Figure 1.

Schematic representation of the T6SS. (A) Model in which Hcp (yellow) and VgrG (green) are secreted through the yet uncharacterized T6SS secreton (dark grey and question marks). The first step in the secretion process is the threading of Hcp and VgrG through the central channel of the hexameric ClpV ATPase (orange). (B) In this panel, the ClpV ATPase is shown involved in the severing of VipA (red)/VipB (blue) tubules, by threading smaller VipA/VipB complexes through the ClpV pore. In this context, it is not understood how this process and the T6SS-dependent secretion of Hcp and VgrG could be linked (bidirectional arrow and question marks).