Lipid A components from Pseudomonas aeruginosa PAO1 (serotype O5) and mutant strains investigated by electrospray ionization ion-trap mass spectrometry.
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.
Bedoux
Gilles
G
Laboratoire de Biologie et Chimie Moléculaires, Université de Bretagne Sud, Lorient, France. gilles.bedoux@uni-ubs.fr
Vallée-Réhel
Karine
K
Kooistra
Oliver
O
Zähringer
Ulrich
U
Haras
Dominique
D
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
D008050:Lipid A