F protein-F protein interaction within the Sendai virus identified by native bonding or chemical cross-linking.

The spatial arrangement of the F protein spike in the Sendai virus was studied after purifying the protein and reconstituting it in lipid vesicles (Sechoy, O., Philippot, J. R., and Bienvenue, A. (1986) Biochim. Biophys. Acta 857, 1-12). The different components of the F protein spikes were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under various conditions of treatment, i.e. at different temperatures and sodium dodecyl sulfate concentrations, using different detergents for F protein solubilization (Triton X-100 and octyl glucoside), by fast protein liquid chromatography analysis, and by chemical cross-linking between subunits with bifunctional agents such as dimethyl adipimidate and dithiobis(succinimidyl propionate). The F protein spike appeared to be a structurally stable complex, composed of a noncovalent association of four homooligomers, each consisting of two peptides, F1 and F2, linked by a disulfide bond. Octyl glucoside and Triton X-100 solubilized the F protein, preserving the tetramer, which is probably the native form. Using chemical cross-linking, a covalent bond was formed between two monomers. We hypothesize that the tetrameric form of the F protein in its native form (spike) consists of two identical dimers that can be chemically cross-linked in a stable complex.