum/metabolismo , Proteínas de Bactérias/genética , Carboxiliases/genética , Interações entre Hospedeiro e Microrganismos/genética , Doenças das Plantas/microbiologia , Folhas de Planta/metabolismo , Raízes de Plantas/metabolismo , Plantas/microbiologia , Biossíntese de Proteínas/genética , Ralstonia solanacearum/genética
13.
Physiol Plant ; 132(2): 136-49, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18251856

RESUMO

Under the auspices of the European Training and Networking Activity programme of the European Union, a 'Metabolic Profiling and Data Analysis' Plant Genomics and Bioinformatics Summer School was hosted in Potsdam, Germany between 20 and 29 September 2006. Sixteen early career researchers were invited from the European Union partner nations and the so-called developing nations (Appendix). Lectures from invited leading European researchers provided an overview of the state of the art of these fields and seeded discussion regarding major challenges for their future advancement. Hands-on experience was provided by an example experiment - that of defining the metabolic response of Arabidopsis to treatment of a commercial herbicide of defined mode of action. This experiment was performed throughout the duration of the course in order to teach the concepts underlying extraction and machine handling as well as to provide a rich data set with which the required computation and statistical skills could be illustrated. Here we review the state of the field by describing both key lectures given at and practical aspects taught at the summer school. In addition, we disclose results that were obtained using the four distinct technical platforms at the different participating institutes. While the effects of the chosen herbicide are well documented, this study looks at a broader number of metabolites than in previous investigations. This allowed, on the one hand, not only to characterise further effects of the herbicide than previously observed but also to detect molecules other than the herbicide that were obviously present in the commercial formulation. These data and the workshop in general are all discussed in the context of the teaching of metabolomics.


Assuntos
Biologia Computacional/métodos , Genômica/métodos , Plantas/genética , Plantas/metabolismo , União Europeia
14.
Phytochemistry ; 124: 46-57, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26833384

RESUMO

In Brassica napus, suppression of the key biosynthetic enzyme UDP-glucose:sinapic acid glucosyltransferase (UGT84A9) inhibits the biosynthesis of sinapine (sinapoylcholine), the major phenolic component of seeds. Based on the accumulation kinetics of a total of 158 compounds (110 secondary and 48 primary metabolites), we investigated how suppression of the major sink pathway of sinapic acid impacts the metabolome of developing seeds and seedlings. In UGT84A9-suppressing (UGT84A9i) lines massive alterations became evident in late stages of seed development affecting the accumulation levels of 58 secondary and 7 primary metabolites. UGT84A9i seeds were characterized by decreased amounts of various hydroxycinnamic acid (HCA) esters, and increased formation of sinapic and syringic acid glycosides. This indicates glycosylation and ß-oxidation as metabolic detoxification strategies to bypass intracellular accumulation of sinapic acid. In addition, a net loss of sinapic acid upon UGT84A9 suppression may point to a feedback regulation of HCA biosynthesis. Surprisingly, suppression of UGT84A9 under control of the seed-specific NAPINC promoter was maintained in cotyledons during the first two weeks of seedling development and associated with a reduced and delayed transformation of sinapine into sinapoylmalate. The lack of sinapoylmalate did not interfere with plant fitness under UV-B stress. Increased UV-B radiation triggered the accumulation of quercetin conjugates whereas the sinapoylmalate level was not affected.


Assuntos
Brassica napus , Glucosiltransferases/metabolismo , Brassica napus/enzimologia , Brassica napus/genética , Brassica napus/metabolismo , Brassica napus/efeitos da radiação , Colina/análogos & derivados , Colina/metabolismo , Colina/efeitos da radiação , Cotilédone/metabolismo , Ácidos Cumáricos/análise , Ácidos Cumáricos/metabolismo , Ácidos Cumáricos/efeitos da radiação , Glucosiltransferases/efeitos da radiação , Malatos/metabolismo , Estrutura Molecular , Fenilpropionatos/metabolismo , Plântula/metabolismo , Sementes/metabolismo , Raios Ultravioleta
15.
J Mol Biol ; 325(1): 123-33, 2003 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-12473456

RESUMO

Bet v 1l is a naturally occurring hypoallergenic isoform of the major birch pollen allergen Bet v 1. The Bet v 1 protein belongs to the ubiquitous family of pathogenesis-related plant proteins (PR-10), which are produced in defense-response to various pathogens. Although the allergenic properties of PR-10 proteins have been extensively studied, their biological function in plants is not known. The crystal structure of Bet v 1l in complex with deoxycholate has been determined to a resolution of 1.9A using the method of molecular replacement. The structure reveals a large hydrophobic Y-shaped cavity that spans the protein and is partly occupied by two deoxycholate molecules which are bound in tandem and only partially exposed to solvent. This finding indicates that the hydrophobic cavity may have a role in facilitating the transfer of apolar ligands. The structural similarity of deoxycholate and brassinosteroids (BRs) ubiquitous plant steroid hormones, prompted the mass spectrometry (MS) study in order to examine whether BRs can bind to Bet v 1l. The MS analysis of a mixture of Bet v 1l and BRs revealed a specific non-covalent interaction of Bet v 1l with brassinolide and 24-epicastasterone. Together, our findings are consistent with a general plant-steroid carrier function for Bet v 1 and related PR-10 proteins. The role of BRs transport in PR-10 proteins may be of crucial importance in the plant defense response to pathological situations as well as in growth and development.


Assuntos
Alérgenos/química , Alérgenos/metabolismo , Fitosteróis/metabolismo , Proteínas de Plantas/química , Proteínas de Plantas/metabolismo , Pólen/química , Alérgenos/imunologia , Sequência de Aminoácidos , Antígenos de Plantas , Betula , Sítios de Ligação , Brassinosteroides , Colestanóis/metabolismo , Dicroísmo Circular , Cristalografia por Raios X , Ácido Desoxicólico/metabolismo , Interações Hidrofóbicas e Hidrofílicas , Modelos Moleculares , Dados de Sequência Molecular , Proteínas de Plantas/imunologia , Pólen/imunologia , Conformação Proteica , Isoformas de Proteínas/química , Isoformas de Proteínas/imunologia , Isoformas de Proteínas/metabolismo , Homologia de Sequência de Aminoácidos , Espectrometria de Massas por Ionização por Electrospray , Esteroides Heterocíclicos/metabolismo , Relação Estrutura-Atividade
16.
Phytochemistry ; 65(24): 3179-85, 2004 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-15561184

RESUMO

Phytochelatins are glutathione-derived, non-translationally synthesized peptides essential for cadmium and arsenic detoxification in plant, fungal and nematode model systems. Recent sequencing programs have revealed the existence of phytochelatin synthase-related genes in a wide range of organisms that have not been reported yet to produce phytochelatins. Among those are several cyanobacteria. We have studied one of the encoded proteins (alr0975 from Nostoc sp. strain PCC 7120) and demonstrate here that it does not possess phytochelatin synthase activity. Instead, this protein catalyzes the conversion of glutathione to gamma-glutamylcysteine. The thiol spectrum of yeast cells expressing alr0975 shows the disappearance of glutathione and the formation of a compound that by LC-MSMS analysis was unequivocally identified as gamma-glutamylcysteine. Purified recombinant protein catalyzes the respective reaction. Unlike phytochelatin synthesis, the conversion of glutathione to gamma-glutamylcysteine is not dependent on activation by metal cations. No evidence was found for the accumulation of phytochelatins in cyanobacteria even after prolonged exposure to toxic Cd2+ concentrations. Expression of alr0975 was detected in Nostoc sp. cells with an antiserum raised against the protein. No indication for a responsiveness of expression to toxic metal exposure was found. Taken together, these data provide further evidence for possible additional functions of phytochelatin synthase-related proteins in glutathione metabolism and provide a lead as to the evolutionary history of phytochelatin synthesis.


Assuntos
Aminoaciltransferases/metabolismo , Cianobactérias/enzimologia , Dipeptídeos/metabolismo , Glutationa/metabolismo , Sequência de Aminoácidos , Escherichia coli/genética , Escherichia coli/metabolismo , Dados de Sequência Molecular , Nostoc/enzimologia , Organismos Geneticamente Modificados , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Schizosaccharomyces/genética , Schizosaccharomyces/metabolismo , Homologia de Sequência de Aminoácidos
17.
J Mass Spectrom ; 44(4): 466-76, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19034950

RESUMO

Total phenolic choline ester fractions prepared from seeds of Arabidopsis thaliana and Brassica napus were analyzed by capillary LC/ESI-QTOF-MS and direct infusion ESI-FTICR-MS. In addition to the dominating sinapoylcholine, 30 phenolic choline esters could be identified based on accurate mass measurements, interpretation of collision-induced dissociation (CID) mass spectra, and synthesis of selected representatives. The compounds identified so far include substituted hydroxycinnamoyl- and hydroxybenzoylcholines, respective monohexosides as well as oxidative coupling products of phenolic choline esters and monolignols. Phenolic choline esters are well separable by reversed-phase liquid chromatography and sensitively detectable using electrospray ionization mass spectrometry in positive ion mode. CID mass spectra obtained from molecular ions facilitate the characterization of both the type and substitution pattern of such compounds. Therefore, LC/ESI-MS/MS represents a valuable tool for comprehensive qualitative and quantitative analysis of this compound class.


Assuntos
Arabidopsis/química , Eletrocromatografia Capilar , Colina/análise , Ésteres/análise , Fenóis/análise , Sementes/química , Espectrometria de Massas por Ionização por Electrospray , Brassica napus/química , Colina/química , Ésteres/química , Estrutura Molecular , Fenóis/química , Espectrometria de Massas em Tandem
18.
Plant Physiol ; 147(4): 2107-20, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18552234

RESUMO

Metabolomics is facing a major challenge: the lack of knowledge about metabolites present in a given biological system. Thus, large-scale discovery of metabolites is considered an essential step toward a better understanding of plant metabolism. We show here that the application of a metabolomics approach generating structural information for the analysis of Arabidopsis (Arabidopsis thaliana) mutants allows the efficient cataloging of metabolites. Fifty-six percent of the features that showed significant differences in abundance between seeds of wild-type, transparent testa4, and transparent testa5 plants could be annotated. Seventy-five compounds were structurally characterized, 21 of which could be identified. About 40 compounds had not been known from Arabidopsis before. Also, the high-resolution analysis revealed an unanticipated expansion of metabolic conversions upstream of biosynthetic blocks. Deficiency in chalcone synthase results in the increased seed-specific biosynthesis of a range of phenolic choline esters. Similarly, a lack of chalcone isomerase activity leads to the accumulation of various naringenin chalcone derivatives. Furthermore, our data provide insight into the connection between p-coumaroyl-coenzyme A-dependent pathways. Lack of flavonoid biosynthesis results in elevated synthesis not only of p-coumarate-derived choline esters but also of sinapate-derived metabolites. However, sinapoylcholine is not the only accumulating end product. Instead, we observed specific and sophisticated changes in the complex pattern of sinapate derivatives.


Assuntos
Arabidopsis/química , Arabidopsis/metabolismo , Sementes/química , Arabidopsis/genética , Cromatografia Líquida , Ciclotrons , Análise de Fourier , Mutação , Extratos Vegetais/química , Sementes/metabolismo , Espectrometria de Massas por Ionização por Electrospray
19.
J Exp Bot ; 57(15): 4003-13, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-17075075

RESUMO

Cadmium is a major environmental pollutant that enters human food via accumulation in crop plants. Responses of plants to cadmium exposure--which directly influence accumulation rates--are not well understood. In general, little is known about stress-elicited changes in plants at the proteome level. Alterations in the root proteome of hydroponically grown Arabidopsis thaliana plants treated with 10 microM Cd(2+) for 24 h are reported here. These conditions trigger the synthesis of phytochelatins (PCs), glutathione-derived metal-binding peptides, shown here as PC2 accumulation. Two-dimensional gel electrophoresis using different pH gradients in the first dimension detected on average approximately 1100 spots per gel type. Forty-one spots indicated significant changes in protein abundance upon Cd(2+) treatment. Seventeen proteins found in 25 spots were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Selected results were independently confirmed by western analysis and selective enrichment of a protein family (glutathione S-transferases) through affinity chromatography. Most of the identified proteins belong to four different classes: metabolic enzymes such as ATP sulphurylase, glycine hydroxymethyltransferase, and trehalose-6-phosphate phosphatase; glutathione S-transferases; latex allergen-like proteins; and unknown proteins. These results represent a basis for reverse genetics studies to better understand plant responses to toxic metal exposure and to the generation of internal sinks for reduced sulphur.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Cádmio/farmacologia , Proteoma/efeitos dos fármacos , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Eletroforese em Gel Bidimensional , Perfilação da Expressão Gênica , Glutationa/biossíntese , Concentração de Íons de Hidrogênio , Fitoquelatinas , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
20.
Plant J ; 29(4): 487-95, 2002 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-11846881

RESUMO

Lipopolysaccharide (LPS) is a ubiquitous component of Gram-negative bacteria which has a number of diverse biological effects on eukaryotic cells. In contrast to the large body of work in mammalian and insect cells, the effects of LPS on plant cells have received little attention. LPS can induce defense-related responses in plants, but in many cases these direct effects are weak. Here we have examined the effects of prior inoculation of LPS on the induction of plant defense-related responses by phytopathogenic xanthomonads in leaves of pepper (Capsicum annuum). The resistance of pepper to incompatible strains of Xanthomonas axonopodis pv. vesicatoria or to X. campestris pv. campestris is associated with increased synthesis of the hydroxycinnamoyl-tyramine conjugates, feruloyl-tyramine (FT) and coumaroyl-tyramine (CT). FT and CT are produced only in trace amounts in response to compatible strains of X. axonopodis pv. vesicatoria. Treatment of leaves with LPS from a number of bacteria did not induce the synthesis of FT and CT but altered the kinetics of induction upon subsequent bacterial inoculation. In incompatible interactions FT and CT synthesis was accelerated, whereas in compatible interactions synthesis was also considerably enhanced. The ability of the tissue to respond more rapidly was induced within 4 h of LPS treatment and the potentiated state was maintained for at least 38 h. Earlier treatment with LPS also potentiated the expression of other defense responses such as transcription of genes encoding acidic beta-1,3-glucanase. Our findings indicate a wider role for LPS in plant-bacterial interactions beyond its limited activity as a direct inducer of plant defenses.


Assuntos
Lipopolissacarídeos/farmacologia , Doenças das Plantas/genética , Tiramina/análogos & derivados , Capsicum/genética , Capsicum/metabolismo , Capsicum/microbiologia , Ácidos Cumáricos/metabolismo , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Glucana 1,3-beta-Glucosidase , Imunidade Inata/efeitos dos fármacos , Imunidade Inata/genética , Doenças das Plantas/microbiologia , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/microbiologia , Ácido Salicílico/metabolismo , Tiramina/biossíntese , Xanthomonas/crescimento & desenvolvimento , Xanthomonas/isolamento & purificação , beta-Glucosidase/genética , beta-Glucosidase/metabolismo
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