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International Journal of Molecular... Jul 2015Three kinds of polysaccharides, namely, BSP1A, BSP2A, and BSP3B, were isolated from raw bamboo shoot (Dendrocalamus latiflorus) after purification and classification by...
Three kinds of polysaccharides, namely, BSP1A, BSP2A, and BSP3B, were isolated from raw bamboo shoot (Dendrocalamus latiflorus) after purification and classification by DEAE cellulose-52 (ion-exchange chromatography) and Sephadex G-50. The molecular weights of BSP1A, BSP2A, and BSP3B were 10.2, 17.0 and 20.0 kDa, respectively, which were measured through GPC (gel performance chromatography) methods. BSP1A contained arabinose, glucose, and galactose in a molar ratio of 1.0:40.6:8.7. BSP2A and BSP3B contained arabinose, xylose, glucose, and galactose in molar ratios of 6.6:1.0:5.2:10.4 and 8.5:1.0:5.1:11.1, respectively. The existence of the O-glycopeptide bond in BSP1A, BSP2A, and BSP3B was demonstrated by β-elimination reaction. FTIR spectra of the three polysaccharides showed that both BSP2A and BSP3B contained β-D-pyranose sugar rings. However, BSP1A exhibited both β-D-pyranose and α-D-pyranose sugar rings. Congo red test indicated that BSP1A and BSP2A displayed triple helix structures, but BSP3B did not. NMR spectroscopy revealed that BSP1A may exhibit a β-1,6-Glucan pyran type as the main link, and few 1,6-glycosidic galactose pyranose and arabinose bonds were connected; BSP2A mainly demonstrated → 5)β-Ara(1 → and → 3)β-Gal(1 → connection. Furthermore, BSP3B mainly presented → 3)β-Glu(1 → and → 3)β-Gal(1 → connection and may also contain few other glycosidic bonds.
Topics: Arabinose; Carbohydrate Conformation; Chromatography, Gas; Chromatography, Gel; Chromatography, Ion Exchange; Galactose; Glucose; Molecular Weight; Plant Shoots; Poaceae; Polysaccharides; Spectroscopy, Fourier Transform Infrared
PubMed: 26184163
DOI: 10.3390/ijms160715560 -
ELife Dec 2016Reward perception guides all aspects of animal behavior. However, the relationship between the perceived value of a reward, the latent value of a reward, and the...
Reward perception guides all aspects of animal behavior. However, the relationship between the perceived value of a reward, the latent value of a reward, and the behavioral response remains unclear. Here we report that, given a choice between two sweet and chemically similar sugars-L- and D-arabinose- prefers D- over L- arabinose, but forms long-term memories of L-arabinose more reliably. Behavioral assays indicate that L-arabinose-generated memories require sugar receptor Gr43a, and calcium imaging and electrophysiological recordings indicate that L- and D-arabinose differentially activate Gr43a-expressing neurons. We posit that the immediate valence of a reward is not always predictive of the long-term reinforcement value of that reward, and that a subset of sugar-sensing neurons may generate distinct representations of similar sugars, allowing for rapid assessment of the salient features of various sugar rewards and generation of reward-specific behaviors. However, how sensory neurons communicate information about L-arabinose quality and concentration-features relevant for long-term memory-remains unknown.
Topics: Animals; Arabinose; Drosophila Proteins; Drosophila melanogaster; Feeding Behavior; Perception; Receptors, Cell Surface; Reward; Sensory Receptor Cells
PubMed: 28005005
DOI: 10.7554/eLife.22283 -
Cell Host & Microbe Mar 2023The molecular understanding of host-pathogen interactions in the gastrointestinal (GI) tract of superspreader hosts is incomplete. In a mouse model of chronic,...
The molecular understanding of host-pathogen interactions in the gastrointestinal (GI) tract of superspreader hosts is incomplete. In a mouse model of chronic, asymptomatic Salmonella enterica serovar Typhimurium (S. Tm) infection, we performed untargeted metabolomics on the feces of mice and found that superspreader hosts possess distinct metabolic signatures compared with non-superspreaders, including differential levels of L-arabinose. RNA-seq on S. Tm from superspreader fecal samples showed increased expression of the L-arabinose catabolism pathway in vivo. By combining bacterial genetics and diet manipulation, we demonstrate that diet-derived L-arabinose provides S. Tm a competitive advantage in the GI tract, and expansion of S. Tm in the GI tract requires an alpha-N-arabinofuranosidase that liberates L-arabinose from dietary polysaccharides. Ultimately, our work shows that pathogen-liberated L-arabinose from the diet provides a competitive advantage to S. Tm in vivo. These findings propose L-arabinose as a critical driver of S. Tm expansion in the GI tracts of superspreader hosts.
Topics: Salmonella typhimurium; Arabinose; Salmonella enterica; Polysaccharides; Serogroup
PubMed: 36812913
DOI: 10.1016/j.chom.2023.01.017 -
FEBS Letters Jan 2018Trichoderma reesei is used to produce saccharifying enzyme cocktails for biofuels. There is limited understanding of the transcription factors (TFs) that regulate genes...
Trichoderma reesei is used to produce saccharifying enzyme cocktails for biofuels. There is limited understanding of the transcription factors (TFs) that regulate genes involved in release and catabolism of l-arabinose and d-galactose, as the main TF XYR1 is only partially involved. Here, the T. reesei ortholog of ARA1 from Pyricularia oryzae that regulates l-arabinose releasing and catabolic genes was deleted and characterized by growth profiling and transcriptomics along with a xyr1 mutant and xyr1/ara1 double mutant. Our results show that in addition to the l-arabinose-related role, T. reesei ARA1 is essential for expression of d-galactose releasing and catabolic genes, while XYR1 is not involved in this process.
Topics: Arabinose; Fungal Proteins; Galactose; Gene Expression Regulation, Fungal; Genes, Fungal; Magnaporthe; Mutation; Trichoderma
PubMed: 29215697
DOI: 10.1002/1873-3468.12932 -
Applied and Environmental Microbiology Mar 2010Bacteria such as Escherichia coli will often consume one sugar at a time when fed multiple sugars, in a process known as carbon catabolite repression. The classic...
Bacteria such as Escherichia coli will often consume one sugar at a time when fed multiple sugars, in a process known as carbon catabolite repression. The classic example involves glucose and lactose, where E. coli will first consume glucose, and only when it has consumed all of the glucose will it begin to consume lactose. In addition to that of lactose, glucose also represses the consumption of many other sugars, including arabinose and xylose. In this work, we characterized a second hierarchy in E. coli, that between arabinose and xylose. We show that, when grown in a mixture of the two pentoses, E. coli will consume arabinose before it consumes xylose. Consistent with a mechanism involving catabolite repression, the expression of the xylose metabolic genes is repressed in the presence of arabinose. We found that this repression is AraC dependent and involves a mechanism where arabinose-bound AraC binds to the xylose promoters and represses gene expression. Collectively, these results demonstrate that sugar utilization in E. coli involves multiple layers of regulation, where cells will consume first glucose, then arabinose, and finally xylose. These results may be pertinent in the metabolic engineering of E. coli strains capable of producing chemical and biofuels from mixtures of hexose and pentose sugars derived from plant biomass.
Topics: Arabinose; Escherichia coli; Gene Expression Regulation, Bacterial; Gene Expression Regulation, Enzymologic; Glucose; Xylose
PubMed: 20023096
DOI: 10.1128/AEM.01970-09 -
Scientific Reports Jun 2022Bifidobacteria are amongst the first bacteria to colonize the human gastro-intestinal system and have been proposed to play a crucial role in the development of the...
Bifidobacteria are amongst the first bacteria to colonize the human gastro-intestinal system and have been proposed to play a crucial role in the development of the infant gut since their absence is correlated to the development of diseases later in life. Bifidobacteria have the capacity to metabolize a diverse range of (complex) carbohydrates, reflecting their adaptation to the lower gastro-intestinal tract. Detailed understanding of carbohydrate metabolism regulation in this genus is of prime importance and availability of additional genetic tools easing such studies would be beneficial. To develop a fluorescent protein-based reporter system that can be used in B. longum NCC 2705, we first selected the most promising fluorescent protein out of the seven we tested (i.e., mCherry). This reporter protein was then used to study the carbohydrate mediated activation of P and P, two promoters respectively predicted to be controlled by the transcriptional factors AraQ and AraU, previously suggested to regulate arabinose utilization and proposed to also act as global transcriptional regulators in bifidobacteria. We confirmed that in B. longum NCC 2705 the AraQ controlled promoter (P) is induced strongly by arabinose and established that the AraU controlled promoter (P) was mostly induced by the hexoses galactose and fructose. Combining the mCherry reporter system with flow cytometry, we established that NCC 2705 is able to co-metabolize arabinose and glucose while galactose was only consumed after glucose exhaustion, thus illustrating the complexity of different carbohydrate consumption patterns and their specific regulation in this strain.
Topics: Arabinose; Bifidobacterium; Bifidobacterium longum; Carbohydrates; Galactose; Glucose; Humans; Infant
PubMed: 35729224
DOI: 10.1038/s41598-022-14638-4 -
Extremophiles : Life Under Extreme... Sep 2020The degradation of the pentoses D-xylose, L-arabinose and D-ribose in the domain of archaea, in Haloferax volcanii and in Haloarcula and Sulfolobus species, has been...
The degradation of the pentoses D-xylose, L-arabinose and D-ribose in the domain of archaea, in Haloferax volcanii and in Haloarcula and Sulfolobus species, has been shown to proceed via oxidative pathways to generate α-ketoglutarate. Here, we report that the haloarchaeal Halorhabdus species utilize the bacterial-type non-oxidative degradation pathways for pentoses generating xylulose-5-phosphate. The genes of these pathways are each clustered and were constitutively expressed. Selected enzymes involved in D-xylose degradation, xylose isomerase and xylulokinase, and those involved in L-arabinose degradation, arabinose isomerase and ribulokinase, were characterized. Further, D-ribose degradation in Halorhabdus species involves ribokinase, ribose-5-phosphate isomerase and D-ribulose-5-phosphate-3-epimerase. Ribokinase of Halorhabdus tiamatea and ribose-5-phosphate isomerase of Halorhabdus utahensis were characterized. This is the first report of pentose degradation via the bacterial-type pathways in archaea, in Halorhabdus species that likely acquired these pathways from bacteria. The utilization of bacterial-type pathways of pentose degradation rather than the archaeal oxidative pathways generating α-ketoglutarate might be explained by an incomplete gluconeogenesis in Halorhabdus species preventing the utilization of α-ketoglutarate in the anabolism.
Topics: Arabinose; Bacteria; Halobacteriaceae; Pentoses; Ribose; Xylose
PubMed: 32761262
DOI: 10.1007/s00792-020-01192-y -
Microbial Cell Factories Aug 2023R. toruloides is an oleaginous yeast, with diverse metabolic capacities and high tolerance for inhibitory compounds abundant in plant biomass hydrolysates. While R....
R. toruloides is an oleaginous yeast, with diverse metabolic capacities and high tolerance for inhibitory compounds abundant in plant biomass hydrolysates. While R. toruloides grows on several pentose sugars and alcohols, further engineering of the native pathway is required for efficient conversion of biomass-derived sugars to higher value bioproducts. A previous high-throughput study inferred that R. toruloides possesses a non-canonical L-arabinose and D-xylose metabolism proceeding through D-arabitol and D-ribulose. In this study, we present a combination of genetic and metabolite data that refine and extend that model. Chiral separations definitively illustrate that D-arabitol is the enantiomer that accumulates under pentose metabolism. Deletion of putative D-arabitol-2-dehydrogenase (RTO4_9990) results in > 75% conversion of D-xylose to D-arabitol, and is growth-complemented on pentoses by heterologous xylulose kinase expression. Deletion of putative D-ribulose kinase (RTO4_14368) arrests all growth on any pentose tested. Analysis of several pentose dehydrogenase mutants elucidates a complex pathway with multiple enzymes mediating multiple different reactions in differing combinations, from which we also inferred a putative L-ribulose utilization pathway. Our results suggest that we have identified enzymes responsible for the majority of pathway flux, with additional unknown enzymes providing accessory activity at multiple steps. Further biochemical characterization of the enzymes described here will enable a more complete and quantitative understanding of R. toruloides pentose metabolism. These findings add to a growing understanding of the diversity and complexity of microbial pentose metabolism.
Topics: Xylose; Arabinose; Pentoses
PubMed: 37537595
DOI: 10.1186/s12934-023-02126-x -
Sheng Wu Gong Cheng Xue Bao = Chinese... Jun 2017Kluyveromyces marxianus, as unconventional yeast, attracts more and more attention in the biofuel fermentation. Although this sort of yeasts can ferment pentose sugars,...
Kluyveromyces marxianus, as unconventional yeast, attracts more and more attention in the biofuel fermentation. Although this sort of yeasts can ferment pentose sugars, the fermentation capacity differs largely. Xylose and arabinose fermentation by three K. marxianus strains (K. m 9009, K. m 1911 and K. m 1727) were compared at different temperatures. The results showed that the fermentation performance of the three strains had significant difference under different fermentation temperatures. Especially, the sugar consumption rate and alcohol yield of K. m 9009 and K. m 1727 at 40 ℃ were better than 30 ℃. This results fully reflect the fermentation advantages of K. marxianus yeast under high-temperature. On this basis, five genes (XR, XDH, XK, AR and LAD) coding key metabolic enzymes in three different yeasts were amplified by PCR, and the sequence were compared by Clustalx 2.1. The results showed that the amino acid sequences coding key enzymes have similarity of over 98% with the reference sequences reported in the literature. Furthermore, the difference of amino acid was not at the key site of its enzyme, so the differences between three stains were not caused by the gene level, but by transcribed or translation regulation level. By real-time PCR experiment, we determined the gene expression levels of four key enzymes (XR, XDH, XK and ADH) in the xylose metabolism pathway of K. m 1727 and K. m 1911 at different fermentation time points. The results showed that, for thermotolerant yeast K. m 1727, the low expression level of XDH and XK genes was the main factors leading to accumulation of xylitol. In addition, according to the pathway of Zygosaccharomyces bailii, which have been reported in NCBI and KEGG, the xylose and arabinose metabolic pathways of K. marxianus were identified, which laid foundation for further improving the pentose fermentation ability by metabolic engineering.
Topics: Arabinose; Ethanol; Fermentation; Industrial Microbiology; Kluyveromyces; Xylose
PubMed: 28895354
DOI: 10.13345/j.cjb.160458 -
Ultrasonics Sonochemistry Sep 2022This study investigated the effects of different ultrasonic power and ultrasonic time on the structure and emulsifying properties of pea protein isolate (PPI)-arabinose...
This study investigated the effects of different ultrasonic power and ultrasonic time on the structure and emulsifying properties of pea protein isolate (PPI)-arabinose conjugates. An examination of the absorbance and color development of PPI-d-arabinose (Ara) conjugates found that compared with traditional heating, the degree of glycosylation of protein reached the maximum when the ultrasonic treatment power was 150 and the treatment time was 30 min. Structural analysis revealed that the content of disordered structures (β-turn and random coil) of the protein conjugates increased, the maximum emission wavelength of the fluorescence spectrum was red-shifted, and the UV second-order derivative values decreased. The protein structure unfolded, exposing more hydrophobic groups on the molecular surface. Ultrasonic treatment improved the emulsification of protein conjugates. The emulsifying activity index (EAI) increased to 19.7 and 19.3 m/g, and the emulsifying stability index (ESI) also increased. The contact angle and zeta potential also demonstrate that ultrasonic power has a positive effect on emulsion stability. Based on examining the thermal stability of the emulsion, the ultrasonic treatment increased the thermal denaturation resistance of the protein. This result confirms that mild sonication can increase the degree of glycosylation reaction and improve the emulsification properties of protein-Ara conjugates, providing a theoretical basis for developing foods with excellent emulsification properties.
Topics: Arabinose; Emulsifying Agents; Emulsions; Glycosylation; Hydrophobic and Hydrophilic Interactions; Maillard Reaction; Pea Proteins; Solubility
PubMed: 36088895
DOI: 10.1016/j.ultsonch.2022.106157