Transport of macromolecules across membranes is achieved by various molecular nanomachines. The bacterial Type VI secretion system (T6SS) plays an important role in bacterial pathogenesis and ecology. The mechanisms behind the generation of power needed to pierce target cell membranes are largely unknown. I will present the recent progress towards the structure of T6SS and the implications for T6SS dynamics and assembly. I will discuss how secreted proteins are efficiently exchanged among by-standing cells within minutes of initial cell-cell contact and can be subsequently reused to form a functional T6SS assembly.