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Mechanisms of peptide-induced pore formation in lipid bilayers investigated by oriented 31P solid-state NMR spectroscopy.

Bertelsen K, Dorosz J, Hansen SK, Nielsen NC, Vosegaard T - PLoS ONE (2012)

Bottom Line: For two AMPs, alamethicin and novicidin, we observe that the majority of the lipids remain in a planar bilayer conformation but that a number of lipids are involved in the peptide anchoring.These lipids display reduced dynamics.Our study supports previous studies showing that alamethicin adopts a transmembrane arrangement without significant disturbance of the surrounding lipids, while novicidin forms toroidal pores at high concentrations leading to more extensive membrane disturbance.

View Article: PubMed Central - PubMed

Affiliation: Center for Insoluble Protein Structures (inSPIN), Department of Chemistry, University of Aarhus, Aarhus, Denmark.

ABSTRACT
There is a considerable interest in understanding the function of antimicrobial peptides (AMPs), but the details of their mode of action is not fully understood. This motivates extensive efforts in determining structural and mechanistic parameters for AMP's interaction with lipid membranes. In this study we show that oriented-sample (31)P solid-state NMR spectroscopy can be used to probe the membrane perturbations and disruption by AMPs. For two AMPs, alamethicin and novicidin, we observe that the majority of the lipids remain in a planar bilayer conformation but that a number of lipids are involved in the peptide anchoring. These lipids display reduced dynamics. Our study supports previous studies showing that alamethicin adopts a transmembrane arrangement without significant disturbance of the surrounding lipids, while novicidin forms toroidal pores at high concentrations leading to more extensive membrane disturbance.

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Related in: MedlinePlus

Experimental (a) and simulated (b) 31P powder NMR spectra of lyophilized DMPC.Experimental (c) and simulated (d) 31P static powder NMR spectra of DMPC vesicles. The peak at 0 ppm in (c) originates from the phosphate buffer.
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pone-0047745-g001: Experimental (a) and simulated (b) 31P powder NMR spectra of lyophilized DMPC.Experimental (c) and simulated (d) 31P static powder NMR spectra of DMPC vesicles. The peak at 0 ppm in (c) originates from the phosphate buffer.

Mentions: The observation of motionally reduced chemical shift anisotropies has been extensively used to determine the membrane-bound conformation of peptides by measuring the scaled nuclear spin interaction parameters of, e.g. 15N and 13C spins belonging to peptides diffusing in lipid bilayers [36], [46], [47]. In this study, we address instead attention to the scaling of the 31P resonances from phosphate headgroups of lipids in presence of the peptides. Figures 1a and 1b shows experimental and simulated 31P powder spectra of dry, lyophilized DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine), respectively, represented by the chemical shift parameters ppm, ppm, and (see definition of parameters in, e.g., Ref. [48]), in agreement with previously determined parameters for similar compounds [49], [50]. In a hydrated bilayer, rotational diffusion of the lipids reduces the anisotropic chemical shift parameters to ppm with the expected axial symmetry () as illustrated by experimental and simulated static powder 31P NMR spectra of the same lipids in Figs. 1c and 1d, respectively.


Mechanisms of peptide-induced pore formation in lipid bilayers investigated by oriented 31P solid-state NMR spectroscopy.

Bertelsen K, Dorosz J, Hansen SK, Nielsen NC, Vosegaard T - PLoS ONE (2012)

Experimental (a) and simulated (b) 31P powder NMR spectra of lyophilized DMPC.Experimental (c) and simulated (d) 31P static powder NMR spectra of DMPC vesicles. The peak at 0 ppm in (c) originates from the phosphate buffer.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3475706&req=5

pone-0047745-g001: Experimental (a) and simulated (b) 31P powder NMR spectra of lyophilized DMPC.Experimental (c) and simulated (d) 31P static powder NMR spectra of DMPC vesicles. The peak at 0 ppm in (c) originates from the phosphate buffer.
Mentions: The observation of motionally reduced chemical shift anisotropies has been extensively used to determine the membrane-bound conformation of peptides by measuring the scaled nuclear spin interaction parameters of, e.g. 15N and 13C spins belonging to peptides diffusing in lipid bilayers [36], [46], [47]. In this study, we address instead attention to the scaling of the 31P resonances from phosphate headgroups of lipids in presence of the peptides. Figures 1a and 1b shows experimental and simulated 31P powder spectra of dry, lyophilized DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine), respectively, represented by the chemical shift parameters ppm, ppm, and (see definition of parameters in, e.g., Ref. [48]), in agreement with previously determined parameters for similar compounds [49], [50]. In a hydrated bilayer, rotational diffusion of the lipids reduces the anisotropic chemical shift parameters to ppm with the expected axial symmetry () as illustrated by experimental and simulated static powder 31P NMR spectra of the same lipids in Figs. 1c and 1d, respectively.

Bottom Line: For two AMPs, alamethicin and novicidin, we observe that the majority of the lipids remain in a planar bilayer conformation but that a number of lipids are involved in the peptide anchoring.These lipids display reduced dynamics.Our study supports previous studies showing that alamethicin adopts a transmembrane arrangement without significant disturbance of the surrounding lipids, while novicidin forms toroidal pores at high concentrations leading to more extensive membrane disturbance.

View Article: PubMed Central - PubMed

Affiliation: Center for Insoluble Protein Structures (inSPIN), Department of Chemistry, University of Aarhus, Aarhus, Denmark.

ABSTRACT
There is a considerable interest in understanding the function of antimicrobial peptides (AMPs), but the details of their mode of action is not fully understood. This motivates extensive efforts in determining structural and mechanistic parameters for AMP's interaction with lipid membranes. In this study we show that oriented-sample (31)P solid-state NMR spectroscopy can be used to probe the membrane perturbations and disruption by AMPs. For two AMPs, alamethicin and novicidin, we observe that the majority of the lipids remain in a planar bilayer conformation but that a number of lipids are involved in the peptide anchoring. These lipids display reduced dynamics. Our study supports previous studies showing that alamethicin adopts a transmembrane arrangement without significant disturbance of the surrounding lipids, while novicidin forms toroidal pores at high concentrations leading to more extensive membrane disturbance.

Show MeSH
Related in: MedlinePlus