Cryo-electron microscopy and 3-D reconstruction of the TV virion.

<p>(<b>A</b>) Cryo-EM micrograph of purified TV virion sample. Scale bar: 50 nm. (<b>B</b>) Surface representation of the reconstructed TV map with the icosahedral 5-, 3- and 2-fold axes labeled. Two kinds of capsid dimers A/B and C/C are arranged on a T = 3 icosahedral cage (colored in blue). The map was colored radially according to the color key. The calculated Fourier shell correlation (FSC) is displayed in (<b>C</b>). Three resolution estimation standards in the cryo-EM field-the 0.5 and 0.3 cutoff criteria giving an estimation of 7.9 Å and 6.9 Å, respectively, and the 0.143 cutoff criterion showing an estimation of 6.3 Å- are presented. The central section perpendicular to the 2-fold axis of TV map is displayed in (<b>D</b>). (<b>E</b>) The radial density profile calculated from the 3D density map of the TV virion. Multiple density layers in TV virion structure are denoted as: “P” for protruding domain, “S” for icosahedral shell domain, and “IS” for an inner shell between the icosahedral shell and the RNA genome.