| 11. |
- Schweda, Elke K H, et al.
(författare)
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Structural profiling of lipopolysaccharide glycoforms expressed by non-typeable Haemophilus influenzae : phenotypic similarities between NTHi strain 162 and the genome strain Rd
- 2003
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Ingår i: Carbohydrate Research. - 0008-6215 .- 1873-426X. ; 338:23, s. 2731-2744
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Tidskriftsartikel (refereegranskat)abstract
- Non-typeable Haemophihis influenzae (NTHi) is a significant cause of otitis media in children. We have employed single and multiple step electrospray ionization mass spectrometry (ESIMS) and NMR spectroscopy to profile and elucidate lipopolysaccharide (LPS) structural types expressed by NTHi strain 162, a strain obtained from an epidemiological study in Finland. ESIMS on O-deacylated LPS (LPS-OH) and core oligosaccharide (OS) samples of LPS provided information on the composition and relative abundance of glycoforms differing in the number of hexoses linked to the conserved inner-core element, L-alpha-D-Hepp-(1--> 2)-[PEtn --> 6]-L-alpha-D-Hepp-(1 --> 3)-L-alpha-D-Hepp-(1 --> 5)(.)[PPEtn --> 4]-alpha-Kdop-(2 --> 6)-Lipid A of H. influenzae LPS. The strain examined was found to elaborate Hex2 to Hex5 LPS glycoform populations having structures identical to those observed for H. influenzae strain Rd [Risberg, A.; Masoud, H.; Martin, A.; Richards, J.C.; Moxon, E.R.; Schweda, E.K.H. Eur. J Biochem. 1999, 261, 171-180], the strain for which the complete genome has been sequenced. In addition, sialyllactose-containing glycoforms previously identified in strain Rd as well as several NTHi strains, were identified as minor components. Multiple step tandem ESIMS (MS") on dephosphorylated and permethylated OS provided information on the arrangement of glycoses within the major population of glycoforms and on the existence of additional isomeric glycoforms. Minor Hex1 and Hex6 glycoforms were detected and characterized where the Hex6 glycoform was comprised of a dihexosamine-containing pentasaccharide chain attached at the proximal heptose residue of the inner-core unit. LPS structural motifs present in the NTHi strain 162 are expressed by a genetically diverse set of disease causing isolates, providing the basis for a vaccine strategy against NTHi otitis media.
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| 12. |
- Tinnert, A S, et al.
(författare)
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Structural investigation of lipopolysaccharides from nontypeable Haemophilus influenzae : investigation of inner-core phosphoethanolamine addition in NTHi strain 981
- 2005
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Ingår i: Carbohydrate Research. - : Elsevier BV. - 0008-6215 .- 1873-426X. ; 340:11, s. 1900-1907
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Tidskriftsartikel (refereegranskat)abstract
- LPS of NTHi comprises a conserved tri-L-glycero-D-manno-heptosyl inner-core moiety (L-alpha-D-Hepp-(1 -> 2)-[PEtn -> 6]-L-alpha-D-Hepp-(1 -> 3)-[beta-D-Glcp-(1 -> 4)]-L-alpha-D-Hepp-(1 -> 5)-alpha-Kdop) in which addition of PEtn to the central heptose (HepII) in strain Rd is controlled by the gene lpt6. It was recently shown that NTHi strain 981 contains an additional PEtn linked to O-3 of the terminal heptose of the inner-core moiety (HepIII). In order to establish whether lpt6 is also involved in adding PEtn to HepIII, lpt6 in strain 981 was inactivated. The structure of the LPS of the resulting mutant strain 981lpt6 was investigated by MS and NMR techniques by which it was confirmed that the lpt6 gene product is responsible for addition of PEtn to O-6 of HepII in strain 981. However, it is not responsible for adding PEtn to O-3 of HepIII since the 981lpt6 mutant still had full substitution with PEtn at HepIII
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| 13. |
- Yildirim, Håkan H., et al.
(författare)
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An alternate pattern for globoside oligosaccharide expression in Haemophilus influenzae lipopolysaccharide : Structural diversity in nontypeable strain 1124
- 2005
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 44:13, s. 5207-5224
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Tidskriftsartikel (refereegranskat)abstract
- Common structural motifs of Haemophilus influenzae lipopolysaccharide (LPS) are globotetraose [beta-D-GalpNAc-(1 -> 3)-alpha-D-Galp-(1 -> 4)-beta-D-Galp-(1 -> 4)-beta-D-Glcp] and its truncated versions globoside [alpha-D-Galp-(1 -> 4)-beta-D-Galp-(1 -> 4)-beta-D-Glcp] and lactose [beta-D-Galp-(1 -> 4)-beta-D-Glcp] linked to the tenninal heptose (HepIII) of the triheptosyl inner-core moiety L-alpha-D-Hepp-(1 -> 2)-[PEA -> 6]-L-alpha-D-Hepp-(1 -> 3)L-alpha-D-Hepp-(1 -> 5)-[PPEA -> 4]-alpha-Kdo-(2 -> 6)-lipid A. We report here structural studies of LPS from nontypeable H. influenzae strain 1124 expressing these motifs linked to both the proximal heptose (HepI) and HepIII at the same time. This novel finding was obtained by structural studies of LPS using NMR techniques and electrospray ionization mass spectrometry (ESI-MS) on O-deacylated LPS and core oligosaccharide material (OS) as well as ESI-MSn on permethylated dephosphorylated OS. The use of defined mutants allowed us to confirm structures unambiguously and understand better the biosynthesis of each of the globotetraose units. We found that lgtC is involved in the expression of beta-D-Galp-(1 -> 4)-beta-D-Galp in both extensions, whereas lic2A directs only the expression Of beta-D-Ga1p-(1 -> 4)-beta-D-Glcp when linked to HepIII. The LPS of NTHi strain 1124 contained sialylated glycoforms that were identified by CE-ESI-MS/MS. A common sialylated structure in H. influenzae LPS is sialyllactose linked to HepIII. This structure exists in strain 1124. However, results for the lpsA mutant indicate that sialyllactose extends from HepI as well, a molecular environment for sialyllactose in H. influenzae that has not been reported previously. In addition, the LPS was found to carry phosphoryleholine, O-linked glycine, and a third PEA group which was linked to O3 of HepIII.
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| 14. |
- Yildirim, Håkan H, et al.
(författare)
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Complex O-acetylation in non-typeable Haemophilus influenzae lipopolysaccharide : evidence for a novel site of O-acetylation
- 2005
-
Ingår i: Carbohydrate Research. - : Elsevier BV. - 0008-6215 .- 1873-426X. ; 340:17, s. 2598-2611
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Tidskriftsartikel (refereegranskat)abstract
- The structure of the lipopolysaccharide (LPS) of non-typeable Haemophilus influenzae strain 723 has been elucidated using NMR spectroscopy and electrospray ionization mass spectrometry (ESI-MS) on O-deacylated LPS and core oligosaccharide material (OS), as well as ESI-MSn on permethylated dephosphorylated OS. It was found that the LPS contains the common structural element of H. influenzae, L-alpha-D-Hepp-(1 -> 2)-[PEtn -> 6]-L-alpha-D-Hepp-(1 -> 3)-[beta-D-Glcp-(1 -> 4)]-L-alpha-D-Hepp-(1 -> 5)-[PPEtn -> 4]-alpha-Kdo-(2 -> 6)-Lipid A, in which the beta-D-Glcp residue (GlcI) is substituted by phosphocholine at O-6 and the distal heptose residue (HepIII) by PEW at O-3, respectively. In a subpopulation of glycoforms O-2 of HepIII was substituted by beta-D-Galp-(1 -> 4)-beta-D-Glcp-(1 -> or beta-D-Glcp-(1 ->. Considerable heterogeneity of the LPS was due to the extent of substitution by O-acetyl groups (Ac) and ester-linked glycine of the core oligosaccharide. The location for glycine was found to be at Kdo. Prominent acetylation sites were found to be at GlcI, HepIII, and the proximal heptose (HepI) residue of the triheptosyl moiety. Moreover, GlcI was acetylated at O-3 and/or O-4 and HepI was acetylated at O-2 as evidenced by capillary electrophoresis ESI-MS" in combination with NMR analyses. This is the first study to show that an acetyl group can substitute HepI of the inner-core region of H. influenzae LPS.
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| 15. |
- Yildirim, Håkan H., et al.
(författare)
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Structural analysis of lipopolysaccharides from Haemophilus influenzae serotype f - Structural diversity observed in three strains
- 2003
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Ingår i: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 270:15, s. 3153-3167
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Tidskriftsartikel (refereegranskat)abstract
- Structural elucidation of the lipopolysaccharide (LPS) from three serotype f Haemophilus influenzae clinical isolates RM6255, RM7290 and RM6252 has been achieved using NMR spectroscopy techniques and ESI-MS on O-deacylated LPS and core oligosaccharide material (OS) as well as ESI-MSn on permethylated dephosphorylated OS. This is the first study to report structural details on LPS from serotype f strains. We found that the LPSs of all strains were highly heterogeneous mixtures of glycoforms expressing the common H. influenzae structural element l-alpha-d-Hepp -(1-->2)-[P Etn-->6]-l-alpha-d-Hepp -(1-->3)-[beta-d-Glcp -(1-->4)]-l-alpha-d-Hepp -(1-->5)-[PP Etn-->4]-alpha-Kdo-(2-->6)-lipid A with variable length of OS chains linked to each of the heptoses. The terminal heptose (HepIII) in RM6255 is substituted at the O-3 position by a beta-d-Glcp residue whereas HepIII in strains RM7290 and RM6252 is substituted at O-2 by the globoside unit (alpha-d-Galp -(1-->4)-beta-d-Galp -(1-->4)-beta-d-Glc) or truncated versions thereof. The central heptose (HepII) is substituted by an alpha-d-Galp -(1-->4)-beta-d-Galp -(1-->4)-beta-d-Glcp -(1-->4)-alpha-d-Glcp unit in RM7290 and RM6252 or truncated versions thereof. Strain RM6255 does not express galactose in its LPS and only shows a cellobiose unit elongating from HepII (beta-d-Glcp -(1-->4)-alpha-d-Glcp ). ESI-MSn on dephosphorylated and permethylated OS provided information on the existence of additional minor isomeric glycoforms.
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| 16. |
- Bäckhed, Fredrik, 1973, et al.
(författare)
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Structural requirements for TLR4-mediated LPS signalling: a biological role for LPS modifications
- 2003
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Ingår i: Microbes Infect. - 1286-4579 .- 1769-714X. ; 5:12, s. 1057-63
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Tidskriftsartikel (refereegranskat)abstract
- Cells of the mucosal lining are the first to encounter invading bacteria during infection, and as such, they have developed numerous ways of detecting microbial intruders. Recently, we showed that epithelial cells recognize lipopolysaccharide (LPS) through the CD14-Toll-like receptor (TLR)-4 complex. Here, we identify the substructures of LPS that are recognized by the TLR4 receptor complex. In contrast to lipid A, the O-antigen does not mediate an inflammatory response; rather it interferes with the lipid A recognition. An Escherichia coli strain genetically modified to express penta-acylated lipid A not only showed reduced immunogenicity, but was also found to inhibit pro-inflammatory signalling induced by wild-type E. coli (hexa-acylated lipid A) as well as LPS from other bacteria of the Enterobacteriaceae family. Furthermore, penta-acylated LPS from Pseudomonas aeruginosa acted as an antagonist to hexa-acylated E. coli LPS, as did E. coli, as shown by its inhibitory effect on IL-8 production in stimulated cells. Hypo-acylated lipid A, such as that of P. aeruginosa, is found in several species within the gut microflora as well as in several bacteria causing chronic infections. Thus, our results suggest that the composition of the microflora may be important in modulating pro-inflammatory signalling in epithelial cells under normal as well as pathologic conditions.
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| 17. |
- Deadman, Mary E., et al.
(författare)
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Specific amino acids of the glycosyltransferase LpsA direct the addition of glucose or galactose to the terminal inner core heptose of Haemophilus influenzae lipopolysaccharide via alternative linkages
- 2006
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 281:40, s. 29455-29467
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Tidskriftsartikel (refereegranskat)abstract
- Lipopolysaccharide is the major glycolipid of the cell wall of the bacterium Haemophilus influenzae, a Gram-negative commensal and pathogen of humans. Lipopolysaccharide is both a virulence determinant and a target for host immune responses. Glycosyltransferases have high donor and acceptor substrate specificities that are generally limited to catalysis of one unique glycosidic linkage. The H. influenzae glycosyltransferase LpsA is responsible for the addition of a hexose to the distal heptose of the inner core of the lipopolysaccharide molecule and belongs to the glycosyltransferase family 25. The hexose added can be either glucose or galactose and linkage to the heptose can be either beta 1-2 or beta 1-3. Each H. influenzae strain uniquely produces only one of the four possible combinations of linked sugar in its lipopolysaccharide. We show that, in any given strain, a specific allelic variant of LpsA directs the anomeric linkage and the added hexose, glucose, or galactose. Site-directed mutagenesis of a single key amino acid at position 151 changed the hexose added in vivo from glucose to galactose or vice versa. By constructing chimeric lpsA gene sequences, it was shown that the 3' end of the gene directs the anomeric linkage (beta 1-2 or beta 1-3) of the added hexose. The lpsA gene is the first known example where interstrain variation in lipopolysaccharide core structure is directed by the specific sequence of a genetic locus encoding enzymes directing one of four alternative possible sugar additions from the inner core.
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| 18. |
- Dzieciatkowska, Monika, et al.
(författare)
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Characterization of intact lipopolysaccharides from the Haemophilus influenzae strain RM 118 using electrophoresis-assisted open-tubular liquid chromatography-mass spectrometry
- 2008
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Ingår i: Electrophoresis. - : Wiley. - 0173-0835 .- 1522-2683. ; 29:10, s. 2171-2181
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Tidskriftsartikel (refereegranskat)abstract
- We have applied an electrophoresis-assisted open-tubular LC-MS method for analyzing intact lipopolysaccharides (LPSs) from Haemophilus influenzae strain RM 118 (Rd). We were able to obtain structural information on both core oligosaccharides (OSs) and the lipid A moiety including the sialylation, glycylation, and the distribution of fatty acid residues on the disaccharide backbone of lipid A. The fragmentation patterns of sodiated and protonated LPS molecules were investigated for determining the location of sialic acid. It was found that the tandem mass spectra of sodiated ions provided unambiguous evidence of both sialylated lactose and sialylated lacto-N-neotetraose. In contrast, the fragment ions of protonated ions only offered the evidence for the existence of sialylated lacto-N-neotetraose. The lipid A of Gram-negative bacteria, as the principal endotoxic component of LP S, plays a major role in the pathogenesis of bacterial infections. We have previously characterized lipid. A species after mild acid hydrolysis of LPS during which lipid A precipitates. In this study, intact LPS was directly introduced to a tandem mass spectrometer. In-source dissociation strategy was employed, followed by multiple-stage MS/MS on the ions originating from the lipid part to obtain structural information. This is the first time that the structure of lipid A of H. influenzae was characterized by MS/MS on intact LPS molecules without any prior chemical modifications. In the same way information on the OS can be obtained by MS/MS by focusing on ions originating from core OS.
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| 19. |
- Dzieciatkowska, Monika, et al.
(författare)
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Rapid method for sensitive screening of oligosaccharide epitopes in the lipooligosaccharide from Campylobacter jejuni strains isolated from Guillain-Barre syndrome and Miller Fisher syndrome patients
- 2008
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 46:10, s. 3429-3436
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Tidskriftsartikel (refereegranskat)abstract
- Campylobacter jejuni lipooligosaccharide (LOS) can trigger Guillain-Barre syndrome (GBS) due to its similarity to human gangliosides. Rapid and accurate structural elucidation of the LOS glycan of a strain isolated from a GBS patient could help physicians determine the spectrum of anti-ganglioside antibodies likely to be found and therefore provide valuable assistance in establishing an appropriate course of treatment. The ability of implemented mass spectrometry-based approaches in a clinical setting has been limited by the laborious and time-consuming nature of the protocols, typically 3 to 4 days, used to prepare LOS. In order to improve the analytical throughput, microwave-assisted enzymatic digestion was investigated. In this study, the bacterial cells were suspended in 50 mu l of 20 mM ammonium acetate buffer containing DNase and RNase and treated by direct microwave irradiation for 3 min. Then, proteinase K was added and the samples were again microwaved. The intact LOS samples were analyzed using electrophoresis-assisted open-tubular liquid chromatography-mass spectrometry. The reliability of the rapid, high-throughput technique was demonstrated through analysis of LOS glycans from 73 C. jejuni strains. The structure was elucidated using material from a single colony. The total time for sample preparation and MS analysis is less than 60 min.
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| 20. |
- Fox, Kate L., et al.
(författare)
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Duplicate copies of lic1 direct the addition of multiple phosphocholine residues in the lipopolysaccharide of Haemophilus influenzae
- 2008
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Ingår i: Infection and Immunity. - 0019-9567 .- 1098-5522. ; 76:2, s. 588-600
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Tidskriftsartikel (refereegranskat)abstract
- The genes of the lic1 operon (lic1A to lic1D) are responsible for incorporation of phosphocholine (PCho) into the lipopolysaccharide (LPS) of Haemophilus influenzae. PCho plays a multifaceted role in the commensal and pathogenic lifestyles of a range of mucosal pathogens, including H. influenzae. Structural studies of the LPS of nontypeable H. influenzae (NTHI) have revealed that PCho can be linked to a hexose on any one of the oligosaccharide chain extensions from the conserved inner core triheptosyl backbone. In a collection of NTHI strains we found several strains in which there were two distinct but variant lic1D DNA sequences, genes predicted to encode the transferase responsible for directing the addition of PCho to LPS. The same isolates were also found to express concomitantly two PCho residues at distinct positions in their LPS. In one such NTHI isolate, isolate 1158, structural analysis of LPS from lic1 mutants confirmed that each of the two copies of lic1D directs the addition of PCho to a distinct location on the LPS. One position for PCho addition is a novel heptose, which is part of the oligosaccharide extension from the proximal heptose of the LPS inner core. Modification of the LPS by addition of two PCho residues resulted in increased binding of C-reactive protein and had consequential effects on the resistance of the organism to the killing effects of normal human serum compared to the effects of glycoforms containing one or no PCho. When bound, C-reactive protein leads to complement-mediated killing, indicating the potential biological significance of multiple PCho residues.
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