RESUMO
Microbial biotechnology employs techniques that rely on the natural interactions that occur in ecosystems. Bacteria, including rhizobacteria, play an important role in plant growth, providing crops with an alternative that can mitigate the negative effects of abiotic stress, such as those caused by saline environments, and increase the excessive use of chemical fertilizers. The present study examined the promoting potential of bacterial isolates obtained from the rhizospheric soil and roots of the Asparagus officinalis cultivar UF-157 F2 in Viru, la Libertad, Peru. This region has high soil salinity levels. Seventeen strains were isolated, four of which are major potential plant growth-promoting traits, and were characterized based on their morphological and molecular characteristics. These salt-tolerant bacteria were screened for phosphate solubilization, indole acetic acid, deaminase activity, and molecular characterization by 16S rDNA sequencing. Fifteen samples were from saline soils of A. officinalis plants in the northern coastal desert of San Jose, Lambayeque, Peru. The bacterial isolates were screened in a range of salt tolerances from 3 to 6%. Isolates 05, 08, 09, and 11 presented maximum salt tolerance, ammonium quantification, phosphate solubilization, and IAA production. The four isolates were identified by sequencing the amplified 16S rRNA gene and were found to be Enterobacter sp. 05 (OQ885483), Enterobacter sp. 08 (OQ885484), Pseudomonas sp. 09 (OR398704) and Klebsiella sp. 11 (OR398705). These microorganisms promoted the germination of Zea mays L. plants, increased the germination rates in the treatments with chemical fertilizers at 100% and 50%, and the PGPRs increased the height and length of the roots 40 days after planting. The beneficial effects of salt-tolerant PGPR isolates isolated from saline environments may lead to new species that can be used to overcome the detrimental effects of salt stress on plants. The biochemical response and inoculation of the three isolates prove the potential of these strains as sources of products to develop new compounds, confirming their potential as biofertilizers for saline environments.
Assuntos
Asparagus , Bactérias , Raízes de Plantas , RNA Ribossômico 16S , Rizosfera , Microbiologia do Solo , Zea mays , Asparagus/microbiologia , Asparagus/crescimento & desenvolvimento , Zea mays/microbiologia , Zea mays/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Raízes de Plantas/crescimento & desenvolvimento , Bactérias/genética , Bactérias/classificação , Bactérias/isolamento & purificação , Bactérias/metabolismo , Bactérias/crescimento & desenvolvimento , RNA Ribossômico 16S/genética , Ácidos Indolacéticos/metabolismo , Peru , Fosfatos/metabolismo , Tolerância ao Sal , Solo/químicaRESUMO
Arsenic (As) contamination in agricultural groundwater and soil is a significant economic and health problem worldwide. It inhibits soybean (Glycine max (L.) Merr.) nodulation and biological nitrogen fixation in symbiosis with Bradyrhizobium japonicum E109 (E109), a commonly used rhizobial strain for commercial biofertiliser formulation in Argentina. In the context of sustainable and climate-smart agriculture promoted by FAO, co-inoculating legumes with As-tolerant plant growth-promoting bacteria (PGPB) is suggested as a superior alternative to single inoculation. This study aimed to evaluate the impact of As on plant growth-promoting (PGP) traits -siderophore and indole acetic acid production, phosphate solubilisation, diazotrophic activity and hydrolytic enzymes activity- in E109 and three other PGPB strains: Pseudomonas sp. AW4 (AW4), Bacillus pumilus SF5 (SF5) and Bacillus toyonensis SFC 500-1E (Bt). In addition, bacterial compatibility and adhesion on soybean seed were evaluated. Arsenic significantly reduced PGP traits of E109 even at low concentrations, AW4's traits remained unchanged, while those of SF5 and Bt traits were affected (positively or negatively) only at the highest concentrations tested (500 µM arsenate, 250 µM arsenite). All PGPB strains were compatible with E109 under both control and As-stress conditions. Soybean seed adhesion was reduced for E109, only under As stress. Findings suggest that the effect of As on PGP traits is highly strain-dependent and influenced by As concentration and speciation. AW4, SF5, and Bt strains show promise for co-inoculation with E109 in soybean cultivation.
Assuntos
Arsênio , Bradyrhizobium , Glycine max , Fixação de Nitrogênio , Sementes , Microbiologia do Solo , Simbiose , Glycine max/microbiologia , Glycine max/crescimento & desenvolvimento , Arsênio/metabolismo , Sementes/microbiologia , Sementes/crescimento & desenvolvimento , Bradyrhizobium/fisiologia , Bradyrhizobium/metabolismo , Bacillus/fisiologia , Bacillus/metabolismo , Aderência Bacteriana , Pseudomonas , Poluentes do Solo/metabolismo , Argentina , Fosfatos/metabolismo , Ácidos Indolacéticos/metabolismo , NodulaçãoRESUMO
Background: Forage production in tropical soils is primarily limited by nutrient deficiencies, especially nitrogen (N) and phosphorus (P). The use of phosphate rock by plants is limited by its low and slow P availability and microbial phosphate solubilization is the main mechanism for P bioavailability in the soil-root system. The objectives of this study were (i) select a nitrogen-fixing bacteria which could be used as a co-inoculant with the Penicillium rugulosum IR94MF1 phosphate-solubilizing fungus and (ii) evaluate under field conditions the effect of inoculation combined with phosphate rock (PR) application on yield and nutrient absorption of a Urochloa decumbens pasture which was previously established in a low-fertility, acidic soil. Methods: Various laboratory and greenhouse tests allowed for the selection of Enterobacter cloacae C17 as the co-inoculant bacteria with the IR94MF1 fungus. Later, under field conditions, a factorial, completely randomized block design was used to evaluate the inoculation with the IR94MF1 fungus, the IR94MF1+C17 co-inoculation, and a non-inoculated control. Two levels of fertilization with PR treatment (0 kg/ha and 200 kg/ha P2O5) were applied to each. Results: During five consecutive harvests it was observed that the addition of biofertilizers significantly increased (p < 0.05) the herbage mass and N and P assimilation compared to the non-inoculated control. However, no statistically significant differences were observed for the PR application as P source. Conclusion: P. rugulosum IR94MF1 is capable of solubilizing and accumulating P from the phosphate rock, making it available for plants growing in acid soils with low N content. These inoculants represent a good option as biofertilizers for tropical grasses already established in acidic soils with low N content.
Assuntos
Fertilizantes , Penicillium , Fosfatos , Microbiologia do Solo , Solo , Fosfatos/metabolismo , Solo/química , Fertilizantes/análise , Penicillium/metabolismo , Poaceae/microbiologia , Fósforo/metabolismo , Enterobacter cloacae/metabolismo , Nitrogênio/metabolismoRESUMO
The association of bacteria resistant to potentially toxic metals (PTMs) with plants to remove, transfer, or stabilize these elements from the soil is an appropriate tool for phytoremediation processes in metal-contaminated environments. The objective of this study was to evaluate the potential of Rhizobium sp. LBMP-C04 for phytoremediation processes and plant growth promotion in metal-contaminated soils. Functional annotation allowed us to predict a variety of genes related to PTMs resistance and plant growth promotion in the bacterial genome. Resistance genes are mainly associated with DNA repair, and the import or export of metals in bacterial cells to maintain cell homeostasis. Genes that promote plant growth are related to mechanisms of osmotic stress tolerance, phosphate solubilization, nitrogen metabolism, biological nitrogen fixation, biofilm formation, heat shock responses, indole-3-acetic acid (IAA) biosynthesis, tryptophan, and organic acids metabolism. Biochemical tests indicated that Rhizobium sp. LBMP-C04 can solubilize calcium phosphate and produce siderophores and IAA in vitro in the presence of the PTMs Cd2+,Cu2+,Cr3+,Cr6+, Zn2+, and Ni2+. Results indicate the possibility of using Rhizobium sp. LBMP-C04 as a potentially efficient bacterium in phytoremediation processesin environments contaminated by PTMs and simultaneously promote plant growth.
Assuntos
Biodegradação Ambiental , Ácidos Indolacéticos , Desenvolvimento Vegetal , Rhizobium , Microbiologia do Solo , Poluentes do Solo , Rhizobium/genética , Rhizobium/metabolismo , Poluentes do Solo/metabolismo , Poluentes do Solo/toxicidade , Ácidos Indolacéticos/metabolismo , Metais/metabolismo , Metais Pesados/toxicidade , Metais Pesados/metabolismo , Sideróforos/metabolismo , Fosfatos/metabolismo , Genoma BacterianoRESUMO
The remarkable nutritional attributes and potential health advantages of quinoa make it an important candidate for developing innovative ready-to-eat food products. This work aimed to develop a functional ready-to-eat snack based on quinoa sourdough fermented by Lactiplantibacillus (L.) plantarum CRL 1964. Phytate, phosphates, and soluble mineral content (Fe, Mn, Zn, Mg, Ca, and P) were determined in snacks formulated with sourdough and control doughs. An in vitro digestion model was performed on quinoa snacks to assess their mineral bioaccessibility and dialyzability. Phytate content was significantly lower (ca. 42.3%) while phosphates were higher (ca. eightfold) in quinoa-based sourdough and sourdough-based snacks (S1964) than in controls. Soluble minerals were higher (10.2%-32.0%) in S1964 than in controls. Mineral bioaccessibility and mineral dialyzability were also higher (ca. 24.5%) among S1964 and control snacks. The developed quinoa snack made from sourdough fermented by L. plantarum CRL 1964 had less phytate concentration and high bioaccessibility of minerals. These findings underscore the relevance of this innovative technology in creating food products that are not only highly nutritious but also represent a valuable contribution to the market of healthy foods. PRACTICAL APPLICATION: In this study, a novel snack based on quinoa sourdough with improved nutritional properties was developed. The addition of quinoa sourdough fermented by Lactiplantibacillus plantarum CRL 1964 to the preparation of quinoa snacks resulted in a product with a lower concentration of phytate and a higher content of phosphates and minerals (soluble, bioaccessible, and dialyzable). These results underline the efficacy of the new snack as a promising alternative to conventional mineral fortification methods. This innovative approach holds promise for addressing nutritional deficiencies and the demand for healthy snack options in today's market.
Assuntos
Pão , Chenopodium quinoa , Fermentação , Lactobacillus plantarum , Valor Nutritivo , Ácido Fítico , Lanches , Chenopodium quinoa/química , Ácido Fítico/análise , Pão/análise , Lactobacillus plantarum/metabolismo , Minerais/análise , Fosfatos/metabolismo , Fosfatos/análise , Manipulação de Alimentos/métodosRESUMO
Background: The dynamics of carbon (C), nitrogen (N), and phosphorus (P) in soils determine their fertility and crop growth in agroecosystems. These dynamics depend on microbial metabolism, which in turn depends on nutrient availability. Farmers typically apply either mineral or organic fertilizers to increase the availability of nutrients in soils. Phosphorus, which usually limits plant growth, is one of the most applied nutrients. Our knowledge is limited regarding how different forms of P impact the ability of microbes in soils to produce the enzymes required to release nutrients, such as C, N and P from different substrates. Methods: In this study, we used the arable layer of a calcareous soil obtained from an alfalfa cropland in Cuatro Cienegas, México, to perform an incubation experiment, where five different phosphate molecules were added as treatments substrates: three organic molecules (RNA, adenine monophosphate (AMP) and phytate) and two inorganic molecules (calcium phosphate and ammonium phosphate). Controls did not receive added phosphorus. We measured nutrient dynamics and soil microbial activity after 19 days of incubation. Results: Different P molecules affected potential microbial C mineralization (CO2-C) and enzyme activities, specifically in the organic treatments. P remained immobilized in the microbial biomass (Pmic) regardless of the source of P, suggesting that soil microorganisms were limited by phosphorus. Higher mineralization rates in soil amended with organic P compounds depleted dissolved organic carbon and increased nitrification. The C:N:P stoichiometry of the microbial biomass implied a change in the microbial community which affected the carbon use efficiency (CUE), threshold elemental ratio (TER), and homeostasis. Conclusion: Different organic and inorganic sources of P affect soil microbial community structure and metabolism. This modifies the dynamics of soil C, N and P. These results highlight the importance of considering the composition of organic matter and phosphate compounds used in agriculture since their impact on the microbial activity of the soil can also affect plant productivity.
Assuntos
Agricultura , Fósforo , Microbiologia do Solo , Solo , Solo/química , Fósforo/metabolismo , Agricultura/métodos , México , Nitrogênio/metabolismo , Ecossistema , Carbono/metabolismo , Fosfatos/metabolismo , Fertilizantes/análise , Medicago sativa/metabolismoRESUMO
Insoluble phosphorous compounds solubilization by soil bacteria is of great relevance since it puts available the phosphorus to be used by plants. The production of organic acids is the main microbiological mechanism by which insoluble inorganic phosphorus compounds are solubilized. In Gram negative bacteria, gluconic acid is synthesized by the activity of the holoenzyme glucose dehydrogenase-pyrroloquinoline quinine named GDH-PQQ. The use of marker genes is a very useful tool to evaluate the persistence of the introduced bacteria and allow to follow-up the effect of biotic and abiotic factors on these beneficial microorganisms in the soil. In previous studies we detected the presence of the pqqE gene in a great percentage of both non-culturable and culturable native soil bacteria. The objective of this study was to analyze the phylogeny of the sequence of pqqE gene and its potential for the study of phosphate solubilizing bacteria from pure and mixed bacterial cultures and rhizospheric soil samples. For this, the presence of the pqqE gene in the genome of phosphate solubilizing bacteria that belong to several bacteria was determined by PCR. Also, this gene was analyzed from mixed bacterial cultures and rhizospheric soil associated to peanut plants inoculated or not with phosphate solubilizing bacteria. For this, degenerate primers designed from several bacterial genera and specific primers for the genus Pseudomonas spp., designed in this study, were used. DNA template used from simple or mixed bacterial cultures and from rhizospheric soil samples was obtained using two different DNA extraction techniques. Results indicated that pqqE gene amplification product was found in the genome of all Gram negative phosphate solubilizing bacteria analyzed. It was possible to detect this gene in the DNA obtained from mixed cultures where these bacteria grew in interaction with other microorganisms and in that obtained from rhizospheric soil samples inoculated or not with these bacteria. The phylogenetic analysis indicated that pqqE gene is a conserved gene within related genera. In conclusion, pqqE gene could be a potential marker for the study of phosphate solubilizing bacterial populations.
Assuntos
Fosfatos , Filogenia , Microbiologia do Solo , Fosfatos/metabolismo , Bactérias Gram-Negativas/genética , Bactérias Gram-Negativas/isolamento & purificação , Bactérias Gram-Negativas/classificação , Solubilidade , Marcadores Genéticos , Rizosfera , Plantas/microbiologiaRESUMO
Bacteria can solubilize phosphorus (P) through the secretion of low-molecular-weight organic acids and acidification. However, the genes involved in the production of these organic acids are poorly understood. The objectives of this study were to verify the calcium phosphate solubilization and the production of low-molecular-weight organic acids by diverse genera of phosphate solubilizing bacterial strains (PSBS); to identify the genes related to the synthesis of the organic acids in the genomes of these strains and; to evaluate growth and nutrient accumulation of maize plants inoculated with PSBS and fertilized with Bayóvar rock phosphate. Genomic DNA was extracted for strain identification and annotation of genes related to the organic acids production. A greenhouse experiment was performed with five strains plus 150 mg dm- 3 P2O5 as Bayóvar rock phosphate (BRP) to assess phosphate solubilization contribution to maize growth and nutrition. Paraburkholderia fungorum UFLA 04-21 and Pseudomonas anuradhapurensis UFPI B5-8A solubilized over 60% of Ca phosphate and produced high amounts of citric/maleic and gluconic acids in vitro, respectively. Eleven organic acids were identified in total, although not all strains produced all acids. Besides, enzymes related to the organic acids production were found in all bacterial genomes. Plants inoculated with strains UFPI B5-6 (Enterobacter bugandensis), UFPI B5-8A, and UFLA 03-10 (Paenibacillus peoriae) accumulated more biomass than the plants fertilized with BRP only. Strains UFLA 03-10 and UFPI B5-8A increased the accumulation of most macronutrients, including P. Collectively, the results show that PSBS can increase maize growth and nutrient accumulation based on Bayóvar rock phosphate fertilization.
Assuntos
Bactérias , Fosfatos , Zea mays , Zea mays/crescimento & desenvolvimento , Zea mays/microbiologia , Zea mays/metabolismo , Fosfatos/metabolismo , Bactérias/genética , Bactérias/metabolismo , Bactérias/classificação , Fosfatos de Cálcio/metabolismo , Microbiologia do Solo , Genoma Bacteriano , Desenvolvimento Vegetal , Solubilidade , Gluconatos/metabolismo , Genômica , Fósforo/metabolismo , FilogeniaRESUMO
Population expansion is a global issue, especially for food production. Meanwhile, global climate change is damaging our soils, making it difficult for crops to thrive and lowering both production and quality. Poor nutrition and salinity stress affect plant growth and development. Although the impact of individual plant stresses has been studied for decades, the real stress scenario is more complex due to the exposure to multiple stresses at the same time. Here we investigate using existing evidence and a meta-analysis approach to determine molecular linkages between 2 contemporaneous abiotic stimuli, phosphate (Pi) deficiency and salinity, on a single plant cell model, the root hairs (RHs), which is the first plant cell exposed to them. Understanding how these 2 stresses work molecularly in RHs may help us build super-adaptable crops and sustainable agriculture in the face of global climate change.
Assuntos
Fosfatos , Raízes de Plantas , Estresse Salino , Produtos Agrícolas/crescimento & desenvolvimento , Produtos Agrícolas/metabolismo , Fosfatos/deficiência , Fosfatos/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismoRESUMO
The flooding pampa is one of the most important cattle-raising regions in Argentina. In this region, natural pastures are dominated by low-productivity native grass species, which are the main feed for livestock. In this context, previous studies in the region with the subtropical exotic grass Panicum coloratum highlight it as a promising species to improve pasture productivity. Cultivable phosphate solubilizing bacteria (PSB) communities associated to native (Sporobolus indicus) and exotic (Panicum coloratum) forage grasses adapted to alkaline-sodic soils of the flooding pampa were analyzed. PSB represented 2-14% of cultivable rhizobacteria and Box-PCR fingerprinting revealed a high genetic diversity in both rhizospheres. Taxonomic identification by MALDI-TOF showed that PSB populations of P. coloratum and S. indicus rhizospheres are dominated by the phylum Proteobacteria (92,51% and 96,60% respectively) and to a lesser extent (< 10%), by the phyla Actinobacteria and Firmicutes. At the genus level, both PSB populations were dominated by Enterobacter and Pseudomonas. Siderophore production, nitrogen fixation, and indoleacetic acid production were detected in a variety of PSB genera of both plant species. A higher proportion of siderophore and IAA producers were associated to P. coloratum than S. indicus, probably reflecting a greater dependence of the exotic species on rhizospheric microorganisms to satisfy its nutritional requirements in the soils of the flooding pampa. This work provides a novel knowledge about functional groups of bacteria associated to plants given that there are no previous reports dedicated to the characterization of PSB rhizosphere communities of S indicus and P coloratum. Finally, it should be noted that the collection obtained in this study can be useful for the development of bioinputs that allow reducing the use of chemical fertilizers, providing sustainability to pasture production systems for livestock.
Assuntos
Bactérias , Fosfatos , Poaceae , Rizosfera , Microbiologia do Solo , Solo , Poaceae/microbiologia , Bactérias/classificação , Bactérias/genética , Bactérias/metabolismo , Bactérias/isolamento & purificação , Solo/química , Fosfatos/metabolismo , Argentina , Animais , Filogenia , Sideróforos/metabolismo , Fixação de Nitrogênio , Ácidos Indolacéticos/metabolismo , Inundações , RNA Ribossômico 16S/genéticaRESUMO
PhoX is a high-affinity phosphate binding protein, present in Xanthomonas citri, a phytopathogen responsible for the citrus canker disease. Performing molecular dynamics simulations and different types of computational analyses, we study the molecular mechanisms at play in relation to phosphate binding, revealing the global functioning of the protein: PhoX naturally oscillates along its global normal modes, which allow it to explore both bound and unbound conformations, eventually attracting a nearby negative phosphate ion to the highly positive electrostatic potential on its surface, particularly close to the binding pocket. There, several hydrogen bonds are formed with the two main domains of the structure. Phosphate creates, in this way, a strong bridge that connects the domains, keeping itself between them, in a tight closed conformation, explaining its high binding affinity.
Assuntos
Proteínas de Bactérias , Simulação de Dinâmica Molecular , Fosfatos , Xanthomonas , Fosfatos/metabolismo , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/química , Ligação Proteica , Proteínas de Ligação a Fosfato/metabolismo , Ligação de Hidrogênio , Sítios de Ligação , Eletricidade EstáticaRESUMO
Iron (Fe) and phosphate (Pi) are two essential nutrients that are poorly available in the soil and should be supplemented either as fertilizers or organic amendments to sustain crop production. Currently, determining how rhizosphere bacteria contribute to plant mineral nutrient acquisition is an area of growing interest regarding its potential application in agriculture. The aim of this study was to investigate the influence of root colonization by Pseudomonas putida for Arabidopsis growth through Fe and Pi nutritional signaling. We found that root colonization by the bacterium inhibits primary root elongation and promotes the formation of lateral roots. These effects could be related to higher expression of two Pi starvation-induced genes and AtPT1, the major Pi transporter in root tips. In addition, P. putida influenced the accumulation of Fe in the root and the expression of different elements of the Fe uptake pathway. The loss of function of the protein ligase BRUTUS (BTS), and the bHLH transcription factors POPEYE (PYE) and IAA-LEUCINE RESISTANT3 (ILR3) compromised the root branching stimulation triggered by bacterial inoculation while the leaf chlorosis in the fit1 and irt1-1 mutant plants grown under standard conditions could be bypassed by P. putida inoculation. The WT and both mutant lines showed similar Fe accumulation in roots. P. putida repressed the expression of the IRON-REGULATED TRANSPORTER 1 (IRT1) gene suggesting that the bacterium promotes an alternative Fe uptake mechanism. These results open the door for the use of P. putida to enhance nutrient uptake and optimize fertilizer usage by plants.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Pseudomonas putida , Arabidopsis/metabolismo , Pseudomonas putida/genética , Pseudomonas putida/metabolismo , Fosfatos/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Raízes de Plantas/metabolismo , Regulação da Expressão Gênica de PlantasRESUMO
Bacterial inoculants have been used in agriculture to improve plant performance. However, laboratory and field requirements must be completed before a candidate can be employed as an inoculant. Therefore, this study aimed to evaluate the parameters for inoculant formulation and the potential of Bacillus subtilis (B70) and B. pumilus (B32) to improve phosphorus availability in maize (Zea mays L.) crops. In vitro experiments assessed the bacterial ability to solubilize and mineralize phosphate, their adherence to roots, and shelf life in cassava starch (CS), carboxymethyl cellulose (CMC), peat, and activated charcoal (AC) stored at 4 °C and room temperature for 6 months. A field experiment evaluated the effectiveness of strains to increase the P availability to plants growing with rock phosphate (RP) and a mixture of RP and triple superphosphate (TS) and their contribution to improving maize yield and P accumulation in grains. The B70 was outstanding in solubilizing RP and phytate mineralization and more stable in carriers and storage conditions than B32. However, root adherence was more noticeable in B32. Among carriers, AC was the most effective for preserving viable cell counts, closely similar to those of the initial inoculum of both strains. Maize productivity using the mixture RPTS was similar for B70 and B32. The best combination was B70 with RP, which improved the maize yield (6532 kg ha-1) and P accumulation in grains (15.95 kg ha-1). Our results indicated that the inoculant formulation with AC carrier and B70 is a feasible strategy for improving phosphorus mobilization in the soil and maize productivity.
Assuntos
Bacillus , Fosfatos , Fosfatos/metabolismo , Bacillus/metabolismo , Raízes de Plantas/microbiologia , Fósforo/metabolismo , Bacillus subtilis/metabolismo , Solo , Zea mays/microbiologiaRESUMO
For cells to obtain inorganic phosphate, ectoenzymes in the plasma membrane, which contain a catalytic site facing the extracellular environment, hydrolyze phosphorylated molecules. In this study, we show that increased Pi levels in the extracellular environment promote a decrease in ecto-phosphatase activity, which is associated with Pi-induced oxidative stress. High levels of Pi inhibit ecto-phosphatase because Pi generates H2 O2 . Ecto-phosphatase activity is inhibited by H2 O2 , and this inhibition is selective for phospho-tyrosine hydrolysis. Additionally, it is shown that the mechanism of inhibition of ecto-phosphatase activity involves lipid peroxidation. In addition, the inhibition of ecto-phosphatase activity by H2 O2 is irreversible. These findings have new implications for understanding ecto-phosphatase regulation in the tumor microenvironment. H2 O2 stimulated by high Pi inhibits ecto-phosphatase activity to prevent excessive accumulation of extracellular Pi, functioning as a regulatory mechanism of Pi variations in the tumor microenvironment.
Assuntos
Neoplasias da Mama , Peróxido de Hidrogênio , Humanos , Feminino , Peróxido de Hidrogênio/farmacologia , Fosfatos/farmacologia , Fosfatos/metabolismo , Monoéster Fosfórico Hidrolases , Hidrólise , Microambiente TumoralRESUMO
Glucosamine-6-phosphate (GlcN6P) deaminases from Escherichia coli (EcNagBI) and Shewanella denitrificans (SdNagBII) are special examples of what constitute nonhomologous isofunctional enzymes due to their convergence, not only in catalysis, but also in cooperativity and allosteric properties. Additionally, we found that the sigmoidal kinetics of SdNagBII cannot be explained by the existing models of homotropic activation. This study describes the regulatory mechanism of SdNagBII using enzyme kinetics, isothermal titration calorimetry (ITC), and X-ray crystallography. ITC experiments revealed two different binding sites with distinctive thermodynamic signatures: a single binding site per monomer for the allosteric activator N-acetylglucosamine 6-phosphate (GlcNAc6P) and two binding sites per monomer for the transition-state analog 2-amino-2-deoxy-D-glucitol 6-phosphate (GlcNol6P). Crystallographic data demonstrated the existence of an unusual allosteric site that can bind both GlcNAc6P and GlcNol6P, implying that the homotropic activation of this enzyme arises from the occupation of the allosteric site by the substrate. In this work we describe the presence of this novel allosteric site in the SIS-fold deaminases, which is responsible for the homotropic and heterotropic activation of SdNagBII by GlcN6P and GlcNAc6P, respectively. This study unveils an original mechanism to generate a high degree of homotropic activation in SdNagBII, mimicking the allosteric and cooperative properties of hexameric EcNagBI but with a reduced number of subunits.
Assuntos
Escherichia coli , Fosfatos , Sítio Alostérico , Regulação Alostérica , Escherichia coli/metabolismo , Sítios de Ligação , Fosfatos/metabolismo , CinéticaRESUMO
Trehalose 6-phosphate (Tre6P), the intermediate of trehalose biosynthesis, is an essential signal metabolite in plants, linking growth and development to carbon status. Our current understanding of Tre6P metabolism and signaling pathways in plants is based almost entirely on studies performed with Arabidopsis thaliana, a model plant that performs C3 photosynthesis. Conversely, our knowledge on the molecular mechanisms involved in Tre6P regulation of carbon partitioning and metabolism in C4 plants is scarce. This topic is especially relevant due to the agronomic importance of crops performing C4 photosynthesis, such as maize, sorghum and sugarcane. In this review, we focused our attention on recent developments related to Tre6P metabolism in C4 species and raised some open questions that should be addressed in the near future to improve the yield of economically important crops.
Assuntos
Arabidopsis , Trealose , Trealose/metabolismo , Plantas/metabolismo , Arabidopsis/metabolismo , Fotossíntese , Carbono/metabolismo , Fosfatos/metabolismoRESUMO
In agricultural soils the productivity is determined by several factors and among them are the metabolic activities of the microorganisms that reside in it. The inoculation of plants with these bacteria is an alternative to the use of agrochemicals in crops. In particular, in those soils in which P levels are low, phosphate-solubilizing bacteria became an important group of soil microorganisms. In order to propose a potential P-biofertilizer to replace chemical fertilizers, the objective of this study was to evaluate the response of peanut and maize plants to the inoculation with the phosphate solubilizer Enterobacter sp. J49 individually or in combination with chemical fertilizers on growth, yield, and nutrient contents on peanut and maize plants in field trials. Two field assays in the peanut growing region of Córdoba Province (Argentina) were carried out. The inoculation of peanut with Enterobacter sp. J49 showed an increase in the yield with respect to the other treatments. Maize plants inoculated with this strain, alone or combined with half dose of chemical fertilizer, presented the highest yields. The results indicated that Enterobacter sp. J49 has a growth-promoting effect on the yield of peanut and maize mainly under drought stress. In conclusion, the inoculation with this strain would be a more sustainable agricultural practice for improving yield of peanut and maize crops in Argentinian agricultural area.
Assuntos
Arachis , Enterobacter , Arachis/microbiologia , Fertilizantes/análise , Zea mays/microbiologia , Solo/química , Fosfatos/metabolismo , Microbiologia do SoloRESUMO
Sugar-alcohols are major photosynthates in plants from the Rosaceae family. Expression of the gene encoding aldose-6-phosphate reductase (Ald6PRase), the critical enzyme for glucitol synthesis in rosaceous species, is regulated by physiological and environmental cues. Additionally, Ald6PRase is inhibited by small molecules (hexose-phosphates and inorganic orthophosphate) and oxidizing compounds. This work demonstrates that Ald6PRase from peach leaves is phosphorylated in planta at the N-terminus. We also show in vitro phosphorylation of recombinant Ald6PRase by a partially purified kinase extract from peach leaves containing Ca2+-dependent protein kinases (CDPKs). Moreover, phosphorylation of recombinant Ald6PRase was inhibited by hexose-phosphates, phosphoenolpyruvate and pyrophosphate. We further show that phosphorylation of recombinant Ald6PRase was maximal using recombinant CDPKs. Overall, our results suggest that phosphorylation could fine-tune the activity of Ald6PRase.
Assuntos
Prunus persica , Fosforilação , Prunus persica/metabolismo , Fosfatos/metabolismo , Folhas de Planta/metabolismo , Hexoses/metabolismoRESUMO
Tumor cells develop a high demand for inorganic phosphate (Pi) due to their high growth rates and energy requirements. Serum Pi concentrations in cancer patients have been found to be two to four times higher than baseline levels in healthy individuals. Twofold Pi accumulation was observed in breast cancer cells in the mouse tumor microenvironment. In the breast tumoral microenvironment, ectonucleotidases and ectophosphatases-presenting catalytic sites facing the extracellular environment-could be involved in the extracellular release of Pi to be internalized by Pi transporters to fuel the high energy requirement typical of cancer cells. Two Pi transporters were characterized in breast cancer cells (Na+-dependent and H+-dependent) with strong associations with tumor processes such as proliferation, migration, adhesion, and epithelium-mesenchymal transition (EMT). Moreover, a high extracellular Pi concentration stimulates ROS production in triple-negative breast cancer cells by Pi transport stimulation. Several compounds show a potent ability to inhibit ectonucleotidases, ectophosphatases, Pi transporters, and Pi-modulated signal pathways in breast cancer cells and regulate proliferation, migration, adhesion, and EMT. This review article aimed to gather the relevant experimental records regarding Pi's effects on the breast cancer microenvironment and points to possible inhibitors for ectonucleotidases, ectophosphatases, Pi transporters, and Pi-modulated signal pathways as potential chemotherapeutic agents or Pi acting as a potent enhancer of classical chemical-induced cytotoxicity in triple-negative breast cancer cells.
Assuntos
Neoplasias de Mama Triplo Negativas , Humanos , Animais , Camundongos , Neoplasias de Mama Triplo Negativas/patologia , Fosfatos/metabolismo , Transdução de Sinais , Microambiente TumoralRESUMO
Phosphorus is an essential nutrient for plant growth and development. The ability of plants to acquire phosphate (Pi) from the rhizosphere soil is critical in the Brazilian Cerrado characterized by acidic soil. The induction of Pi transporters is one of the earliest molecular responses to Pi deficiency in plants. In this study, we characterize the transcriptional regulation of six (ZmPT1 to ZmPT6) high-affinity Pi transporters genes in four Pi-efficient and four Pi-inefficient maize (Zea mays) genotypes. The expression analysis indicated that Pi-starvation induced the transcription of all ZmPT genes tested. The abundance of transcripts was inversely related to Pi concentration in nutrient solution and was observed as early as five days following the Pi deprivation. The Pi-starved plants replenished with 250 µM Pi for four to five days resulted in ZmPT suppression, indicating the Pi role in gene expression. The tissue-specific expression analysis revealed the abundance of ZmPT transcripts in roots and shoots. The six maize Pi transporters were primarily detected in the upper and middle root portions and barely expressed in root tips. The expression profiles of the six ZmPTs phosphate transporters between and among Pi-efficient and Pi-inefficient genotypes showed an absence of significant differences in the expression pattern of the ZmPTs among Pi-efficient and Pi-inefficient genotypes. The results suggested that Pi acquisition efficiency is a complex trait determined by quantitative loci in maize.