title: Lipid A components from Pseudomonas aeruginosa PAO1 (serotype O5) and mutant strains investigated by electrospray ionization ion-trap mass spectrometry.
abstract: The lipid A components of the Pseudomonas aeruginosa strains PAO1 (wild-type) and derived mutants PAO1 algC::tet and PAO1 PDO100 were isolated after mild acetic acid hydrolysis of LPS. Their structural heterogeneities were characterized using electrospray ionization (ESI) ion-trap mass spectrometry (MS) with direct infusion in the negative ion mode without prior derivatization. The ESI-mass spectra revealed monophosphorylated molecules corresponding to known tetra-, penta- and hexaacylated structures of P. aeruginosa lipid A. The MS/MS fragmentation patterns allowed the location of fatty acyl chains on the disaccharide backbone of lipid A. In addition, a hexaacylated lipid A containing a hexadecanoyl chain was detected for the first time in strain P. aeruginosa PAO1. With multiple stages of fragmentation (MS(n)), the position of this hexadecanoyl chain O-linked to the decanoyl chain at the C-3(') position of the glucosamine backbone was determined. This sensitive method is suitable to reveal lipid A heterogeneity, i.e. the nature, number and distribution of acyl chains, without prior lipopolysaccharide purification. The lipid A from mutant strains were also characterized and significant differences were shown in the abundance of monophosphorylated lipid A components between the wild-type and the mutant strains.
authors.affiliation: Laboratoire de Biologie et Chimie Moléculaires, Université de Bretagne Sud, Lorient, France. gilles.bedoux@uni-ubs.fr
authors.forename: Gilles
authors.initials: G
authors.lastname: Bedoux
authors.forename: Karine
authors.initials: K
authors.lastname: Vallée-Réhel
authors.forename: Oliver
authors.initials: O
authors.lastname: Kooistra
authors.forename: Ulrich
authors.initials: U
authors.lastname: Zähringer
authors.forename: Dominique
authors.initials: D
authors.lastname: Haras
mesh_terms: D008050:Lipid A / Q000737:chemistry* / Q000302:isolation & purification; D015394:Molecular Structure; D009154:Mutation / Q000235:genetics*; D011550:Pseudomonas aeruginosa / Q000737:chemistry* / Q000145:classification / Q000235:genetics*; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D008050:Lipid A