Figure 3.

General translocation pathway and core structure of a T4SS. (a) The translocation pathway of substrates through the Agrobacterium VirB/D4 system. For a detailed description see text. (b) A cutout of the Type IV secretion system core complex and crystal structure of the O-layer. The cryo-EM structure (surface representation) of the T4S system core complex is here superimposed with the crystal structure of the O-layer. For the crystal structure, VirB7, the C-terminal domain of VirB9 and the C-terminal domain of VirB10 are shown in magenta, cyan and green. The lever arm sequence of VirB10 is shown in red. Figure contributed by Drs Karen Wallden and Gabriel Waksman.