Year-end Sale % OFF 
Abstract
The secondary structure of a 20-amino acid length synthetic peptide corresponding to the N terminus of the second subunit of hemagglutinin (HA2) of influenza virus A/PR8/34 and its interaction with phospholipid bilayers are investigated using ESR, Fourier transform infrared (FTIR), and CD spectroscopy. N-terminal spin labeling of the peptide did not affect the secondary structure of the peptide either in solution or when bound to liposomes as revealed by FTIR and CD spectroscopy. ESR spectra show that the mobility of the labeled peptide is dramatically restricted in the presence of phosphatidylcholine liposomes, suggesting a strong binding to the lipid membranes. The N terminus of the peptide penetrates into the membrane and is located within the hydrophobic core. We find an oblique insertion of the peptide into the lipid bilayer with an angle of about 45 degrees between helix axis and membrane plane using FTIR spectroscopy. No gross changes of the peptide's orientation, motion, and secondary structure were observed between pH 7.4 and pH 5.0. A model of the insertion of the fusion sequence of HA2 into a lipid bilayer is presented taking into account recent investigations on the low pH conformation of HA2 (Bullough, P. A., Hughson, F. M., Skehel, J. J., and Wiley, D. C. (1994) Nature 371, 37-43).
Highlights
Fusion of influenza viruses with target membranes is mediated by the major membrane protein of influenza, hemagglutinin (HA).[1]
In order to elucidate the particular role of the HA2 N terminus in virus fusion, several studies have been undertaken to investigate the interaction of synthetic peptides, corresponding to the fusion sequence, with lipid membranes
In order to gain information on the membrane orientation of the whole fusion peptide, we examine here the interaction of a synthetic peptide of the influenza fusion sequence with liposomes by using both electron spin resonance (ESR) spectroscopy and ATR-Fourier transform infrared (FTIR) spectroscopy
Summary
Fusion of influenza viruses with target membranes is mediated by the major membrane protein of influenza, hemagglutinin (HA).[1]. The hydrophobic interaction of the HA ectodomain and its fusion sequence with lipid membranes at low pH have been demonstrated by hydrophobic photolabeling (Harter et al, 1988, 1989; Brunner 1989) These studies suggested that the N terminus interacts with membranes and subsequently adopts an ␣-helical structure (Lear and DeGrado, 1987; Wharton et al, 1988; Rafalski et al, 1991). Despite numerous efforts, it is still unclear how the fusion peptide corresponding to the HA2 N-terminal segment destabilizes lipid membranes. The fatty acid spin labels I(12,3) and I(5,10) were obtained from Sigma, I(10,5) were from Aldrich, and the spin label succinimidyl-2,2,5,5-tetramethyl-3-pyrroline-1-oxyl-3-carboxylate from Molecular Probes
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
