LPS Molecules (lp + molecule)

Distribution by Scientific Domains


Selected Abstracts


Lipopolysaccharides of anaerobic beer spoilage bacteria of the genus Pectinatus, lipopolysaccharides of a Gram-positive genus

FEMS MICROBIOLOGY REVIEWS, Issue 5 2004
Ilkka M. Helander
Abstract Bacteria of the genus Pectinatus emerged during the seventies as contaminants and spoilage organisms in packaged beer. This genus comprises two species, Pectinatus cerevisiiphilus and Pectinatus frisingensis; both are strict anaerobes. On the basis of genomic properties the genus is placed among low GC Gram-positive bacteria (phylum Firmicutes, class Clostridia, order Clostridiales, family Acidaminococcaceae). Despite this assignment, Pectinatus bacteria possess an outer membrane and lipopolysaccharide (LPS) typical of Gram-negative bacteria. The present review compiles the structural and compositional studies performed on Pectinatus LPS. These lipopolysaccharides exhibit extensive heterogeneity, i.e. several macromolecularly and structurally distinct LPS molecules are produced by each strain. Whereas heterogeneity is a common property in lipopolysaccharides, Pectinatus LPS have been shown to contain exceptional carbohydrate structures, consisting of a fairly conserved core region that carries a large non-repetitive saccharide that probably replaces the O-specific chain. Such structures represent a novel architectural principle of the LPS molecule. [source]


Mutation in the LPS outer core biosynthesis gene, galU, affects LPS interaction with the RTX toxins ApxI and ApxII and cytolytic activity of Actinobacillus pleuropneumoniae serotype 1

MOLECULAR MICROBIOLOGY, Issue 1 2008
Mahendrasingh Ramjeet
Summary Lipopolysaccharides (LPS) and Apx toxins are major virulence factors of Actinobacillus pleuropneumoniae, a pathogen of the respiratory tract of pigs. Here, we evaluated the effect of LPS core truncation in haemolytic and cytotoxic activities of this microorganism. We previously generated a highly attenuated galU mutant of A. pleuropneumoniae serotype 1 that has an LPS molecule lacking the GalNAc-Gal II-Gal I outer core residues. Our results demonstrate that this mutant exhibits wild-type haemolytic activity but is significantly less cytotoxic to porcine alveolar macrophages. However, no differences were found in gene expression and secretion of the haemolytic and cytotoxic toxins ApxI and ApxII, both secreted by A. pleuropneumoniae serotype 1. This suggests that the outer core truncation mediated by the galU mutation affects the toxins in their cytotoxic activities. Using both ELISA and surface plasmon resonance binding assays, we demonstrate a novel interaction between LPS and the ApxI and ApxII toxins via the core oligosaccharide. Our results indicate that the GalNAc-Gal II-Gal I trisaccharide of the outer core is fundamental to mediating LPS/Apx interactions. The present study suggests that a lack of binding between LPS and ApxI/II affects the cytotoxicity and virulence of A. pleuropneumoniae. [source]


Structural studies on the core and the O-polysaccharide repeating unit of Pseudomonas aeruginosa immunotype 1 lipopolysaccharide

FEBS JOURNAL, Issue 8 2002
Olga V. Bystrova
The structure of the lipopolysaccharide (LPS) of Pseudomonas aeruginosa immunotype 1 was studied after mild acid and strong alkaline degradations by MS and NMR spectroscopy. Three types of LPS molecules were found, including those with an unsubstituted glycoform 1 core (A) or an isomeric glycoform 2 core substituted with one O-polysaccharide repeating unit (B) or with a long-chain O-polysaccharide. Therefore, of two core glycoforms, only glycoform 2 accepts the O-polysaccharide. In the structures A and B, Kdo, Hep, Hep7Cm, GalNAcAN3Ac, GalNFoAN, QuiNAc, GalNAla represent 3-deoxy- d - manno -octulosonic acid, l - glycero - d - manno -heptose, 7- O- carbamoyl- l - glycero - d - manno -heptose, 2-acetamido-3- O -acetyl-2-deoxygalacturonamide, 2-formamido-2-deoxygalacturonamide, 2-acetamido-2,6-dideoxyglucose and 2-(l -alanylamino)-2-deoxygalactose, respectively; all sugars are in the pyranose form and have the d configuration unless otherwise stated. One or more phosphorylation sites may be occupied by diphosphate groups. In a minority of the LPS molecules, an O-acetyl group is present in the outer core region at unknown position. The site and the configuration of the linkage between the O-polysaccharide and the core and the structure of the O-polysaccharide repeating unit were defined in P. aeruginosa immunotype 1. The QuiNAc residue linked to the Rha residue of the core was found to have the , configuration, whereas in the interior repeating units of the O-polysaccharide this residue is in the ,-configuration. The data obtained are in accordance with the initiation of biosynthesis of the O-polysaccharide of P. aeruginosa O6, which is closely related to immunotype 1, by transfer of d -QuiNAc-1- P to undecaprenyl phosphate followed by synthesis of the repeating O-antigen tetrasaccharide. [source]


Lipopolysaccharides of anaerobic beer spoilage bacteria of the genus Pectinatus, lipopolysaccharides of a Gram-positive genus

FEMS MICROBIOLOGY REVIEWS, Issue 5 2004
Ilkka M. Helander
Abstract Bacteria of the genus Pectinatus emerged during the seventies as contaminants and spoilage organisms in packaged beer. This genus comprises two species, Pectinatus cerevisiiphilus and Pectinatus frisingensis; both are strict anaerobes. On the basis of genomic properties the genus is placed among low GC Gram-positive bacteria (phylum Firmicutes, class Clostridia, order Clostridiales, family Acidaminococcaceae). Despite this assignment, Pectinatus bacteria possess an outer membrane and lipopolysaccharide (LPS) typical of Gram-negative bacteria. The present review compiles the structural and compositional studies performed on Pectinatus LPS. These lipopolysaccharides exhibit extensive heterogeneity, i.e. several macromolecularly and structurally distinct LPS molecules are produced by each strain. Whereas heterogeneity is a common property in lipopolysaccharides, Pectinatus LPS have been shown to contain exceptional carbohydrate structures, consisting of a fairly conserved core region that carries a large non-repetitive saccharide that probably replaces the O-specific chain. Such structures represent a novel architectural principle of the LPS molecule. [source]


Changes in lipopolysaccharide structure induce the ,E -dependent response of Escherichia coli

MOLECULAR MICROBIOLOGY, Issue 5 2005
Christina Tam
Summary The envelope of Escherichia coli is composed of an asymmetric lipid bilayer containing lipopolysaccharide, phospholipid and outer membrane proteins (OMPs). Physical and chemical stresses impact on the integrity of the outer membrane envelope and trigger the ,E -dependent response, whereby E. coli activates the expression of genes that increase its capacity for folding OMPs and synthesizing lipopolysaccharide (LPS). While it has already been appreciated that misfolded OMPs induce the ,E response, a role for LPS in activating this pathway was hitherto unknown. Here we show that ammonium metavandate (NH4VO3) induces multiple changes in E. coli LPS structure and activates the ,E -dependent response without altering OMP. One such NH4VO3 -mediated LPS decoration, the CrcA/PagP-catalysed addition of palmitate to lipid A, appeared to be alone sufficient to activate transcription at ,E -dependent promoters. Furthermore, reduced acylation of LPS, caused by htrB or msbB mutations, also resulted in a constitutive expression of the ,E regulon above wild-type levels. Production of these aberrant outer membrane lipids did not noticeably affect the composition or the amount of OMPs. A model is proposed whereby structural intermediates of the LPS biosynthetic pathway or modified LPS molecules may function as signals that activate the ,E response. [source]