Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.09.30.320457v1?rss=1 Authors: Buch, M. H. C., Heymann, J. B., Newcomb, W. W., Winkler, D. C., Steven, A. C. Abstract: Herpes simplex virus type 1 (HSV-1) packages its genome via the portal protein, pUL6, a dodecameric ring at one of the capsids twelve vertices. While the portal has been visualized in mature capsids, we aimed to describe it in procapsids to elucidate its role in assembly and maturation. Using cryo-electron tomography, we compared procapsids and empty mature capsids (A-capsids) by subtomogram averaging. The portal is located on the interior surface with its narrower end facing outwards in contact with the capsid shell. The portal is embedded in the underlying scaffold, consistent with assembly initiating on a portal-scaffold complex. Maturation involves angularization of the capsid shell, with an accompanying outward movement of the vertices. In A-capsids, the portal translocates further than the surrounding capsomers, enhancing and presumably strengthening its contacts with the capsid shell. We also found a density overlying and offset from the portal vertex corresponding to the expected location of the terminase, the DNA packaging motor. Copy rights belong to original authors. Visit the link for more info