Phylogeny of P23-77 Capsid Proteins in Relation to the Double β-Barrel Lineage
(A–D) Structure-based superimpositions and phylogenetic tree of the capsid proteins of P23-77 and members of the double β-barrel lineage using the Structure Homology Program (SHP) (Abrescia et al., 2012; Stuart et al., 1979) and individual V1 and V2 domains. To enable comparison with other β-barrel structures, subunit of VP16-type-1 was rewired across residues 33–35 (see Figure 1) to form an intact chimeric subunit.
(A) VP16 (orange) superposed on VP17 (green).
(B) PM2 V1 (purple) superposed on VP17 (green).
(C) VP17 upper domain (yellow) superposed on VP17 lower domain (green).
(D) Phylogenetic tree illustrating the evolutionary distance of the MCPs of double β-barrel lineage members and P23-77 (light blue group), showing that the closest relatives to VP16 and VP17 are mostly V2 domains (yellow group), V1 domains being further diverged (green group).