Figure 1.
The initial stages of DNA packaging of the related phages, T3 and T7 (adapted from [18]). The legend at the bottom indicates the means of representation of both the DNA molecule and the various proteins. Proteins are named by gp, followed by the number of the encoding gene. The internal cylinder (gps 14–16) is a feature not present in some double-stranded DNA phages and its evolution is not discussed here. The DNA binding protein (gp18) is a general feature of connector-dependent phages, but its evolution is also not discussed here.