Cryo-electron microscopy reconstruction of a poliovirus-receptor-membrane complex

To study non-enveloped virus cell entry, a versatile in vitro model system was developed in which liposomes containing nickel-chelating lipids were decorated with His-tagged poliovirus receptors and bound to virus. This system provides an exciting opportunity for structural characterization of the early steps in cell entry in the context of a membrane. Here we report the three-dimensional structure of a poliovirus - receptor - membrane complex solved by cryo-electron microscopy (cryo-EM) at a resolution of 32 angstrom. Methods were developed to establish the symmetry of the complex objectively. This reconstruction demonstrates that receptor binding brings a viral five-fold axis close to the membrane. Density is clearly defined for the icosahedral virus, for receptors ( including known glycosylation sites) and for the membrane bilayer. Apparent perturbations of the bilayer close to the viral five-fold axis may function in subsequent steps of cell entry.