Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.205
Filtrar
1.
Toxicol Lett ; 340: 15-22, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33421552

RESUMO

Alternariol is a mycotoxin produced by Alternaria spp. relevant to the food safety area due to its abundance in certain foods. The shortage of data on its toxicology, also as a part of chemical mixtures, prevents setting regulation to limit its abundance in food. To extend knowledge on the possible mechanisms underpinning alternariol toxicology in chemical mixtures, this work assessed the effects of urolithin C, a structurally related gut ellagitannin-derived metabolite, on its absorption and phase II metabolism in a monolayer of Caco-2 cells. A computational study was also used to provide a mechanistic explanation for the results obtained. Urolithin C influenced transport and phase II metabolism of alternariol with a late reduction of transport to the basolateral compartment. Moreover, it caused an early effect in terms of accumulation of alternariol glucuronides in the basolateral compartment, followed by a late reduction of glucuronides in both compartments. Concerning alternariol sulfates, the data collected pointed to a possible competition of urolithin C for the sulfotransferases resulting in a reduced production of alternariol sulfates. Our results provide a compelling line-of-evidence pointing to the need to systematically tackle the evaluation of mycotoxin toxicity in the context of chemical mixture.


Assuntos
Taninos Hidrolisáveis/metabolismo , Lactonas/metabolismo , Arilsulfotransferase/metabolismo , Transporte Biológico , Células CACO-2 , Sobrevivência Celular , Humanos , Simulação de Acoplamento Molecular , Estrutura Molecular , Conformação Proteica
2.
Food Chem ; 338: 128134, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33091996

RESUMO

Lactic acid bacteria can improve their resistance to adverse environments through the formation of biofilm. This study found that adding different buffer salts in culture medium had a great impact on the freeze-drying survival rate of the Lactobacillus plantarum LIP-1, which could be linked to biofilm formation. Transcriptome data showed that potassium ions in buffer salt increased the expression of the luxS gene in the LuxS/autoinducer-2 (AI-2) quorum sensing system and increase synthesis of the quorum sensing signal AI-2. The AI-2 signal molecules up-regulated the cysE gene, which helps to promote biofilm formation. By adding a biofilm inhibitor, d-galactose, and performing a real-time quantitative polymerase chain reaction experiment, we found that d-galactose could down-regulated the luxS and cysE genes, reduced biofilm formation, and decreased the freeze-drying survival rate. The results of this study showed that promoting biofilm formation using appropriate buffer salts may lead to better freeze-drying survival rates.


Assuntos
Biofilmes/crescimento & desenvolvimento , Meios de Cultura/química , Liofilização/métodos , Lactobacillus plantarum/efeitos dos fármacos , Lactobacillus plantarum/fisiologia , Viabilidade Microbiana/efeitos dos fármacos , Sais/farmacologia , Proteínas de Bactérias/metabolismo , Biofilmes/efeitos dos fármacos , Tampões (Química) , Liases de Carbono-Enxofre/genética , Relação Dose-Resposta a Droga , Homosserina/análogos & derivados , Homosserina/metabolismo , Lactobacillus plantarum/citologia , Lactobacillus plantarum/metabolismo , Lactonas/metabolismo , Percepção de Quorum/efeitos dos fármacos , Taxa de Sobrevida
3.
Chemosphere ; 262: 127602, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32750589

RESUMO

A 1 L lab-scale anaerobic ammonium oxidation (anammox) biofilm reactor with nitrogen loading rate of 0.11 g/L d was run for 110 days with the operation temperature declining from 36 °C to 15 °C. The total inorganic nitrogen removal efficiency showed a reduction from 80% to 66%, when the temperature declined from 36 °C to 15 °C. N-acyl-l-homoserine lactones (AHLs) concentrations, especially C8-HSL and C6-HSL, declined in both water and biomass phases, and this decline indicated that the quorum sensing weakened. Microbial community analysis revealed that Candidatus Kuenenia was the predominant anammox bacteria during the entire operating period. The abundance of Candidatus Kuenenia increased from 1.43% to 22.89% when the temperature decreasing from 36 °C to 15 °C. The correlation between microbial genus and AHLs was complicated. Overall, the temperature decrease weakened the quorum sensing so that the nitrogen removal performance deteriorated, and increasing the anammox activity might be an efficient way to improve performance.


Assuntos
Reatores Biológicos/microbiologia , Homosserina/metabolismo , Lactonas/metabolismo , Microbiota , Bactérias/classificação , Biofilmes , Biomassa , Nitrogênio , Oxirredução , Percepção de Quorum , Temperatura
4.
Nat Commun ; 11(1): 5371, 2020 10 23.
Artigo em Inglês | MEDLINE | ID: mdl-33097715

RESUMO

Autoinducer-2 (AI-2) is a quorum sensing signal that mediates communication within and between many bacterial species. However, its known receptors (LuxP and LsrB families) are not found in all the bacteria capable of responding to this signaling molecule. Here, we identify a third type of AI-2 receptor, consisting of a dCACHE domain. AI-2 binds to the dCACHE domain of chemoreceptors PctA and TlpQ of Pseudomonas aeruginosa, thus inducing chemotaxis and biofilm formation. Boron-free AI-2 is the preferred ligand for PctA and TlpQ. AI-2 also binds to the dCACHE domains of histidine kinase KinD from Bacillus subtilis and diguanylate cyclase rpHK1S-Z16 from Rhodopseudomonas palustris, enhancing their enzymatic activities. dCACHE domains (especially those belonging to a subfamily that includes the AI-2 receptors identified in the present work) are present in a large number of bacterial and archaeal proteins. Our results support the idea that AI-2 serves as a widely used signaling molecule in the coordination of cell behavior among prokaryotic species.


Assuntos
Quimiotaxia/fisiologia , Homosserina/análogos & derivados , Homosserina/metabolismo , Lactonas/metabolismo , Células Procarióticas/metabolismo , Proteínas Arqueais , Bactérias/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Biofilmes/crescimento & desenvolvimento , Liases de Carbono-Enxofre/genética , Liases de Carbono-Enxofre/metabolismo , Proteínas de Transporte/metabolismo , Escherichia coli/metabolismo , Proteínas de Escherichia coli , Homosserina/química , Homosserina/genética , Lactonas/química , Ligantes , Fósforo-Oxigênio Liases , Pseudomonas aeruginosa/metabolismo , Percepção de Quorum , Rodopseudomonas/metabolismo , Transdução de Sinais/fisiologia
5.
Proc Natl Acad Sci U S A ; 117(33): 19720-19730, 2020 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-32732435

RESUMO

The synthesis of quinolinic acid from tryptophan is a critical step in the de novo biosynthesis of nicotinamide adenine dinucleotide (NAD+) in mammals. Herein, the nonheme iron-based 3-hydroxyanthranilate-3,4-dioxygenase responsible for quinolinic acid production was studied by performing time-resolved in crystallo reactions monitored by UV-vis microspectroscopy, electron paramagnetic resonance (EPR) spectroscopy, and X-ray crystallography. Seven catalytic intermediates were kinetically and structurally resolved in the crystalline state, and each accompanies protein conformational changes at the active site. Among them, a monooxygenated, seven-membered lactone intermediate as a monodentate ligand of the iron center at 1.59-Å resolution was captured, which presumably corresponds to a substrate-based radical species observed by EPR using a slurry of small-sized single crystals. Other structural snapshots determined at around 2.0-Å resolution include monodentate and subsequently bidentate coordinated substrate, superoxo, alkylperoxo, and two metal-bound enol tautomers of the unstable dioxygenase product. These results reveal a detailed stepwise O-atom transfer dioxygenase mechanism along with potential isomerization activity that fine-tunes product profiling and affects the production of quinolinic acid at a junction of the metabolic pathway.


Assuntos
3-Hidroxiantranilato 3,4-Dioxigenase/química , Proteínas de Bactérias/química , Cupriavidus/enzimologia , 3-Hidroxiantranilato 3,4-Dioxigenase/genética , 3-Hidroxiantranilato 3,4-Dioxigenase/metabolismo , Animais , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Domínio Catalítico , Cristalização , Cristalografia por Raios X , Cupriavidus/química , Cupriavidus/genética , Cinética , Lactonas/química , Lactonas/metabolismo , Modelos Moleculares , Especificidade por Substrato
6.
PLoS Biol ; 18(8): e3000830, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32810128

RESUMO

Plants are attacked by herbivores, which often specialize on different tissues, and in response, have evolved sophisticated resistance strategies that involve different types of chemical defenses frequently targeted to different tissues. Most known phytohormones have been implicated in regulating these defenses, with jasmonates (JAs) playing a pivotal role in complex regulatory networks of signaling interactions, often generically referred to as "cross talk." The newly identified class of phytohormones, strigolactones (SLs), known to regulate the shoot architecture, remain unstudied with regard to plant-herbivore interactions. We explored the role of SL signaling in resistance to a specialist weevil (Trichobaris mucorea) herbivore of the native tobacco, Nicotiana attenuata, that attacks the root-shoot junction (RSJ), the part of the plant most strongly influenced by alterations in SL signaling (increased branching). As SL signaling shares molecular components, such as the core F-box protein MORE AXILLARY GROWTH 2 (MAX2), with another new class of phytohormones, the karrikins (KARs), which promote seed germination and seedling growth, we generated transformed lines, individually silenced in the expression of NaMAX2, DWARF 14 (NaD14: the receptor for SL) and CAROTENOID CLEAVAGE DIOXYGENASE 7 (NaCCD7: a key enzyme in SL biosynthesis), and KARRIKIN INSENSITIVE 2 (NaKAI2: the KAR receptor). The mature stems of all transgenic lines impaired in the SL, but not the KAR signaling pathway, overaccumulated anthocyanins, as did the stems of plants attacked by the larvae of weevil, which burrow into the RSJs to feed on the pith of N. attenuata stems. T. mucorea larvae grew larger in the plants silenced in the SL pathway, but again, not in the KAI2-silenced plants. These phenotypes were associated with elevated JA and auxin (indole-3-acetic acid [IAA]) levels and significant changes in the accumulation of defensive compounds, including phenolamides and nicotine. The overaccumulation of phenolamides and anthocyanins in the SL pathway-silenced plants likely resulted from antagonism between the SL and JA pathway in N. attenuata. We show that the repressors of SL signaling, suppressor of max2-like (NaSMXL6/7), and JA signaling, jasmonate zim-domain (NaJAZs), physically interact, promoting NaJAZb degradation and releasing JASMONATE INSENSITIVE 1 (JIN1/MYC2) (NaMYC2), a critical transcription factor promoting JA responses. However, the increased performance of T. mucorea larvae resulted from lower pith nicotine levels, which were inhibited by increased IAA levels in SL pathway-silenced plants. This inference was confirmed by decapitation and auxin transport inhibitor treatments that decreased pith IAA and increased nicotine levels. In summary, SL signaling tunes specific sectors of specialized metabolism in stems, such as phenylpropanoid and nicotine biosynthesis, by tailoring the cross talk among phytohormones, including JA and IAA, to mediate herbivore resistance of stems. The metabolic consequences of the interplay of SL, JA, and IAA signaling revealed here could provide a mechanism for the commonly observed pattern of herbivore tolerance/resistance trade-offs.


Assuntos
Herbivoria/fisiologia , Interações Hospedeiro-Parasita , Lactonas/metabolismo , Caules de Planta/metabolismo , Caules de Planta/parasitologia , Transdução de Sinais , Tabaco/metabolismo , Tabaco/parasitologia , Animais , Antocianinas/metabolismo , Ciclopentanos/metabolismo , Ácidos Indolacéticos/metabolismo , Larva , Metabolômica , Oxilipinas/metabolismo , Proteínas de Plantas/metabolismo , Interferência de RNA , Gorgulhos/fisiologia
7.
DNA Cell Biol ; 39(10): 1850-1861, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32790504

RESUMO

Strigolactones (SLs) are the major plant hormones that play important roles in regulating organ development and environmental stress tolerance in plants. Even though the SL-related genes have been identified and well characterized in some plants, the information of SL-related genes in soybean is not fully established yet, especially in response to salt and alkaline stresses. In this study, we identified nine SL biosynthetic genes that include two D27, two CCD7, two CCD8, and three MAX1, as well as seven SL signaling genes that comprised two D14, two MAX2, and three D53 in the soybean genome. We found that SL biosynthetic and signaling genes are evolutionary conserved among different species. Syntenic analysis of these genes revealed their location on nine chromosomes as well as the presence of 10 pairs of duplication genes. Moreover, plant hormone and stress-responsive elements were identified in the promoter regions of SL biosynthetic and signaling genes. By using reverse transcription quantitative real-time PCR, we confirmed that SL genes have different tissue expressions in roots, stems, and leaves. The expression profile of SL biosynthetic and signaling genes under salt and alkaline stresses further confirmed the regulatory roles of SL biosynthetic and signaling genes under stress. In conclusion, we identified and provided valuable information on the soybean SL biosynthetic and signaling genes, and established a foundation for further functional analysis of soybean SL-related genes in response to salt and alkaline stresses.


Assuntos
Compostos Heterocíclicos com 3 Anéis/metabolismo , Lactonas/metabolismo , Proteínas de Plantas/genética , Estresse Salino , Soja/genética , Cromossomos de Plantas/genética , Duplicação Gênica , Proteínas de Plantas/metabolismo , Transdução de Sinais , Soja/metabolismo , Sintenia
8.
Gene ; 758: 144961, 2020 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-32693148

RESUMO

Ginkgo biloba L. is regarded as the most ancient living tree, and its kernel has been used as a traditional Chinese medicine for more than 2,000 years. The leaf extracts of this tree have been among the bestselling herbal remedies in Western countries since the last century. To understand the biosynthesis of the pharmacologically active ingredients in G. biloba, flavonoids and terpenoid trilactones (TTLs), we sequenced the transcriptomes of G. biloba leaves, kernels and testae with Iso-Seq and RNA-Seq technologies and obtained 152,524 clean consensus reads. When these reads were used to improve the annotation of the G. biloba genome, 4,856 novel genes, 25,583 new isoforms of previously annotated genes and 4,363 lncRNAs were discovered. Gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses indicated that genes involved in growth, regulation and response to stress were more likely to be regulated by alternative splicing (AS) or alternative polyadenylation (APA), which represent the two most important posttranscriptional regulation mechanisms. It was found that some of the characterized genes involved in the biosynthesis of flavonoids and TTLs were also possibly regulated by AS and APA. Using phylogenetic and gene expression pattern analyses, some candidate genes for the biosynthesis of flavonoids and TTLs were screened. After qRT-PCR validation, the final candidate genes for flavonoid biosynthesis included three UDP-glycosyltransferases and one MYB transcription factor, while the candidate genes for TTL biosynthesis included two cytochrome P450 and one WRKY transcription factor. Our study suggested that Iso-Seq may play an important role in improving genome annotation, elucidating AS and APA mechanisms and discovering candidate genes involved in the biosynthesis of some secondary metabolites.


Assuntos
Flavonoides/biossíntese , Regulação da Expressão Gênica de Plantas/genética , Ginkgo biloba/genética , Ginkgo biloba/metabolismo , Lactonas/metabolismo , Terpenos/metabolismo , Processamento Alternativo/genética , Sistema Enzimático do Citocromo P-450/genética , Perfilação da Expressão Gênica , Genoma de Planta/genética , Extratos Vegetais , Transcriptoma , Sequenciamento Completo do Genoma
9.
Nat Commun ; 11(1): 3508, 2020 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-32665554

RESUMO

Directional transport of the phytohormone auxin is a versatile, plant-specific mechanism regulating many aspects of plant development. The recently identified plant hormones, strigolactones (SLs), are implicated in many plant traits; among others, they modify the phenotypic output of PIN-FORMED (PIN) auxin transporters for fine-tuning of growth and developmental responses. Here, we show in pea and Arabidopsis that SLs target processes dependent on the canalization of auxin flow, which involves auxin feedback on PIN subcellular distribution. D14 receptor- and MAX2 F-box-mediated SL signaling inhibits the formation of auxin-conducting channels after wounding or from artificial auxin sources, during vasculature de novo formation and regeneration. At the cellular level, SLs interfere with auxin effects on PIN polar targeting, constitutive PIN trafficking as well as clathrin-mediated endocytosis. Our results identify a non-transcriptional mechanism of SL action, uncoupling auxin feedback on PIN polarity and trafficking, thereby regulating vascular tissue formation and regeneration.


Assuntos
Compostos Heterocíclicos com 3 Anéis/metabolismo , Ácidos Indolacéticos/metabolismo , Lactonas/metabolismo , Ervilhas/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas/genética , Regulação da Expressão Gênica de Plantas/fisiologia , Ervilhas/genética , Reguladores de Crescimento de Planta/metabolismo
10.
Nature ; 583(7815): 277-281, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32528176

RESUMO

Plant hormones known as strigolactones control plant development and interactions between host plants and symbiotic fungi or parasitic weeds1-4. In Arabidopsis thaliana and rice, the proteins DWARF14 (D14), MORE AXILLARY GROWTH 2 (MAX2), SUPPRESSOR OF MAX2-LIKE 6, 7 and 8 (SMXL6, SMXL7 and SMXL8) and their orthologues form a complex upon strigolactone perception and play a central part in strigolactone signalling5-10. However, whether and how strigolactones activate downstream transcription remains largely unknown. Here we use a synthetic strigolactone to identify 401 strigolactone-responsive genes in Arabidopsis, and show that these plant hormones regulate shoot branching, leaf shape and anthocyanin accumulation mainly through transcriptional activation of the BRANCHED 1, TCP DOMAIN PROTEIN 1 and PRODUCTION OF ANTHOCYANIN PIGMENT 1 genes. We find that SMXL6 targets 729 genes in the Arabidopsis genome and represses the transcription of SMXL6, SMXL7 and SMXL8 by binding directly to their promoters, showing that SMXL6 serves as an autoregulated transcription factor to maintain the homeostasis of strigolactone signalling. These findings reveal an unanticipated mechanism through which a transcriptional repressor of hormone signalling can directly recognize DNA and regulate transcription in higher plants.


Assuntos
Arabidopsis/genética , Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas/genética , Compostos Heterocíclicos com 3 Anéis/metabolismo , Lactonas/metabolismo , Reguladores de Crescimento de Planta/metabolismo , Transdução de Sinais/genética , Transcrição Genética , Antocianinas/biossíntese , Arabidopsis/crescimento & desenvolvimento , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Genes de Plantas/genética , Reguladores de Crescimento de Planta/biossíntese , Folhas de Planta/anatomia & histologia , Folhas de Planta/genética , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Brotos de Planta/genética , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/metabolismo , Regiões Promotoras Genéticas , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
11.
Proc Natl Acad Sci U S A ; 117(22): 12472-12480, 2020 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-32409606

RESUMO

Momilactones are bioactive diterpenoids that contribute to plant defense against pathogens and allelopathic interactions between plants. Both cultivated and wild grass species of Oryza and Echinochloa crus-galli (barnyard grass) produce momilactones using a biosynthetic gene cluster (BGC) in their genomes. The bryophyte Calohypnum plumiforme (formerly Hypnum plumaeforme) also produces momilactones, and the bifunctional diterpene cyclase gene CpDTC1/HpDTC1, which is responsible for the production of the diterpene framework, has been characterized. To understand the molecular architecture of the momilactone biosynthetic genes in the moss genome and their evolutionary relationships with other momilactone-producing plants, we sequenced and annotated the C. plumiforme genome. The data revealed a 150-kb genomic region that contains two cytochrome P450 genes, the CpDTC1/HpDTC1 gene and the "dehydrogenase momilactone A synthase" gene tandemly arranged and inductively transcribed following stress exposure. The predicted enzymatic functions in yeast and recombinant assay and the successful pathway reconstitution in Nicotiana benthamiana suggest that it is a functional BGC responsible for momilactone production. Furthermore, in a survey of genomic sequences of a broad range of plant species, we found that momilactone BGC is limited to the two grasses (Oryza and Echinochloa) and C. plumiforme, with no synteny among these genomes. These results indicate that while the gene cluster in C. plumiforme is functionally similar to that in rice and barnyard grass, it is likely a product of convergent evolution. To the best of our knowledge, this report of a BGC for a specialized plant defense metabolite in bryophytes is unique.


Assuntos
Evolução Molecular , Genoma de Planta , Lactonas/metabolismo , Plantas/metabolismo , Vias Biossintéticas , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas/classificação , Plantas/genética
12.
Nat Commun ; 11(1): 2114, 2020 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-32355217

RESUMO

Most plants associate with beneficial arbuscular mycorrhizal (AM) fungi that facilitate soil nutrient acquisition. Prior to contact, partner recognition triggers reciprocal genetic remodelling to enable colonisation. The plant Dwarf14-Like (D14L) receptor conditions pre-symbiotic perception of AM fungi, and also detects the smoke constituent karrikin. D14L-dependent signalling mechanisms, underpinning AM symbiosis are unknown. Here, we present the identification of a negative regulator from rice, which operates downstream of the D14L receptor, corresponding to the homologue of the Arabidopsis thaliana Suppressor of MAX2-1 (AtSMAX1) that functions in karrikin signalling. We demonstrate that rice SMAX1 is a suppressor of AM symbiosis, negatively regulating fungal colonisation and transcription of crucial signalling components and conserved symbiosis genes. Similarly, rice SMAX1 negatively controls strigolactone biosynthesis, demonstrating an unexpected crosstalk between the strigolactone and karrikin signalling pathways. We conclude that removal of SMAX1, resulting from D14L signalling activation, de-represses essential symbiotic programmes and increases strigolactone hormone production.


Assuntos
Proteínas de Arabidopsis/fisiologia , Peptídeos e Proteínas de Sinalização Intracelular/fisiologia , Micorrizas/fisiologia , Oryza/microbiologia , Proteínas de Plantas/fisiologia , Simbiose , Arabidopsis/genética , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , Furanos/metabolismo , Regulação da Expressão Gênica de Plantas , Germinação , Compostos Heterocíclicos com 3 Anéis/metabolismo , Homozigoto , Peptídeos e Proteínas de Sinalização Intracelular/genética , Lactonas/metabolismo , Família Multigênica , Oryza/genética , Filogenia , Proteínas de Plantas/genética , Raízes de Plantas/microbiologia , Piranos/metabolismo , RNA-Seq , Transdução de Sinais
13.
Nat Commun ; 11(1): 1955, 2020 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-32327664

RESUMO

Branching/tillering is an important parameter of plant architecture and is tightly regulated by both internal factors (such as plant hormones) and external factors (such as light conditions). How the various signaling pathways converge to coordinately regulate branching is not well understood. Here, we report that in Arabidopsis, FHY3 and FAR1, two homologous transcription factors essential for phytochrome A-mediated light signaling, and SMXL6/SMXL7/SMXL8, three key repressors of the strigolactone (SL) signaling pathway, directly interact with SPL9 and SPL15 and suppress their transcriptional activation of BRC1, a key repressor of branching, thus promoting branching. In addition, FHY3 and FAR1 also directly up-regulate the expression of SMXL6 and SMXL7 to promote branching. Simulated shade treatment reduces the accumulation of FHY3 protein, leading to increased expression of BRC1 and reduced branching. Our results establish an integrated model of light and SL coordinately regulating BRC1 expression and branching through converging at the BRC1 promoter.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Compostos Heterocíclicos com 3 Anéis/metabolismo , Lactonas/metabolismo , Proteínas Nucleares/metabolismo , Fitocromo/metabolismo , Transdução de Sinais , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Compostos Heterocíclicos com 3 Anéis/antagonistas & inibidores , Lactonas/antagonistas & inibidores , Luz , Transdução de Sinal Luminoso , Mutação , Proteínas Nucleares/genética , Fitocromo/genética , Plantas Geneticamente Modificadas , Regiões Promotoras Genéticas , Ligação Proteica , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Transativadores/genética , Transativadores/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Ativação Transcricional
14.
Appl Environ Microbiol ; 86(10)2020 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-32144102

RESUMO

Vibralactone, a hybrid compound derived from phenols and a prenyl group, is a strong pancreatic lipase inhibitor with a rare fused bicyclic ß-lactone skeleton. Recently, a researcher reported a vibralactone derivative (compound C1) that caused inhibition of pancreatic lipase with a half-maximal inhibitory concentration of 14 nM determined by structure-based optimization, suggesting a potential candidate as a new antiobesity treatment. In the present study, we sought to identify the main gene encoding prenyltransferase in Stereum vibrans, which is responsible for the prenylation of phenol leading to vibralactone synthesis. Two RNA silencing transformants of the identified gene (vib-PT) were obtained through Agrobacterium tumefaciens-mediated transformation. Compared to wild-type strains, the transformants showed a decrease in vib-PT expression ranging from 11.0 to 56.0% at 5, 10, and 15 days in reverse transcription-quantitative PCR analysis, along with a reduction in primary vibralactone production of 37 to 64% at 15 and 21 days, respectively, as determined using ultra-high-performance liquid chromatography-mass spectrometry analysis. A soluble and enzymatically active fusion Vib-PT protein was obtained by expressing vib-PT in Escherichia coli, and the enzyme's optimal reaction conditions and catalytic efficiency (Km /k cat) were determined. In vitro experiments established that Vib-PT catalyzed the C-prenylation at C-3 of 4-hydroxy-benzaldehyde and the O-prenylation at the 4-hydroxy of 4-hydroxy-benzenemethanol in the presence of dimethylallyl diphosphate. Moreover, Vib-PT shows promiscuity toward aromatic compounds and prenyl donors.IMPORTANCE Vibralactone is a lead compound with a novel skeleton structure that shows strong inhibitory activity against pancreatic lipase. Vibralactone is not encoded by the genome directly but rather is synthesized from phenol, followed by prenylation and other enzyme reactions. Here, we used an RNA silencing approach to identify and characterize a prenyltransferase in a basidiomycete species that is responsible for the synthesis of vibralactone. The identified gene, vib-PT, was expressed in Escherichia coli to obtain a soluble and enzymatically active fusion Vib-PT protein. In vitro characterization of the enzyme demonstrated the catalytic mechanism of prenylation and broad substrate range for different aromatic acceptors and prenyl donors. These characteristics highlight the possibility of Vib-PT to generate prenylated derivatives of aromatics and other compounds as improved bioactive agents or potential prodrugs.


Assuntos
Basidiomycota/metabolismo , Dimetilaliltranstransferase/metabolismo , Proteínas Fúngicas/metabolismo , Lactonas/metabolismo , Basidiomycota/enzimologia , Escherichia coli/metabolismo , Microrganismos Geneticamente Modificados/metabolismo , Interferência de RNA , Reação em Cadeia da Polimerase Via Transcriptase Reversa
15.
J Plant Physiol ; 246-247: 153139, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32114415

RESUMO

Rice tillering, which determines the panicle number per plant, is an important agronomic trait for grain production. In higher plants, ascorbic acid (Asc) plays a major role in ROS-scavenging activity. l-Galactono-1, 4-lactone dehydrogenase (GalLDH, EC1.3.2.3) is an enzyme that catalyzes the last step of Asc biosynthesis in plants. Previously, we have reported that homozygous L-GalLDH-suppressed transgenic rice plants (GI) display a reduced tiller number and a lower level of foliar carotenoids (Car) compared with wild type. Strigolactones (SL), which play an important role in the suppression of shoot branching, are synthesized in the roots of rice plant using Car as substrates. In this paper, the relationship between Asc, SL, the accumulation of H2O2, changes in antioxidant capacity, enzyme activities, and gene transcriptions related to the synthesis of SL were analyzed in transgenic rice plants for L-GalLDH suppressed (GI-1 and GI-2) and overexpressing (GO-2). The results showed that the altered level of Asc in the L-GalLDH transgenic rice plants leads to a change in redox homeostasis, resulting in a marked accumulation of H2O2 and decreased antioxidant capacity in GI-1 and GI-2, but lower H2O2 content and increased antioxidant capacity in GO-2. Meanwhile, the altered level of Asc also leads to altered enzyme activities and gene transcript abundances related to SL synthesis in L-GalLDH transgenics. These observations support the conclusion that Asc influences tiller number in the L-GalLDH transgenics by affecting H2O2 accumulation and antioxidant capacity, and altering those enzyme activities and gene transcript abundances related to SL synthesis.


Assuntos
Ácido Ascórbico/metabolismo , Regulação da Expressão Gênica de Plantas , Compostos Heterocíclicos com 3 Anéis/metabolismo , Lactonas/metabolismo , Oryza/metabolismo , Antioxidantes/metabolismo , Peróxido de Hidrogênio/metabolismo , Oryza/enzimologia , Oryza/genética , Oxirredutases atuantes sobre Doadores de Grupo CH-CH , Plantas Geneticamente Modificadas/enzimologia , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/metabolismo
16.
Planta ; 251(4): 84, 2020 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-32189077

RESUMO

MAIN CONCLUSION: In response to low nitrogen stress, multiple hormones together with nitric oxide signaling pathways work synergistically and antagonistically in crop root elongation. Changing root morphology allows plants to adapt to soil nutrient availability. Nitrogen is the most important essential nutrient for plant growth. An important adaptive strategy for crops responding to nitrogen deficiency is root elongation, thereby accessing increased soil space and nitrogen resources. Multiple signaling pathways are involved in this regulatory network, working together to fine-tune root elongation in response to soil nitrogen availability. Based on existing research, we propose a model to explain how different signaling pathways interact to regulate root elongation in response to low nitrogen stress. In response to a low shoot nitrogen status signal, auxin transport from the shoot to the root increases. High auxin levels in the root tip stimulate the production of nitric oxide, which promotes the synthesis of strigolactones to accelerate cell division. In this process, cytokinin, ethylene, and abscisic acid play an antagonistic role, while brassinosteroids and auxin play a synergistic role in regulating root elongation. Further study is required to identify the QTLs, genes, and favorable alleles which control the root elongation response to low nitrogen stress in crops.


Assuntos
Produtos Agrícolas/metabolismo , Nitrogênio/metabolismo , Raízes de Plantas/metabolismo , Ácido Abscísico/metabolismo , Brassinosteroides/metabolismo , Citocininas/metabolismo , Etilenos/metabolismo , Compostos Heterocíclicos com 3 Anéis/metabolismo , Lactonas/metabolismo , Meristema/metabolismo , Óxido Nítrico/metabolismo , Desenvolvimento Vegetal , Reguladores de Crescimento de Planta/metabolismo , Transdução de Sinais , Estresse Fisiológico
17.
Molecules ; 25(3)2020 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-32033280

RESUMO

The proteasome is the central component of the main cellular protein degradation pathway. During the past four decades, the critical function of the proteasome in numerous physiological processes has been revealed, and proteasome activity has been linked to various human diseases. The proteasome prevents the accumulation of misfolded proteins, controls the cell cycle, and regulates the immune response, to name a few important roles for this macromolecular "machine." As a therapeutic target, proteasome inhibitors have been approved for the treatment of multiple myeloma and mantle cell lymphoma. However, inability to sufficiently inhibit proteasome activity at tolerated doses has hampered efforts to expand the scope of proteasome inhibitor-based therapies. With emerging new modalities in myeloma, it might seem challenging to develop additional proteasome-based therapies. However, the constant development of new applications for proteasome inhibitors and deeper insights into the intricacies of protein homeostasis suggest that proteasome inhibitors might have novel therapeutic applications. Herein, we summarize the latest advances in proteasome inhibitor development and discuss the future of proteasome inhibitors and other proteasome-based therapies in combating human diseases.


Assuntos
Antineoplásicos/uso terapêutico , Terapia de Alvo Molecular/métodos , Mieloma Múltiplo/tratamento farmacológico , Inibidores de Proteassoma/uso terapêutico , Proteostase/efeitos dos fármacos , Compostos de Boro/metabolismo , Compostos de Boro/uso terapêutico , Bortezomib/metabolismo , Bortezomib/uso terapêutico , Glicina/análogos & derivados , Glicina/metabolismo , Glicina/uso terapêutico , Humanos , Lactonas/metabolismo , Lactonas/uso terapêutico , Oligopeptídeos/metabolismo , Oligopeptídeos/uso terapêutico , Pirróis/metabolismo , Pirróis/uso terapêutico
18.
mBio ; 11(1)2020 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-32098820

RESUMO

Low doses of antibiotics can trigger secondary metabolite biosynthesis in bacteria, but the underlying mechanisms are generally unknown. We sought to better understand this phenomenon by studying how the antibiotic trimethoprim activates the synthesis of the virulence factor malleilactone in Burkholderia thailandensis Using transcriptomics, quantitative multiplexed proteomics, and primary metabolomics, we systematically mapped the changes induced by trimethoprim. Surprisingly, even subinhibitory doses of the antibiotic resulted in broad transcriptional and translational alterations, with ∼8.5% of the transcriptome and ∼5% of the proteome up- or downregulated >4-fold. Follow-up studies with genetic-biochemical experiments showed that the induction of malleilactone synthesis can be sufficiently explained by the accumulation of methionine biosynthetic precursors, notably homoserine, as a result of inhibition of the folate pathway. Homoserine activated the malleilactone gene cluster via the transcriptional regulator MalR and gave rise to a secondary metabolome which was very similar to that generated by trimethoprim. Our work highlights the expansive changes that low-dose trimethoprim induces on bacterial physiology and provides insights into its stimulatory effect on secondary metabolism.IMPORTANCE The discovery of antibiotics ranks among the most significant accomplishments of the last century. Although the targets of nearly all clinical antibiotics are known, our understanding regarding their natural functions and the effects of subinhibitory concentrations is in its infancy. Stimulatory rather than inhibitory functions have been attributed to low-dose antibiotics. Among these, we previously found that antibiotics activate silent biosynthetic genes and thereby enhance the metabolic output of bacteria. The regulatory circuits underlying this phenomenon are unknown. We take a first step toward elucidating these circuits and show that low doses of trimethoprim (Tmp) have cell-wide effects on the saprophyte Burkholderia thailandensis Most importantly, inhibition of one-carbon metabolic processes by Tmp leads to an accumulation of homoserine, which induces the production of an otherwise silent cytotoxin via a LuxR-type transcriptional regulator. These results provide a starting point for uncovering the molecular basis of the hormetic effects of antibiotics.


Assuntos
Antibacterianos/farmacologia , Burkholderia/efeitos dos fármacos , Burkholderia/metabolismo , Metabolismo Secundário/efeitos dos fármacos , Proteínas de Bactérias , Produtos Biológicos/metabolismo , Vias Biossintéticas/efeitos dos fármacos , Vias Biossintéticas/genética , Burkholderia/genética , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Homosserina/metabolismo , Lactonas/química , Lactonas/metabolismo , Família Multigênica , Metabolismo Secundário/genética , Trimetoprima/farmacologia , Fatores de Virulência/metabolismo
19.
Molecules ; 25(4)2020 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-32093025

RESUMO

The demand for natural lactone gamma-decalactone (GDL) has increased in the fields of food and cosmetic products. However, low productivity during bioprocessing limits its industrial production. In this study, a novel composite porous cell carrier, bacterial cellulose-alginate (BC-ALG), was used for long-term biotransformation and production of GDL. The effects of this carrier on biotransformation and related mechanisms were investigated. BC-ALG carriers showed improved mechanical strength over ALG carriers, with their internal embedded cell pattern changed to an interconnected porous structure. In five repeated-batch biotransformation experiments, the maximum concentration of GDL obtained in culture with BC-ALG carriers was 8.37 g/L, approximately 3.7 times higher than that from the medium with an ALG carrier alone. The result indicated that multiple hydrogen bonding interactions at the interface between BC and ALG contributed to the compatibility and stability of BC-ALG carriers. On the basis of the above results, the BC-ALG composite carrier can be considered ideal for immobilisation of cells for the production of GDL on an industrial scale, and has the potential to be utilised in other biological processes.


Assuntos
Alginatos/química , Células Imobilizadas/metabolismo , Celulose/química , Lactonas/metabolismo , Yarrowia/metabolismo
20.
Sci Rep ; 10(1): 2614, 2020 02 13.
Artigo em Inglês | MEDLINE | ID: mdl-32054953

RESUMO

Plants live in close association with microorganisms that can have beneficial or detrimental effects. The activity of bacteria in association with flowering plants has been extensively analysed. Bacteria use quorum-sensing as a way of monitoring their population density and interacting with their environment. A key group of quorum sensing molecules in Gram-negative bacteria are the N-acylhomoserine lactones (AHLs), which are known to affect the growth and development of both flowering plants, including crops, and marine algae. Thus, AHLs have potentially important roles in agriculture and aquaculture. Nothing is known about the effects of AHLs on the earliest-diverging land plants, thus the evolution of AHL-mediated bacterial-plant/algal interactions is unknown. In this paper, we show that AHLs can affect spore germination in a representative of the earliest plants on land, the Bryophyte moss Physcomitrella patens. Furthermore, we demonstrate that sporophytes of some wild isolates of Physcomitrella patens are associated with AHL-producing bacteria.


Assuntos
Briófitas/crescimento & desenvolvimento , Briófitas/microbiologia , Germinação , Percepção de Quorum , Bactérias/isolamento & purificação , Briófitas/metabolismo , Homosserina/análogos & derivados , Homosserina/metabolismo , Lactonas/química , Lactonas/metabolismo , Esporos/crescimento & desenvolvimento , Esporos/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA