Teichulosonic acid, an anionic polymer of a new class from the cell wall of Actinoplanes utahensis VKM Ac-674T

Abstract

The cell wall of Actinoplanes utahensis VKM Ac-674(T) contains two anionic polymers: teichoic acid 1,3-poly(glycerol phosphate) that is widespread in cell walls of Gram-positive bacteria; and a unique teichulosonic acid belonging to a new class of bioglycans described only in microorganisms of the Actinomycetales order. The latter polymer contains residues of di-N-acyl derivative of sialic acid-like monosaccharide - 5,7-diamino-3,5,7,9-tetradeoxy-L-glycero-β-L-manno-non-2-ulosonic or pseudaminic acid (Pse) which bears the N-(3,4-dihydroxybutanoyl) group (Dhb) at C7. This polymer has irregular structure and consists of fragments of two types, which differ in substitution of the Dhb residues at O4 either with β-D-glucopyranose or with β-Pse residues. Most of the β-Pse residues (~80%) are glycosylated at position 4 with α-D-galactopyranose residues in both types of fragments. The glucose, galactose, and Dhb residues are partly O-acetylated. The structures of the polymers were established by chemical and NMR spectroscopy methods.

Influence of Side Chain Conformation and Configuration on Glycosyl Donor Reactivity and Selectivity as Illustrated by Sialic Acid Donors Epimeric at the 7-Position

“…77-81 Furthermore, in so far as the side chain conformation of glycosyl donors might be influenced by protecting groups at other positions around the pyranose ring, for steric and or stereoelectronic reasons, it appears likely that side conformation has a role to play in the continuing debate on the influence of remote protecting groups on glycosylation reactions. 10,82-85 Finally, it is interesting to speculate that Nature may modulate the activity of enzymes involving in glycosidic bond formation and/or hydrolysis through the evolution of binding sites tailored to lock the side chain in suitable conformations.…”

“…Although the results presented in this Article have been developed through the use of N -acetyl neuraminic acid derivatives and their 7-epimers, the conclusions on the influence of the side chain configuration and conformation on glycosyl donor reactivity and selectivity are likely to have broader implications, not the least of which is in the formation of the legionaminic and pseudaminic acid (Figure ) glycosides found in various pathogenic bacteria. − Furthermore, insofar as the side chain conformation of glycosyl donors might be influenced by protecting groups at other positions around the pyranose ring, for steric and or stereoelectronic reasons, it appears likely that side conformation has a role to play in the continuing debate on the influence of remote protecting groups on glycosylation reactions. ,− Finally, it is interesting to speculate that Nature may modulate the activity of enzymes involved in glycosidic bond formation and/or hydrolysis through the evolution of binding sites tailored to lock the side chain in suitable conformations.…”

Recent progress on the chemical synthesis of bacterial non-2-ulosonic acids

“…Since pseudaminic acid was first identified from the LPS of the bacteria, Pseudomonas aeruginosa O10a and Shigella boydii type 7, in 1984 by Knirel and co-workers, 17,18 various pseudaminic acids and their derivatives bearing different N -substituents (collectively called pseudaminic acids), including Pse5Ac7Ac, Pse5Ac7Fo, Pse5Ac7(3 R Hb), Pse5Ac7(3 S Hb), Pse5Ac7Gr, Pse7Fo5(3 R Hb), Pse5Gr7Gr, Pse5Ac7Am, Pse7Am5(Gr2,3Me 2 ), Pse7Ac5(Gr2,3Me 2 ), Pse7Ac5Am, Pse5Am7Gr, and Pse5Ac7(2-methoxy-4,5,6-trihydroxy-hexanoyl), have been found from the LPS, CPS, EPS, S-layer, pilin, flagellin, and cell wall of a variety of Gram-negative bacteria; 19 only Bacillus thuringiensis israelensis is the Gram-positive exception. 20 A detailed summary of the identified Pse structures and the bacterial occurrence can be found in the ESI †…”