Comparison of lipids A of several Salmonella and Escherichia strains by 252Cf plasma desorption mass spectrometry

Abstract

Plasma desorption mass spectrometry has recently been used with success to characterize underivatized lipid A preparations: the major molecular species present give signals indicating their masses, from which probable compositions could be inferred by using the overall composition determined by chemical analyses. In the present study, plasma desorption mass spectrometry was used to compare structures in lipid A preparations isolated from several smooth and rough strains of Escherichia and Salmonella species. Preparations isolated from strains of both genera revealed considerable variation in degree of heterogeneity (number of fatty acids and presence or absence of hexadecanoic acid, phosphorylethanolamine, and aminoarabinose). Molecular species usually associated with Salmonella lipid A were found in preparations from Escherichia sp. In addition, preparations from three different batches of lipid A from one strain of Salmonella Minnesota showed significant differences in composition. These results demonstrate that preparations used for biological and structural analyses should be defined in terms of their particular molecular constituents and that no generalizations based on analysis of a single preparation should be made.

Microextraction of bacterial lipid A: easy and rapid method for mass spectrometric characterization

“…3 . Figure 3A shows the spectrum obtained for E. coli lipid A (24) under the new conditions with the classical hexa-acylated molecular species at m/z 1,797 followed by penta-and tetra-acylated molecular species at m/z 1,570 and 1,361, respectively. For B. pertussis lipid A (Fig.…”

“…Different rough-type bacteria of known lipid A structure were tested: B. pertussis (22), H. influenzae (23), and E. coli (24). MALDI spectra in the negative-ion mode demonstrated that no structural elements were lost upon hydrolysis.…”

Function of Escherichia coli MsbA, an Essential ABC Family Transporter, in Lipid A and Phospholipid Biosynthesis

“…Our assay is based on the observation that the Kdo-lipid A linkage (Fig. 2) is cleaved selectively by pH 4.5 hydrolysis at 100°C in the presence of SDS without measurable loss of ester-linked fatty acids or of the anomeric phosphate (34)(35)(36). The hydrolysis procedure can be applied directly to radioactive cells or to isolated membrane fractions from a sucrose gradient without first extracting LPS with phenol-containing solvents.…”

The Drosophila immune system detects bacteria through specific peptidoglycan recognition

“…The purification steps involved the extraction of phospholipids with chloroform/methanol (1:2) followed by treatment with DNase, RNase and then protease until thin-layer chromatography and ultraviolet spectra showed no detectable contaminants 39 . We check the electrophoretic behavior and mass of all purified samples by SDS-PAGE and mass spectrometry, respectively 40 . Purified LPS from S. typhimurium LT2 was used directly, whereas E. coli 0111B4 and B. pertussis LPS were treated by a procedure that improves LPS solubility by removing divalent cations that form links between molecules 41 .…”