Fig 1.

Structural model of the bacteriophage T4 DNA packaging machine. The model was constructed using the cryo-EM structure of prohead-bound gp17 (Electron Microscopy Database [EMDB] identification [ID] no. 1573). The dodecameric portal protein gp20 (red) and the pentameric packaging ATPase gp17 (light blue) translocate DNA (purple) into the T4 capsid. The major capsid protein gp23* is shown in green. gp24* vertices are shown in yellow, Soc (Protein Data Bank [PDB] no. 3IG9) is shown as translucent, and Hoc (the highly antigenic outer capsid protein; PDB no. 3SHS) is shown in blue.