Distribution of polysaccharide side chains of lipopolysaccharide determine resistance of Escherichia coli to the bactericidal activity of serum.
The lipopolysaccharide (LPS) of serum-sensitive strains of Escherichia coli was compared with LPS derived from serum-resistant clones. Polysaccharide O-antigen side chains (PSSC) of LPS from serum-resistant clones contained 12%-40% more of the longer carbohydrate molecules (L-PSSC) than did LPS from serum-sensitive parent strains; in contrast, 12%-27% more of the shorter PSSC (S-PSSC) were found in LPS from serum-sensitive strains. The sensitivity or resistance to the bactericidal activity of human serum correlated with the distribution and the length of PSSC fractions of LPS. This was demonstrated in a liposome model in which LPS was incorporated into simulated bacterial membranes. The incubation of serum with liposomes incorporated with various ratios of S-PSSC-to-L-PSSC concentrations resulted in liposomal lysis at S-PSSC-to-L-PSSC ratios greater than 2:1. These findings demonstrate the importance of the length of carbohydrate side chains of LPS in determining sensitivity or resistance to the bactericidal activity of human serum.
Porat
R
R
Department of Medicine, Ichilov Hospital, Tel-Aviv Medical Center, Israel.
Mosseri
R
R
Kaplan
E
E
Johns
M A
MA
Shibolet
S
S
D001770:Blood Bactericidal Activity; D002850:Chromatography, Gel; D004926:Escherichia coli / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D008070:Lipopolysaccharides / Q000737:chemistry* / Q000276:immunology; D008081:Liposomes / Q000276:immunology; D011135:Polysaccharides, Bacterial / Q000737:chemistry*
D008070:Lipopolysaccharides; D008081:Liposomes; D011135:Polysaccharides, Bacterial