RESUMO
A 32-year-old man, who was treated for T-cell lymphoma, presented in cardiac arrest. He had been treated for heart failure with reduced ejection fraction. Veno-arterial extracorporeal membrane oxygenation was initiated immediately. We diagnosed him as non-ST elevated myocardial infarction. Coronary angiography demonstrated the occlusion of the trifurcation in the proximal left anterior descending artery (LAD). We failed to advance the first guidewire into the distal LAD by angio-based conventional wiring. Intravascular ultrasonography (IVUS) of the proximal diagonal branch revealed two diaphragms separating the distal lumen without connection, which looks like lotus root-like appearance. We quickly penetrated the plaque using IVUS-based real-time 3D wiring using the tip detection method. The contrast injection via the microcatheter showed the distal diagonal branch (D2). After the balloon dilation in D2, IVUS image revealed a torn plaque between D2 and the distal LAD. Subsequently we advanced the guidewire to the distal LAD using IVUS-based real-time 3D wiring using the tip detection method through the tear of the plaque. Finally, we successfully performed the revascularization of LAD in a preferable procedure time. The patient recovered well and was discharged 39 days after cardiac arrest. This case highlights the efficacy of IVUS-based real-time 3D wiring using the tip detection method even in the emergent and challenging situation.
Assuntos
Angiografia Coronária , Oclusão Coronária , Parada Cardíaca , Placa Aterosclerótica , Ultrassonografia de Intervenção , Humanos , Masculino , Adulto , Parada Cardíaca/terapia , Parada Cardíaca/etiologia , Parada Cardíaca/fisiopatologia , Resultado do Tratamento , Oclusão Coronária/diagnóstico por imagem , Oclusão Coronária/terapia , Oclusão Coronária/fisiopatologia , Imageamento Tridimensional , Angioplastia Coronária com Balão/instrumentação , Valor Preditivo dos TestesRESUMO
Bacteria utilize electron conduction in their communities to drive their metabolism, which has led to the development of various environmental technologies, such as electrochemical microbial systems and anaerobic digestion. It is challenging to measure the conductivity among bacterial cells when they hardly form stable biofilms on electrodes. This makes it difficult to identify the biomolecules involved in electron conduction. In the present study, we aimed to identify c-type cytochromes involved in electron conduction in Shewanella oneidensis MR-1 and examine the molecular mechanisms. We established a colony-based bioelectronic system that quantifies bacterial electrical conductivity, without the need for biofilm formation on electrodes. This system enabled the quantification of the conductivity of gene deletion mutants that scarcely form biofilms on electrodes, demonstrating that c-type cytochromes, MtrC and OmcA, are involved in electron conduction. Furthermore, the use of colonies of gene deletion mutants demonstrated that flavins participate in electron conduction by binding to OmcA, providing insight into the electron conduction pathways at the molecular level. Furthermore, phenazine-based electron transfer in Pseudomonas aeruginosa PAO1 and flavin-based electron transfer in Bacillus subtilis 3610 were confirmed, indicating that this colony-based system can be used for various bacteria, including weak electricigens.
Assuntos
Flavinas , Shewanella , Eletroquímica , Flavinas/metabolismo , Elétrons , Citocromos/metabolismo , Transporte de Elétrons , Shewanella/química , Shewanella/genética , Shewanella/metabolismoRESUMO
A novel mesophilic, obligately anaerobic, facultatively sulphur-reducing bacterium, designated strain IC12T, was isolated from a deep-sea hydrothermal field in the Mid-Okinawa Trough, Japan. The cells were Gram-negative, motile, short rods with a single polar flagellum. The ranges and optima of the growth temperature, NaCl concentration and pH of strain IC12T were 15-40 °C (optimum, 30-35 °C), 10-60 g l-1 (optimum, 20-30 g l-1) and pH 4.9-6.7 (optimum, pH 5.8), respectively. Yeast extract was utilized as a sole carbon and energy source for fermentative growth. Major fatty acids of strain IC12T were C14â:â0, C16â:â0 and C16â:â1 ω7. Results of phylogenetic analysis based on 16S rRNA gene sequences indicated that strain IC12T was affiliated to the phylum Fusobacteriota and was most closely related to Ilyobacter insuetus VenChi2T (86.5â% sequence similarity). Strain IC12T contained a chromosome of 2.43 Mbp and a large plasmid of 0.30 Mbp. The G+C content of the genomic DNA was 26.4âmol%. The maximum values for average nucleotide identity and in silico DNA-DNA hybridization between strain IC12T and related strains of the phylum Fusobacteriota were 71.4 and 26.4â%, respectively. Phylogenomic, physiological and chemotaxonomic analyses indicate that strain IC12T represents a novel genus and species within the phylum Fusobacteriota, for which the name Haliovirga abyssi gen. nov., sp. nov. is proposed, with strain IC12T (= DSM 112164T=JCM 39166T) as the type strain. We also propose the family Haliovirgaceae fam. nov. to accommodate this novel genus.
Assuntos
DNA , Ácidos Graxos , Ácidos Graxos/química , DNA Bacteriano/genética , Filogenia , RNA Ribossômico 16S/genética , Composição de Bases , Técnicas de Tipagem Bacteriana , Análise de Sequência de DNA , Bactérias Anaeróbias/genéticaRESUMO
A novel hyperthermophilic, heterotrophic archaeon, strain YC29T, was isolated from a deep-sea hydrothermal vent in the Mid-Okinawa Trough, Japan. Cells of strain YC29T were non-motile, irregular cocci with diameters of 1.2-3.0 µm. The strain was an obligatory fermentative anaerobe capable of growth on complex proteinaceous substrates. Growth was observed between 85 and 100 °C (optimum 90-95 °C), pH 4.9-6.4 (optimum 5.1), and in the presence of 1.4-4.0% (w/v) NaCl (optimum 3.0%). Inorganic carbon was required as a carbon source. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that the isolate was a member of the family Pyrodictiaceae. The genome size was 2.02 Mbp with a G+C content of 49.4%. The maximum values for average nucleotide identity (ANI), average amino acid identity (AAI), and in silico DNA-DNA hybridization (dDDH) value of strain YC29T with relatives were 67.9% (with Pyrodictium abyssi strain AV2T), 61.1% (with Pyrodictium occultum strain PL-19T), and 33.8% (with Pyrolobus fumarii strain 1AT), respectively. Based on the phylogenetic, genomic, and phenotypic characteristics, we propose that strain YC29T represents a novel genus and species, Pyrofollis japonicus gen. nov., sp. (type strain YC29T = DSM 113394T = JCM 39171T).
Assuntos
Fontes Hidrotermais , Pyrodictiaceae , Pyrodictiaceae/genética , Filogenia , RNA Ribossômico 16S/genética , DNA , Carbono , Análise de Sequência de DNA , DNA Bacteriano , Água do Mar , Ácidos Graxos/químicaRESUMO
Bacterial outer-membrane multi-heme cytochromes (OMCs) mediate extracellular electron transport (EET). While heme alignment dictates the rate of EET, control of inter-heme coupling in a single OMC remains challenging, especially in intact cells. Given that OMCs diffuse and collide without aggregation on the cell surface, the overexpression of OMCs could increase such mechanical stress to impact the OMCs' protein structure. Here, the heme coupling is modified via mechanical interactions among OMCs by controlling their concentrations. Employment of whole-cell circular dichroism (CD) spectra of genetically engineered Escherichia coli reveals that the OMC concentration significantly impacts the molar CD and redox property of OMCs, resulting in a 4-fold change of microbial current production. The overexpression of OMCs increased the conductive current across the biofilm on an interdigitated electrode, indicating that a higher concentration of OMCs causes more lateral inter-protein electron hopping via collision on the cell surface. The present study would open a novel strategy to increase microbial current production by mechanically enhancing the inter-heme coupling.
Assuntos
Elétrons , Heme , Transporte de Elétrons , Heme/metabolismo , Oxirredução , Citocromos/metabolismo , Bactérias/metabolismoRESUMO
The design and construction of a visible light-driven photoelectrochemical (PEC) device is described based on a CdSe-Co3O4@TiO2 nanoflower (NF). Moreover, an application to the ultrasensitive detection of viruses, such as hepatitis E virus (HEV), HEV-like particles (HEV-LPs), and SARS-CoV-2 spike protein in complicated lysate solution, is demonstrated. The photocurrent response output of a PEC device based on CdSe-Co3O4@TiO2 is enhanced compared with the individual components, TiO2 and CdSe-Co3O4. This can be attributed to the CdSe quantum dot (QD) sensitization effect and strong visible light absorption to improve overall system stability. A robust oxygen-evolving catalyst (Co3O4) coupled at the hole-trapping site (CdSe) extends the interfacial carrier lifetime, and the energy conversion efficiency was improved. The effective hybridization between the antibody and virus resulted in a linear relationship between the change in photocurrent density and the HEV-LP concentration ranging from 10 fg mL-1 to 10 ng mL-1, with a detection limit of 3.5 fg mL-1. This CdSe-Co3O4@TiO2-based PEC device achieved considerable sensitivity, good specificity, and acceptable stability and demonstrated a significant ability to develop an upgraded device with affordable and portable biosensing capabilities.
Assuntos
COVID-19 , Compostos de Cádmio , Compostos de Selênio , Humanos , Luz , SARS-CoV-2 , NanoestruturasRESUMO
Microbial electrochemical catalysis based on respiratory reactions coupled with extracellular electron transport (EET), which is critical for bioenergy applications, strongly depends on the biocompatibility of the electrode material. However, the comparison of materials for such physiological responses has been difficult because of the lack of a quantitative assay for characterizing cellular metabolism at the electrode surface. Here, we developed a single-cell analysis method specific for the cells attached to the electrode to quantify active metabolic pathway heterogeneity as an index of physiological cell/electrode interaction, which generally increases with metabolic robustness in the microbial population. Nanoscale secondary ion mass spectrometry followed by microbial current production with model EET-capable bacteria, Shewanella oneidensis MR-1 and its mutant strains lacking carbon assimilation pathways, showed that different active metabolic pathways resulted in nearly identical 13C/15N assimilation ratios for individual cells in the presence of isotopically labeled nutrients, demonstrating a correlation between the 13C/15N ratio and the active metabolic pathway. Compared to the nonelectrode conditions, the heterogeneity of the assimilated 13C/15N ratio was highly enhanced on the electrode surface, suggesting that the metabolic robustness of the microbial population increased through the electrochemical interaction with the electrode. The present methodology enables us to quantitatively compare and screen electrode materials that increase the robustness of microbial electrocatalysis.
Assuntos
Espectrometria de Massas/métodos , Shewanella/citologia , Shewanella/metabolismo , Análise de Célula Única/métodos , Eletrodos , Transporte de Elétrons , Espectrometria de Massas/instrumentação , Análise de Célula Única/instrumentaçãoRESUMO
The development of a simple and direct assay for quantifying microbial metabolic activity is important for identifying antibiotic drugs. Current production capabilities of environmental bacteria via the process called extracellular electron transport (EET) from the cell interior to the exterior is well investigated in mineral-reducing bacteria and have been used for various energy and environmental applications. Recently, the capability of human pathogens for producing current has been identified in different human niches, which was suggested to be applicable for drug assessment, because the current production of a few strains correlated with metabolic activity. Herein, we report another strain, a highly abundant pathogen in human oral polymicrobial biofilm, Corynebacterium matruchotii, to have the current production capability associated with its metabolic activity. It showed the current production of 50 nA/cm2 at OD600 of 0.1 with the working electrode poised at +0.4 V vs. a standard hydrogen electrode in a three-electrode system. The addition of antibiotics that suppress the microbial metabolic activity showed a significant current decrease (>90%), establishing that current production reflected the cellular activity in this pathogen. Further, the metabolic fixation of atomically labeled 13C (31.68% ± 2.26%) and 15N (19.69% ± 1.41%) confirmed by high-resolution mass spectrometry indicated that C. matruchotii cells were metabolically active on the electrode surface. The identified electrochemical activity of C. matruchotii shows that this can be a simple and effective test for evaluating the impact of antibacterial compounds, and such a method might be applicable to the polymicrobial oral biofilm on electrode surfaces, given four other oral pathogens have already been shown the current production capability.
Assuntos
Fontes de Energia Bioelétrica , Biofilmes , Corynebacterium/fisiologia , EletrodosRESUMO
Microbes synthesize cell-associated nanoparticles (NPs) and utilize their physicochemical properties to produce energy under unfavorable metabolic conditions. Iron sulfide (FeS) NPs are ubiquitous and are predominantly biosynthesized by sulfate-reducing bacteria (SRB). However, the biological role of FeS NPs in SRB remains understudied. Now, conductive FeS NPs function is demonstrated as an electron conduit enabling Desulfovibrio vulgaris Hildenborough, an SRB strain, to utilize solid-state electron donors via direct electron uptake. After forming FeS NPs on the cell surface, D. vulgaris initiated current generation coupled with sulfate reduction on electrodes poised at -0.4â V versus standard hydrogen electrode. Single-cell activity analysis showed that the electron uptake and metabolic rate via FeS NPs in D. vulgaris were about sevenfold higher than those via native cell-surface proteins in other SRB.
Assuntos
Bactérias/metabolismo , Espaço Extracelular/metabolismo , Compostos Ferrosos/química , Compostos Ferrosos/metabolismo , Nanopartículas , Bactérias/citologia , Biocombustíveis/microbiologia , Eletrodos , Transporte de ElétronsRESUMO
Microbial extracellular electron transport occurs via the physical and electrical association of outer-membrane c-type cytochromes (OM c-Cyts) with extracellular solid surfaces. However, studies investigating the characteristics of cytochrome binding with solid materials have been limited to the use of purified units of OM c-Cyts dissolved in solution, rather than OM c-Cyts in intact cells, because of the lack of a methodology that specifically allows for the monitoring of OM c-Cyts in whole-cells. Here, we utilized circular dichroism (CD) spectroscopy to examine the molecular mechanisms and binding characteristics of the interaction between MtrC, a unit of OM c-Cyts, in whole Shewanella oneidensis MR-1 cells and hematite nanoparticles. The addition of hematite nanoparticles significantly decreased the intensity of the Soret CD peaks, indicating geometrical changes in the hemes in MtrC associated with their physical contact with hematite. The binding affinity of MtrC estimated using CD spectra changed predominantly depending upon the redox state of MtrC and the concentration of the hematite nanoparticles. In contrast, purified MtrC demonstrated a constant binding affinity following a Langmuir isotherm, with a standard Gibbs free energy of -43 kJ mol-1, suggesting that the flexibility in the binding affinity of MtrC with hematite was specific in membrane-bound protein complex conditions. Overall, these findings suggest that the binding affinity as well as the heme geometry of OM c-Cyts are flexibly modulated in the membrane complex associated with microbe-mineral interactions.
Assuntos
Grupo dos Citocromos c/química , Heme/química , Heme/metabolismo , Minerais/metabolismo , Shewanella/enzimologia , Grupo dos Citocromos c/metabolismo , Compostos Férricos/metabolismo , Ligação ProteicaRESUMO
Serpentinization is a geologic process that produces highly reduced, hydrogen-rich fluids that support microbial communities under high pH conditions. We investigated the activity of microbes capable of extracellular electron transfer in a terrestrial serpentinizing system known as 'The Cedars'. Measuring current generation with an on-site two-electrode system, we observed daily oscillations in current with the current maxima and minima occurring during daylight hours. Distinct members of the microbial community were enriched. Current generation in lab-scale electrochemical reactors did not oscillate, but was correlated with carbohydrate amendment in Cedars-specific minimal media. Gammaproteobacteria and Firmicutes were consistently enriched from lab electrochemical systems on δ-MnO2 and amorphous Fe(OH)3 at pH 11. However, isolation of an electrogenic strain proved difficult as transfer cultures failed to grow after multiple rounds of media transfer. Lowering the bulk pH in the media allowed us to isolate a Firmicutes strain (Paenibacillus sp.). This strain was capable of electrode and mineral reduction (including magnetite) at pH 9. This report provides evidence of the in situ activity of microbes using extracellular substrates as sinks for electrons at The Cedars, but also highlights the potential importance of community dynamics for supporting microbial life through either carbon fixation, and/or moderating pH stress.
Assuntos
Transporte de Elétrons/fisiologia , Óxido Ferroso-Férrico/metabolismo , Firmicutes/metabolismo , Gammaproteobacteria/metabolismo , Firmicutes/isolamento & purificação , Gammaproteobacteria/isolamento & purificação , Hidrogênio/química , Concentração de Íons de Hidrogênio , Oxirredução , RNA Ribossômico 16SRESUMO
The microbial transfer of electrons to extracellularly located solid compounds, termed extracellular electron transport (EET), is critical for microbial electrode catalysis. Although the components of the EET pathway in the outer membrane (OM) have been identified, the role of electron/cation coupling in EET kinetics is poorly understood. We studied the dynamics of proton transport associated with EET in an OM flavocytochrome complex in Shewanella oneidensis MR-1. Using a whole-cell electrochemical assay, a significant kinetic isotope effect (KIE) was observed following the addition of deuterated water (D2 O). The removal of a flavin cofactor or key components of the OM flavocytochrome complex significantly increased the KIE in the presence of D2 O to values that were significantly larger than those reported for proton channels and ATP synthase, thus indicating that proton transport by OM flavocytochrome complexes limits the rate of EET.
RESUMO
Extracellular redox-active compounds, flavins and other quinones, have been hypothesized to play a major role in the delivery of electrons from cellular metabolic systems to extracellular insoluble substrates by a diffusion-based shuttling two-electron-transfer mechanism. Here we show that flavin molecules secreted by Shewanella oneidensis MR-1 enhance the ability of its outer-membrane c-type cytochromes (OM c-Cyts) to transport electrons as redox cofactors, but not free-form flavins. Whole-cell differential pulse voltammetry revealed that the redox potential of flavin was reversibly shifted more than 100 mV in a positive direction, in good agreement with increasing microbial current generation. Importantly, this flavin/OM c-Cyts interaction was found to facilitate a one-electron redox reaction via a semiquinone, resulting in a 10(3)- to 10(5)-fold faster reaction rate than that of free flavin. These results are not consistent with previously proposed redox-shuttling mechanisms but suggest that the flavin/OM c-Cyts interaction regulates the extent of extracellular electron transport coupled with intracellular metabolic activity.
Assuntos
Grupo dos Citocromos c/metabolismo , Transporte de Elétrons , Flavina-Adenina Dinucleotídeo/análogos & derivados , Shewanella/fisiologia , Biofilmes , Citocromos c/metabolismo , Eletroquímica , Eletrodos , Espectroscopia de Ressonância de Spin Eletrônica , Mononucleotídeo de Flavina/metabolismo , Flavina-Adenina Dinucleotídeo/metabolismo , Heme/metabolismo , Microscopia Confocal , Nucleotídeos/genética , Oxirredução , Shewanella/metabolismoRESUMO
In addition to serving as an energy source for microbial growth, iron sulfides are proposed to act as naturally occurring electrical wires that mediate long-distance extracellular electron transfer (EET) and bridge spatially discrete redox environments. These hypothetical EET reactions stand on the abilities of microbes to use the interfacial electrochemistry of metallic/semiconductive iron sulfides to maintain metabolisms; however, the mechanisms of these phenomena remain unexplored. To obtain insight into EET to iron sulfides, we monitored EET at the interface between Shewanella oneidensis MR-1 cells and biomineralized iron sulfides in an electrochemical cell. Respiratory current steeply increased with the concomitant formation of poorly crystalline mackinawite (FeS) minerals, indicating that S. oneidensis has the ability to exploit extracellularly formed metallic FeS for long-distance EET. Deletion of major proteins of the metal-reduction (Mtr) pathway (OmcA, MtrC, CymA, and PilD) caused only subtle effects on the EET efficiency, a finding that sharply contrasts the majority of studies that report that the Mtr pathway is indispensable for the reduction of metal oxides and electrodes. The gene expression analyses of polysulfide and thiosulfate reductase suggest the existence of a sulfur-mediated electron-shuttling mechanism by which HS(-) ions and water-soluble polysulfides (HS(n)(-), where n ≥ 2) generated in the periplasmic space deliver electrons from cellular metabolic processes to cell surface-associated FeS. The finding of this Mtr-independent pathway indicates that polysulfide reductases complement the function of outer-membrane cytochromes in EET reactions and, thus, significantly expand the number of microbial species potentially capable of long-distance EET in sulfur-rich anoxic environments.
Assuntos
Espaço Extracelular/metabolismo , Compostos Ferrosos/metabolismo , Shewanella/citologia , Shewanella/metabolismo , Enxofre/metabolismo , Eletroquímica , Transporte de Elétrons , Transferência de Energia , Shewanella/genéticaRESUMO
The iron-reducing bacterium Shewanella oneidensis MR-1 has a dual directional electronic conduit involving 40 heme redox centers in flavin-binding outer-membrane c-type cytochromes (OM c-Cyts). While the mechanism for electron export from the OM c-Cyts to an anode is well understood, how the redox centers in OM c-Cyts take electrons from a cathode has not been elucidated at the molecular level. Electrochemical analysis of live cells during switching from anodic to cathodic conditions showed that altering the direction of electron flow does not require gene expression or protein synthesis, but simply redox potential shift about 300â mV for a flavin cofactor interacting with the OM c-Cyts. That is, the redox bifurcation of the riboflavin cofactor in OM c-Cyts switches the direction of electron conduction in the biological conduit at the cell-electrode interface to drive bacterial metabolism as either anode or cathode catalysts.
Assuntos
Flavinas/química , Benzoquinonas/química , Citocromos c/química , Citocromos c/metabolismo , Eletrodos , Transporte de Elétrons , Elétrons , Geobacter/metabolismo , Hidroquinonas/química , Oxirredução , Succinato Desidrogenase/química , Succinato Desidrogenase/metabolismoRESUMO
In this study, we explored the extracellular electron transfer (EET) capabilities of two bacterial strains, OTU0001 and OTU0002, which are demonstrated in biofilm formation in mouse gut and the induction of autoimmune diseases like multiple sclerosis. OTU0002 displayed significant electrogenic behaviour, producing microbial current on an indium tin-doped oxide electrode surface, particularly in the presence of glucose, with a current density of 60 nA/cm2. The presence of cell-surface redox substrate potentially mediating EET was revealed by the redox-based staining method and electrochemical voltammetry assay. However, medium swapping analyses and the addition of flavins, a model redox mediator, suggest that the current production is dominated by soluble endogenous redox substrates in OTU0002. Given redox substrates were detected at the cell surface, the secreted redox molecule may interact with the cellular surface of OTU0002. In contrast to OTU0002, OTU0001 did not exhibit notable electrochemical activity, lacking cell-surface redox molecules. Further, the mixture of the two strains did not increase the current production from OTU0001, suggesting that OTU0001 does not support the EET mechanism of OTU0002. The present work revealed the coexistence of EET and non-EET capable pathogens in multi-species biofilm.
RESUMO
BACKGROUND: There is widespread interest in the design of portable electrochemical sensors for the selective monitoring of biomolecules. Dopamine (DA) is one of the neurotransmitter molecules that play a key role in the monitoring of some neuronal disorders such as Alzheimer's and Parkinson's diseases. Facile synthesis of the highly active surface interface to design a portable electrochemical sensor for the sensitive and selective monitoring of biomolecules (i.e., DA) in its resources such as human fluids is highly required. RESULTS: The designed sensor is based on a three-dimensional phosphorous and sulfur resembling a g-C3N4 hornet's nest (3D-PS-doped CNHN). The morphological structure of 3D-PS-doped CNHN features multi-open gates and numerous vacant voids, presenting a novel design reminiscent of a hornet's nest. The outer surface exhibits a heterogeneous structure with a wave orientation and rough surface texture. Each gate structure takes on a hexagonal shape with a wall size of approximately 100 nm. These structural characteristics, including high surface area and hierarchical design, facilitate the diffusion of electrolytes and enhance the binding and high loading of DA molecules on both inner and outer surfaces. The multifunctional nature of g-C3N4, incorporating phosphorous and sulfur atoms, contributes to a versatile surface that improves DA binding. Additionally, the phosphate and sulfate groups' functionalities enhance sensing properties, thereby outlining selectivity. The resulting portable 3D-PS-doped CNHN sensor demonstrates high sensitivity with a low limit of detection (7.8 nM) and a broad linear range spanning from 10 to 500 nM. SIGNIFICANCE: The portable DA sensor based on the 3D-PS-doped CNHN/SPCE exhibits excellent recovery of DA molecules in human fluids, such as human serum and urine samples, demonstrating high stability and good reproducibility. The designed portable DA sensor could find utility in the detection of DA in clinical samples, showcasing its potential for practical applications in medical settings.
Assuntos
Dopamina , Técnicas Eletroquímicas , Dopamina/análise , Dopamina/urina , Humanos , Técnicas Eletroquímicas/métodos , Técnicas Eletroquímicas/instrumentação , Compostos de Nitrogênio/química , Limite de Detecção , Enxofre/química , Eletrodos , Técnicas Biossensoriais/métodos , Grafite/química , Fósforo/química , Propriedades de SuperfícieRESUMO
The ATP-binding cassette (ABC) transporter ComA is a key molecule essential for the first step of the quorum-sensing system of Streptococcus. The nucleotide binding domains (NBD) of Streptococcus mutans ComA with different N termini, NBD1 (amino acid residues 495-760), NBD2 (517-760), and NBD3 (528-760), were expressed, purified, and characterized. The shortest NBD3 corresponds to the region commonly defined as NBD in the database searches of ABC transporters. A kinetic analysis showed that the extra N-terminal region conferred a significantly higher ATP hydrolytic activity on the NBD at a neutral pH. Gel-filtration, X-ray crystallography, and mutational analyses suggest that at least four to five residues beyond the N-terminal boundary of NBD3 indeed participate in stabilizing the protein scaffold of the domain structure, thereby facilitating the ATP-dependent dimerization of NBD which is a prerequisite to the catalysis. These findings, together with the presence of a highly conserved glycine residue in this region, support the redefinition of the N-terminal boundary of the NBD of these types of ABC exporters.
Assuntos
Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Streptococcus/química , Transportadores de Cassetes de Ligação de ATP/química , Transportadores de Cassetes de Ligação de ATP/metabolismo , Trifosfato de Adenosina/metabolismo , Alanina/metabolismo , Sequência de Aminoácidos , Substituição de Aminoácidos , Proteínas de Bactérias/genética , Sítios de Ligação , Domínio Catalítico , Cromatografia em Gel , Dicroísmo Circular , Sequência Conservada , Cristalografia por Raios X , Proteínas de Ligação a DNA/genética , Glicina/química , Glicina/metabolismo , Concentração de Íons de Hidrogênio , Hidrólise , Cinética , Modelos Moleculares , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Mutação , Nucleotídeos/metabolismo , Conformação Proteica , Multimerização ProteicaRESUMO
[This corrects the article DOI: 10.1016/j.patter.2022.100610.].
RESUMO
Spinel oxides are promising for high-potential cathode materials of photo-rechargeable batteries. However, LiMn1.5M0.5O4 (M = Mn) shows a rapid degradation during charge/discharge under the illumination of UV-visible light. Here, we investigate various spinel-oxide materials by modifying the composition (M = Fe, Co, Ni, Zn) to demonstrate photocharging in a water-in-salt aqueous electrolyte. LiMn1.5Fe0.5O4 exhibited a substantially higher discharge capacity compared to that of LiMn2O4 after long-term photocharging owing to enhanced stability under illumination. This work provides fundamental design guidelines of spinel-oxide cathode materials for the development of photo-rechargeable batteries.