RESUMEN
A Gram-stain-negative, yellow-pigmented, and strictly aerobic bacterium, designated as strain MSW5T, was isolated from seawater of the Yellow Sea in South Korea. The cells were non-motile rods exhibiting oxidase- and catalase-positive activities. Growth was observed at 15-25 °C (optimum, 25 °C) and pH 5.0-9.0 (optimum, pH 7.0-8.0) and in the presence of 1.0-5.0% (w/v) NaCl (optimum, 2.0%). Menaquinone-6 was the sole respiratory quinone, and iso-C15â:â0, summed feature 3 (C16â:â1 ω7c and/or C16â:â1 ω6c), iso-C15â:â0 3-OH, and C15â:â1 ω6c were the major cellular fatty acids. Major polar lipids included phosphatidylethanolamine, two unidentified aminolipids, and three unidentified lipids. Phylogenetic analyses based on 16S rRNA gene sequences and 92 concatenated core protein sequences revealed that strain MSW5T formed a distinct lineage within the genus Polaribacter. The genome of strain MSW5T was 3582 kb in size with a 29.1 mol% G+C content. Strain MSW5T exhibited the highest similarity to Polaribacter atrinae WP25T, with a 97.9% 16S rRNA gene sequence similarity. However, the average nucleotide identity and digital DNA-DNA hybridization values were 79.4 and 23.3%, respectively, indicating that strain MSW5T represents a novel species. Based on its phenotypic, chemotaxonomic, and phylogenetic characteristics, strain MSW5T is proposed to represent a novel species, with the name Polaribacter ponticola sp. nov. The type strain is MSW5T (=KACC 22340T=NBRC 116025T). In addition, whole genome sequence comparisons and phenotypic features suggested that Polaribacter sejongensis and Polaribacter undariae belong to the same species, with P. undariae proposed as a later heterotypic synonym of P. sejongensis. An emended description of Polaribacter sejongensis is also proposed.
Asunto(s)
Técnicas de Tipificación Bacteriana , Composición de Base , ADN Bacteriano , Ácidos Grasos , Filogenia , ARN Ribosómico 16S , Agua de Mar , Análisis de Secuencia de ADN , Vitamina K 2 , ARN Ribosómico 16S/genética , Ácidos Grasos/análisis , Agua de Mar/microbiología , República de Corea , ADN Bacteriano/genética , Vitamina K 2/análogos & derivados , Vitamina K 2/análisis , Fosfatidiletanolaminas , Hibridación de Ácido Nucleico , Bacteroidetes/genética , Bacteroidetes/clasificación , Bacteroidetes/aislamiento & purificación , Fosfolípidos/análisis , Fosfolípidos/químicaRESUMEN
Despite longstanding excitement and progress toward understanding liquid-liquid phase separation in natural and artificial membranes, fundamental questions have persisted about which molecules are required for this phenomenon. Except in extraordinary circumstances, the smallest number of components that has produced large-scale, liquid-liquid phase separation in bilayers has stubbornly remained at three: a sterol, a phospholipid with ordered chains, and a phospholipid with disordered chains. This requirement of three components is puzzling because only two components are required for liquid-liquid phase separation in lipid monolayers, which resemble half of a bilayer. Inspired by reports that sterols interact closely with lipids with ordered chains, we tested whether phase separation would occur in bilayers in which a sterol and lipid were replaced by a single, joined sterol-lipid. By evaluating a panel of sterol-lipids, some of which are present in bacteria, we found a minimal bilayer of only two components (PChemsPC and diPhyPC) that robustly demixes into micron-scale, liquid phases. It suggests an additional role for sterol-lipids in nature, and it reveals a membrane in which tie-lines (and, therefore, the lipid composition of each phase) are straightforward to determine and will be consistent across multiple laboratories.
Asunto(s)
Membrana Dobles de Lípidos , Esteroles , Membrana Dobles de Lípidos/química , Esteroles/química , Transición de Fase , Fosfatidilcolinas/química , Fosfolípidos/química , Separación de FasesRESUMEN
BACKGROUND: Several oxylipins including hydroxy- and epoxy-polyunsaturated fatty acids act as lipid mediators. In biological samples they can be present as non-esterified form, but the major part occurs esterified in phospholipids (PL) or other lipids. Esterified oxylipins are quantified indirectly after alkaline hydrolysis as non-esterified oxylipins. However, in this indirect analysis the information in which lipid class oxylipins are bound is lost. In this work, an untargeted liquid chromatography high-resolution mass spectrometry (LC-HRMS) method for the direct analysis of PL bearing oxylipins was developed. RESULTS: Optimized reversed-phase LC separation achieved a sufficient separation of isobaric and isomeric PL from different lipid classes bearing oxylipin positional isomers. Individual PL species bearing oxylipins were identified based on retention time, precursor ion and characteristic product ions. The bound oxylipin could be characterized based on product ions resulting from the α-cleavage occurring at the hydroxy/epoxy group. PL sn-1/sn-2 isomers were identified based on the neutral loss of the fatty acyl in the sn-2 position. A total of 422 individual oxPL species from 7 different lipid classes i.e., PI, PS, PC, PE, PC-P, PC-O, and PE-P were detected in human serum and cells. This method enabled to determine in which PL class supplemented oxylipins are incorporated in HEK293 cells: 20:4;15OH, 20:4;14Ep, and 20:5;14Ep were mostly bound to PI. 20:4;8Ep and 20:5;8Ep were esterified to PC and PE while other oxylipins were mainly found in PC. SIGNIFICANCE: The developed LC-HRMS method enables the comprehensive detection as well as the semi-quantification of isobaric and isomeric PL species bearing oxylipins. With this method, we show that the position of the oxidation has a great impact and directs the incorporation of oxylipins into the different PL classes in human cells.
Asunto(s)
Espectrometría de Masas , Oxilipinas , Fosfolípidos , Oxilipinas/análisis , Oxilipinas/química , Humanos , Fosfolípidos/análisis , Fosfolípidos/química , Espectrometría de Masas/métodos , Cromatografía Liquida/métodos , IsomerismoRESUMEN
The oxidation-induced phospholipids (PLs) underwent structural and compositional analysis, alongside the establishment of a simulation system to verify the link between phospholipid oxidation and flavor substances formation in sturgeon caviar. Structural alterations of PLs were tracked using 31P and 1H nuclear magnetic resonance (NMR), electron spin resonance spectroscopy (ESR), and Raman spectroscopy. The findings revealed a reduction in phosphatidylcholine (PC) and phosphatidylethanolamine (PE) from 82.3% and 10.4% to 58.2% and 5.8% respectively. Free radical signals exhibited an initial increase followed by a decrease. The diminished intensity in Raman spectra at 970 and 1080 cm-1 indicated reduced fat unsaturation attributable to PLs oxidation. Correlation analysis highlighted a significant association between PC and PE containing C22:6, C20:5, C20:4, and C18:2 with flavor substances, suggesting their role as key precursors for flavor development. This study established a theoretical basis for understanding the change of flavor quality in sturgeon caviar during storage.
Asunto(s)
Peces , Oxidación-Reducción , Fosfolípidos , Animales , Fosfolípidos/química , Aromatizantes/química , Gusto , Productos Pesqueros/análisisRESUMEN
Transdermal administration techniques have gained popularity due to their advantages over oral and parenteral methods. Noninvasive, self-administered delivery devices improve patient compliance and control drug release. Transdermal delivery devices struggle with the skin's barrier function. Molecules over 500 Dalton (Da) and ionized compounds don't permeate through the skin. Drug encapsulation in phospholipid-based vesicular systems is the most effective skin delivery technique. Vesicular carriers include bi-layered liposomes, ultra-deformable liposomes, ethanolic liposomes, transethosomes, and invasomes. These technologies enhance skin drug permeation by increasing formula solubilization, partitioning into the skin, and fluidizing the lipid barrier. Phospholipid-based delivery systems are safe and efficient, making them a promising pharmaceutical and cosmeceutical drug delivery technique. Still, making delivery systems requires knowledge about the physicochemical properties of the drug and carrier, manufacturing and process variables, skin delivery mechanisms, technological advances, constraints, and regulatory requirements. Consequently, this review covers recent research achievements addressing the mentioned concerns.
Asunto(s)
Administración Cutánea , Sistemas de Liberación de Medicamentos , Liposomas , Fosfolípidos , Absorción Cutánea , Piel , Fosfolípidos/química , Humanos , Sistemas de Liberación de Medicamentos/métodos , Piel/metabolismo , Absorción Cutánea/fisiología , Absorción Cutánea/efectos de los fármacos , Liposomas/química , Portadores de Fármacos/química , Animales , Nanopartículas/químicaRESUMEN
Two new strains JP48T and JP55 affiliated with the acidobacterial class Terriglobia have been isolated from fen soil sampled in the Fichtelgebirge Mountains near Bayreuth, Germany. Both strains were Gram-stain-negative, non-motile, non-spore-forming rods that divide by binary fission, segregate exopolysaccharide-like material and form capsules. Strains JP48T and JP55 grew at 4-36 °C (optimum at 27 °C), pH 3.6-7.3 (optimum at pH 4.6-5.5) and with NaCl concentrations of 0-3% (optimum at 1.0%; w/v). Strains JP48T and JP55 grew aerobically on a wide range of organic substrates including mono- and oligosaccharides, amino acids and short-chained fatty acids. MK-8 was identified as the major respiratory quinone. The major fatty acids for strains JP48T and JP55 were iso-C15â:â0, C16â:â1 ω7c, C16â:â0 and iso-diabolic acid. Phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, lysophophatidylethanolamine, phosphatidylcholine, unidentified glyco- and glycophospholipids, and unidentified high mass lipid species were the major polar membrane lipids. The G+C content of strains JP48T and JP55 was 57.4 and 57.2 mol%, respectively. The genomes of strains JP48T and JP55 contained nine potential secondary metabolite regions encoding for the compound classes NRPS(-like), T3PKS, terpene, or lanthipeptide class IV. Phylogenetic reconstruction and 16S rRNA gene sequence similarities of 98.3 and 96.9% identified Edaphobacter dinghuensis DHF9T and Edaphobacter lichenicola DSM 104462T as the most closely related type strains to strains JP48T and JP55. Based on their phenotype, phylogeny and chemotaxonomy, we propose the novel species Edaphobacter paludis sp. nov. (type strain JP48T=DSM 109919T=CECT 30269T; additional strain JP55=DSM 109920=CECT 30268) within the class Terriglobia of the phylum Acidobacteriota.
Asunto(s)
Técnicas de Tipificación Bacteriana , Composición de Base , ADN Bacteriano , Ácidos Grasos , Filogenia , ARN Ribosómico 16S , Análisis de Secuencia de ADN , Microbiología del Suelo , ARN Ribosómico 16S/genética , Ácidos Grasos/química , ADN Bacteriano/genética , Alemania , Vitamina K 2/análogos & derivados , Quinonas/análisis , Acidobacteria/genética , Acidobacteria/clasificación , Acidobacteria/aislamiento & purificación , Fosfolípidos/químicaRESUMEN
A cell membrane is an essential cellular component providing protection against the outer environment. It is also a host for proteins and carbohydrates responsible for, e.g. transporter, receptor, or enzymatic functions. In parallel, the membrane may also be implicated in pathological processes leading, e.g. to the oligomerization of amyloid-forming proteins, a hallmark of i.a. Alzheimer's disease. The increasing need for detailed information on mechanisms driving the amyloid formation and the potential role of cell membranes in the process proves the research on protein-membrane interactions biologically relevant. Considering the potential and limitations of the relatively well established and newly developed methods, this study focused on selecting methods that allow a broad and comprehensive description of interactions between amyloidogenic protein human cystatin C and lipid bilayers. In the first step, dot-blot and ELISA tests were selected as techniques allowing fast screening for protein-ligand interactions. Next, surface plasmon resonance, spectral shift, biolayer interferometry, and switchSENSE® technology were used to determine kinetic parameters and binding constants for interactions between human cystatin C and the selected lipid bilayers. Based on the obtained results we have proposed the most promising candidates for monitoring of interactions and determining affinity between amyloidogenic proteins and membrane mimetics.
Asunto(s)
Cistatina C , Liposomas , Fosfolípidos , Unión Proteica , Cistatina C/química , Cistatina C/metabolismo , Humanos , Liposomas/química , Fosfolípidos/metabolismo , Fosfolípidos/química , Membrana Dobles de Lípidos/química , Membrana Dobles de Lípidos/metabolismo , Resonancia por Plasmón de Superficie , Proteínas Amiloidogénicas/metabolismo , Proteínas Amiloidogénicas/química , Cinética , Membrana Celular/metabolismoRESUMEN
The large yellow croaker roe phospholipids (LYPLs), rich in polyunsaturated fatty acids, is a potential phospholipid additive for meat products. In this work, the effects of LYPLs on the structural and functional properties of myofibrillar protein (MP) were determined, and compared with egg yolk phospholipids (EYPLs) and soybean phospholipids (SBPLs). The results revealed that LYPLs, similar to SBPLs and EYPLs, induced a transformation in the secondary structure of MP from α-helix to ß-sheets and random coils, while also inhibited the formation of carbonyl and disulfide bonds within MP. All three phospholipids induced MP tertiary structure unfolding, with the greatest degree of unfolding observed in MP containing LYPLs. The MP with LYPLs had the highest surface hydrophobicity, emulsification properties and gel strength. In addition, MP with LYPLs added also demonstrated superior rheological properties and water-holding capacity compared with SBPLs and EYPLs. In conclusion, adding LYPLs endowed MP with improved functional properties.
Asunto(s)
Perciformes , Fosfolípidos , Animales , Fosfolípidos/química , Porcinos , Proteínas Musculares/química , Interacciones Hidrofóbicas e Hidrofílicas , Proteínas de Peces/química , Conformación Proteica , Miofibrillas/química , Reología , Estructura Secundaria de ProteínaRESUMEN
Several strains were isolated from subsurface soil of the Atacama Desert and were previously assigned to the Micromonospora genus. A polyphasic study was designed to determine the taxonomic affiliation of isolates 4G51T, 4G53, and 4G57. All the strains showed chemotaxonomic properties in line with their classification in the genus Micromonospora, including meso-diaminopimelic acid in the cell wall peptidoglycan, MK-9(H4) as major respiratory quinone, iso-C15:0 and iso-C16:0 as major fatty acids and diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylinositol as major polar lipids. The 16S rRNA gene sequences of strains 4G51T, 4G53, and 4G57 showed the highest similarity (97.9 %) with the type strain of Micromonospora costi CS1-12T, forming an independent branch in the phylogenetic gene tree. Their independent position was confirmed with genome phylogenies, being most closely related to the type strain of Micromonospora kangleipakensis. Digital DNA-DNA hybridization and average nucleotide identity analyses between the isolates and their closest phylogenomic neighbours confirmed that they should be assigned to a new species within the genus Micromonospora for which the name Micromonospora sicca sp. nov. (4G51T=PCM 3031T=LMG 30756T) is proposed.
Asunto(s)
ADN Bacteriano , Clima Desértico , Ácidos Grasos , Micromonospora , Hibridación de Ácido Nucleico , Filogenia , ARN Ribosómico 16S , Análisis de Secuencia de ADN , Microbiología del Suelo , ARN Ribosómico 16S/genética , Micromonospora/genética , Micromonospora/clasificación , Micromonospora/aislamiento & purificación , ADN Bacteriano/genética , Ácidos Grasos/análisis , Ácidos Grasos/química , Peptidoglicano/química , Peptidoglicano/análisis , Técnicas de Tipificación Bacteriana , Ácido Diaminopimélico/análisis , Pared Celular/química , Chile , Fosfolípidos/análisis , Fosfolípidos/químicaRESUMEN
Phospholipid fatty acid (PLFA) analysis is used for characterizing microbial communities based on their lipid profiles. This method avoids biases from PCR or culture, allowing data collection in a natural state. However, PLFA is labor-intensive due to lipid fractionation. Simplified ester-linked fatty acid analysis (ELFA), which skips lipid fractionation, offers an alternative. It utilizes base-catalyzed methylation to derivatize only lipids, not free fatty acids, and found glycolipid and neutral lipid fractions are scarcely present in most bacteria, allowing lipid fractionation to be skipped. ELFA method showed a high correlation to PLFA data (r = 0.99) and higher sensitivity than the PLFA method by 1.5-2.57-fold, mainly due to the higher recovery of lipids, which was 1.5-1.9 times higher than with PLFA. The theoretical limit of detection (LOD) and limit of quantification (LOQ) for the ELFA method indicated that 1.54-fold less sample was needed for analysis than with the PLFA method. Our analysis of three bacterial cultures and a simulated consortium revealed the effectiveness of the ELFA method by its simple procedure and enhanced sensitivity for detecting strain-specific markers, which were not detected in PLFA analysis. Overall, this method could be easily used for the population analysis of synthetic consortia.
Asunto(s)
Ésteres , Ácidos Grasos , Fosfolípidos , Ácidos Grasos/análisis , Ácidos Grasos/química , Fosfolípidos/análisis , Fosfolípidos/química , Ésteres/análisis , Ésteres/química , Bacterias/metabolismo , Límite de DetecciónRESUMEN
Local anesthetics (LA), as part of multimodal analgesia, have garnered significant interest for their role in delaying the initiation of opioid therapy, reducing postoperative opioid usage, and mitigating both hospitalization duration and related expenses. Despite numerous endeavors to extend the duration of local anesthetic effects, achieving truly satisfactory long-acting analgesia remains elusive. Drawing upon prior investigations, vesicular phospholipid gels (VPGs) emerge as promising candidates for extended-release modalities in small-molecule drug delivery systems. Therefore, we tried to use the amphiphilicity of phospholipids to co-encapsulate levobupivacaine hydrochloride and meloxicam, two drugs with different hydrophilicity, to obtain a long-term synergistic analgesic effect. Initially, the physicochemical attributes of the formulation were characterized, followed by an examination of its in vitro release kinetics, substantiating the viability of extending the release duration of the dual drugs. Sequentially, in vivo investigations encompassing pharmacokinetic profiling and assessment of analgesic efficacy were undertaken, revealing a prolonged release duration of up to 120 h and attainment of optimal postoperative analgesia. Subsequently, inquiries into the mechanism underlying synergistic analgesic effects and safety evaluations pertinent to the delivery strategy were pursued. In summation, we successfully developed a promising formulation to achieve long-acting analgesia.
Asunto(s)
Anestésicos Locales , Preparaciones de Acción Retardada , Liberación de Fármacos , Levobupivacaína , Meloxicam , Dolor Postoperatorio , Dolor Postoperatorio/tratamiento farmacológico , Anestésicos Locales/administración & dosificación , Anestésicos Locales/farmacocinética , Anestésicos Locales/química , Animales , Meloxicam/administración & dosificación , Meloxicam/farmacocinética , Masculino , Levobupivacaína/administración & dosificación , Fosfolípidos/química , Fosfolípidos/administración & dosificación , Ratas Sprague-Dawley , Bupivacaína/administración & dosificación , Bupivacaína/farmacocinética , Bupivacaína/química , Bupivacaína/análogos & derivados , Analgésicos/administración & dosificación , Analgésicos/química , Analgésicos/farmacocinética , Geles , Sinergismo FarmacológicoRESUMEN
Oleate hydratase (OhyA) is a bacterial peripheral membrane protein that catalyzes FAD-dependent water addition to membrane bilayer-embedded unsaturated fatty acids. The opportunistic pathogen Staphylococcus aureus uses OhyA to counteract the innate immune system and support colonization. Many Gram-positive and Gram-negative bacteria in the microbiome also encode OhyA. OhyA is a dimeric flavoenzyme whose carboxy terminus is identified as the membrane binding domain; however, understanding how OhyA binds to cellular membranes is not complete until the membrane-bound structure has been elucidated. All available OhyA structures depict the solution state of the protein outside its functional environment. Here, we employ liposomes to solve the cryo-electron microscopy structure of the functional unit: the OhyAâ¢membrane complex. The protein maintains its structure upon membrane binding and slightly alters the curvature of the liposome surface. OhyA preferentially associates with 20-30 nm liposomes with multiple copies of OhyA dimers assembling on the liposome surface resulting in the formation of higher-order oligomers. Dimer assembly is cooperative and extends along a formed ridge of the liposome. We also solved an OhyA dimer of dimers structure that recapitulates the intermolecular interactions that stabilize the dimer assembly on the membrane bilayer as well as the crystal contacts in the lattice of the OhyA crystal structure. Our work enables visualization of the molecular trajectory of membrane binding for this important interfacial enzyme.
Asunto(s)
Microscopía por Crioelectrón , Membrana Dobles de Lípidos , Liposomas , Staphylococcus aureus , Microscopía por Crioelectrón/métodos , Membrana Dobles de Lípidos/metabolismo , Membrana Dobles de Lípidos/química , Liposomas/química , Liposomas/metabolismo , Staphylococcus aureus/enzimología , Fosfolípidos/metabolismo , Fosfolípidos/química , Hidroliasas/química , Hidroliasas/metabolismo , Hidroliasas/ultraestructura , Proteínas Bacterianas/química , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/ultraestructura , Modelos Moleculares , Proteínas de la Membrana/química , Proteínas de la Membrana/metabolismo , Unión Proteica , Membrana Celular/metabolismoRESUMEN
A progressive aggregation of Tau proteins in the brain is linked to both Alzheimer's disease (AD) and various Tauopathies. This pathological process can be enhanced by several substances, including heparin. However, very little if anything is known about molecules that can inhibit the aggregation of Tau isoforms. In this study, we examined the effect of phosphatidylserines (PSs) with various lengths and saturations of fatty acids (FAs) on the aggregation properties of Tau isoforms with one (1N4R) and two (2N4R) N-terminal inserts that enhance binding of Tau to tubulin. We found that PS with unsaturated and short-length FAs inhibited Tau aggregation and drastically lowered the toxicity of Tau oligomers that were formed in the presence of such phospholipids. Such an effect was not observed for PS with fully saturated long-chain FAs. These results suggest that a short-chain irreversible disbalance between saturated and unsaturated lipids in the brain could be the trigger of Tau aggregation.
Asunto(s)
Fosfolípidos , Proteínas tau , Proteínas tau/metabolismo , Proteínas tau/química , Humanos , Fosfolípidos/química , Fosfolípidos/metabolismo , Agregado de Proteínas/efectos de los fármacos , Heparina/química , Heparina/farmacología , Isoformas de Proteínas/química , Isoformas de Proteínas/metabolismo , Fosfatidilserinas/química , Fosfatidilserinas/metabolismo , Tubulina (Proteína)/metabolismo , Tubulina (Proteína)/químicaRESUMEN
Human milk phospholipids (HMPLs) play an indispensable role in the neurodevelopment and growth of infants. In this study, a total of 37 phospholipid fatty acid (PLFA) species and 139 phospholipid molecular species were detected from human milk and other natural phospholipid sources (including 5 animal-derived species and 2 plant species). Moreover, a similarity evaluation model for HMPLs was established, including phospholipid classes, PLFAs, and phospholipid molecular species, to evaluate their natural substitutes. The closest scores for HMPL substitute in these three dimensions was 0.89, 0.72, and 0.77, which belonged to mare milk, goat milk, and camel milk, respectively. The highest comprehensive similarity score was obtained by camel milk at 0.75, while the lowest score was observed in soybean phospholipid (0.22). Therefore, these results not only monitored the stereochemical structure of HMPLs and their substitutes, but also further provided new insights for the development of infant formulae.
Asunto(s)
Cabras , Leche Humana , Fosfolípidos , Humanos , Fosfolípidos/química , Fosfolípidos/análisis , Leche Humana/química , Animales , Ácidos Grasos/química , Ácidos Grasos/análisis , Camelus/crecimiento & desarrollo , Caballos , Fórmulas Infantiles/química , Fórmulas Infantiles/análisis , Leche/química , Femenino , Estructura MolecularRESUMEN
The fundamental differences in phospholipids between bacterial and mammalian cell membranes present remarkable opportunities for antimicrobial design. However, it is challenging to distinguish bacterial anionic phospholipid phosphatidylglycerol (PG) from mammalian anionic phosphatidylserine (PS) with the same net charge. Here, we report a class of radially amphiphilic α helix antimicrobial peptides (RAPs) that can selectively discriminate PG from PS, relying on the helix structure. The representative RAP, L10-MMBen, can direct the rearrangement of PG vesicles into a lamellar structure with its helix axis parallel to the PG membrane surface. The helical structure imparts both the thermodynamic and kinetic advantages of L10-MMBen/PG assembly, and the hiding of hydrophobic regions in RAPs is crucial for PG recognition. L10-MMBen exhibits high selectivity against bacteria depending on PG recognition, showing low in vivo toxicity and significant treatment efficacy in mice infection models. Our study introduces a helicity-direct bacterial phospholipid recognition paradigm for designing highly selective antimicrobial peptides.
Asunto(s)
Péptidos Antimicrobianos , Fosfolípidos , Animales , Péptidos Antimicrobianos/química , Péptidos Antimicrobianos/farmacología , Ratones , Fosfolípidos/química , Fosfolípidos/metabolismo , Fosfatidilgliceroles/química , Bacterias/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Interacciones Hidrofóbicas e Hidrofílicas , Péptidos Catiónicos Antimicrobianos/química , Péptidos Catiónicos Antimicrobianos/farmacología , Antibacterianos/farmacología , Antibacterianos/químicaRESUMEN
A significant impediment persists in developing multicomponent nanomedicines designed to dismantle the heat shock protein (HSP)-based protective mechanism of malignant tumors during photothermal therapy. Herein, well-defined PEGylated phospholipid micelles were utilized to coencapsulate quercetin (QUE, a natural anticancer agent and potent HSP inhibitor) and indocyanine green (ICG, a photothermal agent) with the aim of achieving synchronized and synergistic drug effects. The subsequent investigations validated that the tailored micellar system effectively enhanced QUE's water solubility and augmented its cellular internalization efficiency. Intriguingly, the compositional PEGylated phospholipids induced extraordinary endoplasmic reticulum stress, thereby sensitizing the tumor cells to QUE. Furthermore, QUE played a crucial role in inhibiting the stress-induced overexpression of HSP70, thereby augmenting the photothermal efficacy of ICG. In systemic applications, the proposed nanotherapeutics exhibited preferential accumulation within tumors and exerted notable tumoricidal effects against 4T1 xenograft tumors under 808 nm near-infrared irradiation, facilitated by prominent near-infrared fluorescence imaging-guided chemo-photothermal therapy. Therefore, our strategy for fabricating multicomponent nanomedicines emerges as a coordinated platform for optimizing antitumor therapeutic efficacy and offers valuable insights for diverse therapeutic modalities.
Asunto(s)
Verde de Indocianina , Ratones Endogámicos BALB C , Micelas , Fosfolípidos , Terapia Fototérmica , Polietilenglicoles , Quercetina , Quercetina/química , Quercetina/farmacología , Quercetina/administración & dosificación , Verde de Indocianina/química , Verde de Indocianina/administración & dosificación , Animales , Ratones , Polietilenglicoles/química , Fosfolípidos/química , Línea Celular Tumoral , Femenino , Terapia Fototérmica/métodos , Ensayos Antitumor por Modelo de Xenoinjerto , Humanos , Antineoplásicos/farmacología , Antineoplásicos/química , Antineoplásicos/administración & dosificación , Ratones DesnudosRESUMEN
Biological cell membranes are primarily comprised of a diverse lipid bilayer with multiple phospholipid (lipid) types, each of which is comprised of a hydrophilic headgroup and two hydrophobic hydrocarbon tails. The lipid type determines the molecular structure of head and tail groups, which can affect membrane mechanics at nanoscale and subsequently cell viability under mechanical loading. Hence, using molecular dynamics simulations, the current study investigated seven membrane phospholipids and the effect of their structural differences on physical deformation, mechanoporation damage, and mechanical failure of the membranes under tension. The inspected phospholipids showed similar yield stresses and strains, as well as pore evolution and damage, but significantly different failure strains. In general, failure occurred at a lower strain for lipids with a larger equilibrium area per lipid. The obtained results suggest that larger headgroup structure, greater degree of unsaturation, and tail-length asymmetry influenced the phospholipids' ability to pack against each other, increased the fluidity and equilibrium area per lipid of the membrane, and resulted in lower failure strain. Overall, this study provides insights on how different phospholipid structures affect membrane physical responses at the molecular level and serves as a reference for future studies of more complex membrane systems with intricate biophysical properties.
Asunto(s)
Membrana Celular , Simulación de Dinámica Molecular , Fosfolípidos , Fosfolípidos/química , Membrana Celular/química , Membrana Dobles de Lípidos/química , Estructura MolecularRESUMEN
Lubricating base oils have been extensively employed for producing various industrial and consumer products. Therefore, their environmental and health impacts should be carefully evaluated. Although there have been many reports on pulmonary cytotoxicity and inflammatory responses of inhaled lubricating base oils, their potential influences on pulmonary surfactant (PS) films that play an essential role in maintaining respiratory mechanics and pulmonary immunity remains largely unknown. Here a systematic study on the interactions between an animal-derived natural PS and aerosols of water and representative mineral and vegetable base oils is performed using a novel biophysical assessing technique called constrained drop surfactometry capable of providing in vitro simulations of normal tidal breathing and physiologically relevant temperature and humidity in the lung. It was found that the mineral oil aerosols can impose strong inhibitions to the biophysical property of PS film, while the airborne vegetable oils and water show negligible adverse effects within the studied concentration range. The inhibitory effect is originated from the strong hydrophobicity of mineral oil, which makes it able to disrupt the interfacial molecular ordering of both phospholipid and protein compositions and consequently suppress the formation of condensed phase and multilayer scaffolds in a PS film. ENVIRONMENTAL IMPLICATION: Understanding the biophysical influence of airborne lubricating base oils on pulmonary surfactant (PS) films can provide new insights into the environmental impacts and health concerns of various industrial lubricant products. Here a comparative study on interactions between an animal-derived natural PS film and the aerosols of water and representative mineral and vegetable base oils under the true physiological conditions was conducted in situ using constrained drop surfactometry. We show that the most frequently used mineral base oil can cause strong inhibitions to the PS film by disrupting the molecular ordering of saturated phospholipids and surfactant-associated proteins at the interface.
Asunto(s)
Aerosoles , Lubricantes , Surfactantes Pulmonares , Aerosoles/química , Surfactantes Pulmonares/química , Lubricantes/química , Aceite Mineral/química , Animales , Aceites de Plantas/química , Fosfolípidos/química , Agua/químicaRESUMEN
The cell membrane functions as a semipermeable barrier that governs the transport of materials into and out of cells. The bilayer features a distinct dielectric gradient due to the amphiphilic nature of its lipid components. This gradient influences various aspects of small molecule permeation and the folding and functioning of membrane proteins. Here, we employ polarizable molecular dynamics simulations to elucidate the impact of the electronic environment on the permeation process. We simulated eight distinct amino-acid side chain analogs within a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayer using the Drude polarizable force field (FF). Our approach includes both unbiased and umbrella sampling simulations. By using a polarizable FF, we sought to investigate explicit dipole responses in relation to local electric fields along the membrane normal. We evaluate molecular dipole moments, which exhibit variation based on their localization within the membrane, and compare the outcomes with analogous simulations using the nonpolarizable CHARMM36 FF. This comparative analysis aims to discern characteristic differences in the free energy surfaces of permeation for the various amino-acid analogs. Our results provide the first systematic quantification of the impact of employing an explicitly polarizable FF in this context compared to the fixed-charge convention inherent to nonpolarizable FFs, which may not fully capture the influence of the membrane dielectric gradient.
Asunto(s)
Membrana Dobles de Lípidos , Simulación de Dinámica Molecular , Fosfatidilcolinas , Membrana Dobles de Lípidos/química , Membrana Dobles de Lípidos/metabolismo , Fosfatidilcolinas/química , Fosfolípidos/química , Permeabilidad , Aminoácidos/químicaRESUMEN
Bacterial conjugation is a process by which DNA is transferred unidirectionally from a donor cell to a recipient cell. It is the main means by which antibiotic resistance genes spread among bacterial populations. It is crucially dependent upon the elaboration of an extracellular appendage, termed "pilus," by a large double-membrane-spanning secretion system termed conjugative "type IV secretion system." Here we present the structure of the conjugative pilus encoded by the R388 plasmid. We demonstrate that, as opposed to all conjugative pili produced so far for cryoelectron microscopy (cryo-EM) structure determination, the conjugative pilus encoded by the R388 plasmid is greatly stimulated by the presence of recipient cells. Comparison of its cryo-EM structure with existing conjugative pilus structures highlights a number of important differences between the R388 pilus structure and that of its homologs, the most prominent being the highly distinctive conformation of its bound lipid.