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1.
Food Sci Nutr ; 12(5): 3164-3176, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38726436

RESUMEN

Orthodontic tooth movement (OTM) is a critical process in dental alignment, driven by the application of calibrated orthodontic forces. This study delves into the intricate molecular and cellular mechanisms by which vitamin D3 influences OTM. Vitamin D3 is identified as a critical regulator in bone metabolism, enhancing osteoblast activity and bone formation while also modulating osteoclast quantity and RANKL expression, essential for the remodeling of the alveolar bone. The precise mechanisms through which vitamin D3 facilitates these processes are explored, highlighting its potential in accelerating bone remodeling and, consequently, tooth alignment. This comprehensive review underscores vitamin D3's anabolic impact on bone metabolism and its pivotal role in the synthesis and mineralization processes governed by osteoblasts. The findings illuminate vitamin D3's promise in augmenting orthodontic therapy, suggesting its utility in improving treatment efficiency and reducing duration. However, the need for further research into the optimal application of vitamin D3 in orthodontics is emphasized, particularly concerning dosage, timing, and delivery methods.

2.
Biochem Biophys Res Commun ; 716: 150009, 2024 Jul 05.
Artículo en Inglés | MEDLINE | ID: mdl-38697010

RESUMEN

The SOS response is a condition that occurs in bacterial cells after DNA damage. In this state, the bacterium is able to reсover the integrity of its genome. Due to the increased level of mutagenesis in cells during the repair of DNA double-strand breaks, the SOS response is also an important mechanism for bacterial adaptation to the antibiotics. One of the key proteins of the SOS response is the SMC-like protein RecN, which helps the RecA recombinase to find a homologous DNA template for repair. In this work, the localization of the recombinant RecN protein in living Escherichia coli cells was revealed using fluorescence microscopy. It has been shown that the RecN, outside the SOS response, is predominantly localized at the poles of the cell, and in dividing cells, also localized at the center. Using in vitro methods including fluorescence microscopy and optical tweezers, we show that RecN predominantly binds single-stranded DNA in an ATP-dependent manner. RecN has both intrinsic and single-stranded DNA-stimulated ATPase activity. The results of this work may be useful for better understanding of the SOS response mechanism and homologous recombination process.


Asunto(s)
ADN Bacteriano , Escherichia coli , Microscopía Fluorescente , Imagen Individual de Molécula , Microscopía Fluorescente/métodos , Escherichia coli/genética , Escherichia coli/metabolismo , Imagen Individual de Molécula/métodos , ADN Bacteriano/metabolismo , ADN Bacteriano/genética , Respuesta SOS en Genética , ADN de Cadena Simple/metabolismo , ADN de Cadena Simple/genética , Proteínas de Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Unión Proteica , Rec A Recombinasas/metabolismo , Rec A Recombinasas/genética , Pinzas Ópticas
3.
Sci Adv ; 10(17): eadl0164, 2024 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-38657076

RESUMEN

Type VI CRISPR-Cas systems are among the few CRISPR varieties that target exclusively RNA. The CRISPR RNA-guided, sequence-specific binding of target RNAs, such as phage transcripts, activates the type VI effector, Cas13. Once activated, Cas13 causes collateral RNA cleavage, which induces bacterial cell dormancy, thus protecting the host population from the phage spread. We show here that the principal form of collateral RNA degradation elicited by Leptotrichia shahii Cas13a expressed in Escherichia coli cells is the cleavage of anticodons in a subset of transfer RNAs (tRNAs) with uridine-rich anticodons. This tRNA cleavage is accompanied by inhibition of protein synthesis, thus providing defense from the phages. In addition, Cas13a-mediated tRNA cleavage indirectly activates the RNases of bacterial toxin-antitoxin modules cleaving messenger RNA, which could provide a backup defense. The mechanism of Cas13a-induced antiphage defense resembles that of bacterial anticodon nucleases, which is compatible with the hypothesis that type VI effectors evolved from an abortive infection module encompassing an anticodon nuclease.


Asunto(s)
Anticodón , Sistemas CRISPR-Cas , Escherichia coli , ARN de Transferencia , ARN de Transferencia/genética , ARN de Transferencia/metabolismo , Anticodón/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Leptotrichia/genética , Leptotrichia/metabolismo , Proteínas Asociadas a CRISPR/metabolismo , Proteínas Asociadas a CRISPR/genética , Bacteriófagos/genética , División del ARN
4.
bioRxiv ; 2024 Jan 09.
Artículo en Inglés | MEDLINE | ID: mdl-38260645

RESUMEN

Viruses compete with each other for limited cellular resources, and some viruses deliver defense mechanisms that protect the host from competing genetic parasites. PARIS is a defense system, often encoded in viral genomes, that is composed of a 53 kDa ABC ATPase (AriA) and a 35 kDa TOPRIM nuclease (AriB). Here we show that AriA and AriB assemble into a 425 kDa supramolecular immune complex. We use cryo-EM to determine the structure of this complex which explains how six molecules of AriA assemble into a propeller-shaped scaffold that coordinates three subunits of AriB. ATP-dependent detection of foreign proteins triggers the release of AriB, which assembles into a homodimeric nuclease that blocks infection by cleaving the host tRNALys. Phage T5 subverts PARIS immunity through expression of a tRNALys variant that prevents PARIS-mediated cleavage, and thereby restores viral infection. Collectively, these data explain how AriA functions as an ATP-dependent sensor that detects viral proteins and activates the AriB toxin. PARIS is one of an emerging set of immune systems that form macromolecular complexes for the recognition of foreign proteins, rather than foreign nucleic acids.

5.
Amino Acids ; 55(11): 1655-1664, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37782378

RESUMEN

Vitamin C plays a very important role in the repair of connective tissue, especially for sports whose training causes the most damage to this tissue. Therefore, many people believe that L-ascorbic acid (C6H8O6: vitamin C) reduces the recovery time between sports exercises. The most abundant form of structural protein in the body is collagen. Collagen is characterized by a high concentration of the three amino acids glycine (Gly), proline (Pro), and hydroxyproline (Hyp), which creates its characteristic triple helix structure. Therefore, in this study, the effect of vitamin C presence on the sequence, interaction, and orientation of amino acids for collagen formation is investigated using computational simulation. This study aimed to investigate the mechanism of action of vitamin C in terms of thermodynamics and structure of the reaction. The calculations are performed using density function theory (DFT) by the base set of B3LYP/6-311++G (p,d). The results show that the presence of vitamin C is effective in the formation of collagen protein for this interaction and the mechanism of amino acid sequence (Gly-Hyp-Pro) is better in the formation of collagen protein in the presence of vitamin C. The presence of Vit-C in the formation and direction of hydroxyproline (Hyp) causes its separation from the prolyl 5-hydroxylase enzyme. In the absence of vitamin C, the reaction stops at this stage and proline cannot be converted into hydroxyproline. The computational data shows vitamin C prevents unwanted interactions and directs amino acid reactions to repair connective tissue (collagen). Therefore, vitamin C acts as a cofactor in the Prolyl 5-Hydroxylase enzyme and causes it to convert proline to hydroxyl.


Asunto(s)
Aminoácidos , Prolina , Humanos , Hidroxiprolina/química , Estructura Secundaria de Proteína , Prolina/química , Colágeno/química , Glicina , Ácido Ascórbico , Oxigenasas de Función Mixta
6.
Viruses ; 15(10)2023 10 16.
Artículo en Inglés | MEDLINE | ID: mdl-37896872

RESUMEN

A nucleus-like structure composed of phage-encoded proteins and containing replicating viral DNA is formed in Pseudomonas aeruginosa cells infected by jumbo bacteriophage phiKZ. The PhiKZ genes are transcribed independently from host RNA polymerase (RNAP) by two RNAPs encoded by the phage. The virion RNAP (vRNAP) transcribes early viral genes and must be injected into the cell with phage DNA. The non-virion RNAP (nvRNAP) is composed of early gene products and transcribes late viral genes. In this work, the dynamics of phage RNAPs localization during phage phiKZ infection were studied. We provide direct evidence of PhiKZ vRNAP injection in infected cells and show that it is excluded from the phage nucleus. The nvRNAP is synthesized shortly after the onset of infection and localizes in the nucleus. We propose that spatial separation of two phage RNAPs allows coordinated expression of phage genes belonging to different temporal classes.


Asunto(s)
Bacteriófagos , Fagos Pseudomonas , Bacteriófagos/genética , Proteínas Virales/metabolismo , Fagos Pseudomonas/metabolismo , ARN Polimerasas Dirigidas por ADN/metabolismo , Genes Virales
7.
Pharmaceuticals (Basel) ; 16(10)2023 Oct 02.
Artículo en Inglés | MEDLINE | ID: mdl-37895869

RESUMEN

The toxicity of local anesthetics is a serious problem, given their widespread use. One of the main causes of the side effects of local anesthetics is their non-selectivity of action in the body. A possible way to increase the selectivity of the action of drugs is to use the photopharmacology approach. Previously, we described the light-controlled local anesthetic ethercaine, the biological effect of which can be controlled using light, thereby increasing its selectivity of action. An important limitation of ethercaine was its low solubility in water, limiting the potential of this compound. In this work, we developed a dosage form of ethercaine, which allowed us to increase its solubility from 0.6% to 2% or more. The resulting 1% solution of ethercaine hydrochloride in 4% Kolliphor ELP had high biological activity on the surface anesthesia model, while demonstrating low acute toxicity in mice with intravenous administration (4-5 times less than that of lidocaine).

8.
Materials (Basel) ; 16(16)2023 Aug 09.
Artículo en Inglés | MEDLINE | ID: mdl-37629834

RESUMEN

The review focuses on the surface modification of Zr and its alloys, which is necessary to expand the applications of these kinds of materials. Data on the properties of pure zirconium and its alloys are presented. Since surface engineering and the operation of the above materials are in most cases associated with the formation of oxide coatings, information on the characteristics of ZrO2 is given. In addition, attention is paid to phasing in the zirconium-oxygen system. It is noted that the most effective method of surface engineering of Zr and its alloys is plasma electrolytic modification (PEM) technology. Specific examples and modes of modification are described, and the reached results are analyzed. The relevance, novelty and originality of the review are determined by the insufficient knowledge about a number of practical features concerning the formation of functional oxide coatings on Zr and some of its alloys by the technology of PEM. In particular, the information on the phase composition and possibilities of stabilization of the tetragonal and cubic modifications of ZrO2, the effects of the component composition of electrolyte solutions and electrolyte suspensions, and the specifics of the treatment of additive shaping and deformed materials are rather contradictory. This review aims to collect recent advances and provide insights into the trends in the modification of Zr and its alloys, promote the formulation of practical recommendations and assess the development prospects.

9.
Molecules ; 28(13)2023 Jun 23.
Artículo en Inglés | MEDLINE | ID: mdl-37446607

RESUMEN

It is shown that the potassium polytitanate powder (PPT) synthesized at 500 °C via the treatment of powdered TiO2 (rutile) in molten mixtures of KOH and KNO3 is a cheap and effective catalyst of H2O2 chemical decomposition in aqueous solutions. At the same time, the PPT catalytic activity strongly depends on the [TiO2]:[KOH]:[KNO3] weight ratio in the mixture used for the synthesis, increasing with [KNO3] in the order of PPT (30:30:40) < PPT (30:50:20) < PPT (30:70:0). The obtained results are explained by increased [Ti3+] in the PPT structure (XPS data), which is grown in this order from 0 to 4.0 and 21.9 at.%, respectively, due to the reduced oxidation activity of the melt used for PPT synthesis. The mechanism of the autocatalytic process taking place in the PPT-H2O2-H2O system is analyzed. Taking into account the data of FT-IR spectroscopy, it is assumed that the increased catalytic activity of the investigated materials is related to the increased surface concentration of the Ti4+-O(H)-Ti4+ groups, formed from the Ti3+-O(H3O+)-Ti4+ clusters and further transformed into Ti-O-O-H catalytic centers. Some possible applications of the PPT-H2O2-H2O catalytic system, including the oxidation processes of green chemistry and photo-catalysis, are discussed.


Asunto(s)
Peróxido de Hidrógeno , Titanio , Peróxido de Hidrógeno/química , Espectroscopía Infrarroja por Transformada de Fourier , Titanio/química , Agua , Cloruro de Sodio , Cloruro de Sodio Dietético , Catálisis
10.
Dalton Trans ; 52(17): 5563-5574, 2023 May 02.
Artículo en Inglés | MEDLINE | ID: mdl-37013382

RESUMEN

We synthesized single and polycrystals of iron oxide with an unconventional Fe4O5 stoichiometry under high-pressure high-temperature (HP-HT) conditions. The crystals of Fe4O5 had a CaFe3O5-type structure composed of linear chains of iron with octahedral and trigonal-prismatic oxygen coordinations. We investigated the electronic properties of this mixed-valence oxide using several experimental techniques, including measurements of electrical resistivity, the Hall effect, magnetoresistance, and thermoelectric power (Seebeck coefficient), X-ray absorption near edge spectroscopy (XANES), reflectance and absorption spectroscopy, and single-crystal X-ray diffraction. Under ambient conditions, the single crystals of Fe4O5 demonstrated a semimetal electrical conductivity with nearly equal partial contributions of electrons and holes (σn ≈ σp), in line with the nominal average oxidation state of iron as Fe2.5+. This finding suggests that both the octahedral and trigonal-prismatic iron cations contribute to the electrical conductivity of Fe4O5via an Fe2+/Fe3+ polaron hopping mechanism. A moderate deterioration of crystal quality shifted the dominant electrical conductivity to n-type and considerably worsened the conductivity. Thus, alike magnetite, Fe4O5 with equal numbers of Fe2+ and Fe3+ ions can serve as a prospective model for other mixed-valence transition-metal oxides. In particular, it could help in the understanding of the electronic properties of other recently discovered mixed-valence iron oxides with unconventional stoichiometries, many of which are not recoverable to ambient conditions; it can also help in designing novel more complex mixed-valence iron oxides.

11.
Front Public Health ; 11: 961066, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36794072

RESUMEN

Dental diseases occur in children with cerebral palsy three times higher than in healthy children. Low values of the unstimulated salivation rate (<0.3 ml per minute), pH and buffer capacity, changes in enzyme activity and sialic acid concentration, as well as increased saliva osmolarity and total protein concentration, which indicates impaired hydration, are the factors in the development of a gingiva disease in case of cerebral palsy. This leads to increased bacterial agglutination and the formation of acquired pellicle and biofilm, leading to the formation of dental plaque. There is a tendency toward an increase in the concentration of hemoglobin and a decrease in the degree of hemoglobin oxygenation, as well as an increase in the generation of reactive oxygen and nitrogen species. Photodynamic therapy (PDT) with the use of photosensitizer methylene blue improves blood circulation and the degree of oxygenation in periodontal tissues, as well as eliminates a bacterial biofilm. Analysis of back diffuse reflection spectra makes it possible to conduct non-invasive monitoring determine tissue areas with a low level of hemoglobin oxygenation for precision photodynamic exposure. Aim: To improve the effectiveness of phototheranostics methods using, namely PDT with simultaneous optical-spectral control, for the treatment of gingivitis in children with complex dental and somatic status (cerebral palsy). Methods: The study involved 15 children (6-18 y.o.) with various forms of cerebral palsy, in particular, spastic diplegia and atonic-astatic form and with gingivitis. The degree of hemoglobin oxygenation was measured in tissues before PDT and on the 12th day. PDT was performed using laser radiation (λ = 660 nm) with a power density of 150 mW/cm2 with a five-minute application of 0.01% MB. The total light dose was 45 ± 15 J/cm2. For statistical evaluation of the results, a paired Student's t-test was used. Results: The paper presents the results of phototheranostics using methylene blue in children with cerebral palsy. An increase in the level of hemoglobin oxygenation from 50 to 67% (p < 0.001) and a decrease in blood volume in the microcirculatory bed of periodontal tissues were shown. Conclusion: Photodynamic therapy methods with application of methylene blue make it possible to assess the state of the gingival mucosa tissue diseases objectively in real time, and to provide effective targeted therapy for gingivitis in children with cerebral palsy. There is a prospect that they can become widely used clinical methods.


Asunto(s)
Parálisis Cerebral , Gingivitis , Fotoquimioterapia , Niño , Humanos , Parálisis Cerebral/tratamiento farmacológico , Azul de Metileno/uso terapéutico , Microcirculación , Hemoglobinas
12.
Nucleic Acids Res ; 50(21): 12355-12368, 2022 11 28.
Artículo en Inglés | MEDLINE | ID: mdl-36477901

RESUMEN

The action of Type II restriction-modification (RM) systems depends on restriction endonuclease (REase), which cleaves foreign DNA at specific sites, and methyltransferase (MTase), which protects host genome from restriction by methylating the same sites. We here show that protection from phage infection increases as the copy number of plasmids carrying the Type II RM Esp1396I system is increased. However, since increased plasmid copy number leads to both increased absolute intracellular RM enzyme levels and to a decreased MTase/REase ratio, it is impossible to determine which factor determines resistance/susceptibility to infection. By controlled expression of individual Esp1396I MTase or REase genes in cells carrying the Esp1396I system, we show that a shift in the MTase to REase ratio caused by overproduction of MTase or REase leads, respectively, to decreased or increased protection from infection. Consistently, due to stochastic variation of MTase and REase amount in individual cells, bacterial cells that are productively infected by bacteriophage have significantly higher MTase to REase ratios than cells that ward off the infection. Our results suggest that cells with transiently increased MTase to REase ratio at the time of infection serve as entry points for unmodified phage DNA into protected bacterial populations.


Asunto(s)
Bacteriófagos , Enzimas de Restricción del ADN/genética , Bacteriófagos/genética , Metiltransferasas , Enzimas de Restricción-Modificación del ADN/genética , ADN
13.
Int J Mol Sci ; 23(24)2022 Dec 12.
Artículo en Inglés | MEDLINE | ID: mdl-36555417

RESUMEN

Photodynamic therapy (PDT) is currently regarded as a promising method for the treatment of oncological diseases. However, it involves a number of limitations related to the specific features of the method and the specific characteristics of photosensitizer molecules, including tumor hypoxia, small depth of light penetration into the tumor tissue, and low accumulation sensitivity. These drawbacks can be overcome by combining PDT with other treatment methods, for example, chemotherapy. In this work, we were the first to obtain agents that contain bacteriopurpurinimide as a photodynamic subunit and complexes of gold(I) that implement the chemotherapy effect. To bind the latter agents, N-heterocyclic carbenes (NHC) based on histidine and histamine were obtained. We considered alternative techniques for synthesizing the target conjugates and selected an optimal one that enabled the production of preparative amounts for biological assays. In vitro studies showed that all the compounds obtained exhibited high photoinduced activity. The C-donor Au(I) complexes exhibited the maximum specific activity at longer incubation times compared to the other derivatives, both under exposure to light and without irradiation. In in vivo studies, the presence of histamine in the NHC-derivative of dipropoxy-BPI (7b) had no significant effect on its antitumor action, whereas the Au(I) metal complex of histamine NHC-derivative with BPI (8b) resulted in enhanced antitumor activity and in an increased number of remissions after photodynamic treatment.


Asunto(s)
Complejos de Coordinación , Neoplasias , Fotoquimioterapia , Humanos , Complejos de Coordinación/farmacología , Histidina , Histamina , Fármacos Fotosensibilizantes/farmacología , Fármacos Fotosensibilizantes/uso terapéutico , Neoplasias/tratamiento farmacológico , Oro/farmacología , Línea Celular Tumoral
14.
Sensors (Basel) ; 22(15)2022 Aug 02.
Artículo en Inglés | MEDLINE | ID: mdl-35957335

RESUMEN

Nitrites are widely used in the food industry, particularly for the preservation of meat products. Controlling the nitrate content in food is an important task to ensure people's health is not at risk; therefore, the search for, and research of, new materials that will modify the electrodes in the electrochemical sensors that detect and control the nitrate content in food products is an urgent task. In this paper, we describe the electrochemical behavior of a glass carbon electrode (GCE), modified with a Fe(II) tetra-tert-butyl phthalocyanine film (FePc(tBu)4/GCE), and decorated with gold nanoparticles (Au/FePc(tBu)4/GCE); this electrode was deposited using gas-phase methods. The composition and morphology of such electrodes were examined using spectroscopy and electron microscopy methods, whereas the main electrochemical characteristics were determined using cyclic voltammetry (CV) and amperometry (CA) methods in the linear ranges of CV 0.25-2.5 mM, CA 2-120 µM in 0.1 M phosphate buffer (pH = 6.8). The results showed that the modification of bare GCEs, with a Au/FePc(tBu)4 heterostructure, provided a high surface-to-volume ratio, thus ensuring its high sensitivity to nitrite ions of 0.46 µAµM-1. The sensor based on the Au/FePc(tBu)4/GCE has a low limit of nitrite detection at 0.35 µM, good repeatability, and stability. The interference study showed that the proposed Au/FePc(tBu)4/GCE exhibited a selective response in the presence of interfering anions, and the analytical capability of the sensor was demonstrated by determining nitrite ions in real samples of meat products.


Asunto(s)
Productos de la Carne , Nanopartículas del Metal , Carbono/química , Técnicas Electroquímicas/métodos , Electrodos , Oro/química , Humanos , Indoles , Hierro , Isoindoles , Límite de Detección , Nanopartículas del Metal/química , Nitratos , Nitritos/química , Compuestos Organometálicos
15.
Biosensors (Basel) ; 12(7)2022 Jun 30.
Artículo en Inglés | MEDLINE | ID: mdl-35884279

RESUMEN

This work is aimed at the development of new heterostructures based on cobalt phthalocyanines (CoPc) and gold nanoparticles (AuNPs), and the evaluation of the prospects of their use to determine low concentrations of ammonia and nitric oxide. For this purpose, CoPc films were decorated with AuNPs by gas-phase methods (MOCVD and PVD) and drop-casting (DC), and their chemiresistive sensor response to low concentrations of NO (10-50 ppb) and NH3 (1-10 ppm) was investigated. A comparative analysis of the characteristics of heterostructures depending on the preparation methods was carried out. The composition, structure, and morphology of the resulting hybrid films were studied by X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma atomic emission (ICP-AES) spectroscopy, as well as electron microscopy methods to discuss the effect of these parameters on the sensor response of hybrid films to ammonia and nitric oxide. It was shown that regardless of the fabrication method, the response of Au/CoPc heterostructures to NH3 and NO gases increased with an increase in the concentration of gold. The sensor response of Au/CoPc heterostructures to NH3 increased 2-3.3 times compared to CoPc film, whereas in the case of NO it increased up to 16 times. The detection limits of the Au/CoPc heterostructure with a gold content of ca. 2.1 µg/cm2 for NH3 and NO were 0.1 ppm and 4 ppb, respectively. It was shown that Au/CoPc heterostructures can be used for the detection of NH3 in a gas mixture simulating exhaled air (N2-74%, O2-16%, H2O-6%, CO2-4%).


Asunto(s)
Oro , Nanopartículas del Metal , Amoníaco/análisis , Gases/análisis , Oro/química , Indoles , Nanopartículas del Metal/química , Óxido Nítrico , Compuestos Organometálicos
16.
Elife ; 112022 06 22.
Artículo en Inglés | MEDLINE | ID: mdl-35730924

RESUMEN

RecA protein mediates homologous recombination repair in bacteria through assembly of long helical filaments on ssDNA in an ATP-dependent manner. RecX, an important negative regulator of RecA, is known to inhibit RecA activity by stimulating the disassembly of RecA nucleoprotein filaments. Here we use a single-molecule approach to address the regulation of (Escherichia coli) RecA-ssDNA filaments by RecX (E. coli) within the framework of distinct conformational states of RecA-ssDNA filament. Our findings revealed that RecX effectively binds the inactive conformation of RecA-ssDNA filaments and slows down the transition to the active state. Results of this work provide new mechanistic insights into the RecX-RecA interactions and highlight the importance of conformational transitions of RecA filaments as an additional level of regulation of its biological activity.


Asunto(s)
Proteínas de Escherichia coli , Escherichia coli , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , ADN de Cadena Simple/metabolismo , Escherichia coli/genética , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Rec A Recombinasas
17.
Biochem Biophys Res Commun ; 614: 29-33, 2022 07 23.
Artículo en Inglés | MEDLINE | ID: mdl-35567941

RESUMEN

RecA is a central enzyme of homologous recombination in bacteria, which plays a major role in DNA repair, natural transformation and SOS-response activation. RecA forms nucleoprotein filaments on single-stranded DNA with a highly conserved architecture that is also shared by eukaryotic recombinases. One of the key features of these filaments is the ability to switch between stretched and compressed conformations in response to ATP binding and hydrolysis. However, the functional role of such conformational changes is not fully understood. Structural data revealed that in the absence of ATP RecA binds DNA with the stoichiometry of 5 nucleotides per one monomer, while in the presence of ATP the binding stoichiometry is 3:1. Such differences suggest incompatibility of the active and inactive conformations, yet dynamic single-molecule studies demonstrated that ATP and apo conformations can be directly interconvertible. In the present work we use a single-molecule approach to address the features of inactive RecA nucleoprotein filaments formed de novo in the absence of nucleotide cofactors. We show that compressed RecA-DNA filaments can exist with both 5:1 and 3:1 binding stoichiometry which is determined by conditions of the filament assembly. However, only a 3:1 stoichiometry allows direct interconvertibility with the active ATP-bound conformation.


Asunto(s)
Nucleoproteínas , Rec A Recombinasas , Adenosina Trifosfato/metabolismo , ADN/metabolismo , ADN de Cadena Simple , Nucleoproteínas/metabolismo , Nucleótidos , Rec A Recombinasas/metabolismo
18.
Int J Mol Sci ; 23(10)2022 May 11.
Artículo en Inglés | MEDLINE | ID: mdl-35628162

RESUMEN

Pain is a common symptom that impairs the quality of life for people around the world. Local anesthetics widely used for pain relief have a number of side effects, which makes the development of both new drugs and new ways to control their activity particularly important. Photopharmacology makes it possible to reduce the side effects of an anesthetic and control its biological activity in the body. The purpose of this work was to create a new light-controlled local anesthetic and study its biological activity in animals. A compound with a simple scheme of synthesis was chosen to shift the UV-Vis absorption band towards the visible range of the spectrum and was synthesized for the first time. Some computer calculations were performed to make sure that the aforementioned changes would not lead to loss of biological activity. The micellar form of the new compound was prepared, and in vivo biological studies were carried out in rabbits. The existence of a local anesthetic effect, which disappeared almost completely on irradiation with light (λ = 395 nm), was shown using the surface anesthesia model. Moreover, the possibility of multiple reversible changes in the biological activity of ethercaine under the action of light was demonstrated. The latter compound manifests no local irritating effect, either. The data obtained indicate the prospects for the development of new compounds based on azobenzene for light-controlled local anesthesia.


Asunto(s)
Anestesia Local , Anestésicos Locales , Anestésicos Locales/farmacología , Animales , Compuestos Azo , Humanos , Dolor , Calidad de Vida , Conejos
19.
Proc Natl Acad Sci U S A ; 119(15): e2114905119, 2022 04 12.
Artículo en Inglés | MEDLINE | ID: mdl-35394860

RESUMEN

CRISPR-Cas systems provide prokaryotes with an RNA-guided defense against foreign mobile genetic elements (MGEs) such as plasmids and viruses. A common mechanism by which MGEs avoid interference by CRISPR consists of acquisition of escape mutations in regions targeted by CRISPR. Here, using microbiological, live microscopy and microfluidics analyses we demonstrate that plasmids can persist for multiple generations in some Escherichia coli cell lineages at conditions of continuous targeting by the type I-E CRISPR-Cas system. We used mathematical modeling to show how plasmid persistence in a subpopulation of cells mounting CRISPR interference is achieved due to the stochastic nature of CRISPR interference and plasmid replication events. We hypothesize that the observed complex dynamics provides bacterial populations with long-term benefits due to continuous maintenance of mobile genetic elements in some cells, which leads to diversification of phenotypes in the entire community and allows rapid changes in the population structure to meet the demands of a changing environment.


Asunto(s)
Sistemas CRISPR-Cas , Escherichia coli , Secuencias Repetitivas Esparcidas , Plásmidos , Sistemas CRISPR-Cas/genética , Sistemas CRISPR-Cas/fisiología , Escherichia coli/genética , Interacción Gen-Ambiente , Secuencias Repetitivas Esparcidas/genética , Modelos Genéticos , Plásmidos/genética
20.
Molecules ; 27(7)2022 Mar 28.
Artículo en Inglés | MEDLINE | ID: mdl-35408606

RESUMEN

To search for new suitable Pd precursors for MOCVD/ALD processes, the extended series of fluorinated palladium complexes [Pd(CH3CXCHCO(R))2] with ß-diketone [tfa-1,1,1-trifluoro-2,4-pentanedionato (1); pfpa-5,5,6,6,6-pentafluoro-2,4-hexanedionato (3); hfba-5,5,6,6,7,7,7-heptafluoro-2,4-heptanedionato (5)] and ß-iminoketone [i-tfa-1,1,1-trifluoro-2-imino-4-pentanonato (2); i-pfpa-5,5,6,6,6-pentafluoro-2-imino-4-hexanonato (4); i-hfba-5,5,6,6,7,7,7-heptafluoro-2-imino-4-heptanonato (6)] ligands were synthesized with 70-80% yields and characterized by a set of experimental (SXRD, XRD, IR, NMR spectroscopy, TG) and theoretical (DFT, Hirshfeld surface analysis) methods. Solutions of Pd ß-diketonates contained both cis and trans isomers, while only trans isomers were detected in the solutions of Pd ß-iminoketonates. The molecules 2-6 and new polymorphs of complexes 3 and 5 were arranged preferentially in stacks, and the distance between molecules in the stack generally increased with elongation of the fluorine chain in ligands. The H…F contacts were the main ones involved in the formation of packages of molecules 1-2, and C…F, F…F, NH…F contacts appeared in the structures of complexes 4-6. The stability of complexes and their polymorphs in the crystal phases were estimated from DFT calculations. The TG data showed that the volatility differences between Pd ß-iminoketonates and Pd ß-diketonates were minimized with the elongation of the fluorine chain in the ligands.


Asunto(s)
Flúor , Paladio , Cristalografía por Rayos X , Ligandos , Modelos Moleculares , Paladio/química
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