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N-Acetylglucosamine and Immunoglobulin Strengthen Gut Barrier Integrity via Complementary Microbiome Modulation.

Background: Gut barrier dysfunction and altered gut microbial metabolism are emerging signatures of chronic gut disorders. Considering growing interest in combining structurally and mechanistically distinct bioactives, we investigated the individual and combined effects of serum-derived bovine immunoglobulin (SBI) and N-acetylglucosamine (NAG) on the gut microbiome and barrier integrity. Methods: The validated ex vivo SIFR® (Systemic Intestinal Fermentation Research) technology, using microbiota from healthy adults (n = 6), was combined with a co-culture of epithelial/immune (Caco-2/THP-1) cel…

The effect and molecular mechanism of N-Acetylglucosamine transferase-V in the pathogenesis of cancers.

N-Acetylglucosaminyltransferase V (GnT-V) is a pivotal glycosyltransferase catalyzing the formation of β1-6 branched N-glycans, a structural modification intimately linked to cancer malignancy. While elevated GnT-V expression correlates with metastasis in breast, gastric, and colorectal cancers, its function is context-dependent, predicting distinct outcomes in lung and bladder cancers. Crucially, the oncogenic potential of GnT-V is not isolated but is dynamically regulated by its competitive interplay with GnT-III and cooperation with α1,6-fucosyltransferase 8 (Fut8). Distinct from previous s

Liberation of N-acetylglucosamine-6-sulfate by human beta-N-acetylhexosaminidase A.

The first step of the degradation of p-nitrophenyl-6-sulfo-2-acetamido-2-deoxy-beta-D-glucopyranoside and of keratan sulfate-derived oligosaccharides bearing N-acetylglucosamine-6-sulfate residues at the nonreducing end was considered to be accomplished by the action of a specific sulfatase (Kresse, H., Paschke, E., von Figura, K., Gilberg, W., and Fuchs W. (1980) Proc. Natl. Acad. Sci. U. S. A. 77, 6822-6826). In purification from human placenta, however, this activity co-chromatographed with isoenzyme A of beta-N-acetylhexosaminidase and had the same electrophoretic mobility as the latter en…

Functional mechanism and structural dynamics of Brucella ovis UDP-N-acetylglucosamine Enolpyruvyl transferase.

UDP-N-acetylglucosamine enolpyruvyl transferase (MurA) is essential for bacterial peptidoglycan biosynthesis, catalyzing the transfer of enolpyruvate from phosphoenolpyruvate (PEP) to UDP-N-acetylglucosamine (UNAG) to form enolpyruvyl-UDP-N-acetylglucosamine (UNAGEP). This study characterizes the kinetic properties and domain dynamics of MurA from Brucella ovis. Global kinetic analysis across varying concentrations of substrates suggests that, under turnover conditions, B. ovis MurA operates via a BiBi sequential rapid ordered mechanism, with a kcat of 90 min-1, a KmUNAG of 470 μM and a KmPEP …

Intralysosomal formation and metabolic fate of N-acetylglucosamine 6-sulfate from keratan sulfate.

The physiological relevance of the ability of beta-N-acetylhexosaminidase A to liberate N-acetylglucosamine 6-sulfate from polymeric keratan sulfate was investigated. Upon intravenous injection into rats of [35S]sulfate-labeled proteokeratan sulfate up to 25% of the radioactivity excreted with the urine were identified as N-acetyl-glucosamine 6-sulfate. Within 24 h, however, excretion of inorganic sulfate rose at the expense of the sulfated monosaccharide. Upon incubation in vitro of liver lysosomes from rats treated with proteokeratan sulfate, inorganic sulfate and minor amounts of sulfated m…

N-Acetylglucosamine is the most effective glucosamine derivative for the treatment of membranous nephropathy in rats.

Nephroprotective drug development for optimizing treatment of chronic kidney disease (CKD) is an important task of pharmaceutical science. Our study evaluated nephroprotective properties of the two glucosamine derivatives N-acetylglucosamine and glucosamine hydrochloride in a 3-week-long parenteral and oral daily administration at doses of 50 mg/kg in rats with doxorubicin nephropathy. Nephroprotective activity (NA) was evaluated by determining the functional state of the kidneys, the level of azotemia and the activity of free-radical processes in the renal tissue. The results show a significa…

Two active forms of UDP-N-acetylglucosamine enolpyruvyl transferase in gram-positive bacteria.

Gene sequences encoding the enzymes UDP-N-acetylglucosamine enolpyruvyl transferase (MurA) from many bacterial sources were analyzed. It was shown that whereas gram-negative bacteria have only one murA gene, gram-positive bacteria have two distinct genes encoding these enzymes which have possibly arisen from gene duplication. The two murA genes of the gram-positive organism Streptococcus pneumoniae were studied further. Each of the murA genes was individually inactivated by allelic replacement. In each case, the organism was viable despite losing one of its murA genes. However, when attempts w…

Structural and functional insights into UDP-N-acetylglucosamine-enolpyruvate reductase (MurB) from Brucella ovis.

The peptidoglycan biosynthetic pathway involves a series of enzymatic reactions in which UDP-N-acetylglucosamine-enolpyruvate reductase (MurB) plays a crucial role in catalyzing the conversion of UDP-N-acetylglucosamine-enolpyruvate (UNAGEP) to UDP-N-acetylmuramic acid. This reaction relies on NADPH and FAD and, since MurB is not found in eukaryotes, it is an attractive target for the development of antimicrobials. MurB from Brucella ovis, the causative agent of brucellosis in sheep, is characterized here. The FAD cofactor in MurB of B. ovis is reduced to the hydroquinone state without semiqui…

A novel allosteric inhibitor of the uridine diphosphate N-acetylglucosamine pyrophosphorylase from Trypanosoma brucei.

Uridine diphosphate N-acetylglucosamine pyrophosphorylase (UAP) catalyzes the final reaction in the biosynthesis of UDP-GlcNAc, an essential metabolite in many organisms including Trypanosoma brucei, the etiological agent of Human African Trypanosomiasis. High-throughput screening of recombinant T. brucei UAP identified a UTP-competitive inhibitor with selectivity over the human counterpart despite the high level of conservation of active site residues. Biophysical characterization of the UAP enzyme kinetics revealed that the human and trypanosome enzymes both display a strictly ordered bi-bi …

The role of protein O-linked beta-N-acetylglucosamine in mediating cardiac stress responses.

The modification of serine and threonine residues of nuclear and cytoplasmic proteins by O-linked beta-N-acetylglucosamine (O-GlcNAc) has emerged as a highly dynamic post-translational modification that plays a critical role in regulating numerous biological processes. Much of our understanding of the mechanisms underlying the role of O-GlcNAc on cellular function has been in the context of its adverse effects in mediating a range of chronic disease processes, including diabetes, cancer and neurodegenerative diseases. However, at the cellular level it has been shown that O-GlcNAc levels are in…

Virulence attenuation of a UDP-galactose/N-acetylglucosamine beta1,4 galactosyltransferase expressing Leishmania donovani promastigote.

Protozoan parasites of the genus Leishmania are the causative agent of leishmaniasis, a disease whose manifestations in humans range from mild cutaneous lesions to fatal visceral infections. Human visceral leishmaniasis is caused by Leishmania donovani. Long-term culture in vitro leads to the attenuation of the parasite. This loss of parasite virulence is associated with the expression of a developmentally regulated UDP-Galactose/N-acetylglucosamine beta 1-4 galactosyltransferase and galactose terminal glycoconjugates as determined by their agglutination with the pea nut agglutinin (PNA). Thus…

Antibodies from patients with psoriasis recognize N-acetylglucosamine terminals in glycoproteins from Pityrosporum ovale.

We have previously reported the finding of circulating antibodies recognizing two proteins of 100 and 120 kD (PO100 and PO120) from Pityrosporum ovale in patients with psoriasis. These antibodies were specific, since they were not detected in normal sera nor in other diseases linked to P. ovale such as seborrhoeic dermatitis or pityriasis versicolor. The present study aimed at further characterizing the specificity of these antibodies. Enzyme-labelled lectins were used to determine the carbohydrate composition of PO120 and PO100. BSII, a lectin that recognizes terminal N-acetylglucosamine (Glc…

Структура и N-ацетилглукамин соединяют дистальную область мышиного аденовируса 2 волокна.

Murine adenovirus 2 (MAdV-2) инфицирует клетки желудочно-кишечного тракта мыши. Как и человеческие аденовирусы, он является членом рода Мастаденовирус, семьи Аденовириды. Геном MAdV-2 имеет один волокнистый ген, который выражает 787 белков длиной с остатки. По аналогии с другими аденовирусными белками волокна, ожидается, что область карбоксин-терминального вируса-диска волокна отвечает за подключение к клетке, хотя природный рецептор неизвестен. Предполагаемая область головы имеет малую последовательность идентификации аденовирусных волокон известной структуры. В этом докладе мы представляем к

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Murine adenovirus 2 (MAdV-2) infects cells of the mouse gastrointestinal tract. Like human adenoviruses, it is a member of the genus Mastade … ry and site-directed mutagenesis, we show that the fibre specifically binds to the monosaccharide N-acetylglucosamine (GlcNAc). The crystal structure of the complex reveals that GlcNAc binds between the AB and CD loops at the top of each of the three monomers of the MAdV-2 fibre head. However, infection competition assays show that soluble GlcNAc monosaccharide and …

Characterization of N-Acetylglucosamine Biosynthesis in Pneumocystis species. A New Potential Target for Therapy.

N-acetylglucosamine (GlcNAc) serves as an essential structural sugar on the cell surface of organisms. For example, GlcNAc is a major component of bacterial peptidoglycan, it is an important building block of fungal cell walls, including a major constituent of chitin and mannoproteins, and it is also required for extracellular matrix generation by animal cells. Herein, we provide evidence for a uridine diphospho (UDP)-GlcNAc pathway in Pneumocystis species. Using an in silico search of the Pneumocystis jirovecii and P. murina (Pm) genomic databases, we determined the presence of at least four …

Tfp1 is required for ion homeostasis, fluconazole resistance and N-Acetylglucosamine utilization in Candida albicans.

The vacuolar-type H+-ATPase (V-ATPase) is crucial for the maintenance of ion homeostasis. Dysregulation of ion homeostasis affects various a … terestingly, carbon source utilization tests found the tfp1∆/∆ mutant was defective for growth on N-Acetylglucosamine (GlcNAc) plate, which was associated with ATP depletion due to the decreased ability to catabolize GlcNAc. Taken together, our study gives new insights into functions of Tfp1, and provides the potential to better exploit V-ATPase as an antifungal ta …

Effect of vitamin A deficiency on the in vitro transfer of mannose and N-acetylglucosamine in rat liver nuclei.

Liver nuclei, prepared from normal and vitamin A-deficient rats, were incubated in the presence of GDP-(14C)mannose or UDP-N-acetyl(14C)glucosamine and the labelled glycoproteins analysed by SDS PAGE. Fluorographic analysis has shown that (14C) mannose labelling is enhanced by vitamin A deficiency whereas N-acetyl(14C)glucosamine transfer remains approximately at the same level regardless of the vitamin A status; we did not notice any modification when the proteins were monitored by Coomassie blue or by silver nitrate.

Rapid Access to Human Milk Oligosaccharide Analogues through a Partially Protected N-Acetylglucosamine Donor.

Access to structurally defined human milk oligosaccharides (HMOs) remains nontrivial because chemical synthesis often relies on extensive protecting-group manipulations. Here, we report a gold(I)-catalyzed, protecting-group-minimized approach to HMO-related tri- and tetrasaccharides using a partially protected 2-acetamido-2-deoxy glycosyl donor. Efficient formation of the β-GlcNAc-(1→3)-Gal motif was found to depend strongly on the protecting-group pattern of the galactosyl acceptor, with a 2-O-benzyl group being crucial for productive glycosylation. Subsequent Au(I)-catalyzed site-selective 3

Interaction of Neisseria meningitidis Group X N-acetylglucosamine-1-phosphotransferase with its donor substrate.

Neisseria meningitidis Group X is an emerging cause of bacterial meningitis in Sub-Saharan Africa. The capsular polysaccharide of Group X is a homopolymer of N-acetylglucosamine α(1-4) phosphate and is a vaccine target for prevention of disease associated with this meningococcal serogroup. We have demonstrated previously that the formation of the polymer is catalyzed by a phosphotransferase which transfers N-acetylglucosamine-1-phosphate from UDP-N-acetylglucosamine to the 4-hydroxyl of the N-acetylglucosamine on the nonreducing end of the growing chain. In this study, we use substrate analogs…

Poly-N-Acetylglucosamine Production by Staphylococcus epidermidis Cells Increases Their In Vivo Proinflammatory Effect.

Poly-N-acetylglucosamine (PNAG) is a major component of the Staphylococcus epidermidis biofilm extracellular matrix. However, it is not yet clear how this polysaccharide impacts the host immune response and infection-associated pathology. Faster neutrophil recruitment and bacterial clearance were observed in mice challenged intraperitoneally with S. epidermidis biofilm cells of the PNAG-producing 9142 strain than in mice similarly challenged with the isogenic PNAG-defective M10 mutant. Moreover, intraperitoneal priming with 9142 cells exacerbated liver inflammatory pathology induced by a subse…