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Interactions of lipopolysaccharide and polymyxin studied by NMR spectroscopy


Mares, J; Kumaran, S; Gobbo, M; Zerbe, O (2009). Interactions of lipopolysaccharide and polymyxin studied by NMR spectroscopy. Journal of Biological Chemistry, 284(17):11498-11506.

Abstract

In the light of occurrence of bacterial strains with multiple resistances against most antibiotics, antimicrobial peptides that interact with the outer layer of gram-negative bacteria, such as polymyxin (PMX), have recently received increased attention. Here we present a study of the interactions of PMX-B, -E and -M with lipopolysaccharide (LPS) from a deep-rough mutant strain of E. coli. A method for efficient purification of biosynthetically produced LPS using RP-HPLC in combination with ternary solvent mixtures was developed. LPS was incorporated into a membrane model, dodecylphosphocholine (DPC) micelles, and its interaction with polymyxins was studied by heteronuclear NMR spectroscopy. Data from chemical shift mapping using isotope-labeled LPS or labeled polymyxin, as well as from isotope-filtered NOESY experiments, reveal the mode of interaction of LPS with polymyxins. Using MD calculations the complex of LPS with PMX-B in the presence of DPC micelles was modelled using restraints derived from chemical shift mapping data and intermolecular NOEs. In the modelled complex the macrocycle of PMX is centered around the phosphate group at GlcN-B, and additional contacts from polar sidechains are formed to GlcN-A and Kdo-C, while hydrophobic sidechains penetrate the acyl chain region.

Abstract

In the light of occurrence of bacterial strains with multiple resistances against most antibiotics, antimicrobial peptides that interact with the outer layer of gram-negative bacteria, such as polymyxin (PMX), have recently received increased attention. Here we present a study of the interactions of PMX-B, -E and -M with lipopolysaccharide (LPS) from a deep-rough mutant strain of E. coli. A method for efficient purification of biosynthetically produced LPS using RP-HPLC in combination with ternary solvent mixtures was developed. LPS was incorporated into a membrane model, dodecylphosphocholine (DPC) micelles, and its interaction with polymyxins was studied by heteronuclear NMR spectroscopy. Data from chemical shift mapping using isotope-labeled LPS or labeled polymyxin, as well as from isotope-filtered NOESY experiments, reveal the mode of interaction of LPS with polymyxins. Using MD calculations the complex of LPS with PMX-B in the presence of DPC micelles was modelled using restraints derived from chemical shift mapping data and intermolecular NOEs. In the modelled complex the macrocycle of PMX is centered around the phosphate group at GlcN-B, and additional contacts from polar sidechains are formed to GlcN-A and Kdo-C, while hydrophobic sidechains penetrate the acyl chain region.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:English
Date:22 April 2009
Deposited On:04 May 2009 07:19
Last Modified:24 Nov 2018 23:24
Publisher:American Society for Biochemistry and Molecular Biology
ISSN:0021-9258
Additional Information:This research was originally published in Mares, J; Kumaran, S; Gobbo, M; Zerbe, O (2009). Interactions of lipopolysaccharide and polymyxin studied by NMR spectroscopy. Journal of Biological Chemistry, 284(17):11498-11506. © the American Society for Biochemistry and Molecular Biology.
OA Status:Green
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1074/jbc.M806587200

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