The amino-terminal nine amino acid sequence of poliovirus capsid VP4 protein is sufficient to confer N-myristoylation and targeting to detergent-insoluble membranes

The confinement of membrane proteins by lipid-lipid interactions into speci alized detergentin-soluble membrane (DIM) microdomains has been proposed as a general mechanism to recruit selectively lipid-modified proteins and spe cific transmembrane proteins. Poliovirus capsid VP4 protein and its precurs ors are myristoylated at the NH2-terminal Gly residue. To determine whether poliovirus uses DIMs during its replicative cycle, we isolated DIMs from p olisvirus-infected HeLa cells and identified the presence of capsid protein s and their precursors, proteinases 2A and 3C, and other viral proteins inv olved in poliovirus RNA replication such as protein 2C and the polymerase 3 D. The morphology of these DIMs was similar to that of the previously descr ibed rosettelike vesicles associated with replication complexes isolated fr om poliovirus-infected cells. To examine the possible role of the myristoyl moiety in the targeting of poliovirus structural proteins to DIMs, we gene rated a chimeric protein consisting of the nine amino-terminal amino acids from VP4 fused to the amino terminus of the green fluorescent protein (GFP) . The selected VP4 sequence was sufficient to confer N-myristoylation and t argeting to DIMs to the GFP chimera. Mutations within this sequence known t o affect both myristoylation and poliovirus assembly abrogated the targetin g of the GFP chimera. These results indicate that the myristoylated amino-t erminal nonapeptide from poliovirus VP4 protein constitutes a signal for in corporation into DLMs.