tailieunhanh - Báo cáo khoa học: Epitope mapping of the O-chain polysaccharide of Legionella pneumophila serogroup 1 lipopolysaccharide by saturation-transfer-difference NMR spectroscopy

Two modi®cations of 5-acetimidoylamino-7-acetamido-3,5,7,9-tetradeoxy-D-glycero-D-galacto-non-2-ulosonic acid (5-N-acetimidoyl-7-N-acetyllegionaminic acid) in the O-chainpolysaccharide (OPS) of theLegionellapneumophila serogroup 1 lipopolysaccharide (LPS) concern N-methyla-tionof the 5-N-acetimidoyl group in legionaminic acid. Both N-methylated substituents, the (N,N-dimethylacetimidoyl) amino and acetimidoyl(N-methyl)amino group, could be allocated to one single legionaminic acid residue in the long-and middle-chain OPS, respectively. . | Eur. J. Biochem. 269 573-582 2002 FEBS 2002 Epitope mapping of the O-chain polysaccharide of Legionella pneumophila serogroup 1 lipopolysaccharide by saturation-transfer-difference NMR spectroscopy Oliver Kooistra1 Lars Herfurth2 Edeltraud Luneberg3 Matthias Frosch3 Thomas Peters2 and Ulrich Zahringer1 1 Research Center Borstel Center for Medicine and Biosciences Germany 2Institute for Chemistry Medical University of Lubeck Germany 3Institute for Hygiene and Microbiology University of Wurzburg Germany Two modifications of 5-acetimidoylamino-7-acetamido-3 5 7 9-tetradeoxy-D-glycero-D-galacto-non-2-ulosonic acid 5-N-acetimidoyl-7-N-acetyllegionaminic acid in the O-chain polysaccharide OPS of the Legionella pneumophila serogroup 1 lipopolysaccharide LPS concern N-methyla-tion of the 5-N-acetimidoyl group in legionaminic acid. Both N-methylated substituents the N N-dimethylacetimidoyl amino and acetimidoyl N-methyl amino group could be allocated to one single legionaminic acid residue in the long-and middle-chain OPS respectively. Using mutants devoid of N-methylated legionaminic acid derivatives it could be shown that N-methylation of legionaminic acid correlated with the expression of the mAb 2625 epitope. In the present study we investigated the binding of the LPS-specific monoclonal antibody mAb 2625 to isolated OPS with surfaceplasmon-resonance biomolecular interaction analysis and saturation-transfer-difference STD NMR spectroscopy in order to map the mAb 2625 epitope on a molecular level. It could be demonstrated that the binding affinity of the N-methylated legionaminic acid derivatives was independent from the size of the isolated OPS molecular species. In addition STD NMR spectroscopic studies with polysaccharide ligands with an average molecular mass of up to 14 kDa revealed that binding was mainly mediated via the N-methylated acetimidoylamino group and via the closely located 7-N-acetyl group of the respective legionaminic acid residue thus indicating .