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International Journal of Biological... Apr 2024Cancer remains a global health challenge, demanding novel therapeutic options due to the debilitating side effects of conventional treatments on healthy tissues. The... (Review)
Review
Cancer remains a global health challenge, demanding novel therapeutic options due to the debilitating side effects of conventional treatments on healthy tissues. The review highlights the potential of L-methioninase, a pyridoxal-5-phosphate (PLP)-dependent enzyme, as a promising avenue in alternative cancer therapy. L-methioninase offers a unique advantage, its ability to selectively target and inhibit the growth of cancer cells without harming healthy cells. This selectivity arises because tumor cells lack an essential enzyme called methionine synthase, which healthy cells use to make the vital amino acid L-methionine. Several sources harbor L-methioninase, including bacteria, fungi, plants, and protozoa. Future research efforts can explore and exploit this diverse range of sources to improve the therapeutic potential of L-methioninase in the fight against cancer. Despite challenges, research actively explores microbial L-methioninase for its anticancer potential. This review examines the enzyme's side effects, advancements in combination therapies, recombinant technologies, polymer conjugation and novel delivery methods like nanoparticles, while highlighting the success of oral administration in preclinical trials. Beyond its promising role in cancer therapy, L-methioninase holds potential applications in food science, antioxidants, and various health concerns like diabetes, cardiovascular issues, and neurodegenerative diseases. This review provides a piece of current knowledge and future prospects of L-methioninase, exploring its diverse therapeutic potential.
Topics: Humans; Carbon-Sulfur Lyases; Neoplasms; Combined Modality Therapy; Fungi; Methionine; Recombinant Proteins
PubMed: 38508568
DOI: 10.1016/j.ijbiomac.2024.130997 -
Biochemistry Apr 2024Several anaerobic bacterial species, including the Gram-negative oral bacterium , ferment lysine to produce butyrate, acetate, and ammonia. The second step of the...
Several anaerobic bacterial species, including the Gram-negative oral bacterium , ferment lysine to produce butyrate, acetate, and ammonia. The second step of the metabolic pathway─isomerization of β-l-lysine to -3,5-diaminohexanoate─is catalyzed by the adenosylcobalamin (AdoCbl) and pyridoxal 5'-phosphate (PLP)-dependent enzyme, lysine 5,6-aminomutase (5,6-LAM). Similar to other AdoCbl-dependent enzymes, 5,6-LAM undergoes mechanism-based inactivation due to loss of the AdoCbl 5'-deoxyadenosyl moiety and oxidation of the cob(II)alamin intermediate to hydroxocob(III)alamin. Herein, we identified B and C, two genes responsible for ATP-dependent reactivation of 5,6-LAM. KamB and KamC, which are encoded upstream of the genes corresponding to α and β subunits of 5,6-LAM (D and E), co-purified following coexpression of the genes in . KamBC exhibited a basal level of ATP-hydrolyzing activity that was increased 35% in a reaction mixture that facilitated 5,6-LAM turnover with β-l-lysine or d,l-lysine. Ultraviolet-visible (UV-vis) spectroscopic studies performed under anaerobic conditions revealed that KamBC in the presence of ATP/Mg increased the steady-state concentration of the cob(II)alamin intermediate in the presence of excess β-l-lysine. Using a coupled UV-visible spectroscopic assay, we show that KamBC is able to reactivate 5,6-LAM through exchange of the damaged hydroxocob(III)alamin for AdoCbl. KamBC is also specific for 5,6-LAM as it had no effect on the rate of substrate-induced inactivation of the homologue, ornithine 4,5-aminomutase. Based on sequence homology, KamBC is structurally distinct from previously characterized B12 chaperones and reactivases, and correspondingly adds to the list of proteins that have evolved to maintain the cellular activity of B12 enzymes.
Topics: Lysine; Intramolecular Transferases; Cobamides; Adenosine Triphosphate
PubMed: 38471967
DOI: 10.1021/acs.biochem.3c00653 -
Medical Microbiology and Immunology Mar 2024Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrhea in children and travelers, especially in low- and middle-income countries. ETEC is a...
Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrhea in children and travelers, especially in low- and middle-income countries. ETEC is a non-invasive gut pathogen colonizing the small intestinal wall before secreting diarrhea-inducing enterotoxins. We sought to investigate the impact of ETEC infection on local and systemic host defenses by examining plasma markers of inflammation and mucosal injury as well as kynurenine pathway metabolites. Plasma samples from 21 volunteers experimentally infected with ETEC were collected before and 1, 2, 3, and 7 days after ingesting the ETEC dose, and grouped based on the level of intestinal ETEC proliferation: 14 volunteers experienced substantial proliferation (SP) and 7 had low proliferation (LP). Plasma markers of inflammation, kynurenine pathway metabolites, and related cofactors (vitamins B2 and B6) were quantified using targeted mass spectrometry, whereas ELISA was used to quantify the mucosal injury markers, regenerating islet-derived protein 3A (Reg3a), and intestinal fatty acid-binding protein 2 (iFABP). We observed increased concentrations of plasma C-reactive protein (CRP), serum amyloid A (SAA), neopterin, kynurenine/tryptophan ratio (KTR), and Reg3a in the SP group following dose ingestion. Vitamin B6 forms, pyridoxal 5'-phosphate and pyridoxal, decreased over time in the SP group. CRP, SAA, and pyridoxic acid ratio correlated with ETEC proliferation levels. The changes following experimental ETEC infection indicate that ETEC, despite causing a non-invasive infection, induces systemic inflammation and mucosal injury when proliferating substantially, even in cases without diarrhea. It is conceivable that ETEC infections, especially when repeated, contribute to negative health impacts on children in ETEC endemic areas.
Topics: Child; Humans; Enterotoxigenic Escherichia coli; Kynurenine; Escherichia coli Infections; Diarrhea; Inflammation; Pyridoxal
PubMed: 38430452
DOI: 10.1007/s00430-024-00786-z -
Brain, Behavior, and Immunity May 2024We have previously shown that systemic inflammation was associated with post-stroke cognitive impairment (PSCI). Because neopterin, kynurenine pathway (KP) metabolites,...
BACKGROUND AND AIMS
We have previously shown that systemic inflammation was associated with post-stroke cognitive impairment (PSCI). Because neopterin, kynurenine pathway (KP) metabolites, and B6 vitamers are linked to inflammation, in our study we investigated whether those biomarkers were associated with PSCI.
MATERIAL AND METHODS
The Norwegian Cognitive Impairment After Stroke study is a prospective multicenter cohort study of patients with acute stroke recruited from May 2015 through March 2017. Plasma samples of 422 participants (59 % male) with ischemic stroke from the index hospital stay and 3 months post-stroke were available for analyses of neopterin, KP metabolites, and B6 vitamers using liquid chromatography-tandem mass spectrometry. Mixed linear regression analyses adjusted for age, sex, and creatinine, were used to assess whether there were associations between those biomarkers and cognitive outcomes, measured by the Montreal Cognitive Assessment scale (MoCA) at 3-, 18-, and 36-month follow-up.
RESULTS
Participants had a mean (SD) age of 72 (12) years, with a mean (SD) National Institutes of HealthStroke Scale score of 2.7 (3.6) at Day 1. Higher baseline values of quinolinic acid, PAr (i.e., an inflammatory marker based on vitamin B6 metabolites), and HKr (i.e., a marker of functional vitamin B6 status based on selected KP metabolites) were associated with lower MoCA score at 3, 18, and 36 months post-stroke (p < 0.01). Higher baseline concentrations of neopterin and 3-hydroxykynurenine were associated with lower MoCA scores at 18 and 36 months, and higher concentrations of xanthurenic acid were associated with higher MoCA score at 36 months (p < 0.01). At 3 months post-stroke, higher concentrations of neopterin and lower values of pyridoxal 5́-phosphate were associated with lower MoCA scores at 18- and 36-month follow-up, while lower concentrations of picolinic acid were associated with a lower MoCA score at 36 months (p < 0.01).
CONCLUSION
Biomarkers and metabolites of systemic inflammation, including biomarkers of cellular immune activation, indexes of vitamin B6 homeostasis, and several neuroactive metabolites of the KP pathway, were associated with PSCI.
TRIAL REGISTRATION
ClinicalTrials.gov: NCT02650531.
Topics: Aged; Female; Humans; Male; Biomarkers; Cognitive Dysfunction; Cohort Studies; Inflammation; Kynurenine; Neopterin; Prospective Studies; Pyridoxal Phosphate; Stroke; Vitamin B 6; Middle Aged; Aged, 80 and over
PubMed: 38428649
DOI: 10.1016/j.bbi.2024.02.030 -
Biochemical and Biophysical Research... Apr 2024IlvA1, a pyridoxal phosphate-dependent (PLP) enzyme, catalyzes the deamination of l-threonine and l-serine to yield 2-ketobutyric acid or pyruvate. To gain insights into...
IlvA1, a pyridoxal phosphate-dependent (PLP) enzyme, catalyzes the deamination of l-threonine and l-serine to yield 2-ketobutyric acid or pyruvate. To gain insights into the function of IlvA1, we determined its crystal structure from Pseudomonas aeruginosa to 2.3 Å. Density for a 2-ketobutyric acid product was identified in the active site and a putative allosteric site. Activity and substrate binding assays confirmed that IlvA1 utilizes l-threonine, l-serine, and L-allo-threonine as substrates. The enzymatic activity is regulated by the end products l-isoleucine and l-valine. Additionally, the efficiency of d-cycloserine and l-cycloserine inhibitors on IlvA1 enzymatic activity was examined. Notably, site-directed mutagenesis confirmed the active site residues and revealed that Gln165 enhances the enzyme activity, emphasizing its role in substrate access. This work provides crucial insights into the structure and mechanism of IlvA1 and serves as a starting point for further functional and mechanistic studies of the threonine deaminase in P. aeruginosa.
Topics: Butyrates; Crystallography, X-Ray; Cycloserine; Phosphates; Pseudomonas aeruginosa; Pyridoxal Phosphate; Threonine; Threonine Dehydratase
PubMed: 38417345
DOI: 10.1016/j.bbrc.2024.149710 -
Biochimie Jul 2024Pyridoxal kinase (PdxK) is a vitamin B salvage pathway enzyme which produces pyridoxal phosphate. We have investigated the impact of PdxK deletion in Leishmania donovani...
Pyridoxal kinase (PdxK) is a vitamin B salvage pathway enzyme which produces pyridoxal phosphate. We have investigated the impact of PdxK deletion in Leishmania donovani on parasite survivability, infectivity and cellular metabolism. LdPdxK mutants were generated by gene replacement strategy. All mutants showed significant reduction in growth in comparison to wild type. For PdxK mediated biochemical perturbations, only heterozygous mutants and complementation mutants were used as the growth of null mutants were compromised. Heterozygous mutant showed reduction invitro infectivity and higher cytosolic and mitochondrial ROS levels. Glutathione levels decreased significantly in heterozygous mutant indicating its involvement in cellular oxidative metabolism. Pyridoxal kinase gene deletion resulted in reduced ATP levels in parasites and arrest at G/G phase of cell cycle. All these perturbations were rescued by PdxK gene complementation. This is the first report to confirm that LdPdxK plays an indispensable role in cell survival, pathogenicity, redox metabolism and cell cycle progression of L. donovani parasites. These results provide substantial evidence supporting PdxK as a therapeutic target for the development of specific antileishmanial drug candidates.
Topics: Leishmania donovani; Oxidation-Reduction; Pyridoxal Kinase; Gene Deletion; Cell Cycle Checkpoints; Animals; Protozoan Proteins; Reactive Oxygen Species; Mice
PubMed: 38403043
DOI: 10.1016/j.biochi.2024.02.009 -
Biomolecules Feb 2024The serine peptidase CLPP is conserved among bacteria, chloroplasts, and mitochondria. In humans and mice, its loss causes Perrault syndrome, which presents with growth...
The serine peptidase CLPP is conserved among bacteria, chloroplasts, and mitochondria. In humans and mice, its loss causes Perrault syndrome, which presents with growth deficits, infertility, deafness, and ataxia. In the filamentous fungus , CLPP loss leads to longevity. CLPP substrates are selected by CLPX, an AAA+ unfoldase. CLPX is known to target delta-aminolevulinic acid synthase (ALAS) to promote pyridoxal phosphate (PLP) binding. CLPX may also influence cofactor association with other enzymes. Here, the evaluation of metabolomics highlighted a reduction in arginine/histidine levels. In cerebellum, reductions in arginine/histidine and citrulline occurred with a concomitant accumulation of the heme precursor protoporphyrin IX. This suggests that the increased biosynthesis of 5-carbon (C5) chain deltaALA consumes not only C4 succinyl-CoA and C1 glycine but also specific C5 delta amino acids. As enzymes responsible for these effects, the elevated abundance of CLPX and ALAS is paralleled by increased OAT (PLP-dependent, ornithine delta-aminotransferase) levels. Possibly as a consequence of altered C1 metabolism, the proteome profiles of CLPP-null cells showed strong accumulation of a methyltransferase and two mitoribosomal large subunit factors. The reduced histidine levels may explain the previously observed metal interaction problems. As the main nitrogen-storing metabolite, a deficiency in arginine would affect the urea cycle and polyamine synthesis. Supplementation of arginine and histidine might rescue the growth deficits of CLPP-mutant patients.
Topics: Animals; Mice; Arginine; Avena; Endopeptidase Clp; Eukaryota; Heme; Histidine; Organic Anion Transporters
PubMed: 38397478
DOI: 10.3390/biom14020241 -
Biochemistry Mar 2024The bacterial metabolic enzyme 1-deoxy-d-xylulose-5-phosphate synthase (DXPS) catalyzes the thiamin diphosphate (ThDP)-dependent formation of DXP from pyruvate and...
The bacterial metabolic enzyme 1-deoxy-d-xylulose-5-phosphate synthase (DXPS) catalyzes the thiamin diphosphate (ThDP)-dependent formation of DXP from pyruvate and d-glyceraldehyde-3-phosphate (d-GAP). DXP is an essential bacteria-specific metabolite that feeds into the biosynthesis of isoprenoids, pyridoxal phosphate (PLP), and ThDP. DXPS catalyzes the activation of pyruvate to give the C2α-lactylThDP (LThDP) adduct that is long-lived on DXPS in a closed state in the absence of the cosubstrate. Binding of d-GAP shifts the DXPS-LThDP complex to an open state which coincides with LThDP decarboxylation. This gated mechanism distinguishes DXPS in ThDP enzymology. How LThDP persists on DXPS in the absence of cosubstrate, while other pyruvate decarboxylases readily activate LThDP for decarboxylation, is a long-standing question in the field. We propose that an active site network functions to prevent LThDP activation on DXPS until the cosubstrate binds. Binding of d-GAP coincides with a conformational shift and disrupts the network causing changes in the active site that promote LThDP activation. Here, we show that the substitution of putative network residues, as well as nearby residues believed to contribute to network charge distribution, predictably affects LThDP reactivity. Substitutions predicted to disrupt the network have the effect to activate LThDP for decarboxylation, resulting in CO and acetate production. In contrast, a substitution predicted to strengthen the network fails to activate LThDP and has the effect to shift DXPS toward the closed state. Network-disrupting substitutions near the carboxylate of LThDP also have a pronounced effect to shift DXPS to an open state. These results offer initial insights to explain the long-lived LThDP intermediate and its activation through disruption of an active site network, which is unique to DXPS. These findings have important implications for DXPS function in bacteria and its development as an antibacterial target.
Topics: Diphosphates; Catalytic Domain; Thiamine Pyrophosphate; Transferases; Pyruvic Acid; Bacteria; Nitric Oxide Synthase; Anti-Bacterial Agents
PubMed: 38393327
DOI: 10.1021/acs.biochem.3c00735 -
The British Journal of Nutrition May 2024Elevated plasma concentrations of several one-carbon metabolites are associated with increased CVD risk. Both diet-induced regulation and dietary content of one-carbon...
Elevated plasma concentrations of several one-carbon metabolites are associated with increased CVD risk. Both diet-induced regulation and dietary content of one-carbon metabolites can influence circulating concentrations of these markers. We cross-sectionally analysed 1928 patients with suspected stable angina pectoris (geometric mean age 61), representing elevated CVD risk, to assess associations between dietary macronutrient composition (FFQ) and plasma one-carbon metabolites and related B-vitamin status markers (GC-MS/MS, LC-MS/MS or microbiological assay). Diet-metabolite associations were modelled on the continuous scale, adjusted for age, sex, BMI, smoking, alcohol and total energy intake. Average (geometric mean (95 % prediction interval)) intake was forty-nine (38, 63) energy percent (E%) from carbohydrate, thirty-one (22, 45) E% from fat and seventeen (12, 22) E% from protein. The strongest associations were seen for higher protein intake, i.e. with higher plasma pyridoxal 5'-phosphate (PLP) (% change (95 % CI) 3·1 (2·1, 4·1)), cobalamin (2·9 (2·1, 3·7)), riboflavin (2·4 (1·1, 3·7)) and folate (2·1 (1·2, 3·1)) and lower total homocysteine (tHcy) (-1·4 (-1·9, -0·9)) and methylmalonic acid (MMA) (-1·4 (-2·0, -0·8)). Substitution analyses replacing MUFA or PUFA with SFA demonstrated higher plasma concentrations of riboflavin (5·0 (0·9, 9·3) and 3·3 (1·1, 5·6)), tHcy (2·3 (0·7, 3·8) and 1·3 (0·5, 2·2)) and MMA (2·0 (0·2, 3·9) and 1·7 (0·7, 2·7)) and lower PLP (-2·5 (-5·3, 0·3) and -2·7 (-4·2, -1·2)). In conclusion, a higher protein intake and replacing saturated with MUFA and PUFA were associated with a more favourable metabolic phenotype regarding metabolites associated with CVD risk.
Topics: Humans; Male; Female; Middle Aged; Cross-Sectional Studies; Diet; Aged; Angina, Stable; Vitamin B Complex; Nutrients; Biomarkers; Dietary Proteins; Pyridoxal Phosphate; Dietary Fats; Dietary Carbohydrates; Methylmalonic Acid; Vitamin B 12
PubMed: 38361451
DOI: 10.1017/S0007114524000473 -
Journal of Biomolecular Structure &... Feb 2024The biosynthetic arginine decarboxylase in is responsible for producing spermidine, a polyamine with numerous biological applications in humans. The arginine...
The biosynthetic arginine decarboxylase in is responsible for producing spermidine, a polyamine with numerous biological applications in humans. The arginine decarboxylase has significant applications in biotechnology industries, suggesting the need to evaluate its biochemical and biophysical characteristics at the molecular level. In this study, both and methods were employed to investigate the structural and functional behavior of the arginine decarboxylase protein. In MALDI-TOF, size exclusion, and assay studies were performed to examine the nature and activity of the protein. The MALDI-TOF analysis confirmed the purified protein as biosynthetic arginine decarboxylase. The assay results revealed that the Pyridoxal 5'-Phosphate (PLP) cofactor plays a crucial role in enhancing enzyme activity by producing agmatine (a by-product of spermidine). Further, optimum enzyme activity was observed at 50 °C, suggesting the extremophilic nature of the enzyme. Unlike other proteins, this enzyme displayed optimal activity at both acidic and basic pH, demonstrating its sensitivity to pH changes. Furthermore, the addition of divalent ions like Mg increased the rate of reaction. In , structure modeling, and comparative molecular dynamics simulation studies were used to assess the protein stability and behavior at different pH and temperature conditions. The findings of this study could be applied to improve enzyme production in the industry.Communicated by Ramaswamy H. Sarma.
PubMed: 38344920
DOI: 10.1080/07391102.2024.2314753