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Conformational Dyna...
Conformational Dynamics of the Lipopolysaccharide from Escherichia coli O91 Revealed by Nuclear Magnetic Resonance Spectroscopy and Molecular Simulations
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- Blasco, Pilar (författare)
- Stockholms universitet,Institutionen för organisk kemi
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Patel, Dhilon S. (författare)
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- Engström, Olof (författare)
- Stockholms universitet,Institutionen för organisk kemi
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Im, Wonpil (författare)
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- Widmalm, Göran (författare)
- Stockholms universitet,Institutionen för organisk kemi
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(creator_code:org_t)
- 2017-06-27
- 2017
- Engelska.
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 56:29, s. 3826-3839
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https://su.diva-port... (primary) (Raw object)
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http://su.diva-porta...
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- The outer leaflet of the outer membrane in Gram-negative bacteria contains lipopolysaccharides (LPS) as a major component, and the outer membrane provides a physical barrier and protection against hostile environments. The enterohemorrhagic Escherichia coli of serogroup O91 has an O-antigen polysaccharide (PS) with five sugar residues in the repeating unit (RU), and the herein studied O-antigen PS contains similar to 10 RUs. H-1-C-13 HSQC-NOESY experiments on a 1-C-13-labeled PS were employed to deduce H-1-H-1 cross-relaxation rates and transglycosidic (3)J(CH) related to the psi torsional angles were obtained by H-1-H-1 NOESY experiments. Dynamical parameters were calculated from the molecular dynamics (MD) simulations of the PS in solution and compared to those from C-13 nuclear magnetic resonance (NMR) relaxation studies. Importantly, the MD simulations can reproduce the dynamical behavior of internal correlation times along the PS chain. Two-dimensional free energy surfaces of glycosidic torsion angles delineate the conformational space available to the O-antigen. Although similar with respect to populated states in solution, the O-antigen in LPS bilayers has more extended chains as a result of spatial limitations due to close packing. Calcium ions are highly abundant in the phosphate-containing core region mediating LPS LPS association that is crucial for maintaining bilayer integrity, and the negatively charged O-antigen promotes a high concentration of counterbalancing potassium ions. The ensemble of structures present for the PS in solution is captured by the NMR experiments, and the similarities between the O-antigen on its own and as a constituent of the full LPS in a bilayer environment make it possible to realistically describe the LPS conformation and dynamics from the MD simulations.
Ämnesord
- NATURVETENSKAP -- Biologi (hsv//swe)
- NATURAL SCIENCES -- Biological Sciences (hsv//eng)
- NATURVETENSKAP -- Kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences (hsv//eng)
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