Fig. 3: Portal structure and its interactions with capsid proteins and genome DNA.

a BBRF1 model, colored by domain. b The C12 portal structure colored by molecule. Insets, density map (transparent gray) and atomic model of the boxed regions, showing the β augmentation (blue box) and the clip helix holding two neighboring monomers (magenta box). c A cutaway view of the portal, showing its interior structure. d, e Side (d) and top (e) views of the portal vertex, showing the interaction between portal and capsid proteins. The clip turret density is segmented from the C5 reconstruction of the portal vertex. Inset in e shows the secondary elements of capsid proteins involved in the interactions with the portal wing. f, g Interactions between the portal and the genome DNA. f Model of the portal (colored as in a) and density map of dsDNA encircling the portal. g Zoomed-in views of the boxed regions in f, showing the side chains of basic residues of BBRF1 that are involved in the interactions with DNA.