Characterization of lipid a profiles from Shigella flexneri variant X lipopolysaccharide

A. C. CASABUONO; C. A. VAN DER PLOEG; A. D. ROGÉ; S. B. BRUNO ; A.S. COUTO

RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM.

JOHN WILEY & SONS LTD

Lugar: Londres; Año: 2012

0951-4198

RATIONALE: In developing countries, Shigella flexneri (Sf) is the major causative agent of the endemic shigellosis(bacillary dysentery) responsible annually for one million fatalities mostly among infants. Lipopolysaccharides (LPSs)are characteristic components of the outer membrane of the overwhelming majority of Gram-negative bacteria.Since lipid A is essential for the viability of the Gram-negative bacteria, it is subject to extensive chemical studies withnew analytical techniques.METHODS: Lipid A was released by mild acid hydrolysis from the lipopolysaccharide which was obtained via thephenol/water extraction, purified and analyzed by matrix-assisted laser desorption/ionization time-of-flight massspectrometry (MALDI-TOF-MS) and matrix-assisted laser desorption/ionization laser-induced dissociation tandemmass spectrometry (MALDI-LID-MS/MS).RESULTS: A detailed structural study of the whole lipid A obtained from S. flexneri variant X was carried out for thefirst time. Thus, we have shown that lipid A is a heterogeneous mixture having different numbers of acylated andphosphoethanolamine groups attached to the diglucosamine backbone. Furthermore, we found in the phenol phase anunusual hepta-acylated lipid A species, although the abundance was very low.CONCLUSIONS: MALDI-TOF-MS allowed us to unravel the lipid A heterogeneity, which was not previously reported inSf LPS. It is well known that slight variations of the chemical structure of lipid A may change its biological activity. Thus,the knowledge of the detailed chemical structure represents an essential step for further development of new preventiveor therapeutically active compounds. Copyright © 2012 John Wiley & Sons, Ltd.