FIG. 4.

Three-dimensional reconstruction of KFV by cryo-EM. (a) Gallery of class averages of raw KFV images, ranked by turret occupancy. This shows that there is no change in overall capsid morphology with the loss of turrets and that the turret structure is the same when fully occupied as when partially occupied. (b) Left: surface-rendered view (contour 2σ) of an icosahedral reconstruction of KFV. Right: central section through the same map. The symmetry axes are marked in both cases. (c) Left: surface-rendered view (contour 4σ) of the map shown in panel a. Right: the same map in another view at the 5.2σ-contour level. (d) Superpositions of a reconstruction selected for low turret occupancy (red), the reconstruction shown in panels b and c (lilac), and a difference map (green), viewed across a fivefold vertex. The difference map highlights features present in the partially turreted map but absent from the map constructed from particles selected for the absence of turrets. Left: reconstructions at 2σ and difference map at 3σ. Right: these thresholds are switched.