Figure 5.

P23-77 Is a Member of the Vertical β-Barrel Superlineage

(A) Phylogenetic tree based on the known capsid protein structures of the vertical β-barrel superlineage members shows that P23-77 forms the earliest diverging branch in the lineage.

(B) P23-77 virion is icosahedrally ordered and utilizes single β-barrel proteins, presented with triangles, to build the capsid.

(C) Organization of bacteriophage PRD1, with individual domains of the double β-barrel capsid proteins shown as triangles. Most prominent interaction surfaces are shown in blue, revealing the difference between P23-77 and other lineage members that use compact trimers to form each capsomer. However, the capsomers of both P23-77 and PRD1 contain six β-barrels.

The structure-based phylogenetic tree was made using the SHP (Stuart et al., 1979) and the known double β-barrel structures of lineage members. For P23-77, single β- barrel capsid proteins were fused together to enable comparison.

See also Figure S2.