Phosphatidylserine binding to solid-phase rhabdoviral peptides: A new method to study phospholipid/viral protein interactions

A new method is described for the study of phosphatidylserine binding to rhabdoviral peptides by using solid-phase assays. This new assay could probably be extended to study the interactions between host membrane phospholipid and viral proteins in other viruses. By using labeled and hydrated phosphatidylserine (PS), PS-binding to solid-phase 15-mer peptides (pepscan) could map putative phospholipid-binding regions of the glycoprotein G of viral haemorrhagic septicaemia virus (VHSV), a salmonid rhabdovirus. The major PS-binding region of 27 aa (aa82-109, p2) did not only bind PS, but also phosphatidylethanolamine (PE) and phosphatidylcholine (PC). Extraction of the PS bound to solid-phase p2 by a variety of chemical compounds and competition experiments with several phospholipid-related compounds showed that PS-binding to p2 was dependent on not only hydrophobic, but also ionic interactions, as suggested by prior work on phospholipid interactions in other rhabdoviruses. Saturation/competition experiments with labeled and cold PS, PE and PC also showed that the reaction probably takes place between high molecular weight aggregates of hydrated phospholipids and several molecules of solid-phase p2. This assay has been used previously to detect hydrophobic amino acid heptad-repeats in rhabdoviruses and when anti-p2 antibodies to VHSV were obtained they were capable of inhibiting VHSV-induced cell to cell fusion.