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  • 1. Bauer, S H J
    et al.
    Månsson, Martin
    Södertörn University, Avdelning Naturvetenskap.
    Hood, D W
    Richards, J C
    Moxon, E R
    Schweda, Elke K H
    Södertörn University, Avdelning Naturvetenskap.
    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 strains2001In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 335, no 4, p. 251-260Article in journal (Refereed)
    Abstract [en]

    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.

  • 2. Engskog, Mikael K. R.
    et al.
    Yildirim, Håkan H.
    Södertörn University, School of Life Sciences.
    Li, Jianjun
    Richards, James C.
    Deadman, Mary
    Hood, Derek W.
    Schweda, Elke K. H.
    Södertörn University, School of Life Sciences, Chemistry.
    A dual role for the lex2 locus: identification of galactosyltransferase activity in non-typeable Haemophilus influenzae strains 1124 and 20192009In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 344, no 5, p. 632-641Article in journal (Refereed)
    Abstract [en]

    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.

  • 3.
    Gulin, Sofia
    et al.
    Södertörn University, Avdelning Naturvetenskap.
    Kussak, A
    Jansson, P E
    Widmalm, G
    Structural studies of S-7, another exocellular polysaccharide containing 2-deoxy-arabino-hexuronic acid2001In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 331, no 3, p. 285-290Article in journal (Refereed)
    Abstract [en]

    The exocellular polysaccharide S-7, a heteropolysaccharide from Azotobacter indicus var, myxogenes has been studied using methylation analysis, Smith degradation, partial acid hydrolysis, NMR spectroscopy and mass spectrometry as the principal methods. It is concluded that the repeating unit has the following structure: -->4)-beta -D-Glcp-(1 -->4)-alpha -L-Rhap-(1 -->3)-beta -D-2-deoxy-arabino-HexpA-(1 --> 6 up arrow 1 beta -D-Glcp-(1 -->6)-beta -D-Glcp The absolute configuration of the deoxyhexuronic acid was deduced from H-1 NMR chemical shifts and is most likely D. Approximately two O-acetyl groups per repeating unit are present, one of which is presumably on the Rha residue. The structure bears great resemblance to another polysaccharide, recently studied, produced by Sphingomonas paucimobilis I-886.

  • 4.
    Schweda, Elke K H
    et al.
    Södertörn University, Avdelning Naturvetenskap.
    Landerholm, Malin K
    Södertörn University, Avdelning Naturvetenskap.
    Li, J J
    Moxon, E R
    Richards, J C
    Structural profiling of lipopolysaccharide glycoforms expressed by non-typeable Haemophilus influenzae: phenotypic similarities between NTHi strain 162 and the genome strain Rd2003In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 338, no 23, p. 2731-2744Article in journal (Refereed)
    Abstract [en]

    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.

  • 5.
    Schweda, Elke K H
    et al.
    Södertörn University, Avdelning Naturvetenskap.
    Li, J J
    Moxon, E R
    Richards, J C
    Structural analysis of lipopolysaccharide oligosaccharide epitopes expressed by non-typeable Haemophilus influenzae strain 1762002In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 337, no 5, p. 409-420Article in journal (Refereed)
    Abstract [en]

    The structure of the lipopolysaccharide (LPS) from non-typeable Haemophilus influenzae strain 176 has been investigated. Electrospray ionization-mass spectrometry (ESIMS) on O-deacylated LPS (LPS-OH) and core oligosaccharide (OS) samples obtained after mild-acid hydrolysis of LPS provided information on the composition and relative abundance of the glycoforms. ESIMS tandem-mass spectrometry on LPS-OH confirmed the presence of minor sialylated and disialylated glycoforms. Oligosaccharide samples were studied in detail using high-field NMR techniques. It was found that the LPS contains the common inner-core element of H. influenzae. L-alpha-D-Hepp-(1-->2)-[PEtn-->6]-L-alpha-D-Hepp-(1-->3)-[beta-D-Glep-(1 -->4)]-L-alpha-D-Hepp-(1-->5)[PPEtn-->4]-alpha-Kdop-(2-->6)-Lipid A having glycosyl substitution at the O-3 position of the terminal heptose as recently observed for non-typeable H. influenzae strain 486 [Mansson, M.: Bauer. S. H. J.: Hood, D. W.; Richards, J. C. Moxon, E. R. Schweda. E. K. H., Eur. J. Biochem. 2001. 268. 2148-2159]. The following LPS structures were identified as the major glycoforms. the most significant being indicated with an asterisk (*) (glycoforms are partly substituted with Gly at the terminal Hep): [GRAPHICS].

  • 6. Tinnert, A S
    et al.
    Månsson, Martin
    Södertörn University, School of Life Sciences.
    Yildirim, Håkan H
    Södertörn University, School of Life Sciences.
    Hood, D W
    Schweda, Elke K H
    Södertörn University, School of Life Sciences.
    Structural investigation of lipopolysaccharides from nontypeable Haemophilus influenzae: investigation of inner-core phosphoethanolamine addition in NTHi strain 9812005In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 340, no 11, p. 1900-1907Article in journal (Refereed)
    Abstract [en]

    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

  • 7.
    Yildirim, Håkan H
    et al.
    Södertörn University, School of Life Sciences. Karolinska institutet.
    Li, J J
    National Research Council, Ottawa, Canada.
    Richards, J C
    National Research Council, Ottawa, Canada.
    Hood, D W
    John Radcliffe Hospital, Oxford, UK.
    Moxon, E R
    John Radcliffe Hospital, Oxford, UK.
    Schweda, Elke K H
    Södertörn University, School of Life Sciences. Karolinska Institutet.
    Complex O-acetylation in non-typeable Haemophilus influenzae lipopolysaccharide: evidence for a novel site of O-acetylation2005In: Carbohydrate Research, ISSN 0008-6215, E-ISSN 1873-426X, Vol. 340, no 17, p. 2598-2611Article in journal (Refereed)
    Abstract [en]

    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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