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1.
Sci Total Environ ; 856(Pt 2): 159168, 2023 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-36195137

RESUMO

Iron and steel industries discharge a large amount of atmospheric particulate matter (PM) containing metals and metallic nanoparticles (NPs) that contaminate not only the air, but also settle into the aquatic environments. However, the effects of settleable atmospheric particulate matter (SePM) on aquatic fauna are still poorly understood. This study aimed to evaluate the sublethal effects of a short-term exposure to a realistic concentration of SePM on Nile tilapia (Oreochromis niloticus) using a multi-biomarker approach: relative ventricular mass (RVM) and heart function, blood oxidative stress, stress indicators, hemoglobin concentration, metallic NPs internalization, and metal bioaccumulation. Exposed fish exhibited reduced hemoglobin content and elevated plasma cortisol and glucose levels, reflecting stressed states. Furthermore, SePM caused blood oxidative stress increasing lipid and protein oxidation, decreasing glutathione levels, and inhibiting superoxide and glutathione reductase activities. SePM exposure also increased RVM and improved cardiac performance, increasing myocardial contractile force and rates of contraction and relaxation. In the heart tissue there was a significant accumulation of Fe > Zn > > Cr > Cu > Rb > Ni > V > Mn > Se > Mo > As. On the other hand, in the erythrocytes there was significant accumulation of Sn > Zn > > Cr > Ti > Mn = Ni > Nb > As > Bi. The highest bioaccumulation factors were found for Cr, Zn and Ni in both tissues. NPs (Ti, Sn, Al, Fe, Cu, Si, Zn) were also detected in ventricular myocardium of fish exposed and nanocrystallographic analysis revealed a predominance of anatase phase of TiO2-NP, which is regarded to be more cytotoxic. The association between blood oxidative stress and energy expenditure to sustain increased cardiac pumping capacity under stress condition suggests that SePM has negative impacts on fish physiological performance, threatening their survival, growth rate and/or population establishment.


Assuntos
Ciclídeos , Animais , Ciclídeos/metabolismo , Material Particulado/metabolismo , Estresse Oxidativo , Biomarcadores/metabolismo , Metais/metabolismo , Hemoglobinas/metabolismo
2.
Food Chem ; 398: 133868, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-35961171

RESUMO

Gametogenesis can significantly affect the biochemical composition of oysters, but little research on the difference between sexes. Therefore, we conducted the first in-depth study on the composition differences between males and females of three different Crassostrea sp.. The results showed that females had higher glycogen, lipid, Cu and Zn contents than males, while males had higher protein and taurine contents than females at maturity, which might be related to special meiosis pattern of eggs and less energy was required for female gametogenesis. In addition, both males and females had well-balanced essential amino acid compositions. The omega-3: omega-6 (n-3: n-6) ratio of males was significantly higher than that of females, indicating that the nutritional quality of males was higher. These results provide a reliable and refined theoretical and research basis for revealing the nutritional quality, extracting beneficial ingredients, and developing functional food of Crassostrea sp., and provide data support for the sex-regulated breeding of oysters.


Assuntos
Crassostrea , Poluentes Químicos da Água , Animais , Crassostrea/genética , Crassostrea/metabolismo , Feminino , Glicogênio/metabolismo , Masculino , Metais/metabolismo , Valor Nutritivo , Poluentes Químicos da Água/análise
3.
Protein Expr Purif ; 201: 106186, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36206960

RESUMO

Human fibroblast growth factor 19 (hFGF19) belongs to the endocrine FGF19 superfamily and is considered a potential agent to treat severe or relapsing nonalcoholic fatty liver disease. Numerous studies have confirmed the beneficial effects of this hormone on the related symptoms of the disease and attempts at producing recombinant proteins in various hosts are steadily proliferating. Recently, we reported that authentic hFGF19 can be solubly expressed through combining synonymous codon substitutions and co-expression with disulfide-bond isomerase (DsbC) in Escherichia coli. However, during purification, hFGF19 without the His-tag occasionally co-eluted with His-tagged DsbC when using metal affinity chromatography, thereby requiring auxiliary purification steps to achieve apparent homogeneity. This phenomenon provides evidence that hFGF19 specifically interacts with immobilized Ni2+, which can thus be used as an alternative tool for the purification of hFGF19. Consequently, we could simply and reproducibly purify hFGF19 from cell lysates by using Ni2+-immobilized metal affinity chromatography and stepwise gradient elution with imidazole.


Assuntos
Escherichia coli , Metais , Cromatografia de Afinidade/métodos , Dissulfetos/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Fatores de Crescimento de Fibroblastos/metabolismo , Hormônios/metabolismo , Humanos , Imidazóis/metabolismo , Isomerases , Metais/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo
4.
Planta ; 256(6): 112, 2022 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-36367624

RESUMO

MAIN CONCLUSION: IRT1 intracellular dynamics and function are finely controlled through protein-protein interactions. In plants, iron uptake from the soil is tightly regulated to allow optimal growth and development. Iron acquisition in Arabidopsis root epidermal cells requires the IRT1 transporter, which also mediates the entry of non-iron metals. In this mini-review, we describe how protein-protein interactions regulate IRT1 intracellular dynamics and IRT1-mediated metal uptake to maintain iron homeostasis. Recent interactomic data provided interesting clues on IRT1 secretion and the putative involvement of COPI- and COPII-mediated pathways. Once delivered to the plasma membrane, IRT1 can interact with other components of the iron uptake machinery to form an iron acquisition complex that likely optimizes iron entrance in root epidermal cells. Then, IRT1 may be internalized from the plasma membrane. In the past decade, IRT1 endocytosis emerged as an essential mechanism to control IRT1 subcellular localization and thus to tune iron uptake. Interestingly, IRT1 endocytosis and degradation are regulated by its non-iron metal substrates in an ubiquitin-dependent manner, which requires a set of interacting-proteins including kinases, E3 ubiquitin ligases and ESCRT complex subunits. This mechanism is essential to avoid non-iron metal overload in Arabidopsis when the iron is scarce.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Proteínas de Transporte de Cátions , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Transporte de Cátions/genética , Proteínas de Transporte de Cátions/metabolismo , Transporte Biológico , Ubiquitina/metabolismo , Metais/metabolismo , Regulação da Expressão Gênica de Plantas , Raízes de Plantas/metabolismo
5.
Int J Mol Sci ; 23(21)2022 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-36361973

RESUMO

Heparins and heparan sulfate polysaccharides are negatively charged glycosaminoglycans and play important roles in cell-to-matrix and cell-to-cell signaling processes. Metal ion binding to heparins alters the conformation of heparins and influences their function. Various experimental techniques have been used to investigate metal ion-heparin interactions, frequently with inconsistent results. Exploiting the quadrupolar 23Na nucleus, we herein develop a 23Na NMR-based competition assay and monitor the binding of divalent Ca2+ and Mg2+ and trivalent Al3+ metal ions to sodium heparin and the consequent release of sodium ions from heparin. The 23Na spin relaxation rates and translational diffusion coefficients are utilized to quantify the metal ion-induced release of sodium ions from heparin. In the case of the Al3+ ion, the complementary approach of 27Al quadrupolar NMR is employed as a direct probe of ion binding to heparin. Our NMR results demonstrate at least two metal ion-binding sites with different affinities on heparin, potentially undergoing dynamic exchange. For the site with lower metal ion binding affinity, the order of Ca2+ > Mg2+ > Al3+ is obtained, in which even the weakly binding Al3+ ion is capable of displacing sodium ions from heparin. Overall, the multinuclear quadrupolar NMR approach employed here can monitor and quantify metal ion binding to heparin and capture different modes of metal ion-heparin binding.


Assuntos
Heparina , Heparitina Sulfato , Heparina/química , Espectroscopia de Ressonância Magnética/métodos , Heparitina Sulfato/metabolismo , Metais/metabolismo , Íons , Sódio/metabolismo , Sítios de Ligação
6.
ACS Synth Biol ; 11(11): 3617-3628, 2022 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-36278822

RESUMO

Cupriavidus metallidurans CH34 exhibits extraordinary metabolic versatility, including chemolithoautotrophic growth; degradation of BTEX (benzene, toluene, ethylbenzene, xylene); high resistance to numerous metals; biomineralization of gold, platinum, silver, and uranium; and accumulation of polyhydroxybutyrate (PHB). These qualities make it a valuable host for biotechnological applications such as bioremediation, bioprocessing, and the generation of bioelectricity in microbial fuel cells (MFCs). However, the lack of genetic tools for strain development and studying its fundamental physiology represents a bottleneck to boosting its commercial applications. In this study, inducible and constitutive promoter libraries were built and characterized, providing the first comprehensive list of biological parts that can be used to regulate protein expression and optimize the CRISPR-Cas9 genome editing tools for this host. A single-plasmid CRISPR-Cas9 system that can be delivered by both conjugation and electroporation was developed, and its efficiency was demonstrated by successfully targeting the pyrE locus. The CRISPR-Cas9 system was next used to target candidate genes encoding type IV pili, hypothesized by us to be involved in extracellular electron transfer (EET) in this organism. Single and double deletion strains (ΔpilA, ΔpilE, and ΔpilAE) were successfully generated. Additionally, the CRISPR-Cas9 tool was validated for constructing genomic insertions (ΔpilAE::gfp and ΔpilAE::λPrgfp). Finally, as type IV pili are believed to play an important role in extracellular electron transfer to solid surfaces, C. metallidurans CH34 ΔpilAE was further studied by means of cyclic voltammetry using disposable screen-printed carbon electrodes. Under these conditions, we demonstrated that C. metallidurans CH34 could generate extracellular currents; however, no difference in the intensity of the current peaks was found in the ΔpilAE double deletion strain when compared to the wild type. This finding suggests that the deleted type IV pili candidate genes are not involved in extracellular electron transfer under these conditions. Nevertheless, these experiments revealed the presence of different redox centers likely to be involved in both mediated electron transfer (MET) and direct electron transfer (DET), the first interpretation of extracellular electron transfer mechanisms in C. metallidurans CH34.


Assuntos
Cupriavidus , Biologia Sintética , Sistemas CRISPR-Cas/genética , Cupriavidus/genética , Cupriavidus/metabolismo , Plasmídeos/genética , Metais/metabolismo
7.
Metallomics ; 14(11)2022 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-36255398

RESUMO

Nickel is an essential micronutrient for the survival of many microbes. On account of the toxicity of nickel and its scarcity in the environment, microbes have evolved specific systems for uptaking and delivering nickel to enzymes. NikA, the solute binding protein for the ATP-binding cassette (ABC) importer NikABCDE, plays a vital role in the nickel homeostasis of Escherichia coli by selectively binding nickel over other metals in the metabolically complex periplasm. While the endogenous ligand for NikA is known to be the Ni(II)-(L-His)2 complex, the molecular basis by which NikA selectively binds Ni(II)-(L-His)2 is unclear, especially considering that NikA can bind multiple metal-based ligands with comparable affinity. Here we show that, regardless of its promiscuous binding activity, NikA preferentially interacts with Ni(II)-(L-His)2, even over other metal-amino acid ligands with an identical coordination geometry for the metal. Replacing both the Ni(II) and the L-His residues in Ni(II)-(L-His)2 compromises binding of the ligand to NikA, in part because these alterations affect the degree by which NikA closes around the ligand. Replacing H416, the only NikA residue that ligates the Ni(II), with other potential metal-coordinating amino acids decreases the binding affinity of NikA for Ni(II)-(L-His)2 and compromises uptake of Ni(II) into E. coli cells, likely due to altered metal selectivity of the NikA mutants. Together, the biochemical and in vivo studies presented here define key aspects of how NikA selects for Ni(II)-(L-His)2 over other metal complexes, and can be used as a reference for studies into the metal selectivity of other microbial solute binding proteins.


Assuntos
Proteínas de Escherichia coli , Proteínas Periplásmicas de Ligação , Escherichia coli/metabolismo , Proteínas Periplásmicas de Ligação/metabolismo , Proteínas de Escherichia coli/metabolismo , Níquel/metabolismo , Ligantes , Transportadores de Cassetes de Ligação de ATP/metabolismo , Metais/metabolismo
8.
Brief Bioinform ; 23(6)2022 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-36274238

RESUMO

More than one-third of the proteins contain metal ions in the Protein Data Bank. Correct identification of metal ion-binding residues is important for understanding protein functions and designing novel drugs. Due to the small size and high versatility of metal ions, it remains challenging to computationally predict their binding sites from protein sequence. Existing sequence-based methods are of low accuracy due to the lack of structural information, and time-consuming owing to the usage of multi-sequence alignment. Here, we propose LMetalSite, an alignment-free sequence-based predictor for binding sites of the four most frequently seen metal ions in BioLiP (Zn2+, Ca2+, Mg2+ and Mn2+). LMetalSite leverages the pretrained language model to rapidly generate informative sequence representations and employs transformer to capture long-range dependencies. Multi-task learning is adopted to compensate for the scarcity of training data and capture the intrinsic similarities between different metal ions. LMetalSite was shown to surpass state-of-the-art structure-based methods by more than 19.7, 14.4, 36.8 and 12.6% in area under the precision recall on the four independent tests, respectively. Further analyses indicated that the self-attention modules are effective to learn the structural contexts of residues from protein sequence. We provide the data sets, source codes and trained models of LMetalSite at https://github.com/biomed-AI/LMetalSite.


Assuntos
Idioma , Proteínas , Conformação Proteica , Ligação Proteica , Sítios de Ligação , Proteínas/química , Metais/química , Metais/metabolismo , Íons/química
9.
Appl Microbiol Biotechnol ; 106(21): 6933-6952, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36194263

RESUMO

Bioleaching of metal sulfides is performed by diverse microorganisms. The dissolution of metal sulfides occurs via two chemical pathways, either the thiosulfate or the polysulfide pathway. These are determined by the metal sulfides' mineralogy and their acid solubility. The microbial cell enables metal sulfide dissolution via oxidation of iron(II) ions and inorganic sulfur compounds. Thereby, the metal sulfide attacking agents iron(III) ions and protons are generated. Cells are active either in a planktonic state or attached to the mineral surface, forming biofilms. This review, as an update of the previous one (Vera et al., 2013a), summarizes some recent discoveries relevant to bioleaching microorganisms, contributing to a better understanding of their lifestyle. These comprise phylogeny, chemical pathways, surface science, biochemistry of iron and sulfur metabolism, anaerobic metabolism, cell-cell communication, molecular biology, and biofilm lifestyle. Recent advances from genetic engineering applied to bioleaching microorganisms will allow in the future to better understand important aspects of their physiology, as well as to open new possibilities for synthetic biology applications of leaching microbial consortia. KEY POINTS: • Leaching of metal sulfides is strongly enhanced by microorganisms • Biofilm formation and extracellular polymer production influences bioleaching • Cell interactions in mixed bioleaching cultures are key for process optimization.


Assuntos
Prótons , Tiossulfatos , Compostos Férricos , Metais/metabolismo , Sulfetos/metabolismo , Ferro/metabolismo , Minerais , Enxofre/metabolismo , Polímeros , Compostos Ferrosos
10.
Chemosphere ; 308(Pt 3): 136482, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36126735

RESUMO

Awareness of toxicokinetics at the subcellular level is crucial to deciphering the underlying intoxication processes of metal(loid)s, although this information is often lacking. Here, the toxicokinetics of two non-essential metal(loid)s (Cd and As) and one essential metal (Zn) in both the whole body and subcellular fractions of earthworm (Eisenia fetida) were assessed. Earthworms were exposed to natural soils originating from a gradient of metal(loid) pollution for 14 days followed by a 14-day elimination phase in clean soil. Clearly distinct toxicokinetic patterns were found in the earthworms according to the metal(loid) considered. An obvious concentration-dependent increase was observed in earthworms or subcellular compartments where no equilibrium was reached (with slow or no elimination) for Cd and As throughout the experiment. As for Zn, the earthworms were able to retain a steady-state concentration of Zn in its body or each fraction without a clear intake behavior via the dynamic trade-off between uptake and elimination at different pollution levels. These differences in toxicokinetics at the subcellular level supported the observed differences in bioaccumulation patterns and were indicative of the strategy by which non-essential and essential elements are handled by earthworms. Notably, the concentration of Cd and As in subcellular compartments showed the same pattern as for Zn in the order of cellular cytosol > cellular debris > metal-rich granules, which might be associated with the binding of non-essential/essential elements with metallothionein enriched in the cytosol. Our findings enhance the understanding of the underlying mechanisms for metal(loid) accumulation kinetics in earthworms from the perspective of subcellular partitioning, and will be beneficial for accurate risk assessment of Cd, As, and Zn.


Assuntos
Arsênio , Oligoquetos , Poluentes do Solo , Animais , Arsênio/metabolismo , Arsênio/toxicidade , Cádmio/análise , Metalotioneína/metabolismo , Metais/metabolismo , Metais/toxicidade , Oligoquetos/metabolismo , Solo , Poluentes do Solo/análise , Toxicocinética , Zinco/análise
11.
Free Radic Biol Med ; 192: 182-190, 2022 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-36170956

RESUMO

Neurodegenerative diseases are associated with a multitude of dysfunctional cellular pathways. One major contributory factor is a redox stress challenge during the development of several protein misfolding conditions including Alzheimer's (AD), Parkinson's disease (PD), and less common conditions such as Creutzfeldt Jakob disease (CJD). CJD is caused by misfolding of the neuronal prion protein and is characterised by a neurotoxic unfolded protein response involving chronic endoplasmic reticulum stress, reduced protein translation and spongiosis leading subsequently to synaptic and neuronal loss. Here we have characterised prion disease in mice to assess redox stress components including nitrergic and oxidative markers associated with neuroinflammatory activation. Aberrant regulation of the homeostasis of several redox metals contributes to the overall cellular redox stress and we have identified altered levels of iron, copper, zinc, and manganese in the hippocampus of prion diseased mice. Our data show that early in disease, there is evidence for oxidative stress in conjunction with reduced antioxidant superoxide dismutase mRNA and protein expression. Moreover, expression of divalent metal transporter proteins was reduced for Atp7b, Atox1, Slc11a2, Slc39a14 at 6-7 weeks but increased for Slc39a14 and Mt1 at 10 weeks of disease. Our data present evidence for a strong pro-oxidant environment and altered redox metal homeostasis in early disease pathology which both may be contributory factors to aggravating this protein misfolding disease.


Assuntos
Síndrome de Creutzfeldt-Jakob , Doenças Priônicas , Príons , Animais , Antioxidantes/metabolismo , Proteínas de Transporte de Cátions , Cobre , Síndrome de Creutzfeldt-Jakob/patologia , Homeostase , Ferro , Manganês , Metais/metabolismo , Camundongos , Oxirredução , Doenças Priônicas/genética , Doenças Priônicas/metabolismo , Doenças Priônicas/patologia , Proteínas Priônicas/metabolismo , Príons/metabolismo , RNA Mensageiro/metabolismo , Espécies Reativas de Oxigênio , Superóxido Dismutase/genética , Superóxido Dismutase/metabolismo , Zinco
12.
Chemosphere ; 308(Pt 1): 136231, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36055596

RESUMO

Epigenetic mechanisms are moving to the forefront of environmental sciences, as environmentally induced epigenetic changes shape biological responses to chemical contamination. This work focused on Daphnia as a representative of potentially threatened freshwater biota, aiming to gain an insight into the involvement of epigenetic mechanisms in their response and eventual adaptation to metal contamination. Copper-induced DNA methylation changes, their potential transgenerational inheritance, and life-history traits were assessed. Organisms with different histories of past exposure to copper were exposed to toxic levels of the element for one generation (F0) and then monitored for three subsequent unexposed generations (F1, F2, and F3). Overall, methylation changes targeted important genes for counteracting the effects of metals and oxidative stress, including dynein light chain, ribosomal kinase and nuclear fragile X mental retardation-interacting protein. Also, contrasting overall and gene-specific methylation responses were observed in organisms differing in their history of exposure to copper, with different transgenerational methylation responses being also identified among the two groups, without apparent life-history costs. Taken together, these results demonstrate the capacity of copper to promote epigenetic transgenerational inheritance in a manner related explicitly to history of exposure, thereby supporting the development and incorporation of epigenetic biomarkers in risk assessment frameworks.


Assuntos
Metilação de DNA , Daphnia , Animais , Biomarcadores/metabolismo , Cobre/metabolismo , Cobre/toxicidade , Daphnia/genética , Daphnia/metabolismo , Dineínas/metabolismo , Epigênese Genética , Metais/metabolismo
13.
Biomolecules ; 12(9)2022 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-36139084

RESUMO

Reactive oxygen species (ROS) play a key role in the neurodegeneration processes. Increased oxidative stress damages lipids, proteins, and nucleic acids in brain tissue, and it is tied to the loss of biometal homeostasis. For this reason, attention has been focused on transition metals involved in several biochemical reactions producing ROS. Even though a bulk of evidence has uncovered the role of metals in the generation of the toxic pathways at the base of Alzheimer's disease (AD), this matter has been sidelined by the advent of the Amyloid Cascade Hypothesis. However, the link between metals and AD has been investigated in the last two decades, focusing on their local accumulation in brain areas known to be critical for AD. Recent evidence revealed a relation between iron and AD, particularly in relation to its capacity to increase the risk of the disease through ferroptosis. In this review, we briefly summarize the major points characterizing the function of iron in our body and highlight why, even though it is essential for our life, we have to monitor its dysfunction, particularly if we want to control our risk of AD.


Assuntos
Doença de Alzheimer , Ácidos Nucleicos , Oligoelementos , Doença de Alzheimer/metabolismo , Humanos , Ferro/metabolismo , Lipídeos , Metais/metabolismo , Espécies Reativas de Oxigênio/metabolismo
14.
Biometals ; 35(5): 1043-1057, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-35913688

RESUMO

Copper (Cu) and zinc (Zn) have a high demand in the industry. However, these ions, at high concentrations, can cause severe damage to both fauna and flora. Phytoremediation has gained international importance because its relatively low cost and it is environmentally friendly. The aim of the present study was to evaluate the capacity of Salvinia minima of accumulating Cu and Zn from aqueous solutions of various external concentrations (20, 40 and 80 µmol L-1 of CuSO4 and ZnSO4, separately). In addition, to estimate the effect of exposure of S. minima plants to those metals, on various physiological parameters (growth potential, maximum quantum efficiency of PSII, electrolyte leakage: as a cell membrane integrity index). S. minima was able of accumulating more Zn than Cu in its tissues, reaching values of 6.96 mg Cu g-1 dry weight (DW) and 19.6 mg Zn g-1 DW when exposed to 80 µM of each metal during 96 h, that were stored mainly at roots. Despite accumulating less Cu in its tissues, Cu had more severe reductions in various physiological parameters than Zn (in maximum quantum efficiency, integrity of cell membranes, and growth). We conclude that this species can be useful in the phytoremediation for copper and zinc in relatively short time, as maximum accumulation occurred within the first 24 h. However, in the long term, the accumulation of such metals is accompanied by a negative impact in the appearance, physiology, and growth of this plant species, which was more severe for copper exposure than for zinc.


Assuntos
Gleiquênias , Zinco , Cobre/metabolismo , Gleiquênias/metabolismo , Íons/metabolismo , Metais/metabolismo , Plantas/metabolismo , Estresse Fisiológico , Zinco/metabolismo
15.
Chemosphere ; 307(Pt 3): 135822, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-35963385

RESUMO

Specimens of Sparus aurata were exposed to sub-lethal concentrations of Hg and Cd for 25 days and the levels of both metals were investigated in organs and tissues. Bioaccumulation of Hg decreased as follow: gills > kidney > liver > skin > muscle, while the order of Cd bioaccumulation was: liver > kidney > gills > skin > muscle. Immediately after exposure, both metals showed the highest bioaccumulation in gills and skin indicating that these organs are reliable targets for biomonitoring studies after short term exposure. Metals introduction caused a significant time-dependent concentrations increase in kidney and liver, while in the muscle a significant increase of Hg was recorded only at the end of the experimentation. The effects of exposure were also investigated, at biochemical level, in the liver, which represents the main target of xenobiotics biotransformation and metabolism in fish. Exposed fishes exhibited a reduction of total lipid level, a decrease of polyunsaturated fatty acids (PUFA), together with a MDA increase. This suggests a direct effect of contaminants on oxidative stress induction that, through the MDA increase, altered the membrane fatty acids composition decreasing the PUFA content. As it regards molecular markers related to oxidative stress and lipid metanolism, a significant increase of Nrf2, Hif-1α and Ampk and a decrease of Fas were observed after exposure to both metals, while an Nf-kB increase was recorded in specimens exposed to Hg, docuemnting a correlation with oxidative stress and consequent metabolism adaptation. Finally, these results suggest the possibility to adopt these biomarkers to explore fish metabolic responses to environmental pollution.


Assuntos
Mercúrio , Dourada , Poluentes Químicos da Água , Proteínas Quinases Ativadas por AMP/metabolismo , Animais , Biomarcadores/metabolismo , Cádmio/metabolismo , Ácidos Graxos/metabolismo , Brânquias/metabolismo , Lipídeos , Fígado/metabolismo , Mercúrio/metabolismo , Metais/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , NF-kappa B/metabolismo , Dourada/metabolismo , Poluentes Químicos da Água/metabolismo , Xenobióticos/metabolismo
16.
Nat Commun ; 13(1): 4731, 2022 08 12.
Artigo em Inglês | MEDLINE | ID: mdl-35961955

RESUMO

The human pathogen Mycobacterium tuberculosis requires a P1B-ATPase metal exporter, CtpC (Rv3270), for resistance to zinc poisoning. Here, we show that zinc resistance also depends on a chaperone-like protein, PacL1 (Rv3269). PacL1 contains a transmembrane domain, a cytoplasmic region with glutamine/alanine repeats and a C-terminal metal-binding motif (MBM). PacL1 binds Zn2+, but the MBM is required only at high zinc concentrations. PacL1 co-localizes with CtpC in dynamic foci in the mycobacterial plasma membrane, and the two proteins form high molecular weight complexes. Foci formation does not require flotillin nor the PacL1 MBM. However, deletion of the PacL1 Glu/Ala repeats leads to loss of CtpC and sensitivity to zinc. Genes pacL1 and ctpC appear to be in the same operon, and homologous gene pairs are found in the genomes of other bacteria. Furthermore, PacL1 colocalizes and functions redundantly with other PacL orthologs in M. tuberculosis. Overall, our results indicate that PacL proteins may act as scaffolds that assemble P-ATPase-containing metal efflux platforms mediating bacterial resistance to metal poisoning.


Assuntos
Adenosina Trifosfatases , Mycobacterium tuberculosis , Adenosina Trifosfatases/metabolismo , Transporte Biológico , Humanos , Metais/metabolismo , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/metabolismo , Zinco/metabolismo
17.
Metallomics ; 14(9)2022 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-35933161

RESUMO

Three Web-based calculators, and three analogous spreadsheets, have been generated that predict in vivo metal occupancies of proteins based on known metal affinities. The calculations exploit estimates of the availabilities of the labile buffered pools of different metals inside a cell. Here, metal availabilities have been estimated for a strain of Escherichia coli that is commonly used in molecular biology and biochemistry research, e.g. in the production of recombinant proteins. Metal availabilities have been examined for cells grown in Luria-Bertani (LB) medium aerobically, anaerobically, and in response to H2O2 by monitoring the abundance of a selected set of metal-responsive transcripts by quantitative polymerase chain reaction (qPCR). The selected genes are regulated by DNA-binding metal sensors that have been thermodynamically characterized in related bacterial cells enabling gene expression to be read out as a function of intracellular metal availabilities expressed as free energies for forming metal complexes. The calculators compare these values with the free energies for forming complexes with the protein of interest, derived from metal affinities, to estimate how effectively the protein can compete with exchangeable binding sites in the intracellular milieu. The calculators then inter-compete the different metals, limiting total occupancy of the site to a maximum stoichiometry of 1, to output percentage occupancies with each metal. In addition to making these new and conditional calculators available, an original purpose of this article was to provide a tutorial that discusses constraints of this approach and presents ways in which such calculators might be exploited in basic and applied research, and in next-generation manufacturing.


Assuntos
Escherichia coli , Peróxido de Hidrogênio , Anaerobiose , Escherichia coli/genética , Escherichia coli/metabolismo , Peróxido de Hidrogênio/metabolismo , Metais/metabolismo , Proteínas Recombinantes/metabolismo
18.
19.
FEMS Microbiol Lett ; 369(1)2022 08 16.
Artigo em Inglês | MEDLINE | ID: mdl-35883222

RESUMO

Pseudomonas aeruginosa is known to exhibit considerable resistance to the antimicrobial activity of the metal-sequestering protein calprotectin (CP). In this study, we demonstrate that although CP induces zinc deficiency in P. aeruginosa, a strain unable to import zinc through the two most important metal acquisition systems, namely ZnuABC and ZrmABCD, maintains significant growth capacity in the presence of high concentrations of CP. Furthermore, we have shown that nicotianamine, a molecule structurally similar to the metallophore pseudopaline, can favor the acquisition of the metal even in the presence of CP. To gain insights into the mechanisms through which metallophores can promote zinc acquisition, we analyzed the effect of nicotianamine on the activity of the metallo-ß-lactamase VIM-1. Our data suggest that metallophores released by bacteria in response to zinc deficiency can extract the protein-bound metal. The ability to interfere with the binding of metals to proteins, as well as favoring the acquisition of zinc, may contribute to increasing the resistance of P. aeruginosa to the antimicrobial action of CP.


Assuntos
Anti-Infecciosos , Infecções por Pseudomonas , Anti-Infecciosos/farmacologia , Humanos , Complexo Antígeno L1 Leucocitário/metabolismo , Complexo Antígeno L1 Leucocitário/farmacologia , Metais/metabolismo , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa , Zinco/metabolismo , Zinco/farmacologia , beta-Lactamases/metabolismo
20.
Front Cell Infect Microbiol ; 12: 952948, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35865816

RESUMO

Metal such as iron, zinc, manganese, and nickel are essential elements for bacteria. These nutrients are required in crucial structural and catalytic roles in biological processes, including precursor biosynthesis, DNA replication, transcription, respiration, and oxidative stress responses. While essential, in excess these nutrients can also be toxic. The immune system leverages both of these facets, to limit bacterial proliferation and combat invaders. Metal binding immune proteins reduce the bioavailability of metals at the infection sites starving intruders, while immune cells intoxicate pathogens by providing metals in excess leading to enzyme mismetallation and/or reactive oxygen species generation. In this dynamic metal environment, maintaining metal homeostasis is a critical process that must be precisely coordinated. To achieve this, bacteria utilize diverse metal uptake and efflux systems controlled by metalloregulatory proteins. Recently, small regulatory RNAs (sRNAs) have been revealed to be critical post-transcriptional regulators, working in conjunction with transcription factors to promote rapid adaptation and to fine-tune bacterial adaptation to metal abundance. In this mini review, we discuss the expanding role for sRNAs in iron homeostasis, but also in orchestrating adaptation to the availability of other metals like manganese and nickel. Furthermore, we describe the sRNA-mediated interdependency between metal homeostasis and oxidative stress responses, and how regulatory networks controlled by sRNAs contribute to survival and virulence.


Assuntos
Manganês , Níquel , Bactérias , Regulação Bacteriana da Expressão Gênica , Íons/metabolismo , Ferro/metabolismo , Manganês/metabolismo , Metais/metabolismo , Níquel/metabolismo , Fatores de Transcrição/metabolismo , Virulência
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