Crystallization of R-form lipopolysaccharides from Salmonella minnesota and Escherichia coli.
Salmonella minnesota Re and Ra lipopolysaccharides (LPSs) and Escherichia coli K-12 LPS formed three-dimensional crystals, either hexagonal plates (preferential growth along the a axis) or solid columns (preferential growth along the c axis), when they were precipitated by the addition of 2 volumes of 95% ethanol containing 375 mM MgCl2 and incubated in 70% ethanol containing 250 mM MgCl2 at 4 degrees C for 10 days. Analyses of crystals suggested that they consist of hexagonal lattices with the a axis (a side of the lozenge as a unit cell on the basal plane) of 0.462 nm for all these three kinds of LPSs and the c axes (perpendicular to the basal plane) of 5.85, 8.47, and 8.75 nm for S. minnesota Re and Ra LPSs and E. coli K-12 LPS, respectively, and that hydrocarbon chains of the lipid A portion play the leading part in crystallization, whereas the hydrophilic part of the lipid A (the disaccharide backbone) and R core exhibit a disordered structure or are in a random orientation. The phenomenon of doubling of the a axis to 0.924 nm was observed with crystals of S. minnesota Re LPS when they were incubated in 70% ethanol for an additional 180 days, but not with crystals of S. minnesota Ra LPS or E. coli K-12 LPS. S. minnesota S-form LPS possessing the O-antigen-specific polysaccharide and S. minnesota free lipid A obtained by acid hydrolysis of Re LPS did not crystallize under the same experimental conditions.
Kato
N
N
Department of Bacteriology, Nagoya University School of Medicine, Aichi, Japan.
Ohta
M
M
Kido
N
N
Ito
H
H
Naito
S
S
Hasegawa
T
T
Watabe
T
T
Sasaki
K
K
D002236:Carbohydrate Conformation; D003460:Crystallization; D004731:Endotoxins / Q000302:isolation & purification; D004926:Escherichia coli / Q000276:immunology*; D008070:Lipopolysaccharides / Q000302:isolation & purification; D008854:Microscopy, Electron; D008958:Models, Molecular; D012475:Salmonella / Q000276:immunology*; D014961:X-Ray Diffraction
D004731:Endotoxins; D008070:Lipopolysaccharides