Tweet
Biophys J. 2013 Mar 5;104(5):1029-37. doi: 10.1016/j.bpj.2012.12.034.
Fusion peptides promote formation of bilayer cubic phases in lipid dispersions. An x-ray diffraction study.
Tenchov BG, Macdonald RC, Lentz BR.
Source
Department of Medical Physics and Biophysics, Medical University Sofia, Sofia, Bulgaria; Biochemistry, Molecular Biology and Cell Biology Department, Northwestern University, Evanston, Illinois. Electronic address: btenchov@gmail.com.
Abstract
Small angle x-ray diffraction revealed a strong influence of the N-terminal influenza hemagglutinin fusion peptide on the formation of nonlamellar lipid phases. Comparative measurements were made on a series of three peptides, a 20-residue wild-type X-31 influenza virus fusion peptide, GLFGAIAGFIENGWEGMIDG, and its two point-mutant, fusion-incompetent peptides G1E and G13L, in mixtures with hydrated phospholipids, either dipalmitoleoylphosphatidylethanolamine (DPoPE), or monomethylated dioleoyl phosphatidylethanolamine (DOPE-Me), at lipid/peptide molar ratios of 200:1 and 50:1. All three peptides suppressed the H phase and shifted the L-H transition to higher temperatures, simultaneously promoting formation of inverted bicontinuous cubic phases, Q, which becomes inserted between the L and H phases on the temperature scale. Peptide-induced Q had strongly reduced lattice constants in comparison to the Q phases that form in pure lipids. Q formation was favored at the expense of both L and H phases. The wild-type fusion peptide, WT-20, was distinguished from G1E and G13L by the markedly greater magnitude of its effect. WT-20 disordered the L phase and completely abolished the H phase in DOPE-Me/WT-20 50:1 dispersions, converted the Q phase type from Im3m to Pn3m and reduced the unit cell size from ∼38 nm for the Im3m phase of DOPE-Me dispersions to ∼15 nm for the Pn3m phase in DOPE-Me/WT-20 peptide mixtures. The strong reduction of the cubic phase lattice parameter suggests that the fusion-promoting WT-20 peptide may function by favoring bilayer states of more negative Gaussian curvature and promoting fusion along pathways involving Pn3m phase-like fusion pore intermediates rather than pathways involving H phase-like intermediates.
Copyright ? 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.
PMID:
23473485
[PubMed - in process]
Fusion peptides promote formation of bilayer cubic phases in lipid dispersions. An x-ray diffraction study.
Tenchov BG, Macdonald RC, Lentz BR.
Source
Department of Medical Physics and Biophysics, Medical University Sofia, Sofia, Bulgaria; Biochemistry, Molecular Biology and Cell Biology Department, Northwestern University, Evanston, Illinois. Electronic address: btenchov@gmail.com.
Abstract
Small angle x-ray diffraction revealed a strong influence of the N-terminal influenza hemagglutinin fusion peptide on the formation of nonlamellar lipid phases. Comparative measurements were made on a series of three peptides, a 20-residue wild-type X-31 influenza virus fusion peptide, GLFGAIAGFIENGWEGMIDG, and its two point-mutant, fusion-incompetent peptides G1E and G13L, in mixtures with hydrated phospholipids, either dipalmitoleoylphosphatidylethanolamine (DPoPE), or monomethylated dioleoyl phosphatidylethanolamine (DOPE-Me), at lipid/peptide molar ratios of 200:1 and 50:1. All three peptides suppressed the H phase and shifted the L-H transition to higher temperatures, simultaneously promoting formation of inverted bicontinuous cubic phases, Q, which becomes inserted between the L and H phases on the temperature scale. Peptide-induced Q had strongly reduced lattice constants in comparison to the Q phases that form in pure lipids. Q formation was favored at the expense of both L and H phases. The wild-type fusion peptide, WT-20, was distinguished from G1E and G13L by the markedly greater magnitude of its effect. WT-20 disordered the L phase and completely abolished the H phase in DOPE-Me/WT-20 50:1 dispersions, converted the Q phase type from Im3m to Pn3m and reduced the unit cell size from ∼38 nm for the Im3m phase of DOPE-Me dispersions to ∼15 nm for the Pn3m phase in DOPE-Me/WT-20 peptide mixtures. The strong reduction of the cubic phase lattice parameter suggests that the fusion-promoting WT-20 peptide may function by favoring bilayer states of more negative Gaussian curvature and promoting fusion along pathways involving Pn3m phase-like fusion pore intermediates rather than pathways involving H phase-like intermediates.
Copyright ? 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.
PMID:
23473485
[PubMed - in process]
