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Advanced Science (Weinheim,... Jun 2024Acid-induced arginine decarboxylase AdiA is a typical homo-oligomeric protein biosynthesizing alkaline nylon monomer putrescine. However, upon loss of the AdiA decamer...
Acid-induced arginine decarboxylase AdiA is a typical homo-oligomeric protein biosynthesizing alkaline nylon monomer putrescine. However, upon loss of the AdiA decamer oligomeric state at neutral and alkaline conditions the activity also diminishes, obstructing the whole-cell biosynthesis of alkaline putrescine. Here, a structure cohesion strategy is proposed to change the pH adaptation of AdiA to alkaline environments based on the rational engineering of meridional and latitudinal oligomerization interfaces. After integrating substitutions of E467K at the latitudinal interface and H736E at the meridional channel interface, the structural stability of AdiA decamer and its substrate transport efficiency at neutral and alkaline conditions are improved. Finally, E467K_H736E is well adapted to neutral and alkaline environments (pH 7.0-9.0), and its enzymatic activity is 35-fold higher than that of wild AdiA at pH 8.0. Using E467K_H736E in the putrescine synthesis pathway, the titer of putrescine is up to 128.9 g·L with a conversion of 0.94 mol·mol in whole-cell catalysis. Additionally, the neutral pH adaptation of lysine decarboxylase, with a decamer structure similar to AdiA, is also improved using this cohesion strategy, providing an option for pH-adaptation engineering of other oligomeric decarboxylases.
Topics: Carboxy-Lyases; Hydrogen-Ion Concentration; Escherichia coli; Putrescine
PubMed: 38569221
DOI: 10.1002/advs.202307779 -
MSystems May 2024Dietary fiber deprivation is linked to probiotic extinction, mucus barrier dysbiosis, and the overgrowth of mucin-degrading bacteria. However, whether and how mucin...
UNLABELLED
Dietary fiber deprivation is linked to probiotic extinction, mucus barrier dysbiosis, and the overgrowth of mucin-degrading bacteria. However, whether and how mucin could rescue fiber deprivation-induced intestinal barrier defects remains largely unexplored. Here, we sought to investigate the potential role and mechanism by which exogenous mucin maintains the gut barrier function. The results showed that dietary mucin alleviated fiber deprivation-induced disruption of colonic barrier integrity and reduced spermine production . Importantly, we highlighted that microbial-derived spermine production, but not host-produced spermine, increased significantly after mucin supplementation, with a positive association with upgraded colonic abundance. After employing an model, the microbial-derived spermine was consistently dominated by both mucin and spp. Furthermore, was identified as an essential spermine-producing spp., and this isolated strain was responsible for spermine accumulation, especially after adhering to mucin . Specifically, the mucin-supplemented bacterial supernatant of was verified to promote intestinal barrier functions through the increased spermine production with a dependence on enhanced arginine metabolism. Overall, these findings collectively provide evidence that mucin-modulated microbial arginine metabolism bridged the interplay between microbes and gut barrier function, illustrating possible implications for host gut health.
IMPORTANCE
Microbial metabolites like short-chain fatty acids produced by dietary fiber fermentation have been demonstrated to have beneficial effects on intestinal health. However, it is essential to acknowledge that certain amino acids entering the colon can be metabolized by microorganisms to produce polyamines. The polyamines can promote the renewal of intestinal epithelial cell and maintain host-microbe homeostasis. Our study highlighted the specific enrichment by mucin on promoting the arginine metabolism in to produce spermine, suggesting that microbial-derived polyamines support a significant enhancement on the goblet cell proliferation and barrier function.
Topics: Spermine; Mucins; Arginine; Intestinal Mucosa; Animals; Gastrointestinal Microbiome; Colon; Male; Mice; Lactobacillus; Humans; Dietary Fiber; Mice, Inbred C57BL
PubMed: 38564708
DOI: 10.1128/msystems.00246-24 -
MicrobiologyOpen Apr 2024Arginine-ornithine metabolism plays a crucial role in bacterial homeostasis, as evidenced by numerous studies. However, the utilization of arginine and the downstream...
Arginine-ornithine metabolism plays a crucial role in bacterial homeostasis, as evidenced by numerous studies. However, the utilization of arginine and the downstream products of its metabolism remain undefined in various gut bacteria. To bridge this knowledge gap, we employed genomic screening to pinpoint relevant metabolic targets. We also devised a targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) metabolomics method to measure the levels of arginine, its upstream precursors, and downstream products in cell-free conditioned media from enteric pathobionts, including Escherichia coli, Klebsiella aerogenes, K. pneumoniae, Pseudomonas fluorescens, Acinetobacter baumannii, Streptococcus agalactiae, Staphylococcus epidermidis, S. aureus, and Enterococcus faecalis. Our findings revealed that all selected bacterial strains consumed glutamine, glutamate, and arginine, and produced citrulline, ornithine, and GABA in our chemically defined medium. Additionally, E. coli, K. pneumoniae, K. aerogenes, and P. fluorescens were found to convert arginine to agmatine and produce putrescine. Interestingly, arginine supplementation promoted biofilm formation in K. pneumoniae, while ornithine supplementation enhanced biofilm formation in S. epidermidis. These findings offer a comprehensive insight into arginine-ornithine metabolism in enteric pathobionts.
Topics: Ornithine; Putrescine; Arginine; Escherichia coli; Chromatography, Liquid; Staphylococcus aureus; Tandem Mass Spectrometry; Bacteria; Klebsiella pneumoniae
PubMed: 38560776
DOI: 10.1002/mbo3.1408 -
Clinical and Translational Medicine Apr 2024
Topics: Humans; Astrocytes; gamma-Aminobutyric Acid; Brain Diseases
PubMed: 38558537
DOI: 10.1002/ctm2.1642 -
Scientific Reports Mar 2024An extreme thermophilic bacterium, Thermus thermophilus produces more than 20 unusual polyamines, but their biosynthetic pathways, including homospermidine, are not yet...
An extreme thermophilic bacterium, Thermus thermophilus produces more than 20 unusual polyamines, but their biosynthetic pathways, including homospermidine, are not yet fully understood. Two types of homospermidine synthases have been identified in plants and bacteria, which use spermidine and putrescine or two molecules of putrescine as substrates. However, homospermidine synthases with such substrate specificity have not been identified in T. thermophilus. Here we identified a novel agmatine homocoupling enzyme that is involved in homospermidine biosynthesis in T. thermophilus. The reaction mechanism is different from that of a previously described homospermidine synthase, and involves conjugation of two molecules of agmatine, which produces a diamidino derivative of homospermidine (caldomycin) as an immediate precursor of homospermidine. We conclude that there is a homospermidine biosynthetic pathway from agmatine via caldomycin synthase followed by ureohydrolase in T. thermophilus. Furthermore, it is shown that caldomycin is a novel compound existing in nature.
Topics: Putrescine; Agmatine; Polyamines; Spermidine; Plants
PubMed: 38555406
DOI: 10.1038/s41598-024-58296-0 -
Foods (Basel, Switzerland) Mar 2024Dill ( L.) essential oil (DEO) obtained by hydrodistillation (HD) and lipid extracts (DSE and DSE) obtained by supercritical CO extraction (SFE) were used as potential...
Dill ( L.) essential oil (DEO) obtained by hydrodistillation (HD) and lipid extracts (DSE and DSE) obtained by supercritical CO extraction (SFE) were used as potential antioxidants and antimicrobial agents in beef burgers at two different concentrations (0.075 and 0.15 µL/g). The chemical profile of the lipid extracts and their in vitro antimicrobial activity against the common pathogens and (MIC and MBC) were determined. The quality and shelf life of the burgers were monitored through (lipid oxidation-TBARS test; protein oxidation-thiol group content and selected biogenic amine content) and microbiological quality (-EB, aerobic mesophilic bacteria-TAMB, lactic acid bacteria-LAB). Dill lipid extracts (DEO and DSE) significantly ( < 0.05) reduced lipid oxidation and protein oxidation in beef burgers, while the lipid extract (DSE) showed pro-oxidative effects. The strongest antimicrobial potential against EB was found in SFE150 (1.15 log cfu/g). Putrescine, cadaverine, histamine, and tyramine were not detected in any of the analyzed samples during the storage period, while the total content of biogenic amines ranged from 21.4 mg/kg to 285 mg/kg. Generally, it can be concluded that dill essential oil (DEO) and extract DSE can be used as novel natural additives in minced-meat products.
PubMed: 38540886
DOI: 10.3390/foods13060896 -
Foods (Basel, Switzerland) Mar 2024The influence of different levels of sodium chloride, sodium nitrite, and glucose on the quality characteristics of spontaneously fermented goat meat sausage was...
The influence of different levels of sodium chloride, sodium nitrite, and glucose on the quality characteristics of spontaneously fermented goat meat sausage was investigated. The amounts of total biogenic amines in all the sausages ranged from 324.70 to 388.77 mg/kg; among them, spermine was the most abundant, with amounts ranging from 230.96 to 275.78 mg/kg. Increasing sodium chloride from 15 to 35 g/kg, the content of cadaverine, putrescine, tyramine, phenylethylamine, tryptamine, and total amines decreased, and Enterobacteriaceae counts decreased at the same time. Increasing sodium nitrite from 150 to 250 mg/kg, the content of cadaverine, histamine, and total amines decreased, while Enterobacteriaceae counts decreased simultaneously. Increasing glucose from 10 to 40 g/kg, the content of cadaverine, spermidine, and total amines decreased. was the most abundant genus across all the samples, and the relative abundance of was reduced obviously by increasing sodium nitrite and glucose levels. The top 10 differential bacterial taxa for each additive group were respectively obtained, and microbial biomarkers for each level of additive within its group were acquired, respectively. Through Pearson correlation, was positively correlated with phenylethylamine, tryptamine, tyramine, and cadaverine, and were positively correlated with phenylethylamine and putrescine, respectively, suggesting they have the potential to produce biogenic amines. The results provided references for controlling the accumulation of biogenic amines in fermented goat meat sausage via the addition of auxiliary additives during the processing.
PubMed: 38540808
DOI: 10.3390/foods13060817 -
Comprehensive shotgun proteomic characterization and virulence factors of seafood spoilage bacteria.Food Chemistry Aug 2024This article summarizes the characterization, by shotgun proteomics, of 11 bacterial strains identified as responsible for seafood spoilage. A total of 4455 peptide...
This article summarizes the characterization, by shotgun proteomics, of 11 bacterial strains identified as responsible for seafood spoilage. A total of 4455 peptide spectrum matches, corresponding to 4299 peptides and 3817 proteins were identified. Analyses of data determined the functional pathways they are involved in. The proteins identified were integrated into a protein-protein network that involves 371 nodes and 3016 edges. Those proteins are implicated in energy pathways, peptidoglycan biosynthesis, spermidine/putrescine metabolism. An additional 773 peptides were characterized as virulence factors, that participates in bacterial pathogenesis; while 14 peptides were defined as biomarkers, as they can be used to differentiate the bacterial species present. This report represents the most extensive proteomic repository available in the field of seafood spoilage bacteria; the data substantially advances the understanding of seafood decay, as well as provides fundamental bases for the recognition of the bacteria existent in seafood that cause spoilage during food processing/storage.
Topics: Seafood; Proteomics; Virulence Factors; Bacterial Proteins; Bacteria; Animals; Food Microbiology
PubMed: 38537549
DOI: 10.1016/j.foodchem.2024.139045 -
Journal of Translational Medicine Mar 2024Due to their complexity and to the presence of common clinical features, differentiation between asthma and chronic obstructive pulmonary disease (COPD) can be a...
BACKGROUND
Due to their complexity and to the presence of common clinical features, differentiation between asthma and chronic obstructive pulmonary disease (COPD) can be a challenging task, complicated in such cases also by asthma-COPD overlap syndrome. The distinct immune/inflammatory and structural substrates of COPD and asthma are responsible for significant differences in the responses to standard pharmacologic treatments. Therefore, an accurate diagnosis is of central relevance to assure the appropriate therapeutic intervention in order to achieve safe and effective patient care. Induced sputum (IS) accurately mirrors inflammation in the airways, providing a more direct picture of lung cell metabolism in comparison to those specimen that reflect analytes in the systemic circulation.
METHODS
An integrated untargeted metabolomics and lipidomics analysis was performed in IS of asthmatic (n = 15) and COPD (n = 22) patients based on Ultra-High-Pressure Liquid Chromatography-Mass Spectrometry (UHPLC-MS) and UHPLC-tandem MS (UHPLC-MS/MS). Partial Least Squares-Discriminant Analysis (PLS-DA) was applied to resulting dataset. The analysis of main enriched metabolic pathways and the association of the preliminary metabolites/lipids pattern identified to clinical parameters of asthma/COPD differentiation were explored. Multivariate ROC analysis was performed in order to determine the discriminatory power and the reliability of the putative biomarkers for diagnosis between COPD and asthma.
RESULTS
PLS-DA indicated a clear separation between COPD and asthmatic patients. Among the 15 selected candidate biomarkers based on Variable Importance in Projection scores, putrescine showed the highest score. A differential IS bio-signature of 22 metabolites and lipids was found, which showed statistically significant variations between asthma and COPD. Of these 22 compounds, 18 were decreased and 4 increased in COPD compared to asthmatic patients. The IS levels of Phosphatidylethanolamine (PE) (34:1), Phosphatidylglycerol (PG) (18:1;18:2) and spermine were significantly higher in asthmatic subjects compared to COPD.
CONCLUSIONS
This is the first pilot study to analyse the IS metabolomics/lipidomics signatures relevant in discriminating asthma vs COPD. The role of polyamines, of 6-Hydroxykynurenic acid and of D-rhamnose as well as of other important players related to the alteration of glycerophospholipid, aminoacid/biotin and energy metabolism provided the construction of a diagnostic model that, if validated on a larger prospective cohort, might be used to rapidly and accurately discriminate asthma from COPD.
Topics: Humans; Lipidomics; Tandem Mass Spectrometry; Sputum; Diagnosis, Differential; Reproducibility of Results; Pilot Projects; Prospective Studies; Pulmonary Disease, Chronic Obstructive; Asthma; Biomarkers; Metabolomics; Lipids
PubMed: 38521955
DOI: 10.1186/s12967-024-05100-2 -
Science Advances Mar 2024Much is known about molecular mechanisms by which animals detect pathogenic microbes, but how animals sense beneficial microbes remains poorly understood. The roundworm...
Much is known about molecular mechanisms by which animals detect pathogenic microbes, but how animals sense beneficial microbes remains poorly understood. The roundworm is a microbivore that must distinguish nutritive microbes from pathogens. We characterized a neural circuit used by to rapidly discriminate between nutritive bacteria and pathogens. Distinct sensory neuron populations responded to chemical cues from nutritive and pathogenic , and these neural signals are decoded by downstream AIB interneurons. The polyamine metabolites cadaverine, putrescine, and spermidine produced by activate this neural circuit and elicit positive chemotaxis. Our study shows how polyamine odorants can be sensed by animals as proxies for microbe identity and suggests that, hence, polyamines might have widespread roles brokering host-microbe interactions.
Topics: Animals; Polyamines; Caenorhabditis elegans; Escherichia coli; Spermidine; Putrescine
PubMed: 38517971
DOI: 10.1126/sciadv.adj4387