Structure of the scaffolding protein and portal within the bacteriophage P22 procapsid provides insights into the self-assembly process
Fig 3
Structure of the SP complex and portal.
(A) Structure of the SP complex and portal within the capsid (EMD-61454). The capsid is not shown. A central windmill-like structure is highlighted in a red dashed box. Each side nodule, which contributes to a windmill blade, is marked with an asterisk. The remaining blades are marked with red dots. The structure of the SP-portal complex is tilted approximately 20°along the horizontal axis relative to that presented in Fig 2A. (B) Local reconstruction of the density map (transparent gray) of the SP tetramer at a resolution of 6.9 Å, superimposed on four copies of the gp8 models (magenta, cyan, green, and orange). The outermost part of each blade is contributed by the base domain (gray model superimposed) of a neighboring gp8 subunit (EMD-61456; PDB ID: 9KYX). (C) Local reconstruction of the top region of the dome, indicating that this region is also formed by the SP tetramers.