ANALYSIS OF A PEPTIDE INHIBITOR OF PARAMYXOVIRUS (NDV) FUSION USING BIOLOGICAL ASSAYS, NMR, AND MOLECULAR MODELING

To investigate the molecular mechanisms involved in paramyxovirus-indu ced cell fusion, the function and structure of a peptide with a 20-ami no-acid sequence from the leucine zipper region (heptad repeat region 2) of the Newcastle disease virus fusion protein (F) were characterize d. A peptide with the sequence ALDKLEESNSKLDKVNVKLT (amino acids 478-4 97 of the F protein) was found to inhibit syncytia formation after vir us infection and after transfection of Cos cells with the HN (hemagglu tinin-neuraminidase) and F protein cDNAs. Using an F protein gene that requires addition of exogenous trypsin for cleavage, it was shown tha t the peptide exerted its inhibitory effect prior to cleavage. The thr ee-dimensional conformation of the peptide in aqueous solution was det ermined through the use of NMR and molecular modeling. Results showed that the peptide formed a helix with properties between an alpha-helix and a 3(10)-helix and that leucine residues aligned along one face of the helix. Side chain salt bridges and hydrogen bonds likely contribu ted to the stability of the peptide secondary structure. Analysis of t he aqueous solution conformation of the peptide suggested mechanisms f or specificity of interaction with the intact 6 protein. (C) 1997 Acad emic Press.