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Structure of an analog of fusion peptide from hemagglutinin
Author(s) -
Dubovskii Peter V.,
Li Hua,
Takahashi Sho,
Arseniev Alexander S.,
Akasaka Kazuyuki
Publication year - 2000
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1110/ps.9.4.786
Subject(s) - chemistry , peptide , micelle , circular dichroism , bound water , crystallography , protonation , carboxylate , hydrogen bond , residue (chemistry) , nuclear magnetic resonance spectroscopy , vesicle , stereochemistry , membrane , organic chemistry , biochemistry , molecule , aqueous solution , ion
A 20‐residue peptide E5 containing five glutamates, an analog of the fusion peptide of influenza virus hemagglutinin (HA) exhibiting fusion activity at acidic pH lower than 6.0–6.5 was studied by circular dichroism (CD), Fourier transform infrared, and 1 H‐NMR spectroscopy in water, water/trifluoroethanol (TFE) mixtures, dodecylphosphocholine (DPC) micelles, and phospholipid vesicles. E5 became structurally ordered at pH ≤6 and the helical content in the peptide increased in the row: water < water/tfe < dpc ∼ phospholipid vesicle while the amount of β‐structure was approximately reverse. 1 H‐NMR data and line‐broadening effect of 5‐, 16‐doxylstearates on proton resonances of DPC bound peptide showed E5 forms amphiphilic α‐helix in residues 2–18, which is flexible in 11–18 part. The analysis of the proton chemical shifts of DPC bound and CD intensity at 220 nm of phospholipid bound E5 showed that the pH dependence of helical content is characterized by the same p K a ≈5.6. Only Glu11 and Glu15 in DPC bound peptide showed such elevated p K a s, presumably due to transient hydrogen bond(s) Glu11 (Glu15) δCOO − (H + ) … HN Glu15 that dispose(s) the side chain of Glu11 (Glu15) residue(s) close to the micelle/water interface. These glutamates are present in the HA‐fusion peptide and the experimental half‐maximal pH of fusion for HA and E5 peptides is ∼5.6. Therefore, a specific anchorage of these peptides onto membrane necessary for fusion is likely driven by the protonation of the carboxylate group of Glu11 (Glu 15) residue (s) participating in transient hydrogen bond(s).