ChemInform Abstract: Synthesis of Helicobacter pylori Lipid A and Its Analogue Using p-(Trifluoromethyl)benzyl Protecting Group.

ChemInform ◽  
2000 ◽  
Vol 31 (44) ◽  
pp. no-no
Author(s):  
Yasuhiro Sakai ◽  
Masato Oikawa ◽  
Hiroaki Yoshizaki ◽  
Tomohiko Ogawa ◽  
Yasuo Suda ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Lipid A ◽  
Protecting Group

Synthesis of Helicobacter pylori lipid A and its analogue using p-(trifluoromethyl)benzyl protecting group

2000 ◽  
Vol 41 (35) ◽  
pp. 6843-6847 ◽  
Author(s):  
Yasuhiro Sakai ◽  
Masato Oikawa ◽  
Hiroaki Yoshizaki ◽  
Tomohiko Ogawa ◽  
Yasuo Suda ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Lipid A ◽  
Protecting Group

scholarly journals A Novel 3-Deoxy-d-manno-Octulosonic Acid (Kdo) Hydrolase That Removes the Outer Kdo Sugar of Helicobacter pylori Lipopolysaccharide

2005 ◽  
Vol 187 (10) ◽  
pp. 3374-3383 ◽  
Author(s):  
Christopher Stead ◽  
An Tran ◽  
Donald Ferguson ◽  
Sara McGrath ◽  
Robert Cotter ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Lipid A ◽  
In Vitro Assay ◽  
Spectrometric Analysis ◽  
Vitro Assay ◽  
The Core ◽  
H Pylori

ABSTRACT The lipid A domain anchors lipopolysaccharide (LPS) to the outer membrane and is typically a disaccharide of glucosamine that is both acylated and phosphorylated. The core and O-antigen carbohydrate domains are linked to the lipid A moiety through the eight-carbon sugar 3-deoxy-d-manno-octulosonic acid known as Kdo. Helicobacter pylori LPS has been characterized as having a single Kdo residue attached to lipid A, predicting in vivo a monofunctional Kdo transferase (WaaA). However, using an in vitro assay system we demonstrate that H. pylori WaaA is a bifunctional enzyme transferring two Kdo sugars to the tetra-acylated lipid A precursor lipid IVA. In the present work we report the discovery of a Kdo hydrolase in membranes of H. pylori capable of removing the outer Kdo sugar from Kdo2-lipid A. Enzymatic removal of the Kdo group was dependent upon prior removal of the 1-phosphate group from the lipid A domain, and mass spectrometric analysis of the reaction product confirmed the enzymatic removal of a single Kdo residue by the Kdo-trimming enzyme. This is the first characterization of a Kdo hydrolase involved in the modification of gram-negative bacterial LPS.

Characterization of a waaF mutant of Helicobacter pylori strain 26695 provides evidence that an extended lipopolysaccharide structure has a limited role in the invasion of gastric cancer cells

2007 ◽  
Vol 85 (5) ◽  
pp. 582-590 ◽  
Author(s):  
Vandana Chandan ◽  
Susan M. Logan ◽  
Blair A. Harrison ◽  
Evgenii Vinogradov ◽  
Annie Aubry ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Mutant Strain ◽  
Lipid A ◽  
Inner Core ◽  
Cell Model ◽  
Critical Factor ◽  
Gastric Cancer Cells ◽  
Level Of Invasion ◽  
Insertional Inactivation

An ld-heptosyltransferase gene, HP1191 (waaF), involved in biosynthesis of the inner-core region of Helicobacter pylori strain 26695 lipopolysaccharide (LPS), has been cloned and its function established by complementation of Salmonella enterica serovar Typhimurium waaF mutant strain, strain 3789. Insertional inactivation of the HP1191 open reading frame in strain 26695 resulted in the formation of a deeply truncated LPS molecule, as observed using SDS–PAGE. Subsequent compositional and fatty acid analyses, followed by capillary electrophoresis – mass spectrometry and nuclear magnetic resonance studies established its structure as the following: PE→7)-l-α-d-Hepp-(1→5)-α-Kdop-(2→6)-Lipid A, where PE represents a phosphoethanolamine group, ld-Hep represents l-glycero-d-manno-heptose, and Kdo represents 3-deoxy-d-manno-oct-2-ulosonic acid. This structural analysis identifies the activity of HP1191 as a heptosyltransferase and a waaF homolog. In vitro invasion assays using human cultured gastric adenocarcinoma cells as a host cell model confirmed that the level of invasion was unaffected for an H. pylori HP1191::Kan deep-rough mutant strain compared with the wild-type strain 26695 expressing the O-chain polysaccharide, providing evidence that LPS is not a critical factor for invasion.

scholarly journals Two Distinct Antigenic Types of the Polysaccharide Chains of Helicobacter pylori Lipopolysaccharides Characterized by Reactivity with Sera from Humans with Natural Infection

2000 ◽  
Vol 68 (1) ◽  
pp. 151-159 ◽  
Author(s):  
Shin-Ichi Yokota ◽  
Ken-Ichi Amano ◽  
Yoshiko Shibata ◽  
Mizuho Nakajima ◽  
Miyuki Suzuki ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Lipid A ◽  
Inner Core ◽  
Antigenic Variation ◽  
Natural Infection ◽  
Clinical Isolates ◽  
Antigenic Epitope ◽  
Lewis Antigen ◽  
Human Sera ◽  
H Pylori

ABSTRACT We have purified lipopolysaccharides (LPS) from 10Helicobacter pylori clinical isolates which were selected on the basis of chemotype and antigenic variation. Data from immunoblotting of the purified LPS with sera from humans with H. pylori infection and from absorption of the sera with LPS indicated the presence of two distinct epitopes, termed the highly antigenic and the weakly antigenic epitopes, on the polysaccharide chains. Among 68 H. pylori clinical isolates, all smooth strains possessed either epitope; the epitopes were each carried by about 50% of the smooth strains. Thus, H. pylori strains can be classified into three types on the basis of their antigenicity in humans: those with smooth LPS carrying the highly antigenic epitope, those with smooth LPS carrying the weakly antigenic epitope, and those with rough LPS. Sera from humans with H. pylori infection could be grouped into three categories: those containing immunoglobulin G (IgG) antibodies against the highly antigenic epitope, those containing IgG against the weakly antigenic epitope, and those containing both specific IgGs; these groups made up about 50%, less than 10%, and about 40%, respectively, of all infected sera tested. In other words, IgG against the highly antigenic epitope were detected in more than 90% of H. pylori-infected individuals with high titers. IgG against the weakly antigenic epitope were detected in about 50% of the sera tested; however, the antibody titers were low. The two human epitopes existed independently from the mimic structures of Lewis antigens, which are known to be an important epitope ofH. pylori LPS. No significant relationship between the reactivities toward purified LPS of human sera and a panel of anti-Lewis antigen antibodies was found. Moreover, the reactivities of the anti-Lewis antigen antibodies, but not human sera, were sensitive to particular α-l-fucosidases. The human epitopes appeared to be located on O-polysaccharide chains containing endo-β-galactosidase-sensitive galactose residues as the backbone. Data from chemical analyses indicated that all LPS commonly contained galactose, glucosamine, glucose, and fucose (except one rough strain) as probable polysaccharide components, together with typical components of inner core and lipid A. We were not able to distinguish between the differences of antigenicity in humans by on the basis of the chemical composition of the LPS.

Immunobiological activities of chemically defined lipid A from Helicobacter pylori LPS in comparison with Porphyromonas gingivalis lipid A and Escherichia coli-type synthetic lipid A (compound 506)

Vaccine ◽  
1997 ◽  
Vol 15 (15) ◽  
pp. 1598-1605 ◽  
Author(s):  
Tomohiko Ogawa ◽  
Yasuo Suda ◽  
Wataru Kashihara ◽  
Tomoko Hayashi ◽  
Takashi Shimoyama ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Helicobacter Pylori ◽  
Porphyromonas Gingivalis ◽  
Lipid A

scholarly journals Cholesterol Enhances Helicobacter pylori Resistance to Antibiotics and LL-37

2011 ◽  
Vol 55 (6) ◽  
pp. 2897-2904 ◽  
Author(s):  
David J. McGee ◽  
Alika E. George ◽  
Elizabeth A. Trainor ◽  
Katherine E. Horton ◽  
Ellen Hildebrandt ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Lipid A ◽  
Polymyxin B ◽  
Defined Medium ◽  
Vital Role ◽  
Content Type ◽  
The Two Cultures ◽  
H Pylori ◽  
The Impact

ABSTRACTThe human gastric pathogenHelicobacter pyloristeals host cholesterol, modifies it by glycosylation, and incorporates the glycosylated cholesterol onto its surface via a cholesterol glucosyltransferase, encoded bycgt. The impact of cholesterol onH. pyloriantimicrobial resistance is unknown.H. pyloristrain 26695 was cultured in Ham's F12 chemically defined medium in the presence or absence of cholesterol. The two cultures were subjected to overnight incubations with serial 2-fold dilutions of 12 antibiotics, six antifungals, and seven antimicrobial peptides (including LL-37 cathelicidin and human alpha and beta defensins). Of 25 agents tested, cholesterol-grownH. pyloricells were substantially more resistant (over 100-fold) to nine agents than wereH. pyloricells grown without cholesterol. These nine agents included eight antibiotics and LL-37.H. pyloriwas susceptible to the antifungal drug pimaricin regardless of cholesterol presence in the culture medium. Acgtmutant retained cholesterol-dependent resistance to most antimicrobials but displayed increased susceptibility to colistin, suggesting an involvement of lipid A. Mutation oflpxE, encoding lipid A1-phosphatase, led to loss of cholesterol-dependent resistance to polymyxin B and colistin but not other antimicrobials tested. Thecgtmutant was severely attenuated in gerbils, indicating that glycosylation is essentialin vivo. These findings suggest that cholesterol plays a vital role in virulence and contributes to the intrinsic antibiotic resistance ofH. pylori.

Lipid A in Helicobacter pylori.

1992 ◽  
Vol 60 (10) ◽  
pp. 4383-4387 ◽  
Author(s):  
I Mattsby-Baltzer ◽  
Z Mielniczuk ◽  
L Larsson ◽  
K Lindgren ◽  
S Goodwin
Keyword(s):  
Helicobacter Pylori ◽  
Lipid A

Synthesis of a biotinylated penta-α-(1→6)-d-glucoside based on the rational design of an α-stereoselective glucosyl donor

2018 ◽  
Vol 5 (6) ◽  
pp. 909-928 ◽  
Author(s):  
Bozhena S. Komarova ◽  
Vera S. Dorokhova ◽  
Yury E. Tsvetkov ◽  
Nikolay E. Nifantiev
Keyword(s):  
Helicobacter Pylori ◽  
Rational Design ◽  
Selective Synthesis ◽  
Protecting Group ◽  
Group Pattern

Rational design of a protecting group pattern in a glucosyl donor allows for the α-selective synthesis of biotinylated pentasaccharides corresponding to the fragment of the α-(1→6)-glucans of Helicobacter pylori.

scholarly journals Hierarchical-Clustering, Scaffold-Mining Exercises and Dynamics Simulations for Effectual Inhibitors Against Lipid-A Biosynthesis of Helicobacter pylori

2019 ◽  
Vol 12 (3) ◽  
pp. 255-274 ◽  
Author(s):  
Chiranjeevi Pasala ◽  
Sudheer Kumar Katari ◽  
Ravina Madhulitha Nalamolu ◽  
Aparna R. Bitla ◽  
Umamaheswari Amineni
Keyword(s):  
Helicobacter Pylori ◽  
Hierarchical Clustering ◽  
Lipid A ◽  
Lipid A Biosynthesis ◽  
Dynamics Simulations
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