| 1. |
- Engskog, Mikael K. R., et al.
(författare)
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A dual role for the lex2 locus : identification of galactosyltransferase activity in non-typeable Haemophilus influenzae strains 1124 and 2019
- 2009
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Ingår i: Carbohydrate Research. - : Elsevier BV. - 0008-6215 .- 1873-426X. ; 344:5, s. 632-641
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Tidskriftsartikel (refereegranskat)abstract
- Lipopolysaccharide (LPS) of Haemophilus influenzae 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-Glclp-(1 -> 4)]-L-alpha-D-Hepp-(1 -> 5)-alpha-Kdop) to which addition of beta-D-Glcp to O-4 of Glcl in serotype b strains is controlled by the gene lex2B. In non-typeable H. influenzae strains 1124 and 2019, however, a beta-D-Galp is linked to O-4 of Glcl. In order to test the hypothesis that the 1ex2 locus is involved in the expression Of beta-D-Galp-(1 -> 4-beta-D-Glcp-(1 -> - from Hepl, 1ex2B was inactivated in strains 1124 and 2019, and LPS glycoform populations from the resulting mutant strains were investigated. Detailed structural analyses using NMR techniques and electrospray-ionisation mass spectrometry (ESIMS) on O-cleacylated LPS and core oligosaccharide material (OS), as well as ESIMS" on permethylated dephosphorylated OS, indicated both lex2B mutant strains to express only beta-D-Glcp extensions from Hepl. This provides strong evidence that Lex2B functions as a galactosyltransferase adding a beta-D-Galp to O-4 of Glcl in these strains, indicating that allelic polymorphisms in the lex2B sequence direct alternative functions of the gene product.
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| 2. |
- Fox, K L, et al.
(författare)
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Novel lipopolysaccharide biosynthetic genes containing tetranucleotide repeats in Haemophilus influenzae, identification of a gene for adding O-acetyl groups
- 2005
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Ingår i: Molecular Microbiology. - : Wiley. - 0950-382X .- 1365-2958. ; 58:1, s. 207-216
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Tidskriftsartikel (refereegranskat)abstract
- Many of the genes for lipopolysaccharide (LPS) biosynthesis in Haemophilus influenzae are phase variable. The mechanism of this variable expression involves slippage of tetranucleotide repeats located within the reading frame of these genes. Based on this, we hypothesized that tetranucleotide repeat sequences might be used to identify as yet unrecognized LPS biosynthetic genes. Synthetic oligonucleotides (20 bases), representing all previously reported LPS-related tetranucleotide repeat sequences in H. influenzae, were used to probe a collection of 25 genetically and epidemiologically diverse strains of non-typeable H. influenzae. A novel gene identified through this strategy was a homologue of oafA, a putative O-antigen LPS acetylase of Salmonella typhimurium, that was present in all 25 non-typeable H. influenzae, 19 of which contained multiple copies of the tetranucleotide 5'-GCAA. Using lacZ fusions, we showed that these tetranucleotide repeats could mediate phase variation of this gene. Structural analysis of LPS showed that a major site of acetylation was the distal heptose (HepIII) of the LPS inner-core. An oafA deletion mutant showed absence of O-acetylation of HepIII. When compared with wild type, oafA mutants displayed increased susceptibility to complement-mediated killing by human serum, evidence that O-acetylation of LPS facilitates resistance to host immune clearance mechanisms. These results provide genetic and structural evidence that H. influenzae oafA is required for phase variable O-acetylation of LPS and functional evidence to support the role of O-acetylation of LPS in pathogenesis.
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| 3. |
- Mikhail, Ivan, et al.
(författare)
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Structural characterization of lipid A from nontypeable and type f Haemophilus influenzae : Variability of fatty acid substitution
- 2005
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Ingår i: Analytical Biochemistry. - : Elsevier BV. - 0003-2697 .- 1096-0309. ; 340:2, s. 303-316
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Tidskriftsartikel (refereegranskat)abstract
- Lipid A isolated by mild acid hydrolysis from lipopolysaccharides of 22 nontypeable and 2 type f Haemophilus influenzae strains was investigated using electrospray ionization coupled to quadrupole ion trap mass spectrometry. The lengths, positions, and number of acyl chains in the lipid A molecule were determined using multiple-step tandem mass spectrometry (MSn). All of the analyzed strains showed a major lipid A molecule comprising beta-2-amino-2-deoxy-D-glucopyranose-(1 -> 6)-alpha-2-amino-2-deoxy-D-glucopyranose phosphorylated at the C4 ' and C1 positions. The C2/C2 ' and C3/C3 ' positions were substituted by amide-linked and esterlinked 3-hydroxytetradecanoic acid chains, respectively. The fatty acid chains oil C3 ' and C2 ' were further esterified by tetradecanoic acid chains. In all strains, minor amounts of lipid A molecules with different acylation patterns were identified. Thus, structures comprising the hexaacylated lipid A with the C2 or C3 position being Substituted by 3-hydroxydecanoic acid, and hexaacylated lipid A with the C3 and C3 ' positions being substituted by 3-hydroxydodecanoic or dodecanoyloxytetradecanoic acid, respectively, were found. In addition, lipid A with an acetyl group attached to the 3-hydroxytetradecanoic acid groups attached to the C2 or C3 position was detected in two nontypeable H. influenzae strains.
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| 4. |
- Bauer, S H J, et al.
(författare)
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A rapid and sensitive procedure for determination of 5-N-acetyl neuraminic acid in lipopolysaccharides of Haemophilus influenzae : a survey of 24 non-typeable H-influenzae strains
- 2001
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Ingår i: Carbohydrate Research. - 0008-6215 .- 1873-426X. ; 335:4, s. 251-260
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Tidskriftsartikel (refereegranskat)abstract
- In view of the importance of 5-N-acetyl neuraminic acid in bacterial pathogenesis, a sensitive, reproducible and reliable method for the determination of 5-N-acetyl neuraminic acid levels in lipopolysaccharide (LPS) is described and applied to 24 different non-typeable Haemophilus influenzae (NTHi) strains. The method involves analysis by high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) of terminal 5-N-acetyl neuraminic acid residues released by neuraminidase treatment of O-deacylated LPS. The procedure is relatively fast and the instrumental effort is moderate. The results of the procedure were compared with data obtained by H-1 NMR and electrospray ionisation-mass spectrometry (ESI-MS). The analysis of LPS from 24 NTHi strains showed that 5-N-acetyl neuraminic acid was found to be a common constituent of LPS in NTHi. Only one strain (NTHi 432) did not show any sialylation. Molar ratios (LPS /5-N-acetyl neuraminic acid) ranged between 5/1 and 500/1. Several strains in which no 5-N-acetyl neuraminic acid could be determined by other methods including 1H NMR and ESI-MS were shown to contain 5-N-acetyl neuraminic acid by this HPAEC-PAD procedure. The method was applied to determine levels of terminal 5-N-acetyl neuraminic acid in LPS from NTHi strains grown under different conditions and mutant strains containing inactive LPS biosynthetic genes.
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| 5. |
- Hood, D W, et al.
(författare)
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Biosynthesis of cryptic lipopolysaccharide glycoforms in Haemophilus influenzae involves a mechanism similar to that required for O-antigen synthesis
- 2004
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Ingår i: Journal of Bacteriology. - 0021-9193 .- 1098-5530. ; 186:21, s. 7429-7439
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Tidskriftsartikel (refereegranskat)abstract
- It is generally thought that mucosal bacterial pathogens of the genera Haemophilus, Neisseria, and Moraxella elaborate lipopolysaccharide (LPS) that is fundamentally different from that of enteric organisms that express O-specific polysaccharide side chains. Haemophilus influenzae elaborates short-chain LPS that has a role in the pathogenesis of H. influenzae infections. We show that the synthesis of LPS in this organism can no longer be as clearly distinguished from that in other gram-negative bacteria that express an O antigen. We provide evidence that a region of the H. influenzae genome, the hmg locus, is involved in the synthesis of glycoforms in which tetrasaccharide units are added en bloc, not stepwise, to the normal core glycoforms, similar to the biosynthesis of an O-antigen.
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| 6. |
- Hood, Derek W., et al.
(författare)
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Genes required for the synthesis of heptose-containing oligosaccharide outer core extensions in Haemophilus influenzae lipopolysaccharide
- 2010
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Ingår i: Microbiology. - : Microbiology Society. - 1350-0872 .- 1465-2080. ; 156, s. 3421-3431
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Tidskriftsartikel (refereegranskat)abstract
- Heptose-containing oligosaccharides (OSs) are found in the outer core of the lipopolysaccharide (LPS) of a subset of non-typable Haemophilus influenzae (NTHi) strains. Candidate genes for the addition of either L-glycero-D-manno-heptose (LD-Hep) or D-glycero-D-manno-heptose (DD-Hep) and subsequent hexose sugars to these OSs have been identified from the recently completed genome sequences available for NTHi strains. losA1/losB1 and losA2/losB2 are two sets of related genes in which losA has homology to genes encoding glycosyltransferases and losB to genes encoding heptosyltransferases. Each set of genes is variably present across NTHi strains and is located in a region of the genome with an alternative gene organization between strains that contributes to LPS heterogeneity. Dependent upon the strain background, the LPS phenotype, structure and serum resistance of strains mutated in these genes were altered when compared with the relevant parent strain. Our studies confirm that losB1 and losB2 usually encode DD-heptosyl- and LD-heptosyl transferases, respectively, and that losA1 and losA2 encode glycosyltransferases that play a role in OS extensions of NTHi LPS.
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| 7. |
- Landerholm, Malin K, et al.
(författare)
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Characterization of novel structural features in the lipopolysaccharide of nondisease associated nontypeable Haemophilus influenzae
- 2004
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Ingår i: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 271:5, s. 941-953
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Tidskriftsartikel (refereegranskat)abstract
- Nontypeable Haemophilus influenzae (NTHi) is a common commensal of the human upper respiratory tract and is associated with otitis media in children. The structures of the oligosaccharide portions of NTHi lipopolysaccharide (LPS) from several otitis media isolates are now well characterized but it is not known whether there are structural differences in LPS from colonizing, nondisease associated strains. Structural analysis of LPS from nondisease associated NTHi strains 11 and 16 has been achieved by the application of high-field NMR techniques, ESI-MS, ESI-MSn, capillary electrophoresis coupled to ESI-MS, composition and linkage analyses on O-deacylated LPS and core oligosaccharide material. This is the first study to report structural details on LPS from strains taken from the nasopharynx from healthy individuals. Both strains express identical structures and contain the common element of H. influenzae LPS, 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-Kdop-(2-->6)-lipid A, in which each heptose is elongated by a single hexose residue with no further oligosaccharide extensions. In the major Hex3 glycoform, the terminal Hepp residue (HepIII) is substituted at the O-2 position by a beta-D-Galp residue and the central Hepp residue (HepII) is substituted at O-3 by a alpha-D-Glcp residue. Notably, the strains express two phosphocholine (PCho) substituents, one at the O-6 position of alpha-D-Glcp and the other at the O-6 position of beta-D-Galp. Major acetylation sites were identified at O-4 of Gal and O-3 of HepIII. Additionally, both strains express glycine, and strain 11 also expresses detectable amounts of N-acetylneuraminic acid.
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| 8. |
- Li, J J, et al.
(författare)
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Glycine is a common substituent of the inner core in Haemophilus influenzae lipopolysaccharide
- 2001
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 11:12, s. 1009-1015
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Tidskriftsartikel (refereegranskat)abstract
- A survey of both typeable and nontypeable strainsof Haemophilus influenzae indicated that they contain glycine (Gly) in their lipopolysaccharide (LPS). Significant amounts (30-250 pmol Gly/mug LPS) were determined by high-performance anion-exchange chromatography using pulsed amperometric detection after treatment of the LPS with mild alkali. Oligosaccharides obtained from LPS after mild acid hydrolysis and gel filtration chromatography were investigated by electrospray ionization mass spectrometry (ESI-MS) and capillary electrophoresis (CE) ESI-MS. In all cases, molecular ions corresponding to the major glycoforms were identified and were accompanied by ions differing by 57 Da, thus indicating the presence of glycine. The position of glycine in these glycoforms was determined by CE-ESI-MS/MS analyses. It was found that, depending on strain, glycine can substitute each of the heptoses of the inner-core element, L-alpha-D-Hepp-(1-->2)-[PEtn-->6]-L-alpha-D-Hepp-(1-->3)-L-alpha-D-Hepp- (1-->5)-alpha-Kdo of H. influenzae LPS as well as Kdo. In some strains, mixtures of monosubstituted Gly-containing glycoforms having different substitution patterns were identified.
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| 9. |
- Lundström, Susanna L., et al.
(författare)
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Novel globoside-like oligosaccharide expression patterns in nontypeable Haemophilus influenzae lipopolysaccharide
- 2007
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Ingår i: The FEBS Journal. - : Wiley. - 1742-464X .- 1742-4658. ; 274:18, s. 4886-4903
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Tidskriftsartikel (refereegranskat)abstract
- We report the novel pattern of lipopolysaccharide (LPS) expressed by two disease-associated nontypeable Haemophilus influenzae strains, 1268 and 1200. The strains express the common structural motifs of H. influenzae; 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 terminal heptose (HepIII) and the corresponding structures with an alpha-D-Glcp as the reducing sugar linked to the middle heptose (HepII) in the same LPS molecule. Previously these motifs had been found linked only to either the proximal heptose (HepI) or HepIII of the triheptosyl inner-core moiety l-alpha-D-Hepp-(1 -> 2)-[PEtn -> 6]-l-alpha-D-Hepp-(1 -> 3)-l-alpha-D-Hepp-(1 -> 5)-[PPEtn -> 4]-alpha-Kdo-(2 -> 6)-lipid A. This novel finding was obtained by structural studies of LPS using NMR techniques and ESI-MS on O-deacylated LPS and core oligosaccharide material, as well as electrospray ionization-multiple-step tandem mass spectrometry on permethylated dephosphorylated oligosaccharide material. A lpsA mutant of strain 1268 expressed LPS of reduced complexity that facilitated unambiguous structural determination. Using capillary electrophoresis-ESI-MS/MS we identified sialylated glycoforms that included sialyllactose as an extension from HepII, this is a further novel finding for H. influenzae LPS. In addition, each LPS was found to carry phosphocholine and O-linked glycine. Nontypeable H. influenzae strain 1200 expressed identical LPS structures to 1268 with the difference that strain 1200 LPS had acetates substituting HepIII, whereas strain 1268 LPS has glycine at the same position.
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| 10. |
- Månsson, Martin, et al.
(författare)
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A new structural type for Haemophilus influenzae lipopolysaccharide : Structural analysis of the lipopolysaccharide from nontypeable Haemophilus influenzae strain 486
- 2001
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Ingår i: European Journal of Biochemistry. - : Wiley. - 0014-2956 .- 1432-1033. ; 268:7, s. 2148-2159
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Tidskriftsartikel (refereegranskat)abstract
- Structural elucidation of the sialylated lipopolysaccharide (LPS) of non-typeable Haemophilus influenzae (NTHi) strain 486 has been achieved by the application of high-field NMR techniques and ESI-MS along with composition and linkage analyses on O-deacylated LPS and oligosaccharide samples. It was found that the LPS contains the common 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 -Kdop- (2-->6)-Lipid A, but instead of glycosyl substitution of the terminal heptose residue (HepIII) at the O2 position observed in other H. influenzae strains, HepIII is chain elongated at the O3 position by either lactose or sialyllactose (i.e. alpha -Neu5Ac(2-->3)-beta -D-Galp-(1-->4)-beta -D-Glcp). The LPS is substituted by an O-acetyl group linked to the O2 position of HepIII and phosphocholine (PCho) which was located at the O6 position of a terminal alpha -D-Glcp, residue attached to the central heptose, a molecular environment different from what has been reported earlier for PCho. In addition, minor substitution by O-linked glycine to the LPS was observed. By investigation of LPS from a lpsA mutant of NTHi strain 486, it was demonstrated that the lpsA gene product also is responsible for chain extension from HepIII in this strain. The involvement of lic1 in expression of PCho was established by investigation of a lic1 mutant of NTHi strain 486.
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