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Found 1 structure.
Displayed structure 1
| a-L-Rhap-(1-3)-+ | -4)-a-D-Glcp-(1-3)-a-L-FucpNAc-(1-3)-b-D-GlcpNAc-(1- | b-D-Glcp-(1-6)-+ | Show graphically |
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Structure type: polymer chemical repeating unit
Compound class: O-polysaccharide, O-antigen
Contained glycoepitopes: IEDB_135813,IEDB_136105,IEDB_137340,IEDB_141806,IEDB_141807,IEDB_142488,IEDB_144998,IEDB_146664,IEDB_151531,IEDB_225177,IEDB_885823,IEDB_983931,SB_192
The structure of the O‐antigen polysaccharide from Escherichia coli strain F171 has been determined. NMR analysis of the polysaccharide showed that it was composed of pentasaccharide repeating units. The 1H and 13C signals were assigned by 2D NMR techniques which revealed severe spectral overlap for key resonances at substitution positions. The structure of the repeating unit was deduced from 1H,13C HMBC and, in particular, by 1H,1H NOESY experiments as follows: [see text]. The structure is identical with that of the O‐antigen from Escherichia coli O25 previously determined by chemical degradation methods and the strain F171 should therefore belong to this serogroup. Copyright © 2003 John Wiley & Sons, Ltd.
Lipopolysaccharide, NMR, O-antigen, 13C NMR, 1H NMR, Escherichia coli strain F171, Escherichia coli O25
Publication DOI: 10.1002/mrc.1162This review summarizes data on the composition and structure of the O-antigens, the polysaccharide chains of the outer-membrane lipopolysaccharides (LPS) of Gram-negative bacteria defining the immunospecificity of these microbial cells. Special reference is given to some structural features of the O-antigens, such as the presence of unique monosaccharides and noncarbohydrate components, masked regularity, and the occurrence in one microorganism of LPS with structurally different polysaccharide chains. Antigenic relationships between microorganisms belonging to different taxonomic groups are discussed.
structure, O-antigen, chemical composition, bacterial lipopolysaccharides, Salmonella livingstone C1
NCBI PubMed ID: 7533007The structure of the Escherichia coli O-antigen 25 has been investigated using n.m.r. spectroscopy, methylation analysis, and various specific degradations. It is concluded that the O-antigen is composed of pentasaccharide repeating-units having the following structure.
Publication DOI: 10.1016/0008-6215(83)88336-0Escherichia coli is usually a non-pathogenic member of the human colonic flora. However, certain strains have acquired virulence factors and may cause a variety of infections in humans and in animals. There are three clinical syndromes caused by E. coli: (i) sepsis/meningitis; (ii) urinary tract infection and (iii) diarrhoea. Furthermore the E. coli causing diarrhoea is divided into different 'pathotypes' depending on the type of disease, i.e. (i) enterotoxigenic; (ii) enteropathogenic; (iii) enteroinvasive; (iv) enterohaemorrhagic; (v) enteroaggregative and (vi) diffusely adherent. The serotyping of E. coli based on the somatic (O), flagellar (H) and capsular polysaccharide antigens (K) is used in epidemiology. The different antigens may be unique for a particular serogroup or antigenic determinants may be shared, resulting in cross-reactions with other serogroups of E. coli or even with other members of the family Enterobacteriacea. To establish the uniqueness of a particular serogroup or to identify the presence of common epitopes, a database of the structures of O-antigenic polysaccharides has been created. The E. coli database (ECODAB) contains structures, nuclear magnetic resonance chemical shifts and to some extent cross-reactivity relationships. All fields are searchable. A ranking is produced based on similarity, which facilitates rapid identification of strains that are difficult to serotype (if known) based on classical agglutinating methods. In addition, results pertinent to the biosynthesis of the repeating units of O-antigens are discussed. The ECODAB is accessible to the scientific community at http://www.casper.organ.su.se/ECODAB/
NMR, structure, serotype, O-antigen, Enterobacteriacea, database
NCBI PubMed ID: 16594963Escherichia coli ST131 is a globally disseminated, multidrug resistant clone responsible for a high proportion of urinary tract and bloodstream infections. The rapid emergence and successful spread of E. coli ST131 is strongly associated with antibiotic resistance; however, this phenotype alone is unlikely to explain its dominance amongst multidrug resistant uropathogens circulating worldwide in hospitals and the community. Thus, a greater understanding of the molecular mechanisms that underpin the fitness of E. coli ST131 is required. In this study, we employed hyper-saturated transposon mutagenesis in combination with multiplexed transposon directed insertion-site sequencing to define the essential genes required for in vitro growth and the serum resistome (i.e. genes required for resistance to human serum) of E. coli EC958, a representative of the predominant E. coli ST131 clonal lineage. We identified 315 essential genes in E. coli EC958, 231 (73%) of which were also essential in E. coli K-12. The serum resistome comprised 56 genes, the majority of which encode membrane proteins or factors involved in lipopolysaccharide (LPS) biosynthesis. Targeted mutagenesis confirmed a role in serum resistance for 46 (82%) of these genes. The murein lipoprotein Lpp, along with two lipid A-core biosynthesis enzymes WaaP and WaaG, were most strongly associated with serum resistance. While LPS was the main resistance mechanism defined for E. coli EC958 in serum, the enterobacterial common antigen and colanic acid also impacted on this phenotype. Our analysis also identified a novel function for two genes, hyxA and hyxR, as minor regulators of O-antigen chain length. This study offers novel insight into the genetic make-up of E. coli ST131, and provides a framework for future research on E. coli and other Gram-negative pathogens to define their essential gene repertoire and to dissect the molecular mechanisms that enable them to survive in the bloodstream and cause disease.
biosynthesis, gene, phenotype, Escherichia coli, pathogens, O-antigen chain length
NCBI PubMed ID: 24098145The Escherichia coli lineage ST131-O25b:H4 is a globally spread multi-drug resistant clone responsible for a significant proportion of extraintestinal infections. Driven by the high medical need associated with this successful pathogenic lineage, we generated murine monoclonal antibodies against its lipopolysaccharide (LPS) O25b antigen in order to develop quick diagnostic tests. Murine mAbs were generated by immunization of mice with whole killed non-encapsulated ST131-O25b E. coli cells and screening hybridoma supernatants for binding to purified LPS molecules obtained from an E. coli ST131-O25b clinical isolate. The mAbs selected for further study bound to the surface of live E. coli O25b strains irrespective of the capsular type expressed, while they could not bind to bacteria or purified LPS from other serotypes - including the related classical O25 antigen (O25a). Using these specific mAbs we have developed a latex bead-based agglutination assay that has greater specificity, more rapid and simpler than the currently available typing methods. The high specificity of these mAbs can be explained by the novel structure of the O25b repeating unit elucidated in this paper. Based on comparative analysis by NMR and mass spectrometry, the N-acetyl-fucose in the O25a O-antigen had been replaced by O-acetyl-rhamnose in the O25b repeating unit. The genetic determinants responsible for this structural variation were identified by alignment of corresponding genetic loci, and were confirmed by trans-complementation of a rough mutant by the sub-serotype specific fragments of the rfb operons.
O-antigen, Serotypes, Escherichia coli, antibodies, monoclonal antibodies, MAb, binding, typing methods
NCBI PubMed ID: 24789798Bacterial pathogen infections are fast-growing public health threats and worldwide problems. Glycoconjugate vaccines are among the most effective means in combating such infections. Recent advances in bacterial protein glycan coupling technology (PGCT) have revolutionized the production of glycoconjugate vaccines and drawn enormous attention from both researchers and pharmaceutical companies. Cloning of bacterial surface polysaccharide gene cluster is a prerequisite for the application of PGCT. In this study, we applied the RecET direct cloning strategy for rapid and efficient cloning of O-antigen polysaccharide gene clusters from Escherichia coli serotypes O25b, O26, and O55 in a high-fidelity manner. Then, these gene clusters were applied in PGCT to produce corresponding glycoconjugates. Subsequent immunological studies verified the abilities of glycoconjugate vaccine candidates O25-maltose-binding protein (MBP), O26-MBP, and O55-MBP to generate serotype-specific antibodies and confer protection against E. coli infections. The combination of RecET direct cloning and PGCT makes the rapid production of glycoconjugate vaccines against fast-expanding bacterial pathogens possible.
glycoengineering, glycoconjugate vaccine, bacterial surface polysaccharide gene cluster, PGCT, RecET direct cloning
NCBI PubMed ID: 30445812Cell surface carbohydrates have been proven optimal targets for vaccine development. Conjugation of polysaccharides to a carrier protein triggers a T-cell dependent immune response to the glycan moiety. Licensed glycoconjugate vaccines are produced by chemical conjugation of capsular polysaccharides to prevent meningitis caused by meningococcus, pneumococcus and Haemophilus influenzae type b. However, other classes of carbohydrates (O-antigens, exopolysaccharides, wall/teichoic acids) represent attractive targets for developing vaccines.Recent analysis from WHO/CHO underpins alarming concern towards antibiotic resistant bacteria, such as the so called ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter spp.) and additional pathogens such as Clostridium difficile and Group A Streptococcus. Fungal infections are also becoming increasingly invasive for immunocompromised patients or hospitalized individuals. Other emergencies could derive from bacteria which spread during environmental calamities (Vibrio cholerae) or with potential as bioterrorism weapons (Burkholderia pseudomallei and mallei, Francisella tularensis). Vaccination could aid reducing the use of broad spectrum antibiotics and provide protection by herd immunity also to individuals who are not vaccinated.This review analyses structural and functional differences of the polysaccharides exposed on the surface of emerging pathogenic bacteria, combined with medical need and technological feasibility of corresponding glycoconjugate vaccines.
carbohydrates, glycoconjugates, vaccines, glycoengineering, antimicrobial resistance
NCBI PubMed ID: 29547971Escherichia coli includes clonal groups of both commensal and pathogenic strains, with some of the latter causing serious infectious diseases. O antigen variation is current standard in defining strains for taxonomy and epidemiology, providing the basis for many serotyping schemes for Gram-negative bacteria. This review covers the diversity in E. coli O antigen structures and gene clusters, and the genetic basis for the structural diversity. Of the 187 formally defined O antigens, six (O31, O47, O67, O72, O94 and O122) have since been removed and four (O14, O34, O89 and O144) strains do not produce any O antigen. Therefore, structures are presented for 176 of the 181 E. coli O antigens, some of which include subgroups. Most (93%) of these O antigens are synthesized via the Wzx/Wzy pathway, 11 via the ABC transporter pathway, with O20, O57 and O60 still uncharacterized due to failure to find their O antigen gene clusters. Biosynthetic pathways are given for 38 of the 49 sugars found in E. coli O antigens, and several pairs or groups of the E. coli antigens that have related structures show close relationships of the O antigen gene clusters within clades, thereby highlighting the genetic basis of the evolution of diversity.
structure, O antigen, Escherichia coli, gene cluster, serogroup, diversity
NCBI PubMed ID: 31778182Extraintestinal pathogenic Escherichia coli (ExPEC) cause a wide range of clinical diseases such as bacteremia and urinary tract infections. The increase of multidrug resistant ExPEC strains is becoming a major concern for the treatment of these infections and E. coli has been identified as a critical priority pathogen by the WHO. Therefore, the development of vaccines has become increasingly important, with the surface lipopolysaccharide constituting a promising vaccine target. This study presents genetic and structural analysis of clinical urine isolates from Switzerland belonging to the serotype O25. Approximately 75% of these isolates were shown to correspond to the substructure O25B only recently described in an emerging clone of E. coli sequence type 131. To address the high occurrence of O25B in clinical isolates, an O25B glycoconjugate vaccine was prepared using an E. coli glycosylation system. The O antigen cluster was integrated into the genome of E. coli W3110, thereby generating an E. coli strain able to synthesize the O25B polysaccharide on a carrier lipid. The polysaccharide was enzymatically conjugated to specific asparagine side chains of the carrier protein exotoxin A (EPA) of Pseudomonas aeruginosa by the PglB oligosaccharyltransferase from Campylobacter jejuni. Detailed characterization of the O25B-EPA conjugate by use of physicochemical methods including NMR and GC-MS confirmed the O25B polysaccharide structure in the conjugate, opening up the possibility to develop a multivalent E. coli conjugate vaccine containing O25B-EPA.
Escherichia coli, physicochemical characterization, bioconjugate vaccine, serotype O25B, ST131
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