RESUMEN
Due to the low permeability characteristics of the deep gas-containing coal seam, the conventional prevention and control measures that cannot solve the problems of gas outbursts are unsatisfactory for the prevention and control of the coal and gas outbursts disaster. Therefore, in this study, a strain of methane-oxidizing bacteria M07 with high-pressure resistance, strong resistance, and high methane degradation rate was selected from coal mines. The growth and degradation abilities of M07 in chelating wetting agent solutions to assess its adaptability and find the optimal agent-to-M07 ratio. It provides a new method for integrating the reduction of impact tendency and gas pressure in deep coal mines. The experimental results show that M07 is a Gram-positive bacterium of the genus Bacillus, which has strong resistance and adaptability to high-pressure water injection. By degrading 70 mol of methane, M07 produces 1 mol of carbon dioxide, which can reduce gas pressure and reduce the risk of gas outbursts in coal mines. As the experiment proves, the best effect was achieved when the M07 concentration of the chelating wetting agent was 0.05%. The methane-oxidizing bacteria based on the chelating wetting agent as carriers prove a new prevention and control method for the integrated prevention and control of coal and gas outbursts in coal mines and also provide a new idea for microbial application in coal mine disaster control.
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Biodegradación Ambiental , Quelantes , Metano , Metano/metabolismo , Metano/química , Quelantes/química , Quelantes/farmacología , Quelantes/metabolismo , Bacillus/metabolismo , Carbón Mineral , Minas de CarbónRESUMEN
The chelation of protein-bound metal ions is typically thought to follow either a dissociative (D) or an associative (A) path. While the former mechanism involves the spontaneous dissociation of the metal from the protein prior to chelation, the latter route is characterized by the formation of an intermediate protein-metal-chelator ternary complex. Using the prototypical zinc protease carboxypeptidase A (CPA) and a variety of charged and neutral chelating agents, we demonstrate that inactivation of the enzyme (and likely other metalloproteins) proceeds through a split pathway with contributions from both D- and A-type mechanisms. In the case of charged chelators such as ethylenediaminetetraacetic acid (EDTA), the proportions of both paths could be tuned over a wide range through variation of the chelator concentration and the ionic strength, I (from â¼95% A type at low I values to â¼5% at high I values). By measuring the EDTA concentration and time dependence of CPA inactivation and fitting the obtained kinetic data to a modified time-dependent inhibition model, we obtained the rate constants for the A and D paths (kinact and koff, respectively) and the inhibition constant (KI) for the formation of the CPA-Zn2+-EDTA ternary complex, indicating that the decreased contribution of the A-type mechanism at high ionic strengths originates from a large (40-fold; at I = 0.5 M) increase in KI. This observation might be related to a triarginine motif in CPA that electrostatically steers negatively charged substrates into the active site and may therefore also guide carboxylate-bearing chelators toward the Zn2+ ion.
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Carboxipeptidasas A , Quelantes , Ácido Edético , Quelantes/química , Quelantes/metabolismo , Ácido Edético/química , Carboxipeptidasas A/metabolismo , Carboxipeptidasas A/química , Carboxipeptidasas A/antagonistas & inhibidores , Cinética , Zinc/metabolismo , Zinc/química , Animales , Concentración OsmolarRESUMEN
I present the perspective that the divalent metalome and the metabolome can be modeled as a network of chelating interactions instead of separate entities. I review progress in understanding the complex cellular environment, in particular recent contributions to modeling metabolite-Mg2+ interactions. I then demonstrate a simple extension of these strategies based approximately on intracellular Escherichia coli concentrations. This model is composed of four divalent metal cations with a range of cellular concentrations and physical properties (Mg2+, Ca2+, Mn2+, and Zn2+), eight representative metabolites, and interaction constants. I applied this model to predict the speciation of divalent metal cations between free and metabolite-chelated species. This approach reveals potentially beneficial properties, including maintenance of free divalent metal cations at biologically relevant concentrations, buffering of free divalent metal cations, and enrichment of functional metabolite-chelated species. While currently limited by available interaction coefficients, this modeling strategy can be generalized to more complex systems. In summary, biochemists should consider the potential of cellular metabolites to form chelating interactions with divalent metal cations.
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Cationes Bivalentes , Escherichia coli , Cationes Bivalentes/metabolismo , Cationes Bivalentes/química , Escherichia coli/metabolismo , Escherichia coli/genética , Quelantes/química , Quelantes/metabolismo , Modelos Biológicos , Metaboloma , Magnesio/metabolismo , Magnesio/química , Tampones (Química) , Zinc/metabolismo , Zinc/químicaRESUMEN
In the past decade, food-derived metal-chelating peptides (MCPs) have attracted significant attention from researchers working towards the prevention of metal (viz., iron, zinc, and calcium) deficiency phenomenon by primarily inhibiting the precipitation of metals caused by the gastrointestinal environment and exogenous substances (including phytic and oxalic acids). However, for the improvement of limits of current knowledge foundations and future investigation directions of MCP or their derivatives, several review categories should be improved and emphasized. The species' uniqueness and differences in MCP productions highly contribute to the different values of chelating ability with particular metal ions, whereas comprehensive reviews of chelation characterization determined by various kinds of technique support different horizons for explaining the chelation and offer options for the selection of characterization methods. The reviews of chelation mechanism clearly demonstrate the involvement of potential groups and atoms in chelating metal ions. The discussions of digestive stability and absorption in various kinds of absorption model in vitro and in vivo as well as the theory of involved cellular absorption channels and pathways are systematically reviewed and highlighted compared with previous reports as well. Meanwhile, the chelation mechanism on the molecular docking level, the binding mechanism in amino acid identification level, the utilizations of everted rat gut sac model for absorption, and the involvement of cellular absorption channels and pathway are strongly recommended as novelty in this review. This review makes a novel contribution to the literature by the comprehensive prospects for the research and development of food-derived mineral supplements.
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Quelantes , Metales , Ratas , Animales , Simulación del Acoplamiento Molecular , Quelantes/química , Quelantes/metabolismo , Quelantes/farmacología , Metales/química , Péptidos/química , Iones , DigestiónRESUMEN
Soil contamination with toxic heavy metals [such as lead (Pb)] is becoming a serious global problem due to the rapid development of the social economy. Organic chelating agents such as maleic acid (MA) and tartaric acid (TA) are more efficient, environmentally friendly, and biodegradable compared to inorganic chelating agents and they enhance the solubility, absorption, and stability of metals. To investigate this, we conducted a hydroponic experiment to assess the impact of MA (0.25 mM) and TA (1 mM) on enhancing the phytoremediation of Pb under its toxic concentration of 100 µM, using the oil seed crop canola (Brassica napus L.). Results from the present study showed that the Pb toxicity significantly (P < 0.05) decreased plant growth and biomass, photosynthetic pigments, gas exchange attributes and nutritional contents from the roots and shoots of the plants. In contrast, toxic concentration of Pb significantly (P < 0.05) increased oxidative stress indicators in term of malondialdehyde, hydrogen peroxide, and electrolyte leakage, increased enzymatic and non-enzymatic antixoidants and their specific gene expression and also increased organic acid exudation patter in the roots of B. napus. In addition, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that Pb toxicity significantly affected double membranous organelles while Fourier-transform infrared (FTIR) spectroscopy showed an nveiled distinct peak variations in Pb-treated plants, when compared to control. Additionally, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that Pb toxicity significantly affected double-membrane organelles, while Fourier-transform infrared (FTIR) spectroscopy unveiled distinct peak variations in Pb-treated plants compared to the control. The negative impact of Pb toxicity can overcome the application of MA and TA, which ultimately increased plant growth and biomass by capturing the reactive oxygen species, and decreased oxidative stress in B. napus. With the application of MA and TA, the values of the bioaccumulation factor (BAF) and translocation factor (TF) exceeded 1, indicating that the use of MA and TA enhances the phytoremediation potential of B. napus under Pb stress conditions. This finding could be beneficial for field environment studies, especially when explored through in-depth genetic and molecular analysis.
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Brassica napus , Contaminantes del Suelo , Plomo/análisis , Brassica napus/metabolismo , Contaminantes del Suelo/análisis , Biodegradación Ambiental , Quelantes/metabolismo , Raíces de Plantas/metabolismo , SueloRESUMEN
Heavy metal pollution of soil, especially by lead (Pb) and cadmium (Cd), is a serious problem worldwide. The application of safe chelating agents, combined with the growing of tolerant trees, constitutes an approach for phytoremediation of heavy-metal-contaminated soil. This study aimed to determine whether the two safe chelators, tetrasodium glutamate diacetate (GLDA) and citric acid (CA), could improve the phytoremediation capacity of black locust (Robinia pseudoacacia L.) in a Pb-Cd-contaminated soil and to find the key factors affecting the biomass accumulation of stressed black locust. In Pb- and Cd-stressed black locust plants, medium- and high-concentration GLDA treatment inhibited the growth, chlorophyll synthesis and maximum photochemical efficiency (Fv/Fm), promoted the absorption of Pb and Cd ions and resulted in the shrinkage of chloroplasts and starch grains when compared with those in Pb- and Cd-stressed plants that were not treated with GLDA. The effects of CA on plant growth, ion absorption, chlorophyll content, chlorophyll fluorescence and organelle size were significantly weaker than those of GLDA. The effect of both agents on Cd absorption was greater than that on Pb absorption in all treatments. The levels of chlorophyll a and plant tissue Cd and rates of starch metabolism were identified as the key factors affecting plant biomass accumulation in GLDA and CA treatments. In the future, GLDA can be combined with functional bacteria and/or growth promoters to promote the growth of Pb- and Cd-stressed plants and to further improve the soil restoration efficiency following pollution by heavy metals. Application of CA combined with the growing of black locust plants has great potential for restoring the Cd-polluted soil. These findings also provide insights into the practical use of GLDA and CA in phytoremediation by R. pseudoacacia and the tolerant mechanisms of R. pseudoacacia to Pb-Cd-contaminated soil.
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Metales Pesados , Robinia , Cadmio/metabolismo , Plantones , Quelantes/metabolismo , Quelantes/farmacología , Clorofila A/metabolismo , Clorofila A/farmacología , Plomo/metabolismo , Metales Pesados/metabolismo , Clorofila/metabolismo , Suelo/química , Almidón/metabolismo , Biodegradación AmbientalRESUMEN
Cleavage and formation of phosphodiester bonds in nucleic acids is accomplished by large cellular machineries composed of both protein and RNA. Long thought to rely on a two-metal-ion mechanism for catalysis, structure comparisons revealed many contain highly spatially conserved second-shell monovalent cations, whose precise function remains elusive. A recent high-resolution structure of the spliceosome, essential for pre-mRNA splicing in eukaryotes, revealed a potassium ion in the active site. Here, we employ biased quantum mechanics/ molecular mechanics molecular dynamics to elucidate the function of this monovalent ion in splicing. We discover that the K+ ion regulates the kinetics and thermodynamics of the first splicing step by rigidifying the active site and stabilizing the substrate in the pre- and post-catalytic state via formation of key hydrogen bonds. Our work supports a direct role for the K+ ion during catalysis and provides a mechanistic hypothesis likely shared by other nucleic acid processing enzymes.
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ARN , Empalmosomas , Empalmosomas/metabolismo , ARN/metabolismo , Empalme del ARN , Catálisis , Metales/metabolismo , Potasio/metabolismo , Quelantes/metabolismo , Conformación de Ácido Nucleico , Sitios de Unión , Cationes Monovalentes/metabolismoRESUMEN
Mycobacteria can colonize environments where the availability of metal ions is limited. Biological or inorganic chelators play an important role in limiting metal availability, and we developed a model to examine Mycobacterium smegmatis survival in the presence of the chelator sodium citrate. We observed that instead of restricting M. smegmatis growth, concentrated sodium citrate killed M. smegmatis. RNAseq analysis during sodium citrate treatment revealed transcriptional signatures of metal starvation and hyperosmotic stress. Notably, metal starvation and hyperosmotic stress, individually, do not kill M. smegmatis under these conditions. A forward genetic transposon selection was conducted to examine why sodium citrate was lethal, and several sodium-citrate-tolerant mutants were isolated. Based on the identity of three tolerant mutants, mgtE, treZ, and fadD6, we propose a dual stress model of killing by sodium citrate, where sodium citrate chelate metals from the cell envelope and then osmotic stress in combination with a weakened cell envelope causes cell lysis. This sodium citrate tolerance screen identified mutants in several other genes with no known function, with most conserved in the pathogen M. tuberculosis. Therefore, this model will serve as a basis to define their functions, potentially in maintaining cell wall integrity, cation homeostasis, or osmotolerance. IMPORTANCE Bacteria require mechanisms to adapt to environments with differing metal availability. When Mycobacterium smegmatis is treated with high concentrations of the metal chelator sodium citrate, the bacteria are killed. To define the mechanisms underlying killing by sodium citrate, we conducted a genetic selection and observed tolerance to killing in mutants of the mgtE magnesium transporter. Further characterization studies support a model where killing by sodium citrate is driven by a weakened cell wall and osmotic stress, that in combination cause cell lysis.
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Mycobacterium smegmatis , Mycobacterium tuberculosis , Mycobacterium smegmatis/metabolismo , Citrato de Sodio/metabolismo , Presión Osmótica , Mycobacterium tuberculosis/genética , Homeostasis , Cationes/metabolismo , Quelantes/metabolismoRESUMEN
OBJECTIVE: To study the aggravation of clinical symptoms after discontinuation of metal chelating agent therapy in Wilson's disease (WD) patients, analyze the causes of aggravation, and observe the prognosis. METHODS: 40 WD patients (cerebral type 30 cases and hepatic type 10 cases) who stopped using metal chelating agent were selected, 40 WD patients with normal therapy, and 10 normal control cases were selected. All patients underwent neurological symptom evaluation using modified Young scale, Child-Pugh liver function grading, metal metabolism, and disease typing. Magnetic sensitivity imaging (SWI), diffusion tensor imaging (DTI), and magnetic resonance spectroscopy imaging (MRS) were performed. According to the imaging results, WD patients were divided into metal deposition stage, fiber damage stage, and neuron necrosis stage. All patients were treated with metal chelating agent for 6 months. RESULTS: The score of modified Young scale in drug withdrawal group was lower than that in normal treatment group before drug withdrawal (p = .032). The score of modified Young scale was higher after drug withdrawal than before (p = .011). The number of Child-Pugh B-grade patients after drug withdrawal was more than that before drug withdrawal and in normal treatment group. The proportion of patients in the stage of neuronal necrosis after drug withdrawal (25%) was higher than that before drug withdrawal (10%) (p = .025). After drug withdrawal, urine copper was significantly higher than that before drug withdrawal and in the normal treatment group (p = .032, .039). After the withdrawal group resumed metal chelating agent treatment, 34.2% of neurological symptoms worsened. CONCLUSIONS: WD patients showed neurological symptoms aggravation and increased liver injury after metal chelating agent withdrawal. Increased metal deposition and new nerve injury occurred in the brain. After re-treatment, the aggravated neurological symptoms of WD patients are difficult to reverse.
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Degeneración Hepatolenticular , Humanos , Degeneración Hepatolenticular/diagnóstico por imagen , Degeneración Hepatolenticular/tratamiento farmacológico , Imagen de Difusión Tensora , Quelantes/efectos adversos , Quelantes/metabolismo , Encéfalo/patología , Necrosis/patología , CobreRESUMEN
Organellar C-to-U RNA editing in plants occurs in complexes composed of various classes of nuclear-encoded proteins. DYW-deaminases are zinc metalloenzymes that catalyze hydrolytic deamination required for C-to-U modification editing. Solved crystal structures for DYW-deaminase domains display all structural features consistent with a canonical cytidine deamination mechanism. However, some recombinant DYW-deaminases from plants have been associated with ribonuclease activity in vitro. Direct ribonuclease activity by an editing factor is confounding since it is not required for deamination of cytosine, theoretically would be inimical for mRNA editing, and does not have a clear physiological function in vivo. His-tagged recombinant DYW1 from Arabidopsis thaliana (rAtDYW1) was expressed and purified using immobilized metal affinity chromatography (IMAC). Fluorescently labeled RNA oligonucleotides were incubated with recombinant AtDYW1 under different conditions. Percent relative cleavage of RNA probes was recorded at multiple time points from triplicate reactions. The effects of treatment with zinc chelators EDTA and 1, 10-phenanthroline were examined for rAtDYW1. Recombinant His-tagged RNA editing factors AtRIP2, ZmRIP9, AtRIP9, AtOZ1, AtCRR4, and AtORRM1 were expressed in E. coli and purified. Ribonuclease activity was assayed for rAtDYW1 in the presence of different editing factors. Lastly, the effects on nuclease activity in the presence of nucleotides and modified nucleosides were investigated. RNA cleavage observed in this study was linked to the recombinant editing factor rAtDYW1 in vitro. The cleavage reaction is sensitive to high concentrations of zinc chelators, indicating a role for zinc ions for activity. The addition of equal molar concentrations of recombinant RIP/MORF proteins reduced cleavage activity associated with rAtDYW1. However, addition of equal molar concentrations of purified recombinant editing complex proteins AtCRR4, AtORRM1, and AtOZ1 did not strongly inhibit ribonuclease activity on RNAs lacking an AtCRR4 cis-element. Though AtCRR4 inhibited AtDYW1 activity for oligonucleotides with a cognate cis-element. The observation that editing factors limit ribonuclease activity of rAtDYW1 in vitro, suggests that nuclease activities are limited to RNAs in absence of native editing complex partners. Purified rAtDYW1 was associated with the hydrolysis of RNA in vitro, and activity was specifically inhibited by RNA editing factors.
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Proteínas de Arabidopsis , Arabidopsis , Ribonucleasas , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas Portadoras/metabolismo , Quelantes/metabolismo , Plantas/metabolismo , Estructura Terciaria de Proteína , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Ribonucleasas/metabolismo , ARN/metabolismo , Zinc/metabolismoRESUMEN
Cadmium (Cd) is a toxic heavy metal, exposure to which leads to adverse health effects including chronic kidney damage. Tremendous efforts have been explored in identifying safe chelating agents for removing accumulated Cd from kidney, but with limited success owing to their associated side effects and the ineffectiveness in eliminating Cd. A newly developed chelating agent, sodium (S)-2-(dithiocarboxylato((2S,3 R,4R,5 R)-2,3,4,5,6-pentahydroxyhexyl) amino)-4(methylthio)butanoate (GMDTC), has been shown to effectively mobilize Cd from kidney. However, the mechanism(s) of removal are unclear, while it has been hypothesized that renal glucose transporters potentially play key roles mainly because GMDTC contains an open chain glucose moiety. To test this hypothesis, we utilized the CRISPR/Cas9 technology and human kidney tubule HK-2 cells, and constructed sodium-dependent glucose transporter 2 (SGLT2) or glucose transporter 2 (GLUT2) gene knockout cell lines. Our data showed that GMDTC's ability in removing Cd from HK-2 cells was significantly reduced both in GLUT2-/- or SGLT2-/- cells, with a removal ratio reduced from 28.28% in the parental HK-2 cells to 7.37% in GLUT2-/- cells and 14.6% in SGLT2-/- cells. Similarly, knocking out the GLUT2 or SGLT2 led to a compromised protective effect of GMDTC in reducing cytotoxicity of HK-2 cells. This observation was further observed in animal studies, in which the inhibition of GLUT2 transporter by phloretin treatment resulted in reduced efficiency of GMDTC in removing Cd from the kidney. Altogether, our results show that GMDTC is safe and highly efficient in removing Cd from the cells, and this effect is mediated by renal glucose transporters.
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Cadmio , Proteínas Facilitadoras del Transporte de la Glucosa , Animales , Humanos , Cadmio/toxicidad , Proteínas Facilitadoras del Transporte de la Glucosa/metabolismo , Transportador 2 de Sodio-Glucosa/genética , Transportador 2 de Sodio-Glucosa/metabolismo , Riñón/metabolismo , Quelantes/farmacología , Quelantes/uso terapéutico , Quelantes/metabolismo , Glucosa/metabolismo , Sodio/metabolismoRESUMEN
Cerebral amyloid angiopathy (CAA) is characterized by the accumulation of the amyloid ß (Aß) protein in blood vessels and leads to hemorrhages, strokes, and dementia in elderly individuals. Recent reports have shown elevated copper levels colocalized with vascular amyloid in human CAA and Alzheimer's disease patients, which have been suggested to contribute to cytotoxicity through the formation of reactive oxygen species. Here, we treated a transgenic rat model of CAA (rTg-DI) with the copper-specific chelator, tetrathiomolybdate (TTM), via intraperitoneal (IP) administration for 6 months to determine if it could lower copper content in vascular amyloid deposits and modify CAA pathology. Results showed that TTM treatment led to elevated Aß load in the hippocampus of the rTg-DI rats and increased microbleeds in the wild type (WT) animals. X-ray fluorescence microscopy was performed to image the distribution of copper and revealed a surprising increase in copper colocalized with Aß aggregates in TTM-treated rTg-DI rats. Unexpectedly, we also found an increase in the copper content in unaffected vessels of both rTg-DI and WT animals. These results show that IP administration of TTM was ineffective in removing copper from vascular Aß aggregates in vivo and increased the development of disease pathology in CAA.
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Enfermedad de Alzheimer , Angiopatía Amiloide Cerebral , Ratas , Humanos , Animales , Anciano , Péptidos beta-Amiloides/metabolismo , Ratas Transgénicas , Cobre/metabolismo , Terapia por Quelación , Angiopatía Amiloide Cerebral/tratamiento farmacológico , Angiopatía Amiloide Cerebral/metabolismo , Enfermedad de Alzheimer/metabolismo , Animales Salvajes , Quelantes/farmacología , Quelantes/metabolismo , Encéfalo/metabolismo , Placa Amiloide/metabolismoRESUMEN
OBJECTIVE: To identify the effect of two chitosan solutions on the release of root dentin matrix proteins and to describe the chemical changes observed following conditioning with chelating agents. MATERIALS AND METHODS: The release of dentin sialoprotein (DSP), transforming growth factor-beta 1 (TGF-ß1), vascular endothelial growth factor (VEGF), and platelet-derived growth factor-BB (PDGF-BB) with different chelating agents, including ethylenediaminetetraacetic acid (EDTA), chitosan solution (CS), and nanoparticulate chitosan (CSnp), was investigated. DSP was quantified using an enzyme-linked immunosorbent assay (ELISA). TGF-ß1, VEGF, and PDGF-BB were quantified using a cytokine bead panel (CBA). Raman spectroscopy was performed to identify surface chemical changes. Statistical analysis was performed using Kruskal-Wallis test with Mann-Whitney-Wilcoxon rank-sum test (p < 0.05). RESULTS: TGF-ß1, VEGF, and DSP solubilized in all irrigants tested. CSnp showed the highest concentration of DSP. PDGF-BB did not exceed the detection limits. Raman spectroscopy revealed a decrease in the phosphate and carbonate peaks, representing the chelating effect of EDTA, CS, and CSnp. Additionally, CSnp showed the greatest preservation of the amide I and III content. CONCLUSION: Proteins can be released from dentin via EDTA, CS, and CSnp conditioning. Raman spectroscopic revealed changes in the inorganic content of the root dentin after chelation. Furthermore, use of CSnp facilitated a preservation of the organic content. CLINICAL RELEVANCE: Chelation allows the release of proteins, justifying the use of chelating agents in regenerative endodontics. The chitosan-dentin matrix interaction also promotes the protection of the organic content as an additional benefit to its protein releasing effect.
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Quitosano , Factor de Crecimiento Transformador beta1 , Factor de Crecimiento Transformador beta1/metabolismo , Quitosano/farmacología , Ácido Edético/farmacología , Factor A de Crecimiento Endotelial Vascular/metabolismo , Becaplermina/metabolismo , Becaplermina/farmacología , Quelantes/farmacología , Quelantes/metabolismo , Dentina , Irrigantes del Conducto Radicular/farmacologíaRESUMEN
More than two billion people around the world are affected by zinc deficiency, mainly due to the inadequate intake and absorption of zinc. Based on recent research findings, the bioactive peptides could potentially be used to combat zinc deficiency particularly due to their Zinc chelating ability. The main aim of this review was to present current findings, supporting the potential use of bioactive peptides based on their ability to enhance zinc absorption. In-vivo, in-vitro, and ex-vivo studies have demonstrated that zinc chelating peptides can enhance the retention, transportation, and absorption of zinc. Comparative studies on zinc bioavailability from protein hydrolysates and zinc salts have demonstrated that the protein hydrolysates-zinc complexes are more bioavailable than the zinc salts. Data from the structure-function relationship of zinc chelating peptides suggest that the zinc chelating capacities of peptides increase in the following order; the position of zinc chelator > zinc chelator strength > abundance of zinc chelators > net charge > molecular weight. In addition, the transport mechanism of peptide-zinc complex is hypothesized, and the potential use of bioactive peptides based on their safety and taste and limitations to their commercialization are also discussed.
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Hidrolisados de Proteína , Zinc , Humanos , Zinc/metabolismo , Hidrolisados de Proteína/química , Sales (Química) , Péptidos/química , Quelantes/metabolismoRESUMEN
Metallothioneins (MTs), a group of cysteine-rich proteins, are effective chelators of cadmium (Cd) and play a key role in plant Cd detoxification. However, little is known about the role of single cysteine (Cys) residues in the MTs involved in the adaptation of plants to Cd stress, especially, in hyperaccumulators. In the present study, we functionally characterised SaMT3 in S. alfredii, a Cd/Zn hyperaccumulator native to China. Our results showed that the C- and N- terminal regions of SaMT3 had differential functional natures in S. alfredii and determined its Cd hypertolerance and detoxification. Two CXC motifs within the C-terminal region were revealed to play a crucial role in Cd sensing and binding, whereas the four Cys-residues within the N-terminal region were involved in scavenging reactive oxygen species (ROS). An S. alfredii transgenic system based on callus transformation was developed to further investigate the in-planta gene function. The SaMT3-overexpressing transgenic plant roots were more tolerant to Cd than those of wild-type plants. Knockout of SaMT3 resulted in significantly decreased Cd concentrations and increased ROS levels after exposure to Cd stress. We demonstrated the SaMT3-mediated adaptation strategy in S. alfredii, which uses metal chelation and ROS scavenging in response to Cd stress. Our results further reveal the molecular mechanisms underlying Cd detoxification in hyperaccumulating plants, as well as the relation between Cys-related motifs and the metal binding properties of MTs. This research provides valuable insights into the functions of SaMT3 in S. alfredii, and improves our understanding of Cd hyperaccumulation in plants.
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Sedum , Contaminantes del Suelo , Sedum/genética , Sedum/metabolismo , Cadmio/toxicidad , Cadmio/metabolismo , Cisteína/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Raíces de Plantas/metabolismo , Metalotioneína/metabolismo , Quelantes/metabolismo , Contaminantes del Suelo/toxicidad , Contaminantes del Suelo/metabolismo , Biodegradación AmbientalRESUMEN
Male sex is one of the most important risk factors of atrial fibrillation (AF), with the incidence in men being almost double that in women. However, the reasons for this sex difference are unknown. Accordingly, in this study, we sought to determine whether there are sex differences in intracellular Ca2+ homeostasis in mouse atrial myocytes that might help explain male predisposition to AF. AF susceptibility was assessed in male (M) and female (F) mice (4-5 months old) using programmed electrical stimulation (EPS) protocols. Males were 50% more likely to develop AF. The Ca2+ transient amplitude was 28% higher in male atrial myocytes. Spontaneous systolic and diastolic Ca2+ releases, which are known sources of triggered activity, were significantly more frequent in males than females. The time to 90% decay of Ca2+ transient was faster in males. Males had 54% higher Na+-Ca2+ exchanger (NCX1) current density, and its expression was also more abundant. L-type Ca2+ current (ICaL) was recorded with and without BAPTA, a Ca2+ chelator. ICaL density was lower in males only in the absence of BAPTA, suggesting stronger Ca2+-dependent inactivation in males. CaV1.2 expression was similar between sexes. This study reports major sex differences in Ca2+ homeostasis in mouse atria, with larger Ca2+ transients and enhanced NCX1 function and expression in males resulting in more spontaneous Ca2+ releases. These sex differences may contribute to male susceptibility to AF by promoting triggered activity.
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Fibrilación Atrial , Intercambiador de Sodio-Calcio/metabolismo , Animales , Fibrilación Atrial/metabolismo , Calcio/metabolismo , Quelantes/metabolismo , Ácido Egtácico/análogos & derivados , Femenino , Atrios Cardíacos/metabolismo , Humanos , Masculino , Ratones , Miocitos Cardíacos/metabolismo , Técnicas de Placa-Clamp , Retículo Sarcoplasmático/metabolismo , Caracteres SexualesRESUMEN
As a multifunctional phytohormone, melatonin (Mel) plays pivotal roles in plant responses to multiple stresses. However, its mechanism of action remains elusive. In the present study, we evaluated the role of NO and Ca2+ signaling in Mel enhanced cold tolerance in winter turnip rape. The results showed that the NO content and concentration of intracellular free Ca2+ ([Ca2+]cyt) increased by 35.42% and 30.87%, respectively, in the leaves of rape seedlings exposed to cold stress. Compared with those of the seedlings in cold stress alone, the NO content and concentration of [Ca2+]cyt in rape seedlings pretreated with Mel increased further. In addition, the Mel-mediated improvement of cold tolerance was inhibited by L-NAME (a NO synthase inhibitor), tungstate (a nitrate reductase inhibitor), LaCl3 (a Ca2+ channel blocker), and EGTA (a Ca2+ chelator), and this finding was mainly reflected in the increase in ROS content and the decrease in osmoregulatory capacity, photosynthetic efficiency and antioxidant enzyme activities, and expression levels of antioxidant enzyme genes. These findings suggest that NO and Ca2+ are necessary for Mel to improve cold tolerance and function synergistically downstream of Mel. Notably, the co-treatment of Mel with L-NAME, tungstate, LaCl3, or EGTA also inhibited the Mel-induced expression of MAPK3/6 under cold stress. In conclusion, NO and Ca2+ are involved in the enhancement of cold tolerance induced by Mel through activating the MAPK cascades in rape seedlings, and a crosstalk may exist between NO and Ca2+ signaling.
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Brassica napus , Brassica rapa , Melatonina , Antioxidantes/metabolismo , Brassica napus/metabolismo , Brassica rapa/genética , Quelantes/metabolismo , Ácido Egtácico , Melatonina/metabolismo , Melatonina/farmacología , NG-Nitroarginina Metil Éster/metabolismo , Óxido Nítrico Sintasa/metabolismo , Reguladores del Crecimiento de las Plantas/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Plantones/metabolismo , Compuestos de TungstenoRESUMEN
The use of glyphosate-based herbicides (GBH) has increased dramatically, being currently the most used herbicides worldwide. Glyphosate acts as a chelating agent, capable of chelate metals. The synergistic effects of metals and agrochemicals may pose an environmental problem as they have been shown to induce neurological abnormalities and behavioural changes in aquatic species. However, as their ecotoxicity effects are poorly understood, evaluating the impacts of GBH complexed with metals is an ecological priority. The main objective of the study was to evaluate the potentially toxic effects caused by exposure to a GBH (1 µg a.i. mL-1), alone or complexed with metals (Copper, Manganese, and Zinc (100 µg L-1)), at environmentally relevant concentrations, during the early period of zebrafish (Danio rerio) embryo development (96 h post-fertilization), a promising model for in vivo developmental studies. To clarify the mechanisms of toxicity involved, lethal and sublethal development endpoints were assessed. At the end of the exposure, biochemical and cell death parameters were evaluated and, 24 h later, different behavioural responses were assessed. The results showed that metals induced higher levels of toxicity. Copper caused high mortality, low hatching, malformations, and changes in biochemical parameters, such as decreased Catalase (CAT) activity, increased Glutathione Peroxidase (GPx), Glutathione S-Transferase (GST), reduced Glutathione (GSH) and decreased Acetylcholinesterase (AChE) activity, also inducing apoptosis and changes in larval behaviour. Manganese increased the activity of SODs enzymes. Zinc increased mortality, reactive oxygen species (ROS) levels, superoxide dismutase activity (SODs) and caused a decrease in AChE activity. Embryos/larvae exposed to the combination of GBH/Metal also showed teratogenic effects during their development but in smaller proportions than the metal alone. Although more studies are needed, the results suggest that GBH may interfere with the mechanisms of metal toxicity at the biochemical, physiological, and behavioural levels of zebrafish.
Asunto(s)
Herbicidas , Contaminantes Químicos del Agua , Acetilcolinesterasa/metabolismo , Animales , Antioxidantes/metabolismo , Catalasa/metabolismo , Quelantes/metabolismo , Cobre/metabolismo , Embrión no Mamífero , Glutatión/metabolismo , Glutatión Peroxidasa/metabolismo , Glutatión Transferasa/metabolismo , Glicina/análogos & derivados , Herbicidas/metabolismo , Manganeso/metabolismo , Estrés Oxidativo , Especies Reactivas de Oxígeno/metabolismo , Superóxido Dismutasa/metabolismo , Contaminantes Químicos del Agua/metabolismo , Pez Cebra/metabolismo , Zinc/metabolismo , GlifosatoRESUMEN
The Zika virus (ZIKV) caused neurological abnormalities in more than 3500 Brazilian newborns between 2015 and 2020. Data have pointed to oxidative stress in astrocytes as well as to dysregulations in neural cell proliferation and cell cycle as important events accounting for the cell death and neurological complications observed in Congenital Zika Syndrome. Copper imbalance has been shown to induce similar alterations in other pathologies, and disturbances in copper homeostasis have already been described in viral infections. Here, we investigated copper homeostasis imbalance as a factor that could contribute to the cytotoxic effects of ZIKV infection in astrocytes. Human induced pluripotent stem cell-derived astrocytes were infected with ZIKV; changes in the gene expression of copper homeostasis proteins were analyzed. The effect of the administration of CuCl2 or a copper chelator on oxidative stress, cell viability and percentage of infection were also studied. ZIKV infection leads to a downregulation of one of the transporters mediating copper release, ATP7B protein. We also observed the activation of mechanisms that counteract high copper levels, including the synthesis of copper chaperones and the reduction of the copper importer protein CTR1. Finally, we show that chelator-mediated copper sequestration in ZIKV-infected astrocytes reduces the levels of reactive oxygen species and improves cell viability, but does not change the overall percentage of infected cells. In summary, our results show that copper homeostasis imbalance plays a role in the pathology of ZIKV in astrocytes, indicating that it may also be a factor accounting for the developmental abnormalities in the central nervous system following viral infection. Evaluating micronutrient levels and the use of copper chelators in pregnant women susceptible to ZIKV infection may be promising strategies to manage novel cases of congenital ZIKV syndrome.
Asunto(s)
Células Madre Pluripotentes Inducidas , Infección por el Virus Zika , Virus Zika , Humanos , Recién Nacido , Femenino , Embarazo , Infección por el Virus Zika/metabolismo , Astrocitos/metabolismo , Cobre/farmacología , Cobre/metabolismo , Células Madre Pluripotentes Inducidas/metabolismo , Estrés Oxidativo , Muerte Celular , Quelantes/metabolismo , Quelantes/farmacologíaRESUMEN
This study evaluated the effects of the exogenous application of ethylenediaminetetraacetic acid (EDTA), indole-3-acetic acid (IAA) and iron sulfate (FeSO4) upon the phytochemical mechanisms of fenugreek grown under Pb-excess (2000 mg L-1 PbCl2). The results showed that chemical additives of EDTA and IAA as well as FeSO4 improved fenugreek germination parameters. The radicle length and the amylase activity were significantly improved under IAA treatment compared to EDTA and FeSO4. Exogenous FeSO4 was more effective to improving growth parameters. Moreover, the decrease in hydrogen peroxide (H2O2) and malondialdehyde (MDA) levels was noted under all chemical additives especially under IAA application. In addition, it was more effective than EDTA and Fe in increasing catalase, glutathione (GSH), ascorbate peroxidase (APX), flavonoids and phenols while the increment superoxide dismutase (SOD) production was more pronounced under EDTA addition to Pb than other chelators. HPLC analysis revealed that the gallic was the major phenol produced under all chelators addition especially with IAA. In addition, the syringic acid was only produced with exogenous IAA while the quercetin was only detected under EDTA addition. Our results exhibited a higher IAA efficiency than EDTA and FeSO4 in mitigating Pb stress in fenugreek through up-regulated mechanisms of the antioxidant system for reducing reactive oxygen species (ROS) activities and enhancing special phenols.