Search Results (237)

The canonical transsulfuration (TSS) pathway enzymes cystathionine β-synthase (CBS) and cystathionine γ-lyase (CTH) are traditionally recognized for their roles in the sequential conversion of homocysteine to cysteine and in endogenous hydrogen sulfide (H₂S) production. Increasing evidence, however, suggests that these enzymes may also exhibit non-canonical (“moonlighting”) functions that extend beyond metabolic regulation. In this review, we evaluate the hypothesis that CTH may participate in translational regulation, particularly in the control of hypoxia-inducible factor-1α (HIF-1α) expression in clear cell ovarian carcinoma (CCOC). We first highlight limitations of the prevailing H₂S- and cysteine-centric view of the TSS pathway, which may not fully explain emerging context-dependent functions of CTH in cancer biology. Current evidence suggests that CTH enhances HIF-1α protein expression through mechanisms independent of transcription, protein stability, or H₂S production, implicating a potential role in translational regulation, although direct mechanistic evidence remains limited. To critically evaluate this emerging hypothesis, we categorize evidence according to its level of experimental support, ranging from direct experimental evidence to indirect mechanistic observations and computational predictions. Within this framework, we examine three non-mutually exclusive models: (1) regulation through PI3K/AKT/mTOR-dependent translational signaling; (2) modulation of translational control through interaction with translation-associated proteins and RNA-binding proteins (RBPs) involved in HIF1A mRNA regulation; and (3) the more speculative possibility of direct interaction between CTH and HIF1A mRNA. Collectively, these observations support a model in which CTH contributes to selective translational regulation beyond its canonical metabolic functions, potentially linking sulfur metabolism to stress-adaptive gene expression in cancer. Full article

Cysteine biosynthesis is increasingly recognized as a critical determinant of bacterial virulence, highlighting this pathway as a promising reservoir of novel antimicrobial targets. In Pseudomonas aeruginosa, however, the molecular basis of cysteine production has only recently begun to emerge. Here, we identify PA3816 as the major P. aeruginosa serine acetyltransferase (PaCysE), the enzyme responsible for generating the activated serine intermediate that feeds O-acetylserine sulfhydrylase-mediated cysteine synthesis. Through a combination of biochemical and genetic approaches, we demonstrate that PaCysE efficiently catalyzes L-serine acetylation in vitro, and in turn, deletion mutants exhibit cysteine auxotrophy, underscoring its essential contribution to O-acetylserine production. Notably, PaCysE is less sensitive to feedback inhibition by cysteine and does not appear to form the canonical cysteine synthase complex, suggesting a regulatory architecture that diverges from well-characterized orthologs. Loss of PaCysE function has broad physiological consequences, including enhanced biofilm formation, reduced pyocyanin production, and attenuated infectivity in an animal model, linking cysteine biosynthesis directly to pathogen fitness. Finally, we identify a thiazole derivative that inhibits PaCysE activity (IC₅₀ ≈ 30 µM) and suppresses bacterial growth in a cysteine-dependent manner, providing a proof-of-concept for therapeutically targeting this pathway. Full article

This study integrated echocardiography with widely targeted metabolomics to decipher how plasma metabolic dynamics couple with cardiac geometry in Yili horses during incremental treadmill exercise. Nine speed-type horses underwent a graded exercise test (6% incline; 0 to 9 m/s). Jugular venous blood samples collected at rest (0 m/s) and at 3, 5, 7, and 9 m/s were profiled by LC-MS, and Pearson correlation analysis was applied to relate differentially expressed metabolites (DEMs) to twenty echocardiographic structural indices. A core set of 314 shared DEMs (124 upregulated, 190 downregulated) was identified across all exercise comparisons, spanning amino acids, organic acids, and fatty acyls. These metabolites were mapped to ABC transporter, thermogenesis, aldosterone-regulated sodium reabsorption, steroid hormone biosynthesis, and one-carbon folate metabolism pathways. At rest (0 m/s), right ventricular end-diastolic dimension correlated positively with arginyl-isoleucine (p < 0.001), whereas left ventricular free wall thickness (diastolic and systolic) correlated positively with undecanedioic acid (p < 0.001) and proline-hydroxyproline (p < 0.01). At peak exercise (9 m/s), left ventricular mass and left ventricular mass index correlated positively with succinic acid (p < 0.05) and methylmalonic acid (p < 0.05), while left ventricular minor axis correlated with carnitine C14:2 and carnitine C12:1 (p < 0.05). Left ventricular end-systolic dimension and left atrial end-diastolic dimension correlated negatively with cysteine-glutathione disulfide and N2-(1-carboxyethyl)-L-arginine, respectively. These findings illuminate a robust metabolic–cardiac structure axis: amino acid metabolites support collagen matrix turnover and redox homeostasis, organic acids sustain mitochondrial energy flux and antioxidant defense, and fatty acyls fuel continuous contractile activity via enhanced fatty acid oxidation. This metabolome-informed framework furnishes a mechanistic basis for precision training and performance phenotyping in equine athletes. Full article

Methionine and cysteine are the principal sulfur-containing proteinogenic amino acids, playing pivotal roles in protein structure, function, and cellular metabolic regulation. The biosynthetic machinery of these amino acids is intricate and exhibits distinct evolutionary divergence across species. This review comprehensively summarizes the biosynthesis of cysteine and methionine in model organisms ranging from Escherichia coli and yeast to plants and Homo sapiens. Specifically, we examine the metabolic interconversion and the transition of roles between these two amino acids during de novo synthesis. Furthermore, we dissect the physiological significance of the transsulfuration pathway in mammals, which utilizes methionine as a precursor for cysteine biosynthesis. Full article

Chattonella marina is an ichthyotoxic, bloom-forming raphidophyte known for its hemolytic activity. However, the mechanisms by which nitrogen (N) and phosphorus (P) limitation influence this hemolytic toxicity remain poorly understood. In this study, both N and P limitation reduced growth, photosynthetic efficiency (F_v/F_m, Y_II, rETR_max), and the expression of nutrient-uptake, tetrapyrrole/chlorophyll biosynthesis genes. Nevertheless, the two nutrients produced opposite effects on toxicity: N limitation lowered hemolytic activity and ROS levels to near zero, whereas P limitation kept both relatively high, similar to nutrient-replete controls. The addition of the antioxidant NAC (N-Acetyl-L-cysteine) reduced hemolytic activity, confirming that ROS contributes to toxicity. Transcriptome data showed that under N limitation, genes for nitrogen uptake and initial reduction (NRT, NR, glnA) were upregulated, while downstream assimilation genes (nirA, GLT1) were downregulated. In contrast, under P limitation, all the nitrogen-metabolism-related genes (NRT, NR, glnA, nirA, GLT1) were downregulated. In the tetrapyrrole pathway, most genes were downregulated under both nutrient-limited conditions, except for HemD, suggesting a bottleneck that may result in the accumulation of porphyrin intermediates within the tetrapyrrole/chlorophyll biosynthesis pathway. Together, the secondary products derived primarily from the reaction of ROS with tetrapyrrole-based compounds appear to be the main contributors to hemolytic toxicity. Consequently, high levels of both ROS and porphyrin intermediates under P-limited conditions, as well as high ROS levels but low porphyrin intermediates under nutrient-sufficient conditions, may both contribute to the high hemolytic toxicity of C. marina. In contrast, under N limitation, despite the accumulation of porphyrin intermediates, the strong suppression of photosynthetic electron transport limits both ROS production and the synthesis of nitrogen-containing toxins, resulting in low hemolytic activity. These findings demonstrate that nutrient conditions regulate hemolytic activity in C. marina in a nutrient-specific manner. Full article

The ‘Pingguoli’ pear (Pyrus pyrifolia cv. Pingguoli) has a cultivation history spanning nearly one hundred years. Bud mutation selection is an important breeding method for the ‘Pingguoli’ pear. In this study, high-throughput sequencing technology (RNA-Seq) and non-targeted metabolomics (LC-MS/MS) were used to analyze the large-fruited bud mutation line (LFS) and normal type (NTF) of the ‘Pingguoli’ pear during the cell division (G1), rapid growth (G2), and mature stages (G3) of the fruit. The results showed that LFS exhibited a 46.32% increase in average single fruit weight (383.01 ± 54.72 g vs. 261.76 ± 10.79 g, p < 0.01) and a 19.10% decrease in soluble solids content (12.70 ± 0.94% vs. 15.40 ± 2.06%, p < 0.05) compared to NTF. Compared with the NTF, the content of total phenols and total flavonoids and the activity of antioxidant enzymes in the LFS fruits were significantly higher, while the contents of soluble sugar, reducing sugar, and soluble protein were significantly lower. Transcriptome analysis revealed that key metabolic pathways—including pentose and glucuronate interconversions, starch and sucrose metabolism, and cutin, suberine, and wax biosynthesis—were significantly enriched between NTF and LFS. These pathways may contain the specific differentially expressed genes (e.g., those involved in sugar metabolism and wax biosynthesis) identified as potential regulators of fruit size, appearance, and nutritional quality in the LFS. LC-MS/MS analysis identified key differentially accumulated metabolites, including L-arginine, caffeic acid, L-cysteine, pyridoxamine 5′-phosphate, adenosine-5′-phosphosulfate, neopentolactone D, chlorogenic acid, and gluconic acid, which are directly associated with the nutritional and antioxidant differences between LFS and NTF. The genes most related to metabolites in the three different developmental periods of the LFS and NTF were identified through combined analysis. These results provide insights for further research on bud mutation breeding and the quality formation mechanism of ‘Pingguoli’ pears. Full article

Coronavirus infections pose a significant threat to both human and animal health, causing widespread morbidity, mortality, and substantial economic losses. While vaccines are crucial for prevention, their efficacy is often limited by the high mutation rate of these viruses. This underscores the urgent need for anti-coronavirus drugs, particularly broad-spectrum antiviral agents. In this study, we demonstrated for the first time that Biochanin A (BCA), a bioactive isoflavonoid found in legumes, exhibits broad-spectrum antiviral activity against coronaviruses. BCA potently inhibits porcine epidemic diarrhea virus (PEDV), as well as human coronaviruses HCoV-OC43 and HCoV-229E in vitro, with EC₅₀ values of 6.90, 2.80 and 15.4 μM, respectively. In a lethal mouse model of HCoV-OC43-induced encephalitis, oral administration of BCA (40–60 mg/kg) significantly improved animal survival and reduced cerebral viral loads. Mechanistic studies revealed that BCA upregulates the AMPK/Nrf2 signaling pathway, thereby increasing expression of the glutamate-cysteine ligase catalytic subunit (GCLC) and enhancing glutathione (GSH) biosynthesis. Our findings identify BCA as a promising host-directed antiviral agent and highlight its therapeutic potential against coronavirus infections. Full article

Background: Cryopreservation induces oxidative stress, membrane disruption, and mitochondrial injury in spermatozoa, leading to impaired motility and fertility. Selenium, as an essential trace element, protects cells from oxidative damage through selenoproteins such as glutathione peroxidase 4 (GPX4), a critical enzyme that detoxifies lipid hydroperoxides and inhibits ferroptosis. This study investigated whether supplementation with L-selenomethionine (L-SeMet), an organic selenium source with superior bioavailability and lower toxicity than inorganic forms, could alleviate cryo-induced sperm injury by suppressing ferroptosis. Methods & Results: Dairy goat sperm were cryopreserved with 0, 2, 4, 6, 8, 10 μM L-SeMet. Supplementation with 6 μM L-SeMet significantly improved motility, membrane and acrosome integrity, and mitochondrial membrane potential. Biochemical assays showed reduced iron, ROS, and MDA levels, alongside increased ATP, SOD, and GSH contents. Proteomic analysis identified 148 differentially expressed proteins, including up-regulation of GPX4, FTH1, VDAC2, and VDAC3—core ferroptosis regulators. Metabolomic profiling further revealed enrichment in unsaturated fatty acid biosynthesis, amino acid metabolism, and the TCA cycle, pathways closely linked to ferroptosis regulation. Transmission electron microscopy confirmed that L-SeMet preserved mitochondrial ultrastructure. Mechanistically, L-SeMet mirrored the ferroptosis inhibitor N-acetyl-L-cysteine and reversed RSL3-induced oxidative damage. Western blotting verified activation of the NRF2–SLC7A11–GPX4 antioxidant axis and inhibition of KEAP1 expression. Conclusions: Collectively, these findings demonstrate that L-SeMet protects spermatozoa from cryo-induced injury by stabilizing redox homeostasis, maintaining mitochondrial function, and inhibiting ferroptosis. The results highlight ferroptosis as a critical mechanism of sperm cryodamage and identify L-SeMet as a promising metabolic intervention to enhance post-thaw sperm quality and fertility. Full article

Mitochondrial dysfunction profoundly alters cellular metabolism, yet its systems-level consequences remain incompletely characterized. Here, we present a comprehensive untargeted metabolomics analysis of respiratory-deficient (ρ⁰) and competent (ρ⁺) Saccharomyces cerevisiae prototrophic cells using ultra-high-performance liquid chromatography coupled to Orbitrap Fusion™ Tribrid™ high-resolution mass spectrometry. By integrating hydrophilic interaction and reversed-phase chromatography in both ionization modes, we detected ~7000 features per chromatographic condition, of which ~12% were structurally annotated through MSⁿ fragmentation and in silico spectral matching. Principal component analysis revealed distinct metabolic signatures between ρ⁰ and ρ⁺ cells, with ~73% of total variance explained by the first two components. Volcano plot and hierarchical clustering analyses identified a marked accumulation of phosphate-containing metabolites, sphingolipids, ceramides, and fatty acid residues in ρ⁰ cells, whereas amino acids, excluding arginine, cysteine, and aromatics, were enriched in ρ⁺ cells. Notably, branched-chain amino acid depletion in ρ⁰ cells correlated with impaired growth and mitochondrial stress. Pathway enrichment analysis, supported by transcriptomic integration, prompted us to further investigate reprogramming of polyamine biosynthesis and aromatic amino acid metabolism. Calibration curves constructed from certified standards validated the accuracy of the LC–MS platform and reinforced annotation confidence. Our findings demonstrate that advanced untargeted metabolomics, coupled with MS³ fragmentation and multi-omics integration, enables high-resolution mapping of metabolic reconfiguration under mitochondrial dysfunction, offering mechanistic insights into mitochondrial retrograde signaling and adaptation. Full article

Background: There is an abundance of the neuroactive β-N-oxalyl-L-α,β-diaminopropionic acid (β-ODAP) in grass pea (Lathyrus sativus), pea (Pisum sativum), and several Chinese traditional herbs such as Panax notoginseng. It is well known for its dose- and context-dependent effects on its toxicological characteristics (inducing neurodegenerative neurolathyrism upon excessive consumption) or for its pharmacological effects (including neuroprotection and wound healing). Therefore, reducing β-ODAP levels improves the safety profile of β-ODAP-containing species for utilization, whereas increasing them facilitates their isolation and purification. LsBAHD3 acyltransferase, named after the first letter of BEAT benzylalcohol O-acetyltransferase (BEAT), anthocyanin O-hydroxycinnamoyltransferase (AHCT), anthranilate N-hydroxycinnamoyl/benzoyltransferase (HCBT), and deacetylvindoline 4-Oacetyltransferase (DAT), was proven to be β-ODAP synthetase. Methods: In this report, the interaction of miR172f with LsBAHD3 was investigated through bioinformatic analysis and transient co-expression assays in Nicotiana benthamiana. Functions of miR172f in β-ODAP biosynthesis were also investigated through knockdown in the hairy roots of L. sativus and via transcriptomic analysis. Results: The results suggest that the knockdown of miR172f in hairy roots of L. sativus increased β-ODAP content via targets to LsBAHD3. In this process, protein ubiquitination, cysteine and methionine metabolism, enzyme regulator activity, and so on were associated with β-ODAP biosynthesis. Conclusions: These results identify miR172f as a novel regulator of β-ODAP biosynthesis through targeting of LsBAHD3, offering new insight into the gene expression of β-ODAP synthetase and the genetic network governing β-ODAP biosynthesis in L. sativus. Full article

In tomato production, grafting enhances stress resistance, increases yield, and improves fruit quality. However, the selection of rootstock types limits its broader adoption. This study systematically evaluated the effects of grafting with 16 different rootstocks on tomato survival rate and yield. Fruits from four rootstocks, Gangshi 319 self-grafted (CK), Gangshi 319 seedlings (A), Torubam (T), and Fanzhen No. 1 (F), were further selected for fruit quality analysis and broad target metabolomics. The results showed that, except for Qiezhen No. 3 (QZ3), the graft survival rates of all rootstocks exceeded 95%. Grafting with rootstock F significantly increased yield per plant and soluble solids content, whereas rootstock T significantly reduced both traits. Broad target metabolomics analysis identified 18 major metabolite categories, including lipids, ketoaldehydes and esters, and terpenoids. KEGG pathway enrichment analysis revealed that differentially accumulated metabolites between the F and T treatments were primarily enriched in pathways such as the citric acid cycle, phenylpropanoid biosynthesis, glyoxylate and dicarboxylate metabolism, flavonoid biosynthesis, cysteine and methionine metabolism, and glycerophospholipid metabolism. These findings indicate that rootstock F effectively enhances tomato fruit yield and soluble solids accumulation by coordinating primary and secondary metabolism. This study provides important metabolic level insights for the selection and application of high quality and high yield tomato rootstocks in grafting. Full article

Several strains of Lysobacter have demonstrated keratin-degrading capabilities, positioning them as promising candidates for the degradation and utilization of wool waste. In our previous study, a novel strain, Lysobacter brunescens YQ20, exhibiting highly efficient keratin degradation capabilities, was isolated. In this study, transcriptomic and proteomic analyses were conducted to elucidate the underlying mechanisms of keratin degradation. Our findings revealed that several metabolic pathways, specifically, valine, leucine, and isoleucine biosynthesis; phenylalanine, tyrosine, and tryptophan biosynthesis; glycine, serine, and threonine metabolism; and histidine metabolism, were highly active during keratin degradation, thereby supporting the growth and metabolism of L. brunescens YQ20. Additionally, the upregulation of genes related to sulfur metabolism, cysteine and methionine metabolism, and glutathione metabolism pathways facilitated the cleavage of disulfide bonds in keratin. Moreover, keratinases identified among the differentially expressed genes and proteins (DEGs/DEPs) were classified into the S8, M14, and M28 families, whose synergistic activity contributed to the efficient hydrolysis of keratin. Collectively, these results provide valuable insights into the molecular mechanisms by which L. brunescens YQ20 contributes to keratin degradation. Full article

Background: Lyases are used in a wide scope of applications, making them invaluable tools in both industrial biotechnology and molecular biology. Many examples of lyases belong to the extensive family of pyridoxal 5′-phosphate (PLP)-dependent enzymes, which catalyze numerous reactions involved in amino acid metabolism, like tryptophan indole-lyase (Trpase or Tnase), tyrosine phenol-lyase (TPL), and methionine γ-lyase (MGL). Beyond their role in physiological processes, these lyases can also facilitate the synthesis of other biologically active products from non-canonical substrates. Objectives: Up till now there were only two C–S lyases known for the thiosulfinates’ biosynthesis from S-substituted L-cysteine sulfoxides—alliinase and MGL. Our study reveals for the first time that C–C lyases are capable of C–S lyase activity in reactions with S-alkyl, S-allyl and S-benzyl cysteine sulfoxides. Methods: We have compared the kinetic profiles of S-substituted L-cysteine sulfoxide degradation mediated by carbon–sulfur lyase MGL versus carbon–carbon lyases TPL and Trpase. Results: Among other S-alkyl-L-cysteine sulfoxides, petiveriin (S-benzyl-L-cysteine sulfoxide) was proven to be a substrate for all three enzymes. The potential utility of these enzymes in thiosulfinate production was supported by in vitro testing of enzyme-generated thiosulfinates against clinically relevant pathogens such as Candida albicans, Pseudomonas aeruginosa, and Staphylococcus aureus. Conclusions: Both C–S and C–C lyases—MGL, TPL, and Trpase—can be implemented for practical application in thiosulfinate synthesis. Full article

Acetaminophen (APAP) overdose is a major global cause of drug-induced liver injury (DILI), and the rising incidence of APAP-induced hepatotoxicity has raised substantial concern in the medical community, highlighting an urgent need for effective therapeutic approaches. Coptidis Rhizoma alkaloids (CRAs) have shown hepatoprotective effects in multiple hepatic disease models. This study aimed to investigate the therapeutic efficacy and the underlying mechanisms of CRA in acetaminophen (APAP)-induced acute liver injury. After identifying 18 alkaloid components in CRA, we employed an integrated strategy of untargeted metabolomics and network pharmacological analysis to investigate the underlying mechanisms. The potential mechanisms were subsequently validated through histopathological examination and molecular biology assays. Our results showed that CRA exerted dose-dependent protection against APAP-induced liver injury in vitro and in vivo. This protective effect was mediated by enhanced hepatic glutathione (GSH) biosynthesis via increased intracellular cysteine (Cys) availability. In the mouse model, hepatic Cys and GSH levels were increased by 2.2-fold and 1.8-fold, respectively, relative to the model group, which consequently attenuated oxidative stress damage. Furthermore, CRA suppressed APAP-induced activation of ERK and NF-κB, reducing the phosphorylation levels by 39.2% and 38.0%, respectively. Accordingly, it also downregulated the subsequent expression of inflammatory mediators in the TNF signaling pathway. These findings provide crucial mechanistic insights into the hepatoprotective role of CRA against APAP-induced toxicity, establishing a valuable foundation for developing novel therapeutic or preventive strategies for APAP-induced liver injury. Full article

This study systematically characterized the L-cysteine biosynthetic pathway in Bacillus licheniformis and demonstrated that exogenous serine supplementation significantly upregulated the expression of pathway-associated genes, confirming serine as the primary precursor driving L-cysteine synthesis. Through targeted gene deletions, we generated knockout strains BL2ΔglyA, BL2ΔsdaAA, BL2ΔmetC, BL2Δ2, and BL2Δ3 to minimize precursor diversion and product degradation. Combinatorial overexpression of the feedback-resistant mutant cysE^f and the transporter eamA yielded an engineered strain achieving 1.075 g/L L-cysteine in shake-flask fermentation with an 18.69% molar conversion yield. These findings highlight the potential of B. licheniformis as a platform for sulfur metabolic engineering and provide a sustainable fermentation strategy to replace traditional high-pollution hydrolysis-based L-cysteine production. Additionally, this work reveals fundamental differences in sulfur metabolism networks between Gram-positive and Gram-negative bacteria, elucidating microbial metabolic diversity and the cross-regulatory mechanisms linking sulfur, carbon, and nitrogen metabolism. Full article