RESUMEN
Chemical syntheses of UDP-rhamnose and UDP-arabinofuranose and respective azido-modified analogues are reported. The prepared substrates are useful for the glycan array-based analysis of glycosyltransferases, as exemplified with the plant cell wall-biosynthetic enzymes PvXAT3, AtRRT4 and PtRRT5.
Asunto(s)
Glicosiltransferasas , Polisacáridos , Azúcares de Uridina Difosfato , Glicosiltransferasas/metabolismo , Glicosiltransferasas/química , Polisacáridos/química , Polisacáridos/síntesis química , Polisacáridos/metabolismo , Azúcares de Uridina Difosfato/química , Azúcares de Uridina Difosfato/metabolismo , Azidas/química , Arabinosa/química , Arabinosa/análogos & derivados , Plantas/químicaRESUMEN
Surfactants are amphiphilic molecules that are capable of mixing water and oil. Biosurfactants are eco-friendly, low-toxicity, and stable to a variety of environmental factors. Optimizing conditions for microorganisms to produce biosurfactants can lead to improved production suitable for scaling up. In this study, we compared heterologous expression levels of the luminescence system luxCDABE operon controlled by regulatable promoters araC-PBAD and its strong version araC-PBAD-SD in Escherichia coli K12, Pseudomonas aeruginosa PAO1, and P. putida KT2440. Real-time monitoring of luminescence levels in the three strains indicated that luxCDABE controlled by araC-PBAD-SD promoter with 0.2% arabinose supplementation in P. putida produced the highest level of luminescence. By using the araC-PBAD-SD promoter-controlled rhlAB expression in P. putida, we were able to produce mono-rhamnolipid at a level of 1.5 g L-1 when 0.02% arabinose was supplemented. With the same system to express olsB, lyso-ornithine lipid was produced at a level of 10 mg L-1 when 0.2% arabinose was supplemented. To our knowledge, this is the first report about optimizing conditions for lyso-ornithine lipid production at a level up to 10 mg L-1. Taken together, our results demonstrate that regulatable araC-PBAD-SD promoter in P. putida KT2440 is a useful system for heterologous production of biosurfactants.
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Glucolípidos , Ornitina , Regiones Promotoras Genéticas , Pseudomonas putida , Tensoactivos , Glucolípidos/biosíntesis , Glucolípidos/metabolismo , Pseudomonas putida/metabolismo , Pseudomonas putida/genética , Tensoactivos/metabolismo , Ornitina/metabolismo , Ornitina/análogos & derivados , Pseudomonas aeruginosa/metabolismo , Pseudomonas aeruginosa/genética , Arabinosa/metabolismo , Regulación Bacteriana de la Expresión Génica , Escherichia coli/metabolismo , Escherichia coli/genética , Operón , LípidosRESUMEN
This study aims to understand the molecular and supramolecular transformations of wheat endosperm biopolymers during bread-making, and their implications to fabricate self-standing films from stale white bread. A reduction in the Mw of amylopectin (51.8 × 106 vs 425.1 × 106 g/mol) and water extractable arabinoxylans WEAX (1.79 × 105 vs 7.63 × 105 g/mol), and a decrease in amylose length (245 vs 748 glucose units) was observed after bread-baking. The chain length distribution of amylopectin and the arabinose-to-xylose (A/X) ratio of WEAX remained unaffected during bread-making, suggesting that heat- or/and shear-induced chain scission is the mechanism responsible for molecular fragmentation. Bread-making also resulted in more insoluble cell wall residue, featured by water unextractable arabinoxylan of lower A/X and Mw, along with the formation of a gluten network. Flexible and transparent films with good light-blocking performance (<30 % transmittance) and DPPH-radical scavenging capacity (~8.5 %) were successfully developed from bread and flour. Bread films exhibited lower hygroscopicity, tensile strength (2.7 vs 8.5 MPa) and elastic modulus (67 vs 501 MPa) than flour films, while having a 6-fold higher elongation at break (10.0 vs 61.2 %). This study provides insights into the changes in wheat biopolymers during bread-making and sets a precedent for using stale bread as composite polymeric materials.
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Amilopectina , Pan , Harina , Triticum , Xilanos , Triticum/química , Pan/análisis , Harina/análisis , Biopolímeros/química , Xilanos/química , Amilopectina/química , Resistencia a la Tracción , Arabinosa/química , Xilosa/química , Glútenes/químicaRESUMEN
This work demonstrates that sesame (Sesamum indicum L.) hull, an unexploited food industrial waste, can be used as an efficient source for the extraction of hemicellulose and/or pectin polysaccharides to further obtain functional oligosaccharides. Different polysaccharides extraction methods were surveyed including alkaline and several enzymatic treatments. Based on the enzymatic release of xylose, arabinose, glucose, and galacturonic acid from sesame hull by using different enzymes, Celluclast®1.5 L, Pectinex®Ultra SP-L, and a combination of them were selected for the enzymatic extraction of polysaccharides at 50 °C, pH 5 up to 24 h. Once the polysaccharides were extracted, Ultraflo®L was selected to produce arabinoxylo-oligosaccharides (AXOS) at 40 °C up to 24 h. Apart from oligosaccharides production from extracted polysaccharides, alternative approaches for obtaining oligosaccharides were also explored. These were based on the analysis of the supernatants resulting from the polysaccharide extraction, alongside a sequential hydrolysis performed with Celluclast®1.5 L and Ultraflo®L of the starting raw sesame hull. The different fractions obtained were comprehensively characterized by determining low molecular weight carbohydrates and monomeric compositions, average Mw and dispersity, and oligosaccharide structure by MALDI-TOF-MS. The results indicated that sesame hull can be a useful source for polysaccharides extraction (pectin and hemicellulose) and derived oligosaccharides, especially AXOS.
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Oligosacáridos , Sesamum , Sesamum/química , Oligosacáridos/química , Hidrólisis , Polisacáridos/química , Xilanos/química , Xilanos/aislamiento & purificación , Pectinas/química , Pectinas/aislamiento & purificación , Residuos Industriales , Arabinosa/química , Xilosa/químicaRESUMEN
Hydroxycinnamic acids, known for their health benefits and widespread presence in plant-based food, undergo complex transformations during high-temperature processing. Recent studies revealed a high browning potential of hydroxycinnamic acids and reactive Maillard reaction intermediates, but the role of phenolic compounds in the early stage of these reactions is not unambiguously understood. Therefore, we investigated the influence of caffeic acid and ferulic acid on the nonenzymatic browning of arabinose, galactose, and/or alanine, focusing on the implications on the formation of relevant early-stage Maillard intermediates and phenol-deriving products. Contrary to previous assumptions, hydroxycinnamic acids were found to promote nonenzymatic browning instead of solely trapping reactive intermediates. This was reflected by an intense browning, which was attributed to the formation of heterogeneous phenol-containing Maillard products. Although, caffeic acid is more reactive than ferulic acid, the formation of reactive furan derivatives and of heterogeneous phenol-containing colorants was promoted in the presence of both hydroxycinnamic acids.
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Arabinosa , Ácidos Cumáricos , Galactosa , Reacción de Maillard , Ácidos Cumáricos/química , Galactosa/química , Arabinosa/química , CalorRESUMEN
The gut microbiota is essential for providing colonization resistance against pathogens. Dietary sugars markedly shift the composition of the intestinal microbiota and alter host susceptibility to enteric infections. Here, we demonstrate the effect of L-arabinose on bacterial infection by using a mouse infection model with Salmonella enterica serovar Typhimurium (S. Tm). In the presence of microbiota, L-arabinose induces a dramatic expansion of Enterobacteriaceae, thereby decreasing the microbiota diversity and causing more severe systemic infection. However, L-arabinose supplementation does not alter the disease progression of Salmonella infection in a microbiota-depleted mouse model. More importantly, short-term supplementation of L-arabinose fails to exert anti-diabetic effects in Salmonella-infected hyperglycemia mice and still promotes infection. Overall, our work reveals that a high intake of dietary L-arabinose supports a bloom of Enterobacteriaceae in Salmonella-infected gut, further accelerating the process of systemic infection.IMPORTANCEL-arabinose is a promising natural sweetener and food additive for the regulation of hyperglycemia. Since diabetic subjects are more susceptible to infections, the safety of dietary L-arabinose in diabetic patients experiencing infection remains a concern. Our findings reveal that L-arabinose exacerbates Salmonella infection outcome by inducing gut microbiota dysbiosis in mice. High dietary intake of L-arabinose may be deleterious for diabetic individuals undergoing infection.
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Arabinosa , Disbiosis , Microbioma Gastrointestinal , Infecciones por Salmonella , Salmonella typhimurium , Animales , Microbioma Gastrointestinal/efectos de los fármacos , Disbiosis/microbiología , Arabinosa/farmacología , Ratones , Infecciones por Salmonella/microbiología , Salmonella typhimurium/efectos de los fármacos , Ratones Endogámicos C57BL , Masculino , Enterobacteriaceae/efectos de los fármacosRESUMEN
Changes in the plant microbiota composition are intimately associated with the health of the plant, but factors controlling the microbial community in flowers are poorly understood. In this study, we used apple flowers and fire blight as a model system to investigate the effects of floral microbiota and microbial competition on disease development and suppression. To compare changes in microbial flora with the RNA expression patterns of plants, the flower samples were collected in three different flowering stages (Bud, Popcorn, and Full-bloom). Using advanced sequencing technology, we analyzed the data and conducted both in vitro and in vivo experiments to validate our findings. Our results show that the Erwinia amylovora use arabinogalactan, which is secreted on the flowers, for early colonization of apple flowers. Pantoea agglomerans was more competitive for arabinogalactan than E. amylovora. Additionally, P. agglomerans suppressed the expression of virulence factors of E. amylovora by using arabinose, which is a major component of arabinogalactan, which induces virulence gene expression. The present data provide new insights into developing control strategies for diverse plant diseases, including fire blight, by highlighting the importance of nutrients in disease development or suppression.
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Erwinia amylovora , Flores , Galactanos , Malus , Microbiota , Enfermedades de las Plantas , Malus/microbiología , Erwinia amylovora/patogenicidad , Erwinia amylovora/fisiología , Enfermedades de las Plantas/microbiología , Flores/microbiología , Galactanos/metabolismo , Nutrientes/metabolismo , Pantoea/fisiología , Pantoea/genética , Pantoea/patogenicidad , Arabinosa/metabolismo , Factores de Virulencia/genéticaRESUMEN
Lignocellulose (dry plant biomass) is an abundant cheap inedible residue of agriculture and wood industry with great potential as a feedstock for biotechnological processes. Lignocellulosic substrates can serve as valuable resources in fermentation processes, allowing the production of a wide array of chemicals, fuels, and food additives. The main obstacle for cost-effective conversion of lignocellulosic hydrolysates to target products is poor metabolism of the major pentoses, xylose and L-arabinose, which are the second and third most abundant sugars of lignocellulose after glucose. We study the oversynthesis of riboflavin in the flavinogenic yeast Candida famata and found that all major lignocellulosic sugars, including xylose and L-arabinose, support robust growth and riboflavin synthesis in the available strains of C. famata. To further increase riboflavin production from xylose and lignocellulose hydrolysate, genes XYL1 and XYL2 coding for xylose reductase and xylitol dehydrogenase were overexpressed. The resulting strains exhibited increased riboflavin production in both shake flasks and bioreactors using diluted hydrolysate, reaching 1.5 g L-1.
Asunto(s)
Candida , Lignina , Ingeniería Metabólica , Riboflavina , Xilosa , Lignina/metabolismo , Riboflavina/metabolismo , Riboflavina/biosíntesis , Candida/metabolismo , Candida/genética , Xilosa/metabolismo , Aldehído Reductasa/metabolismo , Aldehído Reductasa/genética , Fermentación , Reactores Biológicos/microbiología , D-Xilulosa Reductasa/metabolismo , D-Xilulosa Reductasa/genética , Arabinosa/metabolismoRESUMEN
OBJECTIVE: New characterized carbohydrate-active enzymes are needed for use as tools to discriminate complex carbohydrate structural features. Fungal glycoside hydrolase family 3 (GH3) ß-xylosidases have been shown to be useful for the structural elucidation of glucuronic acid (GlcA) and arabinofuranose (Araf) substituted oligoxylosides. A homolog of these GH3 fungal enzymes from the bacterium Segatella baroniae (basonym Prevotella bryantii), Xyl3C, has been previously characterized, but those studies did not address important functional specificity features. In an interest to utilize this enzyme for laboratory methods intended to discriminate the structure of the non-reducing terminus of substituted xylooligosaccharides, we have further characterized this GH3 xylosidase. RESULTS: In addition to verification of basic functional characteristics of this xylosidase we have determined its mode of action as it relates to non-reducing end xylose release from GlcA and Araf substituted oligoxylosides. Xyl3C cleaves xylose from the non-reducing terminus of ß-1,4-xylan until occurrence of a penultimate substituted xylose. If this substitution is O2 linked, then Xyl3C removes the non-reducing xylose to leave the substituted xylose as the new non-reducing terminus. However, if the substitution is O3 linked, Xyl3C does not hydrolyze, thus leaving the substitution one-xylose (penultimate) from the non-reducing terminus. Hence, Xyl3C enables discrimination between O2 and O3 linked substitutions on the xylose penultimate to the non-reducing end. These findings are contrasted using a homologous enzyme also from S. baroniae, Xyl3B, which is found to yield a penultimate substituted nonreducing terminus regardless of which GlcA or Araf substitution exists.
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Xilanos , Xilosa , Xilosidasas , Xilosidasas/metabolismo , Xilosidasas/genética , Xilosidasas/química , Xilanos/metabolismo , Xilosa/metabolismo , Especificidad por Sustrato , Prevotella/enzimología , Prevotella/genética , Oligosacáridos/metabolismo , Oligosacáridos/química , Glucuronatos/metabolismo , Arabinosa/análogos & derivadosRESUMEN
In eukaryotes, the D-enantiomer of arabinose (D-Ara) is an intermediate in the biosynthesis of D-erythroascorbate in yeast and fungi and in the biosynthesis of the nucleotide sugar GDP-α-D-arabinopyranose (GDP-D-Arap) and complex α-D-Arap-containing surface glycoconjugates in certain trypanosomatid parasites. Whereas the biosynthesis of D-Ara in prokaryotes is well understood, the route from D-glucose (D-Glc) to D-Ara in eukaryotes is unknown. In this paper, we study the conversion of D-Glc to D-Ara in the trypanosomatid Crithidia fasciculata using positionally labeled [13C]-D-Glc and [13C]-D-ribose ([13C]-D-Rib) precursors and a novel derivatization and gas chromatography-mass spectrometry procedure applied to a terminal metabolite, lipoarabinogalactan. These data implicate the both arms of pentose phosphate pathway and a likely role for D-ribulose-5-phosphate (D-Ru-5P) isomerization to D-Ara-5P. We tested all C. fasciculata putative sugar and polyol phosphate isomerase genes for their ability to complement a D-Ara-5P isomerase-deficient mutant of Escherichia coli and found that one, the glutamine fructose-6-phosphate aminotransferase (GFAT) of glucosamine biosynthesis, was able to rescue the E. coli mutant. We also found that GFAT genes of other trypanosomatid parasites, and those of yeast and human origin, could complement the E. coli mutant. Finally, we demonstrated biochemically that recombinant human GFAT can isomerize D-Ru-5P to D-Ara5P. From these data, we postulate a general eukaryotic pathway from D-Glc to D-Ara and discuss its possible significance. With respect to C. fasciculata, we propose that D-Ara is used not only for the synthesis of GDP-D-Arap and complex surface glycoconjugates but also in the synthesis of D-erythroascorbate.
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Arabinosa , Glucosa , Arabinosa/metabolismo , Glucosa/metabolismo , Vía de Pentosa Fosfato , Escherichia coli/metabolismo , Escherichia coli/genética , Proteínas Protozoarias/metabolismo , Proteínas Protozoarias/genéticaRESUMEN
Breast cancer patients often have a poor prognosis largely due to lack of effective targeted therapy. It is now well established that monosaccharide enhances growth retardation and chemotherapy sensitivity in tumor cells. We investigated whether D-arabinose has capability to restrict the proliferation of tumor cells and its mechanism. Here, we report that D-arabinose induced cytotoxicity is modulated by autophagy and p38 MAPK signaling pathway in breast cancer cell lines. The proliferation of cells was evaluated by CCK-8 and Colony formation assay. The distribution of cells in cell cycle phases was analyzed by flow cytometry. Cell cycle, autophagy and MAPK signaling related proteins were detected by western blotting. Mouse xenograft model was used to evaluate the efficacy of D-arabinose in vivo. The proliferation of cells was dramatically inhibited by D-arabinose exposure in a dose-dependent manner, which was relevant to cell cycle arrest, as demonstrated by G2/M cell cycle restriction and ectopic expression of cell cycle related proteins. Mechanistically, we further identified that D-arabinose is positively associated with autophagy and the activation of the p38 MAPK signaling in breast cancer. In contrast, 3-Ma or SB203580, the inhibitor of autophagy or p38 MAPK, reversed the efficacy of D-arabinose. Additionally, D-arabinose in vivo treatment could significantly inhibit xenograft growth of breast cancer cells. Our findings were the first to reveal that D-arabinose triggered cell cycle arrest by inducing autophagy through the activation of p38 MAPK signaling pathway in breast cancer cells.
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Arabinosa , Autofagia , Neoplasias de la Mama , Puntos de Control del Ciclo Celular , Proliferación Celular , Sistema de Señalización de MAP Quinasas , Proteínas Quinasas p38 Activadas por Mitógenos , Autofagia/efectos de los fármacos , Humanos , Neoplasias de la Mama/metabolismo , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/patología , Animales , Femenino , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismo , Ratones , Arabinosa/farmacología , Puntos de Control del Ciclo Celular/efectos de los fármacos , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Ensayos Antitumor por Modelo de Xenoinjerto , Ratones Desnudos , Ratones Endogámicos BALB CRESUMEN
Plasmids play important roles in microbial ecosystems, serving as carriers of antibiotic resistance and virulence. In the laboratory, they are essential tools for genetic manipulation and recombinant protein expression. We uncovered an intriguing survival phenotype in a fraction of the bacterial population while using plasmid-mediated arabinose-inducible gene expression to monitor the production of toxic ParE proteins. This phenotype was not correlated with changes to the plasmid sequence and could not be rescued by increasing arabinose uptake. Instead, survival correlates with a marked reduction in plasmid copy number (PCN). Reduced PCN is reproducible, not a function of the pre-existing population, and can be sequentially enriched by continual passage with induction. The reduction in PCN appears to allow mitigation of toxicity from the expression of ParE proteins while balancing the need to maintain a threshold PCN to withstand selection conditions. This indicates an adaptive cellular response to stressful conditions, likely by altering the regulation of plasmid replication. Furthermore, this survival mechanism appears to not be limited to a specific bacterial strain of Escherichia coli or ParE toxin family member, suggesting a generalized response. Finally, bacterial whole genome sequencing indicated an N845S residue substitution in DNA polymerase I, which correlates with the observed reduction in PCN and has been previously reported to impact plasmid replication. Further understanding this molecular mechanism has broader implications for this adaptive response of the dynamics of plasmid-mediated gene expression, microbial adaptation, and genetic engineering methodologies. IMPORTANCE: This research has increased our understanding of how bacteria respond to the pressure from plasmid-borne toxic genes, such as those found in toxin-antitoxin systems. Surprisingly, we found that bacteria survived toxic ParE protein expression by reducing the number of these plasmids in the cells. This discovery reveals another way in which bacteria can balance toxin expression with antibiotic selection to attenuate the effects of deleterious genes. This insight is not only valuable for understanding bacterial survival strategies but may also influence the development of better tools in biotechnology, where plasmids are often used to study the functional roles of genes.
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Toxinas Bacterianas , Proteínas de Escherichia coli , Escherichia coli , Regulación Bacteriana de la Expresión Génica , Plásmidos , Plásmidos/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Toxinas Bacterianas/genética , Toxinas Bacterianas/metabolismo , Arabinosa/metabolismo , Dosificación de GenRESUMEN
Virulence and metabolism are often interlinked to control the expression of essential colonisation factors in response to host-associated signals. Here, we identified an uncharacterised transporter of the dietary monosaccharide Ê-arabinose that is widely encoded by the zoonotic pathogen enterohaemorrhagic Escherichia coli (EHEC), required for full competitive fitness in the mouse gut and highly expressed during human infection. Discovery of this transporter suggested that EHEC strains have an enhanced ability to scavenge Ê-arabinose and therefore prompted us to investigate the impact of this nutrient on pathogenesis. Accordingly, we discovered that Ê-arabinose enhances expression of the EHEC type 3 secretion system, increasing its ability to colonise host cells, and that the underlying mechanism is dependent on products of its catabolism rather than the sensing of Ê-arabinose as a signal. Furthermore, using the murine pathogen Citrobacter rodentium, we show that Ê-arabinose metabolism provides a fitness benefit during infection via virulence factor regulation, as opposed to supporting pathogen growth. Finally, we show that this mechanism is not restricted to Ê-arabinose and extends to other pentose sugars with a similar metabolic fate. This work highlights the importance integrating central metabolism with virulence regulation in order to maximise competitive fitness of enteric pathogens within the host-niche.
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Arabinosa , Citrobacter rodentium , Escherichia coli Enterohemorrágica , Arabinosa/metabolismo , Animales , Ratones , Citrobacter rodentium/patogenicidad , Citrobacter rodentium/metabolismo , Citrobacter rodentium/genética , Humanos , Virulencia , Escherichia coli Enterohemorrágica/patogenicidad , Escherichia coli Enterohemorrágica/metabolismo , Escherichia coli Enterohemorrágica/genética , Regulación Bacteriana de la Expresión Génica , Factores de Virulencia/metabolismo , Factores de Virulencia/genética , Infecciones por Enterobacteriaceae/microbiología , Proteínas de Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Sistemas de Secreción Tipo III/metabolismo , Sistemas de Secreción Tipo III/genética , Infecciones por Escherichia coli/microbiología , FemeninoRESUMEN
We discovered an unusual triflic acid-promoted oligomerization of arabinofuranosides during glycosylation of the primary hydroxy group of α-(1 â 5)-linked tetraarabinofuranoside bearing 4-(2-chloroethoxy)phenyl aglycone with α-(1 â 5), ß-(1 â 2)-linked tetraarabinofuranoside containing N-phenyltrifluoroacetimidoyl leaving group, which led to octa-, dodeca- and hexadecaarabinofuranosides. The possible mechanism of triflic acid-promoted oligomerization was proposed. The choice of promoter was found to be a critical factor for the discovered oligomerization of arabinofuranosides. The obtained octa-, dodeca- and hexadecaarabinofuranosides may serve as useful blocks in the synthesis of oligosaccharide fragments of polysaccharides of Mycobacterium tuberculosis.
Asunto(s)
Arabinosa , Mesilatos , Glicosilación , Arabinosa/química , Mesilatos/química , Mycobacterium tuberculosis/efectos de los fármacos , Mycobacterium tuberculosis/química , Conformación de CarbohidratosRESUMEN
Soil salinity is a major contributor to crop yield losses. To improve our understanding of root responses to salinity, we developed and exploited a real-time salt-induced tilting assay. This assay follows root growth upon both gravitropic and salt challenges, revealing that root bending upon tilting is modulated by Na+ ions, but not by osmotic stress. Next, we measured this salt-specific response in 345 natural Arabidopsis (Arabidopsis thaliana) accessions and discovered a genetic locus, encoding the cell wall-modifying enzyme EXTENSIN ARABINOSE DEFICIENT TRANSFERASE (ExAD) that is associated with root bending in the presence of NaCl (hereafter salt). Extensins are a class of structural cell wall glycoproteins known as hydroxyproline (Hyp)-rich glycoproteins, which are posttranslationally modified by O-glycosylation, mostly involving Hyp-arabinosylation. We show that salt-induced ExAD-dependent Hyp-arabinosylation influences root bending responses and cell wall thickness. Roots of exad1 mutant seedlings, which lack Hyp-arabinosylation of extensin, displayed increased thickness of root epidermal cell walls and greater cell wall porosity. They also showed altered gravitropic root bending in salt conditions and a reduced salt-avoidance response. Our results suggest that extensin modification via Hyp-arabinosylation is a unique salt-specific cellular process required for the directional response of roots exposed to salinity.
Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Pared Celular , Raíces de Plantas , Salinidad , Pared Celular/metabolismo , Raíces de Plantas/metabolismo , Raíces de Plantas/crecimiento & desarrollo , Raíces de Plantas/genética , Raíces de Plantas/efectos de los fármacos , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/efectos de los fármacos , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Glicoproteínas/metabolismo , Glicoproteínas/genética , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Gravitropismo , Arabinosa/metabolismo , Cloruro de Sodio/farmacología , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , GlicosilaciónRESUMEN
PURPOSE: A major obstacle to targeted cancer therapy is identifying suitable targets that are specifically and abundantly expressed by solid tumors. Certain bacterial strains selectively colonize solid tumors and can deliver genetically encoded cargo molecules to the tumor cells. Here, we engineered bacteria to express monomeric streptavidin (mSA) in tumors, and developed a novel tumor pre-targeting system by visualizing the presence of tumor-associated mSA using a biotinylated imaging probe. PROCEDURES: We constructed a plasmid expressing mSA fused to maltose-binding protein and optimized the ribosome binding site sequence to increase solubility and expression levels. E. coli MG1655 was transformed with the recombinant plasmid, expression of which is driven by the pBAD promotor. Expression of mSA was induced by L-arabinose 4 days after injection of bacteria into mice bearing CT26 mouse colon carcinoma cells. Selective accumulation of mSA in tumor tissues was visualized by optical imaging after administration of a biotinylated fluorescent dye. Counting of viable bacterial cells was also performed. RESULTS: Compared with a conventional system, the novel expression system resulted in significantly higher expression of mSA and sustained binding to biotin. Imaging signals in tumor tissues were significantly stronger in the mSA-expressing group than in non-expressing group (P = 0.0005). Furthermore, the fluorescent signal in tumor tissues became detectable again after multiple inductions with L-arabinose. The bacterial counts in tumor tissues showed no significant differences between conditions with and without L-arabinose (P = 0.45). Western blot analysis of tumor tissues confirmed expression and binding of mSA to biotin. CONCLUSIONS: We successfully engineered tumor-targeting bacteria carrying a recombinant plasmid expressing mSA, which was targeted to, and expressed in, tumor tissues. These data demonstrate the potential of this novel tumor pre-targeting system when combined with biotinylated imaging probes or therapeutic agents.
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Estreptavidina , Estreptavidina/química , Animales , Ratones , Línea Celular Tumoral , Escherichia coli/genética , Escherichia coli/metabolismo , Ratones Endogámicos BALB C , Neoplasias/diagnóstico por imagen , Neoplasias/patología , Plásmidos/metabolismo , Femenino , Biotina , Arabinosa/metabolismoRESUMEN
Quinoa, known as the "golden grain" for its high nutritional value, has polysaccharides as one of its sources of important nutrients. However, the biological functions of quinoa polysaccharides remain understudied. In this study, two crude polysaccharide extracts of quinoa (Q-40 and Q-60) were obtained through sequential precipitation with 40% and 60% ethanol, with purities of 58.29% (HPLC) and 62.15% (HPLC) and a protein content of 8.27% and 9.60%, respectively. Monosaccharide analysis revealed that Q-40 contained glucose (Glc), galacturonic acid (GalA), and arabinose (Ara) in a molar ratio of 0.967:0.027:0.006. Q-60 was composed of xylose (xyl), arabinose (Ara), galactose, and galacturonic acid (GalA) with a molar ratio of 0.889:0.036:0.034:0.020. The average molecular weight of Q-40 ranged from 47,484 to 626,488 Da, while Q-60 showed a range of 10,025 to 47,990 Da. Rheological experiments showed that Q-40 exhibited higher viscosity, while Q-60 demonstrated more elastic properties. Remarkably, Q-60 showed potent antioxidant abilities, with scavenging rates of 98.49% for DPPH and 57.5% for ABTS. Antibacterial experiments using the microdilution method revealed that Q-40 inhibited the growth of methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli), while Q-60 specifically inhibited MRSA. At lower concentrations, both polysaccharides inhibited MDA (MD Anderson Cancer Center) cell proliferation, but at higher concentrations, they promoted proliferation. Similar proliferation-promoting effects were observed in HepG2 cells. The research provides important information in the application of quinoa in the food and functional food industries.
Asunto(s)
Chenopodium quinoa , Ácidos Hexurónicos , Staphylococcus aureus Resistente a Meticilina , Arabinosa , Escherichia coli , Grano ComestibleRESUMEN
L-Arabinose, lactulose, and Lactobacillus plantarum (L. plantarum) have been reported to have glucolipid-lowering effects. Here, the effects of L-arabinose and lactulose combined with L. plantarum on obesity traits were investigated. According to the experimental results, the combination of L-arabinose, lactulose, and L. plantarum was more effective at reducing body weight, regulating glucolipid metabolism, and improving insulin resistance. Besides, this combination showed immunomodulatory activity by adjusting the T lymphocyte subsets and reduced the immune-related cytokine production. Moreover, it improved the gut barrier, ameliorated the disorder of gut microbiota, and upregulated the levels of SCFAs. More importantly, the AL group, LP group, and ALLP group showed different regulatory effects on the abundance of Bifidobacterium and Lactobacillus due to the presence of lactulose and L. plantarum. These findings elucidate that the combination of L-arabinose, lactulose, and L. plantarum constitutes a new synbiotic combination to control obesity by modulating glucolipid metabolism, immunomodulatory activity, inflammation, gut barrier, gut microbiota and production of SCFAs.
Asunto(s)
Arabinosa , Dieta Alta en Grasa , Microbioma Gastrointestinal , Lactobacillus plantarum , Lactulosa , Ratones Endogámicos C57BL , Obesidad , Animales , Obesidad/metabolismo , Arabinosa/farmacología , Ratones , Lactulosa/farmacología , Masculino , Microbioma Gastrointestinal/efectos de los fármacos , Probióticos/farmacología , Probióticos/administración & dosificación , Resistencia a la InsulinaRESUMEN
There is a great scientific curiosity to discover all environments sheltering microalgae, especially those with exceptional characteristics from coldest to hottest ones, the purpose remains to explore the potential of the native microalgae flora and the research for new bioactive compounds. This study aimed to isolate a polysaccharide-producing microalga from an extreme ecosystem and to evaluate its capacity to inhibit the α-D-glucosidase enzyme. Chlorella strain is isolated from hypersaline Lake in the Algerian desert. The exopolysaccharide extraction was performed by the concentration of free-cell supernatant in a rotary evaporator. The infrared analysis showed a characteristic footprint of carbohydrates with particular functional groups, such as sulfate. Gas chromatography-mass spectrometry has revealed a hetero-exopolysaccharide composed of galactose 35.75%, glucose 21.13%, xylose 16.81%, fructose 6.96%, arabinose 5.10%, and glucuronic acid 2.68%. The evaluation of the anti-hyperglycemic activity demonstrated a significant α-D-glucosidase inhibition of 80.94 ± 0.01% at 10 mg mL-1 with IC50 equal to 4.31 ± 0.20 mg mL-1. This study opens a vast prospect to use exopolysaccharides as natural nutraceutical or food additive.
Asunto(s)
Chlorella , Sulfatos , Ecosistema , Arabinosa , GlucosidasasRESUMEN
Members of the order Mycobacteriales are distinguished by a characteristic diderm cell envelope, setting them apart from other Actinobacteria species. In addition to the conventional peptidoglycan cell wall, these organisms feature an extra polysaccharide polymer composed of arabinose and galactose, termed arabinogalactan. The nonreducing ends of arabinose are covalently linked to mycolic acids (MAs), forming the immobile inner leaflet of the highly hydrophobic MA membrane. The contiguous outer leaflet of the MA membrane comprises trehalose mycolates and various lipid species. Similar to all actinobacteria, Mycobacteriales exhibit apical growth, facilitated by a polar localized elongasome complex. A septal cell envelope synthesis machinery, the divisome, builds instead of the cell wall structures during cytokinesis. In recent years, a growing body of knowledge has emerged regarding the cell wall synthesizing complexes of Mycobacteriales., focusing particularly on three model species: Corynebacterium glutamicum, Mycobacterium smegmatis, and Mycobacterium tuberculosis.