Chitin exists in yeast cells both as free and bound in a complex with β-1,3/β-1,6-glucan. The formation of covalent links between chitin and β-glucans is catalyzed by the enzymes Crh1 and Crh2, acting as transglycosylases. We found that N-acetyl-chito-oligosaccharides, as well as laminarioligosaccharides, the respective products of partial hydrolysis of chitin, and β-1,3-glucan, interfered with reactions catalyzed by Crh1p and Crh2p in vitro. However, the N-acetyl-chito-oligosaccharides did not influence the growth rate of the yeast, neither did they affect the yeast phenotype, but they prolonged the lag phase. Inhibition of Crh1 and Crh2 in vivo with oligosaccharides derived from chitin leads to an increase of alkali-soluble chitin and a decrease in the amount of chitin linked to β-glucans. In addition, yeast cells growing in the presence of N-acetyl-D-chito-oligosaccharides accumulated more chitin than control cells.
Oligosacharidy, obsažené v mateřském mléce, mají pro správný vývoj novorozence nezastupitelnou úlohu a plní celou řadu biologických funkcí, i přesto jsou často opomíjeny. Z hlediska výživy nemají pro kojence velký význam, avšak jejich hlavní benefity spočívají ve schopnosti ovlivnit vývoj nervové soustavy a imunity kojence díky svým prebiotickým, antimikrobiálním, antiadhezivním a antibiofilmovým vlastnostem. Bohužel nedostatek informací o těchto oligosacharidech nás brzdí v jejich terapeutickém využití.
The oligosaccharides contained in breast milk play an irreplaceable role in the proper development of the newborn and perform a number of biological functions, although they are often neglected. From a nutritional point of view, they are not very important for infants, but their main benefits are their ability to influence the development of the infant's nervous system and immunity due to their prebiotic, antimicrobial, antiadhesive and antibiofilm properties. Unfortunately, the lack of information about them hinders us in their therapeutic use.
- MeSH
- fyziologie výživy kojenců MeSH
- kojenec MeSH
- lidé MeSH
- mateřské mléko * fyziologie metabolismus MeSH
- novorozenec MeSH
- oligosacharidy * fyziologie metabolismus MeSH
- Check Tag
- kojenec MeSH
- lidé MeSH
- novorozenec MeSH
- Publikační typ
- práce podpořená grantem MeSH
- Klíčová slova
- postbiotika,
- MeSH
- fyziologie výživy kojenců imunologie MeSH
- kojenec MeSH
- lidé MeSH
- mateřské mléko * fyziologie imunologie mikrobiologie MeSH
- novorozenec MeSH
- oligosacharidy imunologie metabolismus MeSH
- prebiotika MeSH
- randomizované kontrolované studie jako téma MeSH
- střevní mikroflóra imunologie MeSH
- Check Tag
- kojenec MeSH
- lidé MeSH
- novorozenec MeSH
- Publikační typ
- práce podpořená grantem MeSH
Chitooligosaccharides exhibit several biomedical activities, such as inflammation and tumorigenesis reduction in mammals. The mechanism of the chitooligosaccharides' formation in vivo has been, however, poorly understood. Here we report that mouse acidic chitinase (Chia), which is widely expressed in mouse tissues, can produce chitooligosaccharides from deacetylated chitin (chitosan) at pH levels corresponding to stomach and lung tissues. Chia degraded chitin to produce N-acetyl-d-glucosamine (GlcNAc) dimers. The block-type chitosan (heterogenous deacetylation) is soluble at pH 2.0 (optimal condition for mouse Chia) and was degraded into chitooligosaccharides with various sizes ranging from di- to nonamers. The random-type chitosan (homogenous deacetylation) is soluble in water that enables us to examine its degradation at pH 2.0, 5.0, and 7.0. Incubation of these substrates with Chia resulted in the more efficient production of chitooligosaccharides with more variable sizes was from random-type chitosan than from the block-type form of the molecule. The data presented here indicate that Chia digests chitosan acquired by homogenous deacetylation of chitin in vitro and in vivo. The degradation products may then influence different physiological or pathological processes. Our results also suggest that bioactive chitooligosaccharides can be obtained conveniently using homogenously deacetylated chitosan and Chia for various biomedical applications.
- MeSH
- chitinasy chemie metabolismus MeSH
- chitosan chemie metabolismus MeSH
- difrakce rentgenového záření MeSH
- hydrolýza MeSH
- koncentrace vodíkových iontů * MeSH
- myši MeSH
- oligosacharidy chemie metabolismus MeSH
- orgánová specificita MeSH
- plíce metabolismus MeSH
- substrátová specifita MeSH
- žaludek metabolismus MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The Gram-negative coccobacillus Kingella kingae is increasingly recognized as an important invasive pediatric pathogen that causes mostly bacteremia and skeletal system infections. K. kingae secretes an RtxA toxin that belongs to a broad family of the RTX (Repeats in ToXin) cytotoxins produced by bacterial pathogens. Recently, we demonstrated that membrane cholesterol facilitates interaction of RtxA with target cells, but other cell surface structures potentially involved in toxin binding to cells remain unknown. We show that deglycosylation of cell surface structures by glycosidase treatment, or inhibition of protein N- and O-glycosylation by chemical inhibitors substantially reduces RtxA binding to target cells. Consequently, the deglycosylated cells were more resistant to cytotoxic activity of RtxA. Moreover, experiments on cells expressing or lacking cell surface integrins of the β2 family revealed that, unlike some other cytotoxins of the RTX family, K. kingae RtxA does not bind target cells via the β2 integrins. Our results, hence, show that RtxA binds cell surface oligosaccharides present on all mammalian cells but not the leukocyte-restricted β2 integrins. This explains the previously observed interaction of the toxin with a broad range of cell types of various mammalian species and reveals that RtxA belongs to the group of broadly cytolytic RTX hemolysins.
- MeSH
- antigeny CD18 metabolismus MeSH
- bakteriální toxiny metabolismus MeSH
- buněčná membrána metabolismus MeSH
- buněčná smrt MeSH
- buněčné linie MeSH
- glykosidhydrolasy metabolismus MeSH
- glykosylace MeSH
- Kingella kingae metabolismus MeSH
- lidé MeSH
- makrofágy metabolismus MeSH
- myši MeSH
- oligosacharidy chemie metabolismus MeSH
- vazba proteinů MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Mateřské mléko obsahuje přibližně 200 komplexních oligosacharidů (human milk oligosaccharides - HMO), o nichž se předpokládá, že stimulují růst a tvorbu ochranné mikrobioty ve střevech kojenců. Od objevu HMO před více než 60 lety čelil výzkum mnoha problémům. Ale za posledních 10 let došlo v těchto oblastech k pokroku. Na základě experimentů in vitro, studií na zvířatech a několika studií na lidech bylo objeveno mnoho funkcí HMO. V tomto článku se zaměřujeme na potenciál HMO ovlivnit mikrobiální složení v gastrointestinálním traktu, vývoj imunity dětí nebo epigenetické změny, které mohou ovlivnit zdraví v dospělosti.
Human milk contains approximately 200 complex oligosaccharides believed to stimulate the growth and establishment of a protective microbiota in the infant gut. Since the discovery of human milk oligosaccharides (HMO) more than 60 years ago, research has faced a lot of problems. But in the last 10 years, there has been made progress in these areas. Based upon in vitro experiments, animal studies, and a few studies in humans, many functions of HMO have been discovered. In this article, we focus on the potential of HMO to influence the microbial composition in the gastrointestinal tract, development of children immunity or epigenetic changes, wich can influence health in adulthood.
- MeSH
- alergie na mléko imunologie patofyziologie MeSH
- fukosyltransferasy fyziologie genetika MeSH
- kojenec MeSH
- kojení MeSH
- laktosa fyziologie MeSH
- lidé MeSH
- mateřské mléko * fyziologie metabolismus MeSH
- mikrobiota fyziologie MeSH
- novorozenec MeSH
- oligosacharidy * fyziologie metabolismus MeSH
- prebiotika MeSH
- střevní mikroflóra fyziologie imunologie MeSH
- Check Tag
- kojenec MeSH
- lidé MeSH
- novorozenec MeSH
Fungal β-N-acetylhexosaminidases, though hydrolytic enzymes in vivo, are useful tools in the preparation of oligosaccharides of biological interest. The β-N-acetylhexosaminidase from Talaromyces flavus is remarkable in terms of its synthetic potential, broad substrate specificity, and tolerance to substrate modifications. It can be heterologously produced in Pichia pastoris in a high yield. The mutation of the Tyr470 residue to histidine greatly enhances its transglycosylation capability. The aim of this work was to identify the structural requirements of this model β-N-acetylhexosaminidase for its transglycosylation acceptors and formulate a structure-activity relationship study. Enzymatic reactions were performed using an activated glycosyl donor, 4-nitrophenyl N-acetyl-β-d-glucosaminide or 4-nitrophenyl N-acetyl-β-d-galactosaminide, and a panel of glycosyl acceptors of varying structural features (N-acetylglucosamine, glucose, N-acetylgalactosamine, galactose, N-acetylmuramic acid, and glucuronic acid). The transglycosylation products were isolated and structurally characterized. The C-2 N-acetamido group in the acceptor molecule was found to be essential for recognition by the enzyme. The presence of the C-2 hydroxyl moiety strongly hindered the normal course of transglycosylation, yielding unique non-reducing disaccharides in a low yield. Moreover, whereas the gluco-configuration at C-4 steered the glycosylation into the β(1-4) position, the galacto-acceptor afforded a β(1-6) glycosidic linkage. The Y470H mutant enzyme was tested with acceptors based on β-glycosides of uronic acid and N-acetylmuramic acid. With the latter acceptor, we were able to isolate and characterize one glycosylation product in a low yield. To our knowledge, this is the first example of enzymatic glycosylation of an N-acetylmuramic acid derivative. In order to explain these findings and predict enzyme behavior, a modeling study was accomplished that correlated with the acquired experimental data.
- MeSH
- beta-N-acetylhexosaminidasy chemie metabolismus MeSH
- glykosidy metabolismus MeSH
- glykosylace MeSH
- kinetika MeSH
- konformace proteinů MeSH
- molekulární modely MeSH
- oligosacharidy metabolismus MeSH
- substrátová specifita MeSH
- Talaromyces enzymologie MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Publikační typ
- časopisecké články MeSH
- Klíčová slova
- FODMAPs,
- MeSH
- dieta s omezením sacharidů * metody MeSH
- dietní sacharidy metabolismus škodlivé účinky MeSH
- dyspepsie * etiologie patofyziologie terapie MeSH
- histamin metabolismus škodlivé účinky MeSH
- lidé MeSH
- oligosacharidy metabolismus škodlivé účinky MeSH
- potravinová intolerance etiologie patofyziologie terapie MeSH
- Check Tag
- lidé MeSH
Low molecular weight signaling compounds (LMWC) are important players in regulating various aspects of Streptomyces biology. Their exact roles in certain strain will ultimately depend on overall configuration of regulatory network and thus cannot be predicted on basis of in silico studies. Here, we explored S. ghanaensis gene SSFG_07725 (afsAgh) presumably involved in initial steps of formation of γ-butyrolactone LMWC. Disruption of afsAgh impaired aerial mycelium formation and increased the transcription of pleiotropic regulatory gene adpAgh, whereas level of moenomycin production remained virtually unaffected. We provide evidence that morphogenetic deficiency of afsAgh-minus mutant was caused by inability to produce diffusible LMWC. Possible links between γ-butyrolactone signaling and various aspects of S. ghanaensis biology are discussed.
