Mutation in Bordetella bronchiseptica core lipopolysaccharide transferase genes triggers different lipid a structures.

A.C. CASABUONO, ; F. SISTI,; D.HOZBOR ; A. S. COUTO

FLORENCIA

Congreso; 13th Euro Fed Lipid Congress; 2015

Eur fed of lipids

Lipopolysacharides (LPSs) are the major constituents of the Gram-negative bacterial cell wall and consist of two or three main parts: (1) a glycolipid region, called lipid A, (2) an oligosaccharide (OS) region, called core, to which (3) a polysaccharide region, called O chain, is attached in the S-type endotoxins. The structural composition and the variability of these endotoxins is of importance in their pathophysiological impact.Bordetella bronchiseptica once thought to only infect animals, is currently acquiring increased importance as a human pathogen mainly in immunocompromised patients; it can infect and colonize the ciliated epithelium of the respiratory tract. The analysis of defective mutants in different portions of the LPS structure has allowed progress in understanding the role of these molecules in bacterial-host interaction.On a B. bronchiseptica 9.73 (Bb9.73) background, different mutants defective in the expression of genes involved in the biosynthesis of the core region were performed: a mutant defective in the expression of waaC gene (BbLP39), a mutant defective in gene BB3394 (BbLP3394), and another one defective in gene BB3398 (BbLP3398). Hydrolysis of the isolated LPSs under weak acid conditions yield the corresponding lipids A. Detail structural studies confirmed novel modifications in the lipid A profile; MALDI-TOF MS and MALDI-TOF MS/MS analysis using different matrices, reflectron or lineal mode and positive and negative polarity highlighted not only diversity in the acylation pattern (degree of acylation, nature of the fatty acids), but also in the diglucosamine backbone substitution, pointing out the influence of the core structure in lipid A biosynthesis.