Molecular determinants of picornavirus 3C protease binding to phosphoinositide-enriched lipid membranes

Picornavirus infection leads to the production of new membranous structures that are enriched in phosphoinositide lipids. The multifunctional 3C protease interacts with these phosphoinositide-enriched membranes. We performed paramagnetic relaxation enhancement NMR experiments to gain insight into the molecular determinants driving these interactions. We found that 3C interacts with lipid membranes through both its positively charged N-terminal helix and the 80 to 90's region, previously proposed to interact with RNA. Experiments using different pH and salt concentrations suggest that the interaction is primarily electrostatically driven. The optimized lipid membrane systems developed here provides molecular insights into the 3C-membrane interactions and can be leveraged to study peripheral protein-membrane interactions of other viral proteins.