ISOMALTO-OLIGOSACCHARIDE-CONTAINING LIPOTEICHOIC ACID OF STREPTOCOCCUS-SANGUIS - BASIC STRUCTURE

The lipoteichoic acid of Streptococcus sanguis DSM 20567 and of DSM 20 068 was isolated by phenol/water extraction and hydrophobic-interactio n chromatography. The preparations from both strains have an identical structure: a 1,3-linked poly(glycerophosphate) chain phosphodiester-l inked to Glc-(alpha1 - 2)Glc(alpha1 - 3)acyl2Gro as the lipid anchor. The chain is substituted with D-alanine ester and glycosyl residues wh ich comprise mono-, di-, tri- and tetra-alpha-D-glucopyranosyl residue s with (1 - 6) interglycosidic linkages. The glycosylglycerols were re leased with 48 % (by mass) hydrofluoric acid, separated and characteri zed by a combination of chemical procedures and modem techniques of H- 1-NMR and C-13-NMR spectroscopy. The alpha-isomalto-oligosaccharides a dd a novel motif to lipoteichoic-acid chain substituents. H-1-NMR and C-13-NMR spectroscopy also provided a detailed picture of the basic gl ycosylated poly(1,3-glycerophosphate) diglucosylglycerol, It proved a single unbranched chain structure, provided evidence for the chain len gth, the extent of glycosylation, the structure of the lipid anchor an d the site of attachment of the poly(glycerophosphate) chain on the li pid anchor. Owing to its unique glycosyl substituents the lipoteichoic acid may serve as a taxonomic marker for the redefined species S. san guis (formerly S. sanguis type I).