Orientation of a polyleucine-based peptide in phosphatidylcholine bilayers of different thickness. Solid-state NMR and CD spectroscopy

Byström, Tomas; Gröbner, Gerhard; Lindblom, Göran

doi:10.1016/s0927-7757(03)00303-0

Cited by 7 publications

(7 citation statements)

References 14 publications

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“…While this is not sufficient to average the 1 H− 1 H dipolar couplings in solid samples, broadening caused by susceptibility anisotropy, chemical shift anisotropy, small heteronuclear dipolar couplings, and partially motionally averaged 1 H− 1 H dipolar interactions can be removed. In the framework of amphiphile phase behavior studies, MAS experiments have been successfully used to study cubic liquid crystalline phases as well as structure and conformational exchange of molecules in lamellar phases. − Solid-state NMR has been also used to study the molecular conformation of different forms of DNA …”

Section: Resultsmentioning

confidence: 99%

NMR Studies of Molecular Mobility in a DNA−Amphiphile Complex

Leal¹,

Topgaard²,

Martin

et al. 2004

J. Phys. Chem. B

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The molecular mobility in a hexagonal DNA−cationic surfactant complex is studied using 1H and 13C nuclear magnetic resonance spectroscopy. The charge-compensated complex can swell in water up to a content of approximately seven water molecules per charge. The NMR measurements show that in the dry state the alkyl chains of the surfactant have the properties of a disordered solid with internal motions of sufficient amplitude to substantially narrow the 1H resonance line from the rigid lattice limit. As water is introduced, there is an increase in molecular motion resulting in further narrowing of the signal. In the fully swollen system, the signal is narrower than that observed for a normal hexagonal liquid crystalline phase with the same surfactant. This shows that the alkyl chains are packed with a degree of disorder that is higher than in the corresponding liquid crystalline surfactant system, reflecting the aggregate deformations induced by the requirement of charge matching with DNA. Furthermore, the translational diffusional motion of the surfactant molecule is slower than D < 10-13 m2/s, while for the water molecules we observe D going from 1 × 10-11m2/s at 5 water molecules per base pair to 2 × 10-10 m2/s at the swelling limit of 27 waters per base pair. The DNA remains solid throughout the hydration range. By combining the NMR observations with the thermodynamic characterization of the system by Leal et al. we arrive at a detailed description of the molecular organization in the complex between DNA and the single chain cationic surfactant hexadecyltrimethylammonium, CTA.

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Section: Resultsmentioning

confidence: 99%

NMR Studies of Molecular Mobility in a DNA−Amphiphile Complex

Leal¹,

Topgaard²,

Martin

et al. 2004

J. Phys. Chem. B

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“…The hydrocarbon thickness of a fully hydrated DOPC bilayer is 26.8 -28.6 Å (16,52,53,(61)(62)(63). The addition of SM and cholesterol increases the thickness of the hydrophobic core of monounsaturated membranes by 2-4.1 Å (54 -57).…”

Section: Effect Of the Hydrophobic Core Length Of Kalr On Insertion Intomentioning

confidence: 99%

Mode of Membrane Interaction and Fusogenic Properties of a de Novo Transmembrane Model Peptide Depend on the Length of the Hydrophobic Core

Lorin

Charloteaux

Fridmann-Sirkis

et al. 2007

Journal of Biological Chemistry

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Model peptides composed of alanine and leucine residues are often used to mimic single helical transmembrane domains. Many studies have been carried out to determine how they interact with membranes. However, few studies have investigated their lipid-destabilizing effect. We designed three peptides designated KALRs containing a hydrophobic stretch of 14, 18, or 22 alanines/leucines surrounded by charged amino acids. Molecular modeling simulations in an implicit membrane model as well as attenuated total reflection-Fourier transform infrared analyses show that KALR is a good model of a transmembrane helix. However, tryptophan fluorescence and attenuated total reflection-Fourier transform infrared spectroscopy indicate that the extent of binding and insertion into lipids increases with the length of the peptide hydrophobic core. Although binding can be directly correlated to peptide hydrophobicity, we show that insertion of peptides into a membrane is determined by the length of the peptide hydrophobic core. Functional studies were performed by measuring the ability of peptides to induce lipid mixing and leakage of liposomes. The data reveal that whereas KALR 14 does not destabilize liposomal membranes, KALR 18 and KALR 22 induce 40 and 50% of lipid-mixing, and 65 and 80% of leakage, respectively. These results indicate that a transmembrane model peptide can induce liposome fusion in vitro if it is long enough. The reasons for the link between length and fusogenicity are discussed in relation to studies of transmembrane domains of viral fusion proteins. We propose that fusogenicity depends not only on peptide insertion but also on the ability of peptides to destabilize the two leaflets of the liposome membrane.

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“…The model lipid membranes typically constitute just one or two lipid species, rather than the complex mixture of lipids present in the cell membranes. The model proteins are typically single a-helical peptides with a large central hydrophobic region and flanking polar or charged residues (23)(24)(25)(26). Peptides containing poly-leucine/ alanine flanked by tryptophan or lysine have established themselves as preferred models of trans-membrane peptides (23,(27)(28)(29)(30)(31).…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulations of Model Trans-Membrane Peptides in Lipid Bilayers: A Systematic Investigation of Hydrophobic Mismatch

Kandasamy

Larson

2006

Biophysical Journal

167

190

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Hydrophobic mismatch, which is the difference between the hydrophobic length of trans-membrane segments of a protein and the hydrophobic width of the surrounding lipid bilayer, is known to play a role in membrane protein function. We have performed molecular dynamics simulations of trans-membrane KALP peptides (sequence: GKK(LA)nLKKA) in phospholipid bilayers to investigate hydrophobic mismatch alleviation mechanisms. By varying systematically the length of the peptide (KALP15, KALP19, KALP23, KALP27, and KALP31) and the lipid hydrophobic length (DLPC, DMPC, and DPPC), a wide range of mismatch conditions were studied. Simulations of durations of 50-200 ns show that under positive mismatch, the system alleviates the mismatch predominantly by tilting the peptide and to a smaller extent by increased lipid ordering in the immediate vicinity of the peptide. Under negative mismatch, alleviation takes place by a combination of local bilayer bending and the snorkeling of the lysine residues of the peptide. Simulations performed at a higher peptide/lipid molar ratio (1:25) reveal slower dynamics of both the peptide and lipid relative to those at a lower peptide/lipid ratio (1:128). The lysine residues have favorable interactions with specific oxygen atoms of the phospholipid headgroups, indicating the preferred localization of these residues at the lipid/water interface.

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Orientation of a polyleucine-based peptide in phosphatidylcholine bilayers of different thickness. Solid-state NMR and CD spectroscopy

Cited by 7 publications

References 14 publications

NMR Studies of Molecular Mobility in a DNA−Amphiphile Complex

NMR Studies of Molecular Mobility in a DNA−Amphiphile Complex

Mode of Membrane Interaction and Fusogenic Properties of a de Novo Transmembrane Model Peptide Depend on the Length of the Hydrophobic Core

Molecular Dynamics Simulations of Model Trans-Membrane Peptides in Lipid Bilayers: A Systematic Investigation of Hydrophobic Mismatch

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