标题：A rapid, small-scale procedure for the structural characterization of lipid A applied to Citrobacter and Bordetella strains: discovery of a new structural element
出版社：American Society for Biochemistry and Molecular Biology
摘要：Endotoxins [lipopolysaccharides (LPSs)] are part of the outercell membrane of Gram-negative bacteria. Their biological activitiesare associated mainly with the lipid component (lipid A) andeven more specifically with discrete aspects of their fine structure.The need for a rapid and small-scale analysis of lipid A motivatedus to develop a procedure that combines direct isolation oflipids A from bacterial cells with sequential release of theirester-linked fatty acids by a mild alkali treatment followedby MALDI-MS analysis. This method avoids the multiple-step LPSextraction procedure and lipid A isolation. The whole processcan be performed in a working day and applied to lyophilizedbacterial samples as small as 1 mg. We illustrate the methodby applying it to the analysis of lipids A of three speciesof Citrobacter that were found to be identical. On the otherhand, when applied to two batches of Bordetella bronchisepticastrain 4650, it highlighted the presence, in one of them, ofhitherto unreported hexosamine residues substituting the lipidA phosphate groups, possibly a new camouflage opportunity toescape a host defense system.Supplementary key words de-O-acylation • Gram-negative bacteria • hexosamine • endotoxin • lipopolysaccharide • mass spectrometry
Abbreviations: C16, hexadecanoic acid; C12, dodecanoic acid; C14, tetradecanoic acid; C14-OH, hydroxytetradecanoic acid; GlcN, glucosamine; HF, hydrofluoric acid; LPS, lipopolysaccharide
