RRC ID 47575
Author Kondo K, Takeda M, Mashima T, Katahira M, Koizumi J, Ueda K.
Title Conformational analysis of an extracellular polysaccharide produced by Sphaerotilus natans.
Journal Carbohydr Res
Abstract Sphaerotilus natans is a filamentous sheath-forming bacterium, commonly found in bulking activated sludge. The bulky nature of this bacterium is caused by an extracellular polysaccharide (EPS). EPS is a linear acidic polysaccharide with the following chemical structure: [ → 4)-α-D-Glcp-(1 → 2)-β-D-GlcpA-(1 → 2)-α-L-Rhap-(1 → 3)-β-L-Rhap-(1 → ](n). (1)H-(1)H and (1)H-(13)C correlation nuclear magnetic resonance (NMR) experiments were performed to acquire nuclear Overhauser effect signals, which were used for conformational elucidation. Molecular mechanics calculations were performed on each disaccharide unit of the EPS building blocks. On the basis of the results of the calculations, the conformation of a pentasaccharide fragment was estimated. After confirmation of the coincidence between the NMR data and the predicted conformation of the pentasaccharide fragment, the conformation of a heptadecasaccharide fragment was estimated using the same procedure. The heptadecasaccharide was found to form a (12/1) helix and take locally folded chain, which is attributed to a triangular arrangement formed by a series of residues, α-D-Glcp-(1 → 2)-β-D-GlcpA-(1 → 2)-α-L-Rhap. This arrangement is caused by the peculiar consecutive (1 → 2) linkages and reinforced by a hydrogen bond between the α-glucosyl and α-rhamnosyl residues. Considering the steric hindrance due to this triangular arrangement, EPS molecules are not supposed to form double helix in an aqueous environment. We propose the name 'sphaeran' to refer to this unique chemical structure and properties of EPS.
Volume 360
Pages 102-8
Published 2012-10-1
DOI 10.1016/j.carres.2012.07.023
PII S0008-6215(12)00315-1
PMID 22940182
MeSH Carbohydrate Conformation Models, Molecular Nuclear Magnetic Resonance, Biomolecular Polysaccharides / biosynthesis Polysaccharides / chemistry* Sphaerotilus / chemistry* Sphaerotilus / metabolism
IF 1.841
Times Cited 3
General Microbes JCM 20382