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https://www.readbyqxmd.com/read/29745231/synthesis-of-3-c-branched-kdo-analogs-via-sonogashira-coupling-of-3-iodo-kdo-glycal-with-terminal-alkynes
#1
Wenjing Fan, Yan Chen, Qixin Lou, Liqin Zhuang, You Yang
A highly efficient approach for the synthesis of 3- C-branched mono- and di-Kdo enyne analogs is developed for the first time based on Sonogashira coupling of terminal alkynes with 3-iodo Kdo glycal obtained by NIS/TMSOTf-promoted one-step reaction from peracetylated Kdo ethyl ester. Further transformation of 3- C-branched mono- and di-Kdo enyne analogs by asymmetric hydrogenation and saponification provided 2-deoxy-β-carboxyl Kdo analogs in a stereocontrolled mode.
May 10, 2018: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29697244/investigation-on-sugar-protein-connectivity-in-salmonella-o-antigen-glycoconjugate-vaccines
#2
Gianluigi De Benedetto, Laura Salvini, Stefano Gotta, Paola Cescutti, Francesca Micoli
Invasive nontyphoidal Salmonella disease, for which licensed vaccines are not available, is a leading cause of bloodstream infections in Africa. The O-antigen portion of lipopolysaccharide is a good target for protective immunity. Covalent conjugation of the O-antigen to a carrier protein increases its immunogenicity and O-antigen based glycoconjugate vaccines are currently under investigation at the preclinical stage. We developed a conjugation chemistry for linking O-antigen to CRM197 carrier protein, through sequential insertion of adipic acid dihydrazide (ADH) and adipic acid bis-(N-hydroxysuccinimide) ester (SIDEA) as linkers, without impacting on O-antigen chain epitopes...
April 26, 2018: Bioconjugate Chemistry
https://www.readbyqxmd.com/read/29606084/towards-novel-inhibitors-against-kdsb-a-highly-specific-and-selective-broad-spectrum-bacterial-enzyme
#3
Sajjad Ahmad, Saad Raza, Asma Abro, Klaus R Liedl, Syed Sikander Azam
KdsB (3-deoxy-manno-octulosonate cytidylyltransferase) is a highly specific and selective bacterial enzyme that catalyzes KDO (3-Deoxy-D-mano-oct-2-ulosonic acid) activation in KDO biosynthesis pathway. Failure in KDO biosynthesis causes accumulation of lipid A in the bacterial outer membrane that leads to cell growth arrest. This study reports a combinatorial approach comprising virtual screening of natural drugs library, molecular docking, computational pharmacokinetics, molecular dynamics simulation, and binding free energy calculations for the identification of potent lead compounds against the said enzyme...
March 31, 2018: Journal of Biomolecular Structure & Dynamics
https://www.readbyqxmd.com/read/29481074/stereodirecting-effect-of-c5-carboxylate-substituents-on-the-glycosylation-stereochemistry-of-3-deoxy-d-manno-oct-2-ulosonic-acid-kdo-thioglycoside-donors-stereoselective-synthesis-of-%C3%AE-and-%C3%AE-kdo-glycosides
#4
Wei Huang, Ying-Yu Zhou, Xing-Ling Pan, Xian-Yang Zhou, Jin-Cai Lei, Dong-Mei Liu, Yue Chu, Jin-Song Yang
The stereodirecting effect of C5-ester functions on the glycosylation stereoselectivity of 3-deoxy-d- manno-oct-2-ulosonic acid (Kdo) ethyl thioglycoside donors is presented. The coupling of 5- O-arylcarbonyl or acetyl protected Kdo thioglycosides with acceptors proceeds in an α-selective and high-yielding manner, leading to formation of α-linked Kdo glycosides products. On the other hand, the glycosylation stereoselectivity of the 5- O-2-quinolinecarbonyl (Quin) or 4-nitropicoloyl substituted Kdo thioglycoside donors is switchable: (1) The glycosylation of the 5- O-Quin carrying Kdo donors with primary glycosyl acceptors shows complete β-stereoselectivity, furnishing the corresponding β-glycosides in good-to-excellent yield...
March 14, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/29101229/almg-responsible-for-polymyxin-resistance-in-pandemic-vibrio-cholerae-is-a-glycyltransferase-distantly-related-to-lipid-a-late-acyltransferases
#5
Jeremy C Henderson, Carmen M Herrera, M Stephen Trent
Cationic antimicrobial peptides (CAMPs), such as polymyxins, are used as a last-line defense in treatment of many bacterial infections. However, some bacteria have developed resistance mechanisms to survive these compounds. Current pandemic O1 Vibrio cholerae biotype El Tor is resistant to polymyxins, whereas a previous pandemic strain of the biotype Classical is polymyxin-sensitive. The almEFG operon found in El Tor V. cholerae confers >100-fold resistance to antimicrobial peptides through aminoacylation of lipopolysaccharide (LPS), expected to decrease the negatively charged surface of the V...
December 22, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29099761/the-role-of-carbohydrates-in-the-lipopolysaccharide-lps-toll-like-receptor-4-tlr4-signalling
#6
REVIEW
Florent Cochet, Francesco Peri
The interactions between sugar-containing molecules from the bacteria cell wall and pattern recognition receptors (PRR) on the plasma membrane or cytosol of specialized host cells are the first molecular events required for the activation of higher animal's immune response and inflammation. This review focuses on the role of carbohydrates of bacterial endotoxin (lipopolysaccharide, LPS, lipooligosaccharide, LOS, and lipid A), in the interaction with the host Toll-like receptor 4/myeloid differentiation factor 2 (TLR4/MD-2) complex...
November 3, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29050611/structure-and-in-vitro-anticancer-activity-of-sulfated-o-polysaccharide-from-marine-bacterium-poseidonocella-pacifica-kmm-9010-t
#7
Maxim S Kokoulin, Alexandra S Kuzmich, Anatoly I Kalinovsky, Eugene S Rubtsov, Lyudmila A Romanenko, Valery V Mikhailov, Nadezhda A Komandrova
We presented the structure of the sulfated polysaccharide moiety and anticancer activity in vitro of the О-deacylated lipopolysaccharide (DPS) isolated from the marine bacterium Poseidonocella pacifica KMM 9010T . The structure of O-polysaccharide was investigated by chemical methods along with1 H and13 C NMR spectroscopy. The O-polysaccharide was built up of sulfated disaccharide repeating units consisted of d-rhamnose (d-Rhaр) and 3-deoxy-d-manno-oct-2-ulosonic acid (Kdop): →7)-β-Kdoр4Ac5S-(2→3)-β-d-Rhaр2S-(1→...
December 15, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/29028168/synthesis-of-a-pentasaccharide-fragment-related-to-the-inner-core-region-of-rhizobial-and-agrobacterial-lipopolysaccharides
#8
Nino Trattnig, Jean-Baptiste Farcet, Philipp Gritsch, Anna Christler, Ralph Pantophlet, Paul Kosma
The pentasaccharide fragment α-d-Man-(1 → 5)-[α-d-Kdo-(2 → 4)-]α-d-Kdo-(2 → 6)-β-d-GlcNAc-(1 → 6)-α-d-GlcNAc equipped with a 3-aminopropyl spacer moiety was prepared by a sequential assembly of monosaccharide building blocks. The glucosamine disaccharide-as a backbone surrogate of the bacterial lipid A region-was synthesized using an 1,3-oxazoline donor, which was followed by coupling with an isopropylidene-protected Kdo-fluoride donor to afford a protected tetrasaccharide intermediate. Eventually, an orthogonally protected manno-configured trichloroacetimidate donor was used to achieve the sterically demanding glycosylation of the 5-OH group of Kdo in good yield...
December 1, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29018092/molecular-characterization-and-verification-of-azido-3-8-dideoxy-d-manno-oct-2-ulosonic-acid-incorporation-into-bacterial-lipopolysaccharide
#9
Inga Nilsson, Kerri Grove, Dustin Dovala, Tsuyoshi Uehara, Guillaume Lapointe, David A Six
3-Deoxy-d- manno -oct-2-ulosonic acid (Kdo) is an essential component of LPS in the outer leaflet of the Gram-negative bacterial outer membrane. Although labeling of Escherichia coli with the chemical reporter 8-azido-3,8-dideoxy-d- manno -oct-2-ulosonic acid (Kdo-N3 ) has been reported, its incorporation into LPS has not been directly shown. We have now verified Kdo-N3 incorporation into E. coli LPS at the molecular level. Using microscopy and PAGE analysis, we show that Kdo-N3 is localized to the outer membrane and specifically incorporates into rough and deep-rough LPS...
December 1, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28874446/characterization-of-two-novel-lipopolysaccharide-phosphoethanolamine-transferases-in-pasteurella-multocida-and-their-role-in-resistance-to-cathelicidin-2
#10
Marina Harper, Amy Wright, Frank St Michael, Jianjun Li, Deanna Deveson Lucas, Mark Ford, Ben Adler, Andrew D Cox, John D Boyce
The lipopolysaccharide (LPS) produced by the Gram-negative bacterial pathogen Pasteurella multocida has phosphoethanolamine (PEtn) residues attached to lipid A, 3-deoxy-d-manno-octulosonic acid (Kdo), heptose, and galactose. In this report, we show that PEtn is transferred to lipid A by the P. multocida EptA homologue, PetL, and is transferred to galactose by a novel PEtn transferase that is unique to P. multocida called PetG. Transcriptomic analyses indicated that petL expression was positively regulated by the global regulator Fis and negatively regulated by an Hfq-dependent small RNA...
November 2017: Infection and Immunity
https://www.readbyqxmd.com/read/28794950/structure-of-the-lipopolysaccharide-from-the-bradyrhizobium-sp-ors285-rfal-mutant-strain
#11
Flaviana Di Lorenzo, Angelo Palmigiano, Katarzyna A Duda, Mateusz Pallach, Nicolas Busset, Luisa Sturiale, Eric Giraud, Domenico Garozzo, Antonio Molinaro, Alba Silipo
The importance of the outer membrane and of its main constituent, lipopolysaccharide, in the symbiosis between rhizobia and leguminous host plants has been well studied. Here, the first complete structural characterization of the entire lipopolysaccharide from an O-chain-deficient Bradyrhizobium ORS285 rfaL mutant is achieved by a combination of chemical analysis, NMR spectroscopy, MALDI MS and MS/MS. The lipid A structure is shown to be consistent with previously reported Bradyrhizobium lipid A, that is, a heterogeneous blend of penta- to hepta-acylated species carrying a nonstoichiometric hopanoid unit and possessing very-long-chain fatty acids ranging from 26:0(25-OH) to 32:0(31-OH)...
August 2017: ChemistryOpen
https://www.readbyqxmd.com/read/28646448/purification-of-the-exopolysaccharide-produced-by-alteromonas-infernus-identification-of-endotoxins-and-effective-process-to-remove-them
#12
Alicia Grivaud-Le Du, Agata Zykwinska, Corinne Sinquin, Jacqueline Ratiskol, Pierre Weiss, Claire Vinatier, Jérôme Guicheux, Christine Delbarre-Ladrat, Sylvia Colliec-Jouault
Alteromonas infernus bacterium isolated from deep-sea hydrothermal vents can produce by fermentation a high molecular weight exopolysaccharide (EPS) called GY785. This EPS described as a new source of glycosaminoglycan-like molecule presents a great potential for pharmaceutical and biotechnological applications. However, this unusual EPS is secreted by a Gram-negative bacterium and can be therefore contaminated by endotoxins, in particular the lipopolysaccharides (LPS). Biochemical and chemical analyses of the LPS extracted from A...
September 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28533794/boron-supply-enhances-aluminum-tolerance-in-root-border-cells-of-pea-pisum-sativum-by-interacting-with-cell-wall-pectins
#13
Xue Wen Li, Jia You Liu, Jing Fang, Lin Tao, Ren Fang Shen, Ya Lin Li, Hong Dong Xiao, Ying Ming Feng, Hai Xiang Wen, Jia Hua Guan, Li Shu Wu, Yong Ming He, Heiner E Goldbach, Min Yu
Aluminum (Al) toxicity is the primary factor limiting crop growth in acidic soils. Boron (B) alleviates Al toxicity in plants, which is mainly considered to be due to the formation of Rhamnogalacturonan II-B (RGII-B) complexes, which helps to stabilize the cytoskeleton. It is unclear yet whether this is due to the increasing of net negative charges and/or further mechanisms. Kinetics of Al accumulation and adsorption were investigated using entire cells, cell wall and pectin of root border cells (RBCs) of pea (Pisum sativum), to reveal the mechanism of B in interacting with alkali-soluble and chelator-soluble pectin for an increased Al tolerance in RBCs...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28478910/gold-i-catalyzed-synthesis-of-%C3%AE-kdo-glycosides-using-kdo-ortho-hexynylbenzoate-as-donor
#14
Xuemeng Mi, Qixin Lou, Wenjing Fan, Liqin Zhuang, You Yang
A gold(I)-catalyzed glycosylation of Kdo with glycosyl ortho-hexynylbenzoate as donor is reported. The couplings of Kdo ortho-hexynylbenzoate with a set of alcohols promoted by PPh3AuOTf afford Kdo glycosides with good β-selectivities. This glycosylation method allows for the synthesis of β-Kdo monosaccharide with a C5 linker at the reducing end for subsequent conjugation to carrier proteins and arrays.
April 28, 2017: Carbohydrate Research
https://www.readbyqxmd.com/read/28438125/chlamydia-spp-development-is-differentially-altered-by-treatment-with-the-lpxc-inhibitor-lpc-011
#15
Erik D Cram, Daniel D Rockey, Brian P Dolan
BACKGROUND: Chlamydia species are obligate intracellular bacteria that infect a broad range of mammalian hosts. Members of related genera are pathogens of a variety of vertebrate and invertebrate species. Despite the diversity of Chlamydia, all species contain an outer membrane lipooligosaccharide (LOS) that is comprised of a genus-conserved, and genus-defining, trisaccharide 3-deoxy-D-manno-oct-2-ulosonic acid Kdo region. Recent studies with lipopolysaccharide inhibitors demonstrate that LOS is important for the C...
April 24, 2017: BMC Microbiology
https://www.readbyqxmd.com/read/28342805/phosphoethanolamine-addition-to-the-heptose-i-of-the-lipopolysaccharide-modifies-the-inner-core-structure-and-has-an-impact-on-the-binding-of-polymyxin-b-to-the-escherichia-coli-outer-membrane
#16
Javier Salazar, Mackarenna Alarcón, Jaime Huerta, Belén Navarro, Daniel Aguayo
Phosphoethanolamine (pEtN) decoration of E. coli Lipopolysaccharide (LPS) provides resistance to the antimicrobial Polymyxin B (PolB). While EptA and EptB enzymes catalyze the addition of pEtN to the Lipid A and Kdo (pEtN-Kdo-Lipid A), EptC catalyzes the pEtN addition to the Heptose I (pEtN-HeptI ). In this study, we investigated the contribution of pEtN-HeptI to PolB resistance using eptA/eptB and eptC deficient E. coli K12 and its wild-type parent strains. These mutations were shown to decrease the antimicrobial activity of PolB on cells grown under pEtN-addition inducing conditions...
April 15, 2017: Archives of Biochemistry and Biophysics
https://www.readbyqxmd.com/read/28328947/a-spontaneous-mutation-in-kdsd-a-biosynthesis-gene-for-3-deoxy-d-manno-octulosonic-acid-occurred-in-a-ciprofloxacin-resistant-strain-of-francisella-tularensis-and-caused-a-high-level-of-attenuation-in-murine-models-of-tularemia
#17
Taylor Chance, Jennifer Chua, Ronald G Toothman, Jason T Ladner, Jonathan E Nuss, Jo Lynne Raymond, Fabrice V Biot, Samandra Demons, Lynda Miller, Stephanie Halasohoris, Sherry Mou, Galina Koroleva, Sean Lovett, Gustavo Palacios, Nicholas J Vietri, Patricia L Worsham, Christopher K Cote, Todd M Kijek, Joel A Bozue
Francisella tularensis, a gram-negative facultative intracellular bacterial pathogen, is the causative agent of tularemia and able to infect many mammalian species, including humans. Because of its ability to cause a lethal infection, low infectious dose, and aerosolizable nature, F. tularensis subspecies tularensis is considered a potential biowarfare agent. Due to its in vitro efficacy, ciprofloxacin is one of the antibiotics recommended for post-exposure prophylaxis of tularemia. In order to identify therapeutics that will be efficacious against infections caused by drug resistant select-agents and to better understand the threat, we sought to characterize an existing ciprofloxacin resistant (CipR) mutant in the Schu S4 strain of F...
2017: PloS One
https://www.readbyqxmd.com/read/28306723/the-redefinition-of-helicobacter-pylori-lipopolysaccharide-o-antigen-and-core-oligosaccharide-domains
#18
Hong Li, Tiandi Yang, Tingting Liao, Aleksandra W Debowski, Hans-Olof Nilsson, Alma Fulurija, Stuart M Haslam, Barbara Mulloy, Anne Dell, Keith A Stubbs, Barry J Marshall, Mohammed Benghezal
Helicobacter pylori lipopolysaccharide promotes chronic gastric colonisation through O-antigen host mimicry and resistance to mucosal antimicrobial peptides mediated primarily by modifications of the lipid A. The structural organisation of the core and O-antigen domains of H. pylori lipopolysaccharide remains unclear, as the O-antigen attachment site has still to be identified experimentally. Here, structural investigations of lipopolysaccharides purified from two wild-type strains and the O-antigen ligase mutant revealed that the H...
March 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/28137848/single-polysaccharide-assembly-protein-that-integrates-polymerization-termination-and-chain-length-quality-control
#19
Danielle M Williams, Olga G Ovchinnikova, Akihiko Koizumi, Iain L Mainprize, Matthew S Kimber, Todd L Lowary, Chris Whitfield
Lipopolysaccharides (LPS) are essential outer membrane glycolipids in most gram-negative bacteria. Biosynthesis of the O-antigenic polysaccharide (OPS) component of LPS follows one of three widely distributed strategies, and similar processes are used to assemble other bacterial surface glycoconjugates. This study focuses on the ATP-binding cassette (ABC) transporter-dependent pathway, where glycans are completed on undecaprenyl diphosphate carriers at the cytosol:membrane interface, before export by the ABC transporter...
February 14, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27906600/role-of-polysaccharide-and-lipid-in-lipopolysaccharide-induced-prion-protein-conversion
#20
Carol L Ladner-Keay, Marcia LeVatte, David S Wishart
Conversion of native cellular prion protein (PrP(c)) from an α-helical structure to a toxic and infectious β-sheet structure (PrP(Sc)) is a critical step in the development of prion disease. There are some indications that the formation of PrP(Sc) is preceded by a β-sheet rich PrP (PrP(β)) form which is non-infectious, but is an intermediate in the formation of infectious PrP(Sc). Furthermore the presence of lipid cofactors is thought to be critical in the formation of both intermediate-PrP(β) and lethal, infectious PrP(Sc)...
November 2016: Prion
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