Fusion induced aggregation of model vesicles studied by dynamic and staticlight scattering

Membrane fusion is a key step in the virus mediated cell fusion. The vesicu lar dispersion serves as a model system to study the membrane fusion. We em ployed dynamic and static light scattering to study the fusion of phosphati dylcholine vesicles in the presence of model fusion peptide fragments from the hemagglutinin HA2 protein. The fusion-induced aggregation under the pre sent experimental setup exhibited strong pH dependence, similar to the pare ntal viral protein. Replacement of the glycine residue at the extreme amino terminus by glutamic acid (G1E) abolished fusion activity. The average mol ecular mass and diameter of vesicular dispersion obtained from static and d ynamic light scattering measurements respectively at neutral and acidic pH showed about three fold increase in acidic solution containing wild type fu sion peptide. The light scattering data are consistent with lipid mixing re sults. The present work demonstrates the utility of light scattering as a f acile means to monitor the fusion process. (C) 2000 Elsevier Science Irelan d Ltd. All rights reserved.