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1.
Cell ; 186(16): 3400-3413.e20, 2023 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-37541197

RESUMO

Approximately 15% of US adults have circulating levels of uric acid above its solubility limit, which is causally linked to the disease gout. In most mammals, uric acid elimination is facilitated by the enzyme uricase. However, human uricase is a pseudogene, having been inactivated early in hominid evolution. Though it has long been known that uric acid is eliminated in the gut, the role of the gut microbiota in hyperuricemia has not been studied. Here, we identify a widely distributed bacterial gene cluster that encodes a pathway for uric acid degradation. Stable isotope tracing demonstrates that gut bacteria metabolize uric acid to xanthine or short chain fatty acids. Ablation of the microbiota in uricase-deficient mice causes severe hyperuricemia, and anaerobe-targeted antibiotics increase the risk of gout in humans. These data reveal a role for the gut microbiota in uric acid excretion and highlight the potential for microbiome-targeted therapeutics in hyperuricemia.


Assuntos
Gota , Hominidae , Hiperuricemia , Adulto , Animais , Humanos , Camundongos , Gota/genética , Gota/metabolismo , Hominidae/genética , Hiperuricemia/genética , Mamíferos/metabolismo , Urato Oxidase/genética , Ácido Úrico/metabolismo , Evolução Molecular
3.
Nature ; 508(7497): 546-9, 2014 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-24670640

RESUMO

Angiosperms developed floral nectaries that reward pollinating insects. Although nectar function and composition have been characterized, the mechanism of nectar secretion has remained unclear. Here we identify SWEET9 as a nectary-specific sugar transporter in three eudicot species: Arabidopsis thaliana, Brassica rapa (extrastaminal nectaries) and Nicotiana attenuata (gynoecial nectaries). We show that SWEET9 is essential for nectar production and can function as an efflux transporter. We also show that sucrose phosphate synthase genes, encoding key enzymes for sucrose biosynthesis, are highly expressed in nectaries and that their expression is also essential for nectar secretion. Together these data are consistent with a model in which sucrose is synthesized in the nectary parenchyma and subsequently secreted into the extracellular space via SWEET9, where sucrose is hydrolysed by an apoplasmic invertase to produce a mixture of sucrose, glucose and fructose. The recruitment of SWEET9 for sucrose export may have been a key innovation, and could have coincided with the evolution of core eudicots and contributed to the evolution of nectar secretion to reward pollinators.


Assuntos
Arabidopsis/metabolismo , Glucosiltransferases/metabolismo , Néctar de Plantas/metabolismo , Proteínas de Plantas/metabolismo , Sacarose/metabolismo , Alquil e Aril Transferases/metabolismo , Animais , Arabidopsis/citologia , Arabidopsis/enzimologia , Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Brassica rapa/anatomia & histologia , Brassica rapa/enzimologia , Brassica rapa/metabolismo , Metabolismo dos Carboidratos , Espaço Extracelular/metabolismo , Flores/fisiologia , Glucosiltransferases/genética , Células HEK293 , Humanos , Proteínas de Membrana Transportadoras/metabolismo , Oócitos , Néctar de Plantas/biossíntese , Polinização , Transporte Proteico , Homologia de Sequência , Amido/metabolismo , Nicotiana/anatomia & histologia , Nicotiana/enzimologia , Nicotiana/metabolismo , Xenopus , beta-Frutofuranosidase/metabolismo
4.
Nature ; 468(7323): 527-32, 2010 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-21107422

RESUMO

Sugar efflux transporters are essential for the maintenance of animal blood glucose levels, plant nectar production, and plant seed and pollen development. Despite broad biological importance, the identity of sugar efflux transporters has remained elusive. Using optical glucose sensors, we identified a new class of sugar transporters, named SWEETs, and show that at least six out of seventeen Arabidopsis, two out of over twenty rice and two out of seven homologues in Caenorhabditis elegans, and the single copy human protein, mediate glucose transport. Arabidopsis SWEET8 is essential for pollen viability, and the rice homologues SWEET11 and SWEET14 are specifically exploited by bacterial pathogens for virulence by means of direct binding of a bacterial effector to the SWEET promoter. Bacterial symbionts and fungal and bacterial pathogens induce the expression of different SWEET genes, indicating that the sugar efflux function of SWEET transporters is probably targeted by pathogens and symbionts for nutritional gain. The metazoan homologues may be involved in sugar efflux from intestinal, liver, epididymis and mammary cells.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Glucose/metabolismo , Interações Hospedeiro-Patógeno/fisiologia , Proteínas de Membrana Transportadoras/metabolismo , Animais , Arabidopsis/genética , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , Transporte Biológico/genética , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Células HEK293 , Humanos , Modelos Biológicos , Oryza/genética , Oryza/metabolismo , Oryza/microbiologia , RNA Mensageiro/metabolismo , Saccharomyces cerevisiae/genética , Xenopus/genética
5.
Biosci Biotechnol Biochem ; 80(1): 162-5, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26214383

RESUMO

Trehalose acts as a stress protectant and an autophagy inducer in mammalian cells. The molecular mechanisms of action remain obscure because intracellular trehalose at micromolar level is difficult to quantitate. Here, we show a novel trehalose monitoring technology based on FRET. FLIP-suc90µ∆1Venus sensor expressed in mammalian cells enables to quickly and non-destructively detect an infinitesimal amount of intracellular trehalose.


Assuntos
Proteínas de Bactérias/genética , Técnicas Biossensoriais , Proteínas de Transporte/genética , Transferência Ressonante de Energia de Fluorescência/métodos , Vetores Genéticos/metabolismo , Proteínas Luminescentes/genética , Trealose/análise , Animais , Proteínas de Bactérias/metabolismo , Proteínas de Transporte/metabolismo , Citoplasma/efeitos dos fármacos , Citoplasma/metabolismo , Dípteros , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Vetores Genéticos/química , Células HEK293 , Humanos , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Proteínas Luminescentes/metabolismo , Transfecção , Trealose/metabolismo , Trealose/farmacologia
6.
Proc Natl Acad Sci U S A ; 110(39): E3685-94, 2013 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-24027245

RESUMO

Eukaryotic sugar transporters of the MFS and SWEET superfamilies consist of 12 and 7 α-helical transmembrane domains (TMs), respectively. Structural analyses indicate that MFS transporters evolved from a series of tandem duplications of an ancestral 3-TM unit. SWEETs are heptahelical proteins carrying a tandem repeat of 3-TM separated by a single TM. Here, we show that prokaryotes have ancestral SWEET homologs with only 3-TM and that the Bradyrhizobium japonicum SemiSWEET1, like Arabidopsis SWEET11, mediates sucrose transport. Eukaryotic SWEETs most likely evolved by internal duplication of the 3-TM, suggesting that SemiSWEETs form oligomers to create a functional pore. However, it remains elusive whether the 7-TM SWEETs are the functional unit or require oligomerization to form a pore sufficiently large to allow for sucrose passage. Split ubiquitin yeast two-hybrid and split GFP assays indicate that Arabidopsis SWEETs homo- and heterooligomerize. We examined mutant SWEET variants for negative dominance to test if oligomerization is necessary for function. Mutation of the conserved Y57 or G58 in SWEET1 led to loss of activity. Coexpression of the defective mutants with functional A. thaliana SWEET1 inhibited glucose transport, indicating that homooligomerization is necessary for function. Collectively, these data imply that the basic unit of SWEETs, similar to MFS sugar transporters, is a 3-TM unit and that a functional transporter contains at least four such domains. We hypothesize that the functional unit of the SWEET family of transporters possesses a structure resembling the 12-TM MFS structure, however, with a parallel orientation of the 3-TM unit.


Assuntos
Proteínas de Bactérias/metabolismo , Metabolismo dos Carboidratos , Proteínas de Membrana Transportadoras/metabolismo , Família Multigênica , Proteínas de Plantas/metabolismo , Multimerização Proteica , Sacarose/metabolismo , Aminoácidos/metabolismo , Arabidopsis/metabolismo , Proteínas de Bactérias/química , Transporte Biológico , Bradyrhizobium/metabolismo , Teste de Complementação Genética , Glucose/metabolismo , Proteínas de Fluorescência Verde/metabolismo , Proteínas de Membrana Transportadoras/química , Modelos Biológicos , Filogenia , Proteínas de Plantas/química , Estrutura Secundária de Proteína , Saccharomyces cerevisiae/metabolismo , Transdução de Sinais , Relação Estrutura-Atividade
7.
Mol Plant Microbe Interact ; 27(11): 1186-98, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25083909

RESUMO

The gene-for-gene concept has historically been applied to describe a specific resistance interaction wherein single genes from the host and the pathogen dictate the outcome. These interactions have been observed across the plant kingdom and all known plant microbial pathogens. In recent years, this concept has been extended to susceptibility phenotypes in the context of transcription activator-like (TAL) effectors that target SWEET sugar transporters. However, because this interaction has only been observed in rice, it was not clear whether the gene-for-gene susceptibility was unique to that system. Here, we show, through a combined systematic analysis of the TAL effector complement of Xanthomonas axonopodis pv. manihotis and RNA sequencing to identify targets in cassava, that TAL20Xam668 specifically induces the sugar transporter MeSWEET10a to promote virulence. Designer TAL effectors (dTALE) complement TAL20Xam668 mutant phenotypes, demonstrating that MeSWEET10a is a susceptibility gene in cassava. Sucrose uptake-deficient X. axonopodis pv. manihotis bacteria do not lose virulence, indicating that sucrose may be cleaved extracellularly and taken up as hexoses into X. axonopodis pv. manihotis. Together, our data suggest that pathogen hijacking of plant nutrients is not unique to rice blight but also plays a role in bacterial blight of the dicot cassava.


Assuntos
Proteínas de Bactérias/metabolismo , Regulação da Expressão Gênica de Plantas , Manihot/microbiologia , Doenças das Plantas/microbiologia , Xanthomonas axonopodis/patogenicidade , Proteínas de Bactérias/genética , Resistência à Doença , Expressão Gênica , Manihot/genética , Manihot/imunologia , Proteínas de Membrana Transportadoras/genética , Proteínas de Membrana Transportadoras/metabolismo , Mutação , Doenças das Plantas/imunologia , Folhas de Planta/genética , Folhas de Planta/microbiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Análise de Sequência de RNA , Nicotiana/genética , Nicotiana/imunologia , Nicotiana/microbiologia , Regulação para Cima , Virulência , Xanthomonas axonopodis/genética
8.
Nat Microbiol ; 7(5): 695-706, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35505245

RESUMO

Gut bacteria face a key problem in how they capture enough energy to sustain their growth and physiology. The gut bacterium Clostridium sporogenes obtains its energy by utilizing amino acids in pairs, coupling the oxidation of one to the reduction of another-the Stickland reaction. Oxidative pathways produce ATP via substrate-level phosphorylation, whereas reductive pathways are thought to balance redox. In the present study, we investigated whether these reductive pathways are also linked to energy generation and the production of microbial metabolites that may circulate and impact host physiology. Using metabolomics, we find that, during growth in vitro, C. sporogenes produces 15 metabolites, 13 of which are present in the gut of C. sporogenes-colonized mice. Four of these compounds are reductive Stickland metabolites that circulate in the blood of gnotobiotic mice and are also detected in plasma from healthy humans. Gene clusters for reductive Stickland pathways suggest involvement of electron transfer proteins, and experiments in vitro demonstrate that reductive metabolism is coupled to ATP formation and not just redox balance. Genetic analysis points to the broadly conserved Rnf complex as a key coupling site for energy transduction. Rnf complex mutants show aberrant amino acid metabolism in a defined medium and are attenuated for growth in the mouse gut, demonstrating a role of the Rnf complex in Stickland metabolism and gut colonization. Our findings reveal that the production of circulating metabolites by a commensal bacterium within the host gut is linked to an ATP-yielding redox process.


Assuntos
Clostridium , Metabolômica , Trifosfato de Adenosina/metabolismo , Animais , Bactérias/metabolismo , Clostridium/genética , Clostridium/metabolismo , Fermentação , Camundongos
9.
Science ; 335(6065): 207-11, 2012 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-22157085

RESUMO

Plants transport fixed carbon predominantly as sucrose, which is produced in mesophyll cells and imported into phloem cells for translocation throughout the plant. It is not known how sucrose migrates from sites of synthesis in the mesophyll to the phloem, or which cells mediate efflux into the apoplasm as a prerequisite for phloem loading by the SUT sucrose-H(+) (proton) cotransporters. Using optical sucrose sensors, we identified a subfamily of SWEET sucrose efflux transporters. AtSWEET11 and 12 localize to the plasma membrane of the phloem. Mutant plants carrying insertions in AtSWEET11 and 12 are defective in phloem loading, thus revealing a two-step mechanism of SWEET-mediated export from parenchyma cells feeding H(+)-coupled import into the sieve element-companion cell complex. We discuss how restriction of intercellular transport to the interface of adjacent phloem cells may be an effective mechanism to limit the availability of photosynthetic carbon in the leaf apoplasm in order to prevent pathogen infections.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Floema/metabolismo , Sacarose/metabolismo , Animais , Arabidopsis/genética , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Transporte Biológico , Membrana Celular/metabolismo , Transferência Ressonante de Energia de Fluorescência , Células HEK293 , Humanos , Proteínas de Membrana Transportadoras/genética , Proteínas Mutantes/metabolismo , Oryza/metabolismo , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Regiões Promotoras Genéticas
10.
Nat Protoc ; 6(11): 1818-33, 2011 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-22036884

RESUMO

Knowledge of the in vivo levels, distribution and flux of ions and metabolites is crucial to our understanding of physiology in both healthy and diseased states. The quantitative analysis of the dynamics of ions and metabolites with subcellular resolution in vivo poses a major challenge for the analysis of metabolic processes. Genetically encoded Förster resonance energy transfer (FRET) sensors can be used for real-time in vivo detection of metabolites. FRET sensor proteins, for example, for glucose, can be targeted genetically to any cellular compartment, or even to subdomains (e.g., a membrane surface), by adding signal sequences or fusing the sensors to specific proteins. The sensors can be used for analyses in individual mammalian cells in culture, in tissue slices and in intact organisms. Applications include gene discovery, high-throughput drug screens or systematic analysis of regulatory networks affecting uptake, efflux and metabolism. Quantitative analyses obtained with the help of FRET sensors for glucose or other ions and metabolites provide valuable data for modeling of flux. Here we provide a detailed protocol for monitoring glucose levels in the cytosol of mammalian cell cultures through the use of FRET glucose sensors; moreover, the protocol can be used for other ions and metabolites and for analyses in other organisms, as has been successfully demonstrated in bacteria, yeast and even intact plants. The whole procedure typically takes ∼4 d including seeding and transfection of mammalian cells; the FRET-based analysis of transfected cells takes ∼5 h.


Assuntos
Transferência Ressonante de Energia de Fluorescência/instrumentação , Transferência Ressonante de Energia de Fluorescência/métodos , Animais , Linhagem Celular , Glucose/metabolismo , Humanos
11.
Cell Calcium ; 46(2): 130-5, 2009 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19628278

RESUMO

Calcium serves as a second messenger in glucose-triggered insulin secretion of pancreatic cells. Less is known about sugar signaling in non-excitable cells. Here, the high sensitivity FRET calcium sensor TN-XXL was used to characterize glucose-induced calcium responses in non-excitable human embryonic kidney HEK293T cells. HEK293T cells responded to perfusion with glucose with a sustained and concentration-dependent increase in cytosolic calcium levels. Sucrose and mannitol triggered comparable calcium responses, suggesting that the increase of the calcium concentration was caused by osmotic effects. HEK293T cells are characterized by low endogenous glucose uptake capacity as shown with a high sensitivity glucose sensor. Consistently, when glucose influx was artificially increased by co-expression of GLUT glucose transporters, the glucose-induced calcium increase was significantly reduced. Neither calcium depletion, nor gadolinium or thapsigargin were able to inhibit the calcium accumulation. Taken together, membrane impermeable osmolytes such as sucrose and mannitol lead to an increase in calcium levels, while the effect of glucose depends on the cell's glucose uptake capacity and will thus vary between cell types in the body that differ in their glucose uptake capacity.


Assuntos
Técnicas Biossensoriais , Cálcio/metabolismo , Corantes Fluorescentes/metabolismo , Transportador de Glucose Tipo 1/metabolismo , Glucose/metabolismo , Rim/metabolismo , Linhagem Celular , Citosol/efeitos dos fármacos , Citosol/metabolismo , Transferência Ressonante de Energia de Fluorescência , Gadolínio/farmacologia , Transportador de Glucose Tipo 1/genética , Humanos , Transporte de Íons/efeitos dos fármacos , Transporte de Íons/genética , Rim/patologia , Manitol/metabolismo , Osmose/efeitos dos fármacos , Sacarose/metabolismo , Tapsigargina/farmacologia , Transfecção
12.
Plant J ; 53(1): 144-56, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18047473

RESUMO

The non-protein amino acid beta-aminobutyric acid (BABA) primes Arabidopsis to respond more quickly and strongly to pathogen and osmotic stress. Here, we report that BABA also significantly enhances acquired thermotolerance in Arabidopsis. This thermotolerance was dependent on heat shock protein 101, a critical component of the normal heat-shock response. BABA did not enhance basal thermotolerance under a severe heat-shock treatment. No roles for the hormones ethylene and salicylic acid in BABA-induced acquired thermotolerance were identified by mutant analysis. Using global gene expression analysis, transcript levels for several transcription factors and DNA binding proteins regulating responses to the stress hormone abscisic acid (ABA) were found to be elevated in BABA-treated plants compared with water-treated plants. The role of ABA in BABA-induced thermotolerance was complex. BABA-enhanced thermotolerance was partially compromised in the ABA-insensitive mutant, abi1-1, but was augmented in abi2-1. In an unrelated process, BABA, like ABA, inhibited root growth, and the level of inhibition was roughly additive in roots treated with both compounds. Root growth of both abi1-1 and abi2-1 was also inhibited by BABA. Unexpectedly, abi1-1 and abi2-1 root growth was inhibited more strongly by combined ABA and BABA treatments than by BABA alone. Our results, together with previously published data, suggest that BABA is a general enhancer of plant stress resistance, and that cross-talk occurs between BABA and ABA signalling cascades. Specifically, the BABA-mediated accumulation of ABA transcription factors without concomitant activation of a downstream ABA response could represent one component of the BABA-primed state in Arabidopsis.


Assuntos
Ácido Abscísico/metabolismo , Aclimatação/genética , Aminobutiratos/farmacocinética , Arabidopsis/genética , Arabidopsis/fisiologia , Temperatura Alta , Transdução de Sinais/fisiologia , Ácido Abscísico/farmacologia , Aminobutiratos/metabolismo , Proteínas de Choque Térmico/metabolismo , Plântula/fisiologia , Xenobióticos
13.
Mol Plant ; 1(3): 510-27, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-19825557

RESUMO

The lesion-mimic Arabidopsis mutant, syp121 syp122, constitutively expresses the salicylic acid (SA) signaling pathway and has low penetration resistance to powdery mildew fungi. Genetic analyses of the lesion-mimic phenotype have expanded our understanding of programmed cell death (PCD) in plants. Inactivation of SA signaling genes in syp121 syp122 only partially rescues the lesion-mimic phenotype, indicating that additional defenses contribute to the PCD. Whole genome transcriptome analysis confirmed that SA-induced transcripts, as well as numerous other known pathogen-response transcripts, are up-regulated after inactivation of the syntaxin genes. A suppressor mutant analysis of syp121 syp122 revealed that FMO1, ALD1, and PAD4 are important for lesion development. Mutant alleles of EDS1, NDR1, RAR1, and SGT1b also partially rescued the lesion-mimic phenotype, suggesting that mutating syntaxin genes stimulates TIR-NB-LRR and CC-NB-LRR-type resistances. The syntaxin double knockout potentiated a powdery mildew-induced HR-like response. This required functional PAD4 but not functional SA signaling. However, SA signaling potentiated the PAD4-dependent HR-like response. Analyses of quadruple mutants suggest that EDS5 and SID2 confer separate SA-independent signaling functions, and that FMO1 and ALD1 mediate SA-independent signals that are NPR1-dependent. These studies highlight the contribution of multiple pathways to defense and point to the complexity of their interactions.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/fisiologia , Doenças das Plantas/prevenção & controle , Proteínas Qa-SNARE/genética , Transdução de Sinais/fisiologia , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Proteínas de Arabidopsis/fisiologia , Hidrolases de Éster Carboxílico/genética , Proteínas de Transporte/fisiologia , Proteínas de Ciclo Celular/fisiologia , Ciclopentanos/farmacologia , Proteínas de Ligação a DNA/fisiologia , Perfilação da Expressão Gênica , Variação Genética/efeitos dos fármacos , Peptídeos e Proteínas de Sinalização Intracelular , Mutação , Oxilipinas/farmacologia , Fenótipo , Doenças das Plantas/genética , Proteínas Qa-SNARE/fisiologia , Transdução de Sinais/efeitos dos fármacos , Transaminases/genética , Fatores de Transcrição/fisiologia , Transcrição Gênica
14.
Plant Cell ; 19(11): 3379-90, 2007 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18055602

RESUMO

The Arabidopsis thaliana REVOLUTA (REV) protein is a member of the class III homeodomain-leucine zipper (HD-ZIPIII) proteins. REV is a potent regulator of leaf polarity and vascular development. Here, we report the identification of a gene family that encodes small leucine zipper-containing proteins (LITTLE ZIPPER [ZPR] proteins) where the leucine zipper is similar to that found in REV, PHABULOSA, and PHAVOLUTA proteins. The transcript levels of the ZPR genes increase in response to activation of a steroid-inducible REV protein. We show that the ZPR proteins interact with REV in vitro and that ZPR3 prevents DNA binding by REV in vitro. Overexpression of ZPR proteins in Arabidopsis results in phenotypes similar to those seen when HD-ZIPIII function is reduced. We propose a negative feedback model in which REV promotes transcription of the ZPR genes. The ZPR proteins in turn form heterodimers with the REV protein, preventing it from binding DNA. The HD-ZIPIII/ZPR regulatory module would serve not only to dampen the effect of fluctuations in HD-ZIPIII protein levels but more importantly would provide a potential point of regulation (control over the ratio of inactive heterodimers to active homodimers) that could be influenced by other components of the pathway governing leaf polarity.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Retroalimentação Fisiológica , Genes de Plantas , Sequência de Aminoácidos , Arabidopsis/citologia , Arabidopsis/efeitos dos fármacos , Proteínas de Arabidopsis/química , Dexametasona/farmacologia , Retroalimentação Fisiológica/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Proteínas de Homeodomínio/metabolismo , Dados de Sequência Molecular , Folhas de Planta/citologia , Folhas de Planta/efeitos dos fármacos , Ligação Proteica/efeitos dos fármacos
15.
Plant Cell ; 18(3): 731-46, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16473969

RESUMO

Arabidopsis thaliana is a host to the powdery mildew Erysiphe cichoracearum and nonhost to Blumeria graminis f. sp hordei, the powdery mildew pathogenic on barley (Hordeum vulgare). Screening for Arabidopsis mutants deficient in resistance to barley powdery mildew identified PENETRATION3 (PEN3). pen3 plants permitted both increased invasion into epidermal cells and initiation of hyphae by B. g. hordei, suggesting that PEN3 contributes to defenses at the cell wall and intracellularly. pen3 mutants were compromised in resistance to the necrotroph Plectosphaerella cucumerina and to two additional inappropriate biotrophs, pea powdery mildew (Erysiphe pisi) and potato late blight (Phytophthora infestans). Unexpectedly, pen3 mutants were resistant to E. cichoracearum. This resistance was salicylic acid-dependent and correlated with chlorotic patches. Consistent with this observation, salicylic acid pathway genes were hyperinduced in pen3 relative to the wild type. The phenotypes conferred by pen3 result from the loss of function of PLEIOTROPIC DRUG RESISTANCE8 (PDR8), a highly expressed putative ATP binding cassette transporter. PEN3/PDR8 tagged with green fluorescent protein localized to the plasma membrane in uninfected cells. In infected leaves, the protein concentrated at infection sites. PEN3/PDR8 may be involved in exporting toxic materials to attempted invasion sites, and intracellular accumulation of these toxins in pen3 may secondarily activate the salicylic acid pathway.


Assuntos
Transportadores de Cassetes de Ligação de ATP/fisiologia , Arabidopsis/metabolismo , Arabidopsis/microbiologia , Doenças das Plantas/microbiologia , Transportadores de Cassetes de Ligação de ATP/química , Transportadores de Cassetes de Ligação de ATP/genética , Motivos de Aminoácidos , Sequência de Aminoácidos , Arabidopsis/genética , Ascomicetos/patogenicidade , Morte Celular/fisiologia , Ciclopentanos/metabolismo , Perfilação da Expressão Gênica , Imunidade Inata/fisiologia , Modelos Biológicos , Dados de Sequência Molecular , Análise de Sequência com Séries de Oligonucleotídeos , Oomicetos/patogenicidade , Oxilipinas , Folhas de Planta/anatomia & histologia , Folhas de Planta/genética , Folhas de Planta/microbiologia , Estrutura Terciária de Proteína , Ácido Salicílico/metabolismo , Alinhamento de Sequência , Transdução de Sinais
16.
Science ; 301(5635): 969-72, 2003 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-12920300

RESUMO

Plants attacked by pathogens rapidly deposit callose, a beta-1,3-glucan, at wound sites. Traditionally, this deposition is thought to reinforce the cell wall and is regarded as a defense response. Surprisingly, here we found that powdery mildew resistant 4 (pmr4), a mutant lacking pathogen-induced callose, became resistant to pathogens, rather than more susceptible. This resistance was due to mutation of a callose synthase, resulting in a loss of the induced callose response. Double-mutant analysis indicated that blocking the salicylic acid (SA) defense signaling pathway was sufficient to restore susceptibility to pmr4 mutants. Thus, callose or callose synthase negatively regulates the SA pathway.


Assuntos
Arabidopsis/metabolismo , Arabidopsis/microbiologia , Ascomicetos/fisiologia , Glucosiltransferases/genética , Proteínas de Membrana , Doenças das Plantas , Ácido Salicílico/metabolismo , Proteínas de Schizosaccharomyces pombe , Alelos , Arabidopsis/citologia , Arabidopsis/genética , Morte Celular , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Glucanos/metabolismo , Glucosiltransferases/metabolismo , Mutação , Análise de Sequência com Séries de Oligonucleotídeos , Fenótipo , Folhas de Planta/metabolismo , Transdução de Sinais
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