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Astrobiology May 2021Preferential uptake of either levorotatory (L) or dextrorotatory (D) enantiomer of a chiral molecule is a potential planetary life-detection method. On Earth, bacteria,...
Preferential uptake of either levorotatory (L) or dextrorotatory (D) enantiomer of a chiral molecule is a potential planetary life-detection method. On Earth, bacteria, as a rule, metabolize D-sugars and L-amino acids. Here, we use growth experiments to identify exceptions to the rule and their potential impact on the method's reliability. Our experiments involve six strains of and collective uptake of the sugars glucose and arabinose, and the amino acids alanine, glutamic acid, leucine, cysteine, and serine-all of which are highly soluble. We find that selective uptake is not evident unless (1) each sugar is tested individually and (2) multiple amino acids are tested together in a mixture. Combining sugars should be avoided because, as we show in bacteria, the same organisms may catabolize one sugar, glucose, in D-form and another sugar, arabinose, in L-form. Single amino acids should be avoided because bacteria can access certain proteinogenically incompatible enantiomers using specific racemases. Specifically, bacteria contain an alanine acid racemase and can catabolize D-alanine if no other D-amino acids are present. The proposed improvements would reliably separate nonselective chemical reactions from biological reactions and, if life is indicated, inform whether the selective patterns for amino acids and sugars are the same as on Earth.
Topics: Alanine; Amino Acids; Carbohydrates; Reproducibility of Results; Stereoisomerism
PubMed: 33885325
DOI: 10.1089/ast.2020.2381 -
Food & Function Mar 2021l-Arabinose is a kind of plant-specific five-carbon aldose with benefits in type 2 diabetes mellitus. It has been shown to have good properties in improving glucose...
l-Arabinose is a kind of plant-specific five-carbon aldose with benefits in type 2 diabetes mellitus. It has been shown to have good properties in improving glucose homeostasis, but the underlying molecular mechanisms are still not clear. Hepatic gluconeogenesis is critical for regulating glucose homeostasis. Here, this study aimed to investigate whether l-arabinose could improve glucose metabolism via suppressing hepatic gluconeogenesis. High-fat-high-sucrose diet (HFHSD) or high-sucrose diet (HSD)-fed mice were supplemented with or without l-arabinose for 12 weeks. Fasting blood glucose levels were measured and glucose tolerance test and the histological analysis were performed after l-arabinose administration. AMP-activated protein kinase (AMPK), acetyl-CoA carboxylase (ACC), peroxisome proliferator activated receptor-γ coactivator-1α (PGC1α), Forkhead box O1 (FoxO1), phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase) expression levels were determined by RT-PCR and western blotting. As expected, l-arabinose apparently decreased body weight and attenuated hyperglycemia and glucose intolerance caused by HFHSD or HSD. l-Arabinose also had beneficial effects on glycogen synthesis by inactivating GSK3β. The expression levels of gluconeogenic genes were all decreased by l-arabinose administration in vivo and in vitro. In addition, our work revealed that AMPK is required for the inhibitory effects of l-arabinose on hepatic gluconeogenesis. l-Arabinose significantly up-regulated the phosphorylated levels of AMPK and its downstream protein ACC. Furthermore, blocking AMPK signaling through an inhibitor (compound C) or siAMPK significantly attenuated the inhibition of hepatic gluconeogenesis and the promotion of glycogen synthesis with l-arabinose, indicating that the inhibitory effect of l-arabinose on hepatic gluconeogenesis was AMPK dependent. Our work revealed that l-arabinose is a promising natural product for the regulation of hyperglycemia through inhibition of hepatic gluconeogenesis by activating AMPK.
Topics: AMP-Activated Protein Kinases; Animals; Arabinose; Blood Glucose; Disease Models, Animal; Gluconeogenesis; Hyperglycemia; Male; Mice; Mice, Inbred C57BL
PubMed: 33502423
DOI: 10.1039/d0fo02163f -
Molecules (Basel, Switzerland) Dec 2022The extraction, characterization and antioxidant activity of polysaccharides from leaves were investigated in the present study. Two purified polysaccharide fractions,...
The extraction, characterization and antioxidant activity of polysaccharides from leaves were investigated in the present study. Two purified polysaccharide fractions, CALP-1 and CALP-2, were isolated from crude leaf polysaccharides (CALP) by DEAE-52 cellulose chromatography and Sephadex G-100 column chromatography. The characteristics of CAL-1 and CALP-2 were determined by using High-performance Gel Permeation Chromatography (HPGPC), High-Performance Anion-Exchange Chromatography, HPAEC (HPAEC-PAD) and Fourier transform infrared spectroscopy (FTIR). CALP-1 with molecular weight of 11.20 KDa was comprised of Rhamnose, Arabinose, Galactose, Glucose, Xylose, Mannose and galacturonic acid in a molar ratio of 5.16:2.31:5.50:27.18:1.00:0.76:1.07. CAL-2 with molecular weight of 8.03 KDa consisted of Rhamnose, Arabinose, Galactose, Glucose, and galacturonic acid at a ratio of 1.38:3.63:18.84:8.28:1.45. FTIR revealed that CALP-1 and CALP-2 were acidic polysaccharides. The antioxidant activity of crude CALP, CALP-1 and CALP-2 was evaluated in vitro. The fraction CALP-2 was demonstrated to be of polysaccharide nature containing a large percentage of Galactose but no Xylose and Mannose. The antioxidant activity assays showed that CALP-1 and CALP-2 exhibited antioxidant and scavenging activities on hydroxyl and DPPH radicals in vitro. Compared with pure polysaccharide, crude CALP exhibited stronger anti-oxidant activities. These results will provide a better understanding of axillaris leaf polysaccharide and promote the potential applications of axillaris leaf polysaccharide in the pharmacological field and as a natural antioxidant.
Topics: Antioxidants; Galactose; Mannose; Rhamnose; Arabinose; Molecular Weight; Chromatography, Gel; Polysaccharides; Plant Leaves; Glucose
PubMed: 36558014
DOI: 10.3390/molecules27248881 -
Biochemical and Biophysical Research... Sep 2020L-Arabinose 1-dehydrogenase (AraDH) is responsible for the first step of the non-phosphorylative L-arabinose pathway from bacteria, and catalyzes the NAD(P)-dependent...
L-Arabinose 1-dehydrogenase (AraDH) is responsible for the first step of the non-phosphorylative L-arabinose pathway from bacteria, and catalyzes the NAD(P)-dependent oxidation of L-arabinose to L-arabinonolactone. This enzyme belongs to the so-called Gfo/Idh/MocA protein superfamily, but has a very poor phylogenetic relationship with other functional members. We previously reported the crystal structures of AraDH without a ligand and in complex with NADP. To clarify the underlying catalytic mechanisms in more detail, we herein elucidated the crystal structure in complex with L-arabinose and NADP. In addition to the previously reported five amino acid residues (Lys91, Glu147, His153, Asp169, and Asn173), His119, Trp152, and Trp231 interacted with L-arabinose, which were not found in substrate recognition by other Gfo/Idh/MocA members. Structure-based site-directed mutagenic analyses suggested that Asn173 plays an important role in catalysis, whereas Trp152, Trp231, and His119 contribute to substrate binding. The preference of NADP over NAD was significantly subjected by a pair of Ser37 and Arg38, whose manners were similar to other Gfo/Idh/MocA members.
Topics: Amino Acid Sequence; Arabinose; Azospirillum brasilense; Bacterial Proteins; Carbohydrate Dehydrogenases; Crystallography, X-Ray; Models, Molecular; NADP; Protein Conformation
PubMed: 32828286
DOI: 10.1016/j.bbrc.2020.07.071 -
International Journal of Molecular... Oct 2022Cardiovascular diseases are associated with platelet hyperactivity, and downregulating platelet activation is one of the promising antithrombotic strategies. This study...
Cardiovascular diseases are associated with platelet hyperactivity, and downregulating platelet activation is one of the promising antithrombotic strategies. This study newly extracted two polysaccharides (purified exopolysaccharides, EPSp and purified intercellular exopolysaccharides, IPSp) from Cs-4 mycelial fermentation powder, and investigated the effects of the two polysaccharides and their gut bacterial metabolites on platelet functions and thrombus formation. EPSp and IPSp are majorly composed of galactose, mannose, glucose, and arabinose. Both EPSp and IPSp mainly contain 4-Gal and 4-Glc glycosidic linkages. EPSp and IPSp significantly inhibited human platelet activation and aggregation with a dose-dependent manner, and attenuated thrombus formation in mice without increasing bleeding risk. Furthermore, the EPSp and IPSp after fecal fermentation showed enhanced platelet inhibitory effects. The results have demonstrated the potential value of Cs-4 polysaccharides as novel protective ingredients for cardiovascular diseases.
Topics: Mice; Humans; Animals; Galactose; Fibrinolytic Agents; Mannose; Arabinose; Cardiovascular Diseases; Powders; Polysaccharides; Cordyceps; Thrombosis; Glucose
PubMed: 36293463
DOI: 10.3390/ijms232012608 -
Applied and Environmental Microbiology Nov 2021PcAxy43B is a modular protein comprising a catalytic domain of glycoside hydrolase family 43 (GH43), a family 6 carbohydrate-binding module (CBM6), and a family 36...
A Novel Multifunctional Arabinofuranosidase/Endoxylanase/β-Xylosidase GH43 Enzyme from Paenibacillus curdlanolyticus B-6 and Its Synergistic Action To Produce Arabinose and Xylose from Cereal Arabinoxylan.
PcAxy43B is a modular protein comprising a catalytic domain of glycoside hydrolase family 43 (GH43), a family 6 carbohydrate-binding module (CBM6), and a family 36 carbohydrate-binding module (CBM36) and found to be a novel multifunctional xylanolytic enzyme from Paenibacillus curdlanolyticus B-6. This enzyme exhibited α-l-arabinofuranosidase, endoxylanase, and β-d-xylosidase activities. The α-l-arabinofuranosidase activity of PcAxy43B revealed a new property of GH43, via the release of both long-chain cereal arabinoxylan and short-chain arabinoxylooligosaccharide (AXOS), as well as release from both the C(O) and C(O) positions of AXOS, which is different from what has been seen for other arabinofuranosidases. PcAxy43B liberated a series of xylooligosaccharides (XOSs) from birchwood xylan and xylohexaose, indicating that PcAxy43B exhibited endoxylanase activity. PcAxy43B produced xylose from xylobiose and reacted with -nitrophenyl-β-d-xylopyranoside as a result of β-xylosidase activity. PcAxy43B effectively released arabinose together with XOSs and xylose from the highly arabinosyl-substituted rye arabinoxylan. Moreover, PcAxy43B showed significant synergistic action with the trifunctional endoxylanase/β-xylosidase/α-l-arabinofuranosidase PcAxy43A and the endoxylanase Xyn10C from strain B-6, in which almost all products produced from rye arabinoxylan by these combined enzymes were arabinose and xylose. In addition, the presence of CBM36 was found to be necessary for the endoxylanase property of PcAxy43B. PcAxy43B is capable of hydrolyzing untreated cereal biomass, corn hull, and rice straw into XOSs and xylose. Hence, PcAxy43B, a significant accessory multifunctional xylanolytic enzyme, is a potential candidate for application in the saccharification of cereal biomass. Enzymatic saccharification of cereal biomass is a strategy for the production of fermented sugars from low-price raw materials. In the present study, PcAxy43B from B-6 was found to be a novel multifunctional α-l-arabinofuranosidase/endoxylanase/β-d-xylosidase enzyme of glycoside hydrolase family 43. It is effective in releasing arabinose, xylose, and XOSs from the highly arabinosyl-substituted rye arabinoxylan, which is usually resistant to hydrolysis by xylanolytic enzymes. Moreover, almost all products produced from rye arabinoxylan by the combination of PcAxy43B with the trifunctional xylanolytic enzyme PcAxy43A and the endoxylanase Xyn10C from strain B-6 were arabinose and xylose, which can be used to produce several value-added products. In addition, PcAxy43B is capable of hydrolyzing untreated cereal biomass into XOSs and xylose. Thus, PcAxy43B is an important multifunctional xylanolytic enzyme with high potential in biotechnology.
Topics: Arabinose; Bacterial Proteins; Edible Grain; Endo-1,4-beta Xylanases; Glycoside Hydrolases; Multifunctional Enzymes; Paenibacillus; Xylans; Xylose; Xylosidases
PubMed: 34613758
DOI: 10.1128/AEM.01730-21 -
Bioresource Technology Jan 2021Two-stage pretreatment conditions were optimized to convert corn fiber, separated from whole stillage in a corn dry grind ethanol plant, to fermentable sugars via...
Two-stage pretreatment conditions were optimized to convert corn fiber, separated from whole stillage in a corn dry grind ethanol plant, to fermentable sugars via hydrolysis. Liquid hot water pretreatment (25% solids) at 180 °C for 10 min, followed by three cycles of disk milling, provided maximum glucose, xylose, and arabinose yields of 88.5%, 41.0%, and 30.4% respectively after hydrolysis with Cellulase I. The glucose, xylose, and arabinose yields with Cellulase II at optimum conditions were 94.9%, 74.2%, and 66.3%, respectively. SSF of corn fiber using engineered yeast, with both Cellulase I and II, provided maximum ethanol concentrations of 2.13% and 2.73% (v/v). The protein content in the residual solid after fermentation was 47.95% and 52.05% for Cellulase I and II, respectively. This technology provides additional ethanol in a dry grind plant by converting corn fiber into ethanol and increases the protein content of DDGS, thereby improving the quality.
Topics: Ethanol; Fermentation; Hydrolysis; Technology; Xylose; Zea mays
PubMed: 33217695
DOI: 10.1016/j.biortech.2020.124380 -
Animal Nutrition (Zhongguo Xu Mu Shou... Sep 2019Dietary fibers (DF) contain an abundant amount of energy, although the mammalian genome does not encode most of the enzymes required to degrade them. However, a mutual... (Review)
Review
Dietary fibers (DF) contain an abundant amount of energy, although the mammalian genome does not encode most of the enzymes required to degrade them. However, a mutual dependence is developed between the host and symbiotic microbes, which has the potential to extract the energy present in these DF. Dietary fibers escape digestion in the foregut and are fermented in the hindgut, producing short-chain fatty acids (SCFA) that alter the microbial ecology in the gastrointestinal tract (GIT) of pigs. Most of the carbohydrates are fermented in the proximal part, allowing protein fermentation in the distal part, resulting in colonic diseases. The structures of resistant starch (RS), arabinoxylan (AX), and β-glucan (βG) are complex; hence, makes their way into the hindgut where these are fermented and provide energy substrates for the colonic epithelial cells. Different microbes have different preferences of binding to different substrates. The RS, AX and βG act as a unique substrate for the microbes and modify the relative composition of the gut microbial community. The granule dimension and surface area of each substrate are different, which influences the penetration capacity of microbes. Arabinose and xylan are 2 different hemicelluloses, but arabinose is substituted on the xylan backbone and occurs in the form of AX. Fermentation of xylan produces butyrate primarily in the small intestine, whereas arabinose produces butyrate in the large intestine. Types of RS and forms of βG also exert beneficial effects by producing different metabolites and modulating the intestinal microbiota. Therefore, it is important to have information of different types of RS, AX and βG and their roles in microbial modulation to get the optimum benefits of fiber fermentation in the gut. This review provides relevant information on the similarities and differences that exist in the way RS, AX, and βG are fermented, and their positive and negative effects on SCFA production and gut microbial ecology of pigs. These insights will help nutritionists to develop dietary strategies that can modulate specific SCFA production and promote beneficial microbiota in the GIT of swine.
PubMed: 31528722
DOI: 10.1016/j.aninu.2019.04.003 -
Sheng Wu Gong Cheng Xue Bao = Chinese... Mar 2023Lysis is a common functional module in synthetic biology and is widely used in genetic circuit design. Lysis could be achieved by inducing expression of lysis cassettes...
Lysis is a common functional module in synthetic biology and is widely used in genetic circuit design. Lysis could be achieved by inducing expression of lysis cassettes originated from phages. However, detailed characterization of lysis cassettes hasn't been reported yet. Here, we first adopted arabinose- and rhamnose-inducible systems to develop inducible expression of five lysis cassettes (, , , , ) in Top10. By measuring , we characterized the lysis behavior of strains harboring different lysis cassettes. These strains were harvested at different growth stages, induced with different concentrations of chemical inducers, or contained plasmids with different copy numbers. We found that although all five lysis cassettes could induce bacterial lysis in Top10, lysis behaviors differed a lot at various conditions. We further found that due to the difference in background expression levels between strain Top10 and PAO1, it was hard to construct inducible lysis systems in strain PAO1. The lysis cassette controlled by rhamnose-inducible system was finally inserted into the chromosome of strain PAO1 to construct lysis strains after careful screen. The results indicated that and were more effective in strain PAO1 than , and . At last, we constructed an engineered bacteria Q16 using an optogenetic module BphS and the lysis cassette . The engineered strain was capable of adhering to target surface and achieving light-induced lysis by tuning the strength of ribosome binding sites (RBSs), showing great potential in surface modification.
Topics: Rhamnose; Plasmids; Pseudomonas aeruginosa; Escherichia coli
PubMed: 36994578
DOI: 10.13345/j.cjb.220757 -
International Journal of Biological... Dec 2020Three novel polysaccharides (PCPW, PCPS1 and PCPS2) were isolated from Potentilla chinensis and subjected to structural analysis by using spectral and physicochemical...
Three novel polysaccharides (PCPW, PCPS1 and PCPS2) were isolated from Potentilla chinensis and subjected to structural analysis by using spectral and physicochemical methods. The molecular weights of PCPW, PCPS1 and PCPS2 were calculated to be 4.45 × 10 Da, 1.18 × 10 Da and 4.23 × 10 Da, respectively. Analysis of monosaccharides composition confirmed that PCPW was composed of mannose, rhamnose, glucose, galactose and arabinose, while the two acidic polysaccharides PCPS1 and PCPS2 were consisted of six monosaccharides, including mannose, rhamnose, galacturonic acid, glucose, galactose and arabinose respectively. In addition, the main linkages of glycosidic bonds of PCPS2 were 1, 4-linked-rha, 1, 4-linked-man,1, 4-linked-galA and 1, 6-linked-man. Immunological tests indicated that both PCPW and PCPS2 could increase NO production of RAW264.7 cells, and promote splenocyte proliferation. All three polysaccharides proved to be activators of NF-κB. Overall, three polysaccharides showed a good immunological activity and pose great potential as a novel food or drug additive.
Topics: Animals; Carbohydrate Conformation; Cell Proliferation; Mice; Polysaccharides; Potentilla; RAW 264.7 Cells; Spleen
PubMed: 32961189
DOI: 10.1016/j.ijbiomac.2020.09.118