Rhizobium (Sinorhizobium) sp. strain NGR234 contains three replicons, the smallest of which (pNGR234a) carries most symbiotic genes, including those required for nodulation and lipo-chito-oligosaccharide (Nod factor) biosynthesis. Activation of nod gene expression depends on plant-derived flavonoids, NodD transcriptional activators, and nod box promoter elements. Nod boxes NB6 and NB7 delimit s...

Gram-negative bacteria possess an outer membrane (OM) containing lipopolysaccharide (LPS). Proper assembly of the OM not only prevents certain antibiotics from entering the cell, but also allows others to be pumped out. To assemble this barrier, the seven-protein lipopolysaccharide transport (Lpt) system extracts LPS from the outer leaflet of the inner membrane (IM), transports it across the pe...

The interactions of polycationic antibiotics with lipopolysaccharide (LPS) isolated from parental and polymyxin-resistant strains of Salmonella typhimurium and Escherichia coli were measured by using a cationic spin probe. Electron spin resonance spectra indicated that increasing concentrations of cations competitively displaced probe from LPS aggregates. Polymyxin B and other cations displaced...

Using various envelope mutants of Escherichia coli, the relationship between cell surface struc­ ture and the Ca2*or Ba2+-dependent competence for transfection was investigated. In contrast with rough strains, smooth bacteria treated with Ca2+ or Ba2+ were incompetent for the trans­ fection by 0 A RF. In E. coli K12 D21 derivatives, Ca2+-dependent competence remarkably in­ creased by IpsA l mut...

The outer membrane of most Gram-negative bacteria is made up of LPS, and in nearly all bacteria that contain LPS it is essential for the life of the organism. The lipid portion of this molecule, lipid A, also known as endotoxin, is a potent activator of the innate immune response. More than 50 genes are required to synthesize LPS and assemble it at the cell surface. Enormous progress has been m...

Selected cell envelope components of Porphyromonas gingivalis were tested in a BALB/c mouse model in an attempt to elucidate further the outer membrane components of this putative oral pathogen that might be considered as virulence factors in host tissue destruction. Lipopolysaccharide (LPS), outer membrane, and outer membrane vesicles of P. gingivalis W50, ATCC 53977, and ATCC 33277 were selec...

Lipopolysccharide (LPS) is an integral component of the Pseudomonas aeruginosa cell envelope, occupying the outer leaflet of the outer membrane in this Gram-negative opportunistic pathogen. It is important for bacterium-host interactions and has been shown to be a major virulence factor for this organism. Structurally, P. aeruginosa LPS is composed of three domains, namely, lipid A, core oligos...

Natural killer (NK) cells have been shown to play a regulatory role in sepsis. According to the current view, NK cells become activated via macrophages or dendritic cells primed by lipopolysaccharide (LPS). Recently, TLR4 gene expression was detected in human NK cells suggesting the possibility of a direct action of LPS on NK cells. In this study, effects of LPS on NK cell cytokine production a...

The basis of differentiation of Pseudomonas aeruginosa into the 17 serotypes of the International Antigenic Typing Scheme is differences in an outer membrane glycolipid, lipopolysaccharide (LPS). This observation, together with the high toxicity and pyrogenicity of LPS, has led to the search for alternative "common" antigens for use as vaccines. The relation between the major outer membrane pro...