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Quintin Borgersen, David T Bolick, Glynis L Kolling, Matthew Aijuka, Fernando Ruiz-Perez, Richard L Guerrant, James P Nataro, Araceli E Santiago
Enteroaggregative E. coli (EAEC) is associated with food-borne outbreaks of diarrhea and growth faltering among children in developing countries. A Shiga toxin-producing EAEC strain of serotype O104:H4 strain caused one of the largest outbreaks of a food-borne infection in Europe in 2011. The outbreak was traced to contaminated fenugreek sprouts, yet the mechanisms whereby such persistent contamination of sprouts could have occurred are not clear. We found that under ambient conditions of temperature and in minimal media, pathogenic Shiga toxin-producing EAEC O104:H4 227-11 and non-Shiga toxin-producing 042 strains both produce high levels of exopolysaccharide structures (EPS) that are released to the external milieu...
March 15, 2018: Gut Microbes
John B McArthur, Hai Yu, Nova Tasnima, Christie M Lee, Andrew J Fisher, Xi Chen
The lack of α2-6-linkage specific sialidases limits the structural and functional studies of sialic acid-containing molecules. Photobacterium damselae α2-6-sialyltransferase (Pd2,6ST) was shown previously to have α2-6-specific, but weak, sialidase activity. Here we develop a high-throughput blue-white colony screening method to identify Pd2,6ST mutants with improved α2-6-sialidase activity from mutant libraries generated by sequential saturation mutagenesis. A triple mutant (Pd2,6ST S232L/T356S/W361F) has been identified with 101-fold improved activity, high α2-6-sialyl linkage selectivity, good activity in cleaving two common sialic acid forms N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc)...
March 15, 2018: ACS Chemical Biology
Sara Silva Pereira, Andrew P Jackson
BACKGROUND: Trypanosomatid parasites such as Trypanosoma spp. and Leishmania spp. are a major source of infectious disease in humans and domestic animals worldwide. Fundamental to the host-parasite interactions of these potent pathogens are their cell surfaces, which are highly decorated with glycosylated proteins and other macromolecules. Trypanosomatid genomes contain large multi-copy gene families encoding UDP-dependent glycosyltransferases (UGTs), the primary role of which is cell-surface decoration...
March 14, 2018: BMC Evolutionary Biology
Annika Wahl, Erik van den Akker, Lucija Klaric, Jerko Štambuk, Elisa Benedetti, Rosina Plomp, Genadij Razdorov, Irena Trbojević-Akmačić, Joris Deelen, Diana van Heemst, P Eline Slagboom, Frano Vučković, Harald Grallert, Jan Krumsiek, Konstantin Strauch, Annette Peters, Thomas Meitinger, Caroline Hayward, Manfred Wuhrer, Marian Beekman, Gordan Lauc, Christian Gieger
Immunoglobulin G (IgG), a glycoprotein secreted by plasma B-cells, plays a major role in the human adaptive immune response and are associated with a wide range of diseases. Glycosylation of the Fc binding region of IgGs, responsible for the antibody's effector function, is essential for prompting a proper immune response. This study focuses on the general genetic impact on IgG glycosylation as well as corresponding subclass specificities. To identify genetic loci involved in IgG glycosylation, we performed a genome-wide association study (GWAS) on liquid chromatography electrospray mass spectrometry (LC-ESI-MS)-measured IgG glycopeptides of 1,823 individuals in the Cooperative Health Research in the Augsburg Region (KORA F4) study cohort...
2018: Frontiers in Immunology
Kelley M Heffner, Qiong Wang, Deniz Baycin Hizal, Özge Can, Michael J Betenbaugh
Mammalian expression systems such as Chinese hamster ovary (CHO), mouse myeloma (NS0), and human embryonic kidney (HEK) cells serve a critical role in the biotechnology industry as the production host of choice for recombinant protein therapeutics. Most of the recombinant biologics are glycoproteins that contain complex oligosaccharide or glycan attachments representing a principal component of product quality. Both N-glycans and O-glycans are present in these mammalian cells, but the engineering of N-linked glycosylation is of critical interest in industry and many efforts have been directed to improve this pathway...
March 13, 2018: Advances in Biochemical Engineering/biotechnology
Eliana Marzol, Cecilia Borassi, Mauro Bringas, Ana Sede, Diana Rosa Rodríguez Garcia, Luciana Capece, Jose M Estevez
Extensins (EXTs) are highly repetitive plant O-glycoproteins that require several post-translational modifications (PTMs) to become functional in plant cell walls. First, they are hydroxylated on contiguous proline residues; then, they are O-glycosylated on hydroxyproline (Hyp) and serine. After secretion into the apoplast, O-glycosylated EXTs form a tridimensional network organized by inter- and intra-Tyr linkages. Recent studies have made significant progress in the identification of the enzymatic machinery required to process EXTs, which includes prolyl 4-hydroxylases (P4Hs), glycosyltransferases (GTs), papain-type cysteine-endopeptidases (CEPs), and peroxidases (PERs)...
March 9, 2018: Molecular Plant
Hua Wang, Wenxi Zhou, Hua Li, Rie Bu
The cyclodextrin glycosyltransferase (CGTase) was used to catalyze the conversion of starch into cyclodextrins (CD) in industry. Improving the activity of CGTase to produce more CD with relative low cost is intensely interesting and has drawn wide attention. Amino acid mutation of His167 into Cys significantly enhanced β-CGTase activity; however, optimization of culture conditions for β-CGTase-H167C remains unclear. To determine this, the medium and culture conditions for β-CGTase-H167C were optimized with response surface methodology...
March 2018: 3 Biotech
Maria C Rodriguez Benavente, Pablo Argüeso
Glycosylation is a major form of enzymatic modification of organic molecules responsible for multiple biological processes in an organism. The biosynthesis of glycans is controlled by a series of glycosyltransferases, glycosidases and glycan-modifying enzymes that collectively assemble and process monosaccharide moieties into a diverse array of structures. Many studies have provided insight into various pathways of glycosylation at the ocular surface, such as those related to the biosynthesis of mucin-type O -glycans and N -glycans on proteins, but many others still remain largely unknown...
March 9, 2018: Biochemical Society Transactions
Kai Feng, Zhi-Sheng Xu, Jie-Xia Liu, Jing-Wen Li, Feng Wang, Ai-Sheng Xiong
This study showed that a galactosyltransferase, AgUCGalT1, is involved in anthocyanin galactosylation in purple celery. Celery is a well-known vegetable because of its rich nutrients, low calories, and medicinal values. Its petioles and leaf blades are the main organs acting as nutrient sources. UDP-galactose: cyanidin 3-O-galactosyltransferase can transfer the galactosyl moiety from UDP-galactose to the 3-O-position of cyanidin through glycosylation. This process enhances the stability and water solubility of anthocyanins...
March 8, 2018: Planta
Ming-Wei Chien, Shin-Huei Fu, Chao-Yuan Hsu, Yu-Wen Liu, Huey-Kang Sytwu
Glycosylation is a ubiquitous posttranslational modification of proteins that occurs in the endoplasmic reticulum/Golgi. N -glycans and mucin-type O -glycans are achieved via a series of glycohydrolase- and glycosyltransferase-mediated reactions. Glycosylation modulates immune responses by regulating thymocyte development and T helper cell differentiation. Autoimmune diseases result from an abnormal immune response by self-antigens and subsequently lead to the destruction of the target tissues. The modification of N -glycans has been studied in several animal models of T-cell-mediated autoimmune diseases...
March 8, 2018: International Journal of Molecular Sciences
Benoit Couvigny, Saulius Kulakauskas, Nicolas Pons, Benoit Quinquis, Anne-Laure Abraham, Thierry Meylheuc, Christine Delorme, Pierre Renault, Romain Briandet, Nicolas Lapaque, Eric Guédon
Biofilm formation is crucial for bacterial community development and host colonization by Streptococcus salivarius , a pioneer colonizer and commensal bacterium of the human gastrointestinal tract. This ability to form biofilms depends on bacterial adhesion to host surfaces, and on the intercellular aggregation contributing to biofilm cohesiveness. Many S. salivarius isolates auto-aggregate, an adhesion process mediated by cell surface proteins. To gain an insight into the genetic factors of S. salivarius that dictate host adhesion and biofilm formation, we developed a screening method, based on the differential sedimentation of bacteria in semi-liquid conditions according to their auto-aggregation capacity, which allowed us to identify twelve mutations affecting this auto-aggregation phenotype...
2018: Frontiers in Microbiology
Xiao Li, Chao-Qun Xu, Yu-Di Luo, Song Zhang, Cong Huang, Kun Zou, Ya-Li Tan, Ye-Xu Wu, Zhang-Shuang Deng
The computational fluid dynamics (CFD) software package Fluent was utilized to simulate the flow field of Escherichia coli (E. coli) BL21 fermentation in a 50 L automatic bioreactor for producing α-cyclodextrin glycosyltransferase (α-CGTase) in this study. 4-down-pumping propeller (4DPP), 6-curved-blade disc turbine (6CBDT), and Rushton turbine (RT) were assembled to form eight impeller combinations (C1-C8). Through flow field simulating, four referential impeller combinations, in which C6, C7, and C8 were three layers stirring blades and C1 as a control, were selected to carry out batch fermentation experiments (TC1, TC6, TC7, and TC8) for validation...
March 6, 2018: Bioprocess and Biosystems Engineering
Uche Godfrey Okeke, Deniz Akdemir, Ismail Rabbi, Peter Kulakow, Jean-Luc Jannink
The HarvestPlus program for cassava ( Crantz) fortifies cassava with β-carotene by breeding for carotene-rich tubers (yellow cassava). However, a negative correlation between yellowness and dry matter (DM) content has been identified. We investigated the genetic control of DM in white and yellow cassava. We used regional heritability mapping (RHM) to associate DM with genomic segments in both subpopulations. Significant segments were subjected to candidate gene analysis and candidates were validated with prediction accuracies...
March 2018: Plant Genome
Xiaogang Liu, Cailing Lin, Xiaodi Ma, Yan Tan, Jiuzhao Wang, Ming Zeng
Fruits of sweet orange ( Citrus sinensis ), a popular commercial Citrus species, contain high concentrations of flavonoids beneficial to human health. These fruits predominantly accumulate O -glycosylated flavonoids, in which the disaccharides [neohesperidose (rhamnosyl-α-1,2-glucose) or rutinose (rhamnosyl-α-1,6-glucose)] are linked to the flavonoid aglycones through the 3- or 7-hydroxyl sites. The biotransformation of the flavonoid aglycones into O -rutinosides or O -neohesperidosides in the Citrus plants usually consists of two glycosylation reactions involving a series of uridine diphosphate-sugar dependent glycosyltransferases (UGTs)...
2018: Frontiers in Plant Science
Fang-Yuan Gong, Zheng Gong, Cui-Cui Duo, Jun Wang, Chao Hong, Xiao-Ming Gao
Calreticulin (CRT), a luminal resident calcium-binding glycoprotein of the cell, is a tumor-associated antigen involved in tumorigenesis and also an autoantigen targeted by autoantibodies found in patients with various autoimmune diseases. We have previously shown that prokaryotically expressed recombinant murine CRT (rCRT) exhibits strong stimulatory activities against monocytes/macrophages in vitro and potent immunogenicity in vivo, which is partially attributable to self-oligomerization of soluble rCRT. However, even in oligomerized form native CRT (nCRT) isolated from mouse liver is much less active than rCRT, arguing against the possibility that self-oligomerization alone would license potent pro-inflammatory properties to nCRT...
February 27, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Xiaochao Xue, Ruixiang Blake Zheng, Akihiko Koizumi, Ling Han, John S Klassen, Todd L Lowary
Mycobacteria, including the human pathogen Mycobacterium tuberculosis, produce a complex cell wall that is critical for their survival. The largest structural component of the cell wall, the mycolyl-arabinogalactan-peptidoglycan complex, has at its core a galactan domain composed of d-galactofuranose residues. Mycobacterial galactan biosynthesis has been proposed to involve two glycosyltransferases, GlfT1 and GlfT2, which elongate polyprenol-pyrophosphate linked glycosyl acceptor substrates using UDP-galactofuranose as the donor substrate...
March 1, 2018: Organic & Biomolecular Chemistry
Jennie Grace Briard, Hao Jiang, Kelley W Moremen, Matthew Scott Macauley, Peng Wu
Glycan microarrays provide a high-throughput means of profiling the interactions of glycan-binding proteins with their ligands. However, the construction of current glycan microarray platforms is time consuming and expensive. Here, we report a fast and cost-effective method for the assembly of cell-based glycan arrays to probe glycan-glycan-binding protein interactions directly on the cell surface. Chinese hamster ovary cell mutants with a narrow and relatively homogeneous repertoire of glycoforms serve as the foundation platforms to develop these arrays...
February 28, 2018: Nature Communications
Longhai Dai, Can Liu, Jiao Li, Caixia Dong, Jiangang Yang, Zhubo Dai, Xueli Zhang, Yuanxia Sun
Ginsenosides, the major effective ingredients of Panax ginseng, exhibit various biological properties. UDP-glycosyltransferase (UGT)-mediated glycosylation is the last biosynthetic step of ginsenosides and contributes to their immense structural and functional diversity. In this study, UGT Bs-YjiC from Bacillus subtilis 168 was demonstrated can transfer a glucosyl moiety to the free C3-OH and C12-OH of protopanaxadiol (PPD) and PPD-type ginsenosides to synthesize natural and unnatural ginsenosides. In vitro assays showed that unnatural ginsenoside F12 (3-O-β-D-glucopyranosyl-12-O-β-D-glucopyranosyl-20(S)-protopanaxadiol) exhibited remarkable activity against diverse human cancer cell lines...
February 27, 2018: Journal of Agricultural and Food Chemistry
XuXu Huang, Guo-Qing Zhu, Qian Liu, Lu Chen, Yan-Jie Li, Bing-Kai Hou
Salicylic acid (SA) plays a crucial role in plant innate immunity. The deployment of SA-associated immune responses is primarily affected by SA concentration, which is determined by a balance between SA biosynthesis and catabolism. However, the mechanisms regulating SA homeostasis are poorly understood. In this study, we characterized a unique UDP-glycosyltransferase, UGT76D1, which plays an important role in SA homeostasis and associated immune responses in Arabidopsis thaliana. Expression of UGT76D1 was induced by treatment with both the pathogen Pseudomonas syringae pv...
February 26, 2018: Plant Physiology
Rachel Chen
Oligosaccharides, in either free or bound forms, play crucial roles in a wide range of biological processes. Increasing appreciation of their roles in cellular communication, interaction, pathogenesis, and prebiotic functions has stimulated tremendous interests in their synthesis. Pure and structurally defined oligosaccharides are essential for fundamental studies. On the other hand, for those with near term medical and nutraceutical applications, their large-scale synthesis is necessary. Unfortunately, oligosaccharides are notoriously difficult in their synthesis, and their enormous diverse structures leave a vast gap between what have been synthesized in laboratory and those present in various biological systems...
February 23, 2018: Applied Microbiology and Biotechnology
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