' Liberibacter asiaticus'-Encoded BCP Peroxiredoxin Suppresses Lipopolysaccharide-Mediated Defense Signaling and Nitrosative Stress In Planta.

The lipopolysaccharides (LPS) of gram-negative bacteria trigger a nitrosative and oxidative burst in both animals and plants during pathogen invasion. strain BT-1 is a surrogate for functional genomic studies of the uncultured pathogenic ' Liberibacter' spp. that are associated with severe diseases such as citrus greening and potato zebra chip.

Structure of Lipopolysaccharide from Is Low Molecular Weight and Offers Insight into Liberibacter Biology.

Huanglongbing (HLB) disease, also known as citrus greening disease, was first reported in the US in 2005. Since then, the disease has decimated the citrus industry in Florida, resulting in billions of dollars in crop losses and the destruction of thousands of acres of citrus groves. The causative agent of citrus greening disease is the phloem limited pathogen Liberibacter asiaticus.

Linkage Analysis of Oligosaccharides and Polysaccharides: A Tutorial.

Polysaccharides and oligosaccharides are a diverse group of natural polymers with important biological functions. The diversity of carbohydrate polymers is vast, ranging from small oligosaccharides of defined composition decorating proteins, to large, complex heteropolymers comprising integral cell wall components of plants, fungi and bacteria. An important step in the elucidation of unknown carbohydrate structures in a sample is the assessment of the various linkages present.

, a Pathogen from Patients with Chronic Granulomatous Disease, Produces a Penta-Acylated Hypostimulatory Glycero-D-talo-oct-2-ulosonic Acid-Lipid A Glycolipid (Ko-Lipid A).

can infect patients with chronic granulomatous disease, an immunodeficiency caused by reduced phagocyte NADPH oxidase function. Intact () is hypostimulatory compared to , i.e.

An atypical lipoteichoic acid from elicits a broadly cross-reactive and protective immune response.

is a leading cause of food-poisoning and causes avian necrotic enteritis, posing a significant problem to both the poultry industry and human health. No effective vaccine against is currently available. Using an antiserum screen of mutants generated from a transposon-mutant library, here we identified an immunoreactive antigen that was lost in a putative glycosyltransferase mutant, suggesting that this antigen is likely a glycoconjugate.

Elucidating Peptidoglycan Structure: An Analytical Toolset.

Peptidoglycan (PG) is a ubiquitous structural polysaccharide of the bacterial cell wall, essential in preserving cell integrity by withstanding turgor pressure. Any change that affects its biosynthesis or degradation will disturb cell viability, therefore PG is one of the main targets of antimicrobial drugs. Considering its major role in cell structure and integrity, the study of PG is of utmost relevance, with prospective ramifications to several disciplines such as microbiology, pharmacology, agriculture, and pathogenesis.

Lipopolysaccharides Trigger Two Successive Bursts of Reactive Oxygen Species at Distinct Cellular Locations.

Lipopolysaccharides (LPS) are major components of the outer membrane of gram-negative bacteria and are an important microbe-associated molecular pattern (MAMP) that triggers immune responses in plants and animals. A previous genetic screen in Arabidopsis () identified LIPOOLIGOSACCHARIDE-SPECIFIC REDUCED ELICITATION (LORE), a B-type lectin -domain receptor kinase, as a sensor of LPS. However, the LPS-activated LORE signaling pathway and associated immune responses remain largely unknown.

Structural and immunochemical relatedness suggests a conserved pathogenicity motif for secondary cell wall polysaccharides in Bacillus anthracis and infection-associated Bacillus cereus.

Bacillus anthracis (Ba) and human infection-associated Bacillus cereus (Bc) strains Bc G9241 and Bc 03BB87 have secondary cell wall polysaccharides (SCWPs) comprising an aminoglycosyl trisaccharide repeat: →4)-β-d-ManpNAc-(1→4)-β-d-GlcpNAc-(1→6)-α-d-GlcpNAc-(1→, substituted at GlcNAc residues with both α- and β-Galp. In Bc G9241 and Bc 03BB87, an additional α-Galp is attached to O-3 of ManNAc. Using NMR spectroscopy, mass spectrometry and immunochemical methods, we compared these structures to SCWPs from Bc biovar anthracis strains isolated from great apes displaying "anthrax-like" symptoms in Cameroon (Bc CA) and Côte d'Ivoire (Bc CI).

The Lipopolysaccharide Lipid A Long-Chain Fatty Acid Is Important for Rhizobium leguminosarum Growth and Stress Adaptation in Free-Living and Nodule Environments.

Rhizobium bacteria live in soil and plant environments, are capable of inducing symbiotic nodules on legumes, invade these nodules, and develop into bacteroids that fix atmospheric nitrogen into ammonia. Rhizobial lipopolysaccharide (LPS) is anchored in the bacterial outer membrane through a specialized lipid A containing a very long-chain fatty acid (VLCFA). VLCFA function for rhizobial growth in soil and plant environments is not well understood.

Structures of Exopolysaccharides Involved in Receptor-mediated Perception of Mesorhizobium loti by Lotus japonicus.

In the symbiosis formed between Mesorhizobium loti strain R7A and Lotus japonicus Gifu, rhizobial exopolysaccharide (EPS) plays an important role in infection thread formation. Mutants of strain R7A affected in early exopolysaccharide biosynthetic steps form nitrogen-fixing nodules on L. japonicus Gifu after a delay, whereas mutants affected in mid or late biosynthetic steps induce uninfected nodule primordia.

The MisR Response Regulator Is Necessary for Intrinsic Cationic Antimicrobial Peptide and Aminoglycoside Resistance in Neisseria gonorrhoeae.

During infection, the sexually transmitted pathogen Neisseria gonorrhoeae (the gonococcus) encounters numerous host-derived antimicrobials, including cationic antimicrobial peptides (CAMPs) produced by epithelial and phagocytic cells. CAMPs have both direct and indirect killing mechanisms and help link the innate and adaptive immune responses during infection. Gonococcal CAMP resistance is likely important for avoidance of host nonoxidative killing systems expressed by polymorphonuclear granulocytes (e.

Xyloglucan, galactomannan, glucuronoxylan, and rhamnogalacturonan I do not have identical structures in soybean root and root hair cell walls.

Chemical analyses and glycome profiling demonstrate differences in the structures of the xyloglucan, galactomannan, glucuronoxylan, and rhamnogalacturonan I isolated from soybean ( Glycine max ) roots and root hair cell walls. The root hair is a plant cell that extends only at its tip. All other root cells have the ability to grow in different directions (diffuse growth).

The role of oxidoreductases in determining the function of the neisserial lipid A phosphoethanolamine transferase required for resistance to polymyxin.

The decoration of the lipid A headgroups of the lipooligosaccharide (LOS) by the LOS phosphoethanolamine (PEA) transferase (LptA) in Neisseria spp. is central for resistance to polymyxin. The structure of the globular domain of LptA shows that the protein has five disulphide bonds, indicating that it is a potential substrate of the protein oxidation pathway in the bacterial periplasm.

Phosphoethanolamine decoration of Neisseria gonorrhoeae lipid A plays a dual immunostimulatory and protective role during experimental genital tract infection.

The induction of an intense inflammatory response by Neisseria gonorrhoeae and the persistence of this pathogen in the presence of innate effectors is a fascinating aspect of gonorrhea. Phosphoethanolamine (PEA) decoration of lipid A increases gonococcal resistance to complement-mediated bacteriolysis and cationic antimicrobial peptides (CAMPs), and recently we reported that wild-type N. gonorrhoeae strain FA1090 has a survival advantage relative to a PEA transferase A (lptA) mutant in the human urethral-challenge and murine lower genital tract infection models.

Lipid A's structure mediates Neisseria gonorrhoeae fitness during experimental infection of mice and men.

Unlabelled: Phosphoethanolamine (PEA) on Neisseria gonorrhoeae lipid A influences gonococcal inflammatory signaling and susceptibility to innate host defenses in in vitro models. Here, we evaluated the role of PEA-decorated gonococcal lipid A in competitive infections in female mice and in male volunteers. We inoculated mice and men with mixtures of wild-type N.

Noncanonical inflammasome activation by intracellular LPS independent of TLR4.

Gram-negative bacteria including Escherichia coli, Citrobacter rodentium, Salmonella typhimurium, and Shigella flexneri are sensed in an ill-defined manner by an intracellular inflammasome complex that activates caspase-11. We show that macrophages loaded with synthetic lipid A, E. coli lipopolysaccharide (LPS), or S.

The structure of the neisserial lipooligosaccharide phosphoethanolamine transferase A (LptA) required for resistance to polymyxin.

Gram-negative bacteria possess an outer membrane envelope consisting of an outer leaflet of lipopolysaccharides, also called endotoxins, which protect the pathogen from antimicrobial peptides and have multifaceted roles in virulence. Lipopolysaccharide consists of a glycan moiety attached to lipid A, embedded in the outer membrane. Modification of the lipid A headgroups by phosphoethanolamine (PEA) or 4-amino-arabinose residues increases resistance to the cationic cyclic polypeptide antibiotic, polymyxin.

Elucidation of the 3-O-deacylase gene, pagL, required for the removal of primary β-hydroxy fatty acid from the lipid A in the nitrogen-fixing endosymbiont Rhizobium etli CE3.

Until now, the gene responsible for the 3-O-deacylation of lipid A among nitrogen-fixing endosymbionts has not been characterized. Several Gram-negative animal pathogens such as Salmonella enterica, Pseudomonas aeruginosa, and Bordetella bronchiseptica contain an outer membrane 3-O-deacylase (PagL) that has been implicated in host immune evasion. The role of 3-O-deacylated lipid A among nitrogen-fixing endosymbionts, plant endophytes, and plant pathogens has not been studied.

The secondary cell wall polysaccharide of Bacillus anthracis provides the specific binding ligand for the C-terminal cell wall-binding domain of two phage endolysins, PlyL and PlyG.

Endolysins are bacteriophage enzymes that lyse their bacterial host for phage progeny release. They commonly contain an N-terminal catalytic domain that hydrolyzes bacterial peptidoglycan (PG) and a C-terminal cell wall-binding domain (CBD) that confers enzyme localization to the PG substrate. Two endolysins, phage lysin L (PlyL) and phage lysin G (PlyG), are specific for Bacillus anthracis.

Late acyltransferase genes lpxX and lpxL jointly contribute to the biological activities of Moraxella catarrhalis.

Lipo-oligosaccharide (LOS) is a major surface component and virulence factor of the human respiratory pathogen Moraxella catarrhalis. Two late acyltransferase genes, lpxX and lpxL, have been identified involved in the incorporation of acyloxyacyl-linked secondary acyl chains into lipid A during M. catarrhalis LOS biosynthesis.

Identification of the mutation responsible for the temperature-sensitive lipopolysaccharide O-antigen defect in the Pseudomonas aeruginosa cystic fibrosis isolate 2192.

Pseudomonas aeruginosa in the lungs of cystic fibrosis (CF) patients is characterized by a series of genotypic and phenotypic changes that reflect the transition from acute to chronic infection. These include the overproduction of the exopolysaccharide alginate and the loss of complete lipopolysaccharide (LPS). LPS is a major component of the Gram-negative outer membrane and is composed of lipid A, core oligosaccharide, and O antigen.

Conditional requirement for exopolysaccharide in the Mesorhizobium-Lotus symbiosis.

Rhizobial surface polysaccharides are required for nodule formation on the roots of at least some legumes but the mechanisms by which they act are yet to be determined. As a first step to investigate the function of exopolysaccharide (EPS) in the formation of determinate nodules, we isolated Mesorhizobium loti mutants affected in various steps of EPS biosynthesis and characterized their symbiotic phenotypes on two Lotus spp. The wild-type M.