tailieunhanh - Báo cáo khoa học: Sendai virus N-terminal fusion peptide consists of two similar repeats, both of which contribute to membrane fusion

The N-terminal fusion peptide of Sendai virus F1envelope glycoprotein is a stretchof 14aminoacids,most ofwhichare hydrophobic. Following this region, we detected a segment of 11 residues that are strikingly similar to the N-terminal fusion peptide. We found that, when anchored to the mem-brane by palmitoylation of its N-terminus, this segment (WT-palm-19–33) induces membrane fusion of large unila-mellar liposomes toalmost the same extent as a segment that includes the N-terminal fusion peptide | Eur. J. Biochem. 269 4342-4350 2002 FEBS 2002 doi Sendai virus N-terminal fusion peptide consists of two similar repeats both of which contribute to membrane fusion Sergio G. Peisajovich1 Raquel F. Epand2 Richard M. Epand2 and Yechiel Shai1 1 Department of Biological Chemistry Weizmann Institute of Science Rehovot Israel department of Biochemistry McMaster University Health Sciences Centre Hamilton Ontario Canada The N-terminal fusion peptide of Sendai virus F1 envelope glycoprotein is a stretch of 14 amino acids most of which are hydrophobic. Following this region we detected a segment of 11 residues that are strikingly similar to the N-terminal fusion peptide. We found that when anchored to the membrane by palmitoylation of its N-terminus this segment WT-palm-19-33 induces membrane fusion of large unilamellar liposomes to almost the same extent as a segment that includes the N-terminal fusion peptide. The activity of WT-palm-19-33 was dependent on its specific sequence as a palmitoylated peptide with the same amino-acid composition but a scrambled sequence was inactive. Interestingly two mutations G7A and G12A known to increase F1-induced cell-cell fusion also increased the homology between the N-terminal fusion peptide and WT-palm-19-33. The role of the amino-acid sequence on the fusogenicity secondary structure and mechanism of membrane fusion was analyzed by comparing a peptide comprising both homologous segments Wt 1-33 a G12A mutant G12A 1-33 a G7A-G12A double mutant G7A-G12A1-33 and a peptide with a scrambled sequence SC 1-33 . Based on these experiments we postulate that replacement of Gly 7 and Gly12 by Ala increases the a helical content of the N-terminal region with a concomitant increase in its fusogenic activity. Furthermore the dissimilar abilities of the different peptides to induce membrane negative curvature as well as to promote isotropic 31P NMR signals suggest that these mutations might also alter the extent of