Search Results (292)

Complex I (NADH:quinone oxidoreductase, CI) is central to cellular aerobic energy metabolism. The L-shaped structure of CI is unique, where the hydrophilic arm is responsible for the electron transfer function and the membrane arm operates proton pumping. These two functional sites are spatially far apart yet functionally connected. This basic core subunit architecture is highly conserved from bacterial to mammalian CI. Here, to gain detailed mechanistic insight into the role of the membrane subunit ND2 in the coupling mechanism, we mutated several highly conserved residues in the middle of the membrane axis of NuoN, the E. coli CI homolog of ND2. To more precisely investigate the consequences of mutational effects on highly conserved residues, we purified each mutant CI and compared the mutational effects on electron transfer and proton pumping activity using our instant membrane reconstitution method with E. coli double knockout (DKO) membrane vesicles lacking both CI and alternative NADH dehydrogenase (NDH-2). Thre results were corroborated by conventional proteoliposome reconstitution experiments. We found that Lys247 and Lys395 are absolutely essential for both electron transfer and proton pumping activities, while about 50% reduction of NADH oxidase activity but no reduction in proton pumping activity was observed in Lys217, and no significant decrease was detected in Glu133. Furthermore, unexpectedly, we were able to purify an NuoN knockout (ΔNuoN) mutant, which contained stoichiometric peripheral subunits NuoB, NuoCD, NuoE, NuoF, NuoG, and NuoI; and a substoichiometric amount of NuoH and a reduced amount of quinone. However, surprisingly, this isolated ΔNuoN CI showed CI activities (~30% of the WT) after being reconstituted into DKO membranes but not into proteoliposomes. Later, we confirmed by blue native PAGE that the wild-type CI was partially formed from ΔNuoN CI by recruiting its missing membrane subunits that existed in DKO membranes. Our data strongly suggest that ND2/NuoN plays an essential role in the coupling mechanism in CI. CI is the entry respiratory chain enzyme and is central to cellular energy metabolism. Two highly conserved lysine residues in the center of the antiporter-like membrane subunit ND2 are essential for the coupling mechanism between electron transfer and proton translocation. Full article

Background: Metabolic disorder-associated fatty liver disease (MASLD) is closely related to obesity and type 2 diabetes. Its pathogenesis involves many factors, including mitochondrial dysfunction, endoplasmic reticulum stress and intestinal flora disorders. Notoginsenoside R1 (NGR1) is a key bioactive component of Panax notoginseng. The purpose of this study was to investigate the therapeutic effect of notoginsenoside R1 (NGR1) on metabolic disorder-associated steatohepatitis (MASH) and its potential mechanism. Methods: Mice were fed a choline-deficient, L-amino acid-defined high-fat diet (CDAHFD) for 6 weeks and received NGR1 (50/100 mg/kg/day) in the last 3 weeks. The role of NGR1 was evaluated by developing metabolomics, proteomics and functional analysis. In addition, the effects of NGR1 on lipid droplet content, mitochondrial function and fatty acid oxidation in hepatocytes were also verified. Results: NGR1 improved MASH progression in CDAHFD-fed mice, significantly reduced liver triglyceride content from 31.2 ± 5.1 mmol/g to 20.5 ± 4.8 mg/g (p < 0.001), free fatty acid from 0.12 ± 0.03 mmol/g prot to 0.06 ± 0.028 mg/g (p < 0.001), TNF-α (p < 0.01), IL-1β (p < 0.001), α-SMA (p < 0.05) and Collagen1A1 levels (p < 0.01), as well as serum ALT and AST concentrations (p < 0.001), and alleviated hepatomegaly and lipid droplet accumulation. Metabolomics and proteomics analysis showed that NGR1 normalized liver metabolism in MASH mice and upregulated mitochondrial OXPHOS components, including NADH: ubiquinone oxidoreductase core subunit S2 (NDUFS2), and effectively reversed CDAHFD-induced mitochondrial dysfunction. Mitochondrial membrane potential and ATP production were restored. Conclusions: This study confirmed that NGR1 has significant therapeutic potential for MASH and improves mitochondrial function by upregulating NDUFS2. This study provides new insights for the future clinical treatment of MASH. Full article

Influenza A virus (IAV) remains a major global health threat, and host-directed antivirals may help overcome rapid viral mutation and drug resistance. Here, we performed a genome-wide siRNA screen in A549 cells using cell viability as an integrated endpoint to identify host determinants of IAV (PR8/H1N1) infection. Using plate-normalized viability ratios, we identified 2134 genes with >40% viability change after infection (2048 UP and 86 DOWN; two-tailed t-test, n = 3; p < 0.05, FDR < 0.1). MetaCore pathway analysis showed enrichment of programs linked to host response and tissue injury control, including RAS-related signaling and multiple metabolic pathways such as estradiol, ubiquinone/mitochondrial redox, and benzo[a]pyrene/xenobiotic metabolism. DAVID Gene Ontology analysis further highlighted biological processes relevant to infection, including endocytosis, transcription, and translation, consistent with host pathways supporting viral replication. Benchmarking against meta-analyzed RNAi and CRISPR resources revealed that shared hits were enriched for translation, nucleocytoplasmic transport, and ER-Golgi trafficking, supporting external validity, whereas the large unique UP fraction was dominated by hormone metabolism, detoxification, and mitochondrial redox/CoQ pathways, consistent with viability-specific, tolerance-associated host response programs. Integrating the screen with DrugBank identified 174 druggable host genes corresponding to 345 candidate compounds. Together, these findings provide a systematic resource of host factors influencing H1N1 infection, improve understanding of influenza virus–host interactions, and offer a foundation for future development of host-directed antiviral strategies and drug repurposing efforts. Full article

Coenzyme Q10 (CoQ10) plays an important role in human health; for example, through the antioxidant function of its reduced form (ubiquinol). As the long-term health effects of circulating CoQ10 remain largely unknown, we examined the association of total CoQ10, ubiquinol, ubiquinone (oxidized CoQ10), and CoQ10 redox state (percentage of ubiquinone in total CoQ10) with all-cause mortality in a sample from the northern German general population. In n = 1333 individuals (60.1% females, median baseline age: 48.0 years [37.7; 58.0]), serum total CoQ10, ubiquinol, ubiquinone, and CoQ10 redox state were measured at baseline and found to be related to all-cause mortality using Cox regression models (adjusted for sex, age, body mass index, smoking, systolic blood pressure, total cholesterol, diabetes, and C-reactive protein). After 12.9 years [12.4; 17.1], n = 123 deaths had occurred. A higher CoQ10 redox state was independently associated with a higher risk of all-cause mortality after multivariable adjustment (HR: 1.18 [95% CI 1.02–1.36] per 1-SD increment, HR: 1.92 [95% CI 1.16–3.17] for tertile 3 vs. tertile 1), while higher ubiquinone levels were associated with greater all-cause mortality risk only in the unadjusted model. A higher CoQ10 redox state was associated with a higher risk of all-cause mortality in a population-based sample, possibly indicating detrimental long-term health effects of the lower antioxidant capacity of CoQ10. Full article

Aquaculture sustainability requires a reduction in the reliance on marine-derived raw materials such as fish oil in aquafeeds while maintaining fish health and product quality. This study investigated the effects of replacing fish oil with plant oils supplemented with DHA-rich Schizochytrium limacinum biomass on the gut microbiota of European sea bass (Dicentrarchus labrax). S. limacinum SR21—an oleaginous microalga naturally rich in omega-3 fatty acids—was produced through heterotrophic fermentation using crude glycerol, a waste stream from biodiesel production, within a circular economy framework. A 21-week feeding trial was conducted in an indoor recirculating aquaculture system using 280 fish distributed across eight tanks. Four experimental diets were tested: fish oil-based (FO), plant oil-based without microalga (VO + 0), and plant oil-based supplemented with 5% (VO + 5) or 10% (VO + 10) microalgal biomass. Gut microbiota was analyzed in 22 fish per group using 16S rRNA gene sequencing. While alpha and beta diversity analyses of gut microbiota revealed modest structural shifts at phylum and class ranks, genus-rank differences were evident, with Lactobacillus and Clostridium sensu stricto associated with FO and VO + 0 diets, and Pseudomonas and Staphylococcus enriched in microalga-supplemented groups. Functional inference highlighted enhanced bile acid biosynthesis and carbohydrate metabolism in VO + 0, whereas antioxidant-related pathways, including ubiquinone and carotenoid biosynthesis, were stimulated in VO + 5 and VO + 10 groups. These results demonstrate that S. limacinum biomass modulates microbiota functional capacity, potentially contributing to oxidative stress mitigation and host resilience. The findings support microbiota-informed feed formulation strategies to advance sustainable aquaculture. Full article

Objective: This study aimed to investigate the potential mechanisms by which moderate-intensity aerobic exercise improves cardiovascular dysfunction in high-fat diet-induced obese rats through integrated multi-omics analysis. Methods: Animals were assigned to three groups: normal diet, HFD, and HFD with exercise. Cardiovascular function was assessed by echocardiography and vascular tension measurement. Gut microbiota, serum metabolites, and protein expression were analyzed using 16S rRNA sequencing, untargeted metabolomics, and proteomics, respectively. Integrated multi-omics analysis was performed using Mantel tests and mediation effect analysis. Results: Eight weeks of aerobic exercise significantly improved cardiovascular function in obese rats, including enhanced acetylcholine-induced vasodilation and increased left ventricular ejection fraction. Furthermore, exercise also reshaped the gut microbiota composition, notably altering the relative abundances of Lactobacillus and Ruminiclostridium_9. Metabolomics revealed that exercise shifted the metabolic phenotype from high-fat diet-induced basal metabolic disorder toward beneficial pathways, including fatty acid biosynthesis and ubiquinone biosynthesis. Proteomics identified key differentially expressed proteins such as APOE, FN1, and Lap3. Integrated multi-omics analysis for the first time revealed a core regulatory axis: exercise may influence Lap3 expression, modulate the abundance of Lactobacillus, and thereby systematically regulate the level of palmitoyl lysophosphatidylcholine, ultimately improving cardiovascular function. Conclusions: Aerobic exercise counteracts HFD-induced cardiovascular dysfunction through systemic remodeling of the gut microbiota–host metabolism–protein network. The discovery of the Lap3–Lactobacillus–palmitoyl lysophosphatidylcholine axis provides new molecular insights into the exercise-mediated protective mechanisms of the gut–cardiovascular system axis. Full article

Two sulfur-oxidizing bacterial strains, FCG-A2^T and FCG-A23^T, were isolated from coastal sediments collected in Fangchenggang, Guangxi Province, China. Phylogenetic analyses based on 16S rRNA gene and whole-genome sequences placed strain FCG-A2^T within the genus Pseudothioclava and strain FCG-A23^T within the genus Terasakiella. Genomic relatedness (ANI, AAI, dDDH, and POCP) to the closest described taxa was below the accepted species thresholds, demonstrating that both isolates represent novel species. Strain FCG-A2^T grew at 15–35 °C (optimum 25–30 °C), at pH 5.0–10.0 (optimum pH 8.0), and with 1–4% (w/v) NaCl concentrations (optimum 3%). Strain FCG-A23^T grew at 20–33 °C (optimum 25–30 °C), at pH 6.0–9.0 (optimum, pH 8.0), and with 2–6% (w/v) NaCl (optimum 2%). For both strains, ubiquinone-10 was the major respiratory quinone, and the predominant fatty acids were summed feature 3 (C_16:1ω7c and/or C_16:1ω6c) and summed feature 8 (C_18:1ω7c and/or C_18:1ω6c); strain FCG-A2^T additionally contained C_16:0 as a major fatty acid. Both strains oxidized thiosulfate to sulfate, consistent with the presence of genes encoding the Sox system and assimilatory sulfate reduction pathways. Comparative genome annotation further suggested a broader carbohydrate-degradation potential in FCG-A2^T than in FCG-A23^T, implying a wider ecological distribution and greater opportunities for FCG-A2^T to perform sulfur oxidation across habitats. The draft genomes had G + C contents of 62.09% (FCG-A2^T) and 49.06% (FCG-A23^T). Based on these results, we propose Pseudothioclava alba sp. nov. (type strain FCG-A2^T = MCCC 1K08969^T = KCTC 8462^T) and Terasakiella sediminum sp. nov. (type strain FCG-A23^T = MCCC 1K08972^T = KCTC 8464^T). Full article

Waterlily (Nymphaea L.), a globally renowned aquatic ornamental plant, is prized for its aesthetic flowers and intense floral fragrance. However, the molecular mechanisms underlying floral scent biosynthesis in waterlily remain poorly characterized, and integrated analyses of dynamic volatile emission patterns and their associated biosynthetic pathways are lacking. In this study, we combined headspace solid-phase microextraction/gas chromatography–mass spectrometry (HS-SPME/GC-MS) with transcriptome sequencing (RNA-seq) to investigate the composition, emission dynamics, and biosynthesis of volatile organic compounds (VOCs) in the stamens of Nymphaea ‘Paul Stetson’ across three developmental stages. A total of 671 VOCs, classified into 14 categories, were identified. Transcriptome analysis revealed 47,951 differentially expressed genes (DEGs). Integrative omics analysis demonstrated correlated DEGs and differentially accumulated volatiles were significantly enriched in pathways related to phenylpropanoid biosynthesis, terpenoid backbone biosynthesis, diterpenoid biosynthesis, and ubiquinone/other terpenoid-quinone biosynthesis. Five candidate functional genes exhibiting strong positive correlations with VOC accumulation levels were identified, three of which are implicated in terpenoid biosynthesis. These findings provide a theoretical foundation for elucidating aroma composition and biosynthesis in waterlily and offer novel avenues for the genetic improvement of fragrance traits for ornamental, beverage, and cosmetic applications. Full article

The therapeutic efficacy of antibiotics has been significant in extending human life expectancy by combating virulent bacterial infections. Nevertheless, multidrug-resistant (MDR) microorganisms remain a global crisis as these bacteria have developed resistance to conventional antibacterial agents. An unexplored antibiotic target found exclusively in bacteria is the Na⁺-translocating NADH:ubiquinone oxidoreductase (NQR), which is an indispensable membrane-bound bacterial enzyme complex that enables cellular functionality and is present in many infectious bacterial species, including Vibrio cholerae and H. influenzae. NQR serves as an essential complex in the bacterial electron transport chain (ETC) and operates as a highly conserved primary Na⁺ pump that drives many bioenergetic functions. This six-subunit protein shuttles electrons from NADH to ubiquinone, which drives the translocation of Na⁺ ions and creates a gradient that provides the driving force for various cellular processes. We have synthesized and evaluated a series of 1,4-naphthoquinones that exhibit high potency against NQR with minimal cytotoxicity and potential to serve as new, NQR-targeting antibacterial agents for use against V. cholerae. Full article

Recent evidence has highlighted the pivotal roles of reactive oxygen species (ROS) and the SIRT1, AMPK, and mTOR signaling pathways in aging and longevity, making them attractive targets for studies of lifespan-extending interventions. We previously demonstrated that 1,1-diethoxyethane (1,1-DEE) could interact with mitochondrial complex I (NADH–ubiquinone oxidoreductase), leading to transient mitochondrial ROS (mtROS) production and activation of the AMPK pathway. This study further examined the effects of 1,1-DEE on longevity in model organisms. Treatment with 1,1-DEE decreased senescence in endothelial cell EA.hy926. In Caenorhabditis elegans (C. elegans), 1,1-DEE induced a hormetic response and extended the lifespan, whereas its structural isoform, 1,2-diethoxyethane (1,2-DEE), showed no such effect. In rat models, administration of 1,1-DEE markedly improved survival rate, mortality risk, restricted mean survival time (RMST), and median lifespan, associated with an accelerated body weight reduction. Additionally, 1,1-DEE could also enhance learning and memory, as assessed by the Morris water maze test in rats. These findings suggest that 1,1-DEE may serve as a novel small-molecule modulator of mitochondrial function and redox signaling, with potentials for promoting anti-aging and longevity. Full article

Sodium-pumping NADH: ubiquinone oxidoreductase (Na⁺-NQR) is an important component of the aerobic respiratory chain of Vibrio cholerae. It oxidizes NADH, reduces ubiquinone, and uses the free energy of this redox reaction to move sodium across the cell membrane. The enzyme is a membrane complex of six subunits, two 2Fe−2S centers, and four flavins. Both the oxidized and reduced forms of Na⁺-NQR exhibit EPR signals due to flavin semiquinone radicals. It has been shown that in the oxidized form of the enzyme, the radical is a neutral flavin, while in the NADH-reduced form, the radical is an anionic flavin. Electron Spin Echo Envelope Modulation Spectroscopy (ESEEM) was used to probe the presence of the magnetic nucleus ²³Na in the immediate vicinity of the paramagnetic centers. The contribution of the ²³Na nucleus was observed only in the ESEEM spectra of the anionic flavin semiquinone previously assigned to FMN_NqrB. Analysis shows that the Na⁺ ion is within ~3–4 Å of the flavin radical. This distance is consistent with two models: (i) complexation of the Na⁺ ion with the carbonyl group of CO4; or alternatively, (ii) a “cation-π interaction,” between Na⁺ and the electron-rich π-system of the flavin aromatic rings. Full article

Two Gram-negative aerobic halophilic bacteria, designated KMM 9989^T and KMM 9879, were isolated from a bottom sediment sample of the Okhotsk Sea, Russia. The novel strains grew in 0.5–4% NaCl, at 5–35 °C and pH 5.5–10.0. Phylogenetic analyses based on 16S rRNA gene and whole genome sequences placed strains KMM 9989^T and KMM 9879 within the family Roseobacteraceae, where they were clustered with their closest relative Marinovum algicola KCTC 22095^T. The average nucleotide identity (ANI) between strain KMM 9989^T and Marinovum algicola KCTC 22095^T was 81.4%. The level of digital DNA–DNA hybridization (dDDH) between the novel isolates KMM 9989^T and KMM 9879 was 97%, while between strain KMM 9989^T and Marinovum algicola KCTC 22095^T, it was 27%. Strains KMM 9989^T and KMM 9879 contained Q-10 as the predominant ubiquinone and C_18:1ω7c as the major fatty acid. The polar lipids were phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, an unidentified aminolipid, two unidentified phospholipids, and three unidentified lipids. The genomic size of strains KMM 9989^T and KMM 9879 was determined to be 4,040,543 bp and 3,969,839 bp with a DNA GC content of 61.3 and 61.4 mol%, respectively. Both strains contained a common plasmid of 238,277 bp and a strain-specific plasmid (188,734 bp for KMM 9989^T and 118,029 bp for KMM 9879). It is suggested that the motility of KMM 9879 may be mediated by the presence of a complete fla2-type operon in the strain-specific chromid. Thus, based on the phylogenetic analyses and distinctive phenotypic characteristics, the novel marine strains KMM 9989^T and KMM 9879 are proposed to be classified as a novel species Marinovum sedimenti sp. nov. with the strain KMM 9989^T (=KCTC 8835^T) as the type strain of the species. Full article

Marine sponges possess complex metabolic systems that support their growth, physiology, and ecological interactions. However, the primary metabolic capacity of the sponge hosts remains incompletely characterized at the molecular level. In this study, we performed de novo transcriptome sequencing of a pooled sample of three individuals of Xestospongia sp. collected in Vietnam, using a high-throughput Illumina sequencing system, to characterize the host-derived metabolic pathways. A total of 43,278 unigenes were assembled, of which 69.15% were functionally annotated using multiple public databases. Functional annotation revealed a broad repertoire of genes associated with core metabolic pathways, including carbohydrate, lipid, and sterol metabolisms, as well as cofactor-related processes. Specifically, complete pathways involved in folate biosynthesis, terpenoid backbone biosynthesis, ubiquinone (Coenzyme Q) metabolism, and steroid biosynthesis were identified, reflecting the independent metabolic framework of the sponge host. Several highly expressed genes related to these pathways, including COQ7, ERG6, NUDX1, QDPR, and PCBD, were detected, and their expression patterns were confirmed by quantitative RT-PCR. Furthermore, protein-based phylogenetic analyses indicated that these genes are closely related to homologous proteins from other sponge species, supporting their host origin. This study provides the first comprehensive transcriptomic resource for Xestospongia sp. from Vietnam, and offers baseline molecular insights into the primary metabolic capacity of the sponge host. These data establish a foundation for future investigations of sponge physiology and host–microbe metabolic partitioning. Full article

This study investigates the adaptive mechanisms that enable a single wild barley (Hordeum spontaneum) accession to withstand extreme salinity. Salt stress reshapes plant metabolism and gene expression, offering targets for breeding salt-tolerant cereals. A time-course RNA-Seq experiment was conducted on leaves exposed to 500 mM NaCl, followed by differential expression and functional annotations to characterize transcriptomic responses. Transcriptomic profiling identified 140 dynamically upregulated genes distributed across 19 interconnected metabolic pathways, with phased activation of oxidative phosphorylation, nitrogen assimilation, lipid remodeling, and glutathione metabolism. Central metabolic nodes, including acetyl-CoA, hexadecanoyl-CoA, and ubiquinone, coordinated bioenergetic output, membrane stabilization, and redox homeostasis. Ribose-5-phosphate and ribulose-5-phosphate linked glycolysis and the pentose phosphate pathway, supplying NADPH for antioxidant defense and nucleotide repair, while riboflavin derived from Ru5P enhanced flavoprotein activity. In parallel, glucose and fructose-6-phosphate supported osmotic adjustment and glycolytic flux, and increased sterol and cuticular lipid biosynthesis, including cholesterol-like compounds, reinforced membrane integrity and calcium signaling. Glutathione and N-acetyl-glutamate together mitigated oxidative stress and modulated polyamine metabolism, strengthening cellular resilience under salt stress. These findings outline a coordinated network of metabolic and redox pathways that can guide the engineering of salt-tolerant cereals for sustainable production in saline agroecosystems. Full article

A rapid and robust analytical method was validated for the simultaneous extraction and quantification of carotenoids and other lipophilic antioxidants (tocopherols, tocotrienols, retinol and coenzyme Q10) in human and animal tissues using a tandem RRLC-DAD-FLD system. Thirty-eight compounds were identified, with limits of quantification as low as 0.001 µg for astaxanthin, retinol, and coenzyme Q10. Most analytes exhibited high recoveries (85–94%) and good precision (coefficient of variation < 10%), except for Co-Q10, which showed moderate variability. The method was applied to seven human tissue types and their corresponding animal tissues, demonstrating high versatility and analytical reliability. Several isomers of colourless carotenoids were identified in human tissues for the first time, reinforcing their emerging relevance in photoprotection and health. This method provides a valuable analytical tool for investigating the tissue distribution, bioavailability, functionality and nutritional significance of lipophilic antioxidants, thereby supporting future research on antioxidant status and health-related actions. Full article