Structure of the herpes simplex virus portal-vertex
Fig 3
The structure of the portal-vertex interior.
A central slice through the C5 reconstruction of the HSV-1 virion reveals the internal features of the portal-vertex (a). Notably, a strong linear density is seen to run through the portal-vertex that we attribute to genomic DNA (white arrow). The outermost feature, the PVAT, is weakly resolved as fuzzy density, suggesting that this feature is not well constrained. Isosurface representation of the unsharpened map presents a clearer representation of the PVAT (b), while in the sharpened density map, the packaged DNA is not seen, revealing the interior features of the capsid shell (c). A clipped, close-up view of the portal-vertex (boxed in c) highlights the morphology of the portal (pUL6) and, lying between the portal and the PVAT, the pentameric portal-vertex protein (wall-eyed stereo pair view, d). A close-up stereo view of the pentameric portal-vertex protein (boxed in d) clearly shows the density that is consistent with a two-helix coiled-coil motif (pink arrow, e). The density running through the centre of the portal-vertex that we attribute to DNA is also clearly visible (blue arrow). The density map was segmented to highlight three features: the portal (mauve), the pentameric portal-vertex protein (purple), and the periportal triplex–like density (magenta). The segmented portal-vertex is presented as stereo views both perpendicular to (e) and along (f) the portal axis. In panel e, the capsid and triplex-like assemblies are clipped to expose the pentameric portal-vertex protein; this and the portal are not clipped. In panel f, the pUL25/PVAT component is clipped away to expose the underlying features. HSV, Herpes Simplex Virus; PVAT, portal-vertex–associated tegument.