Figure 1.

Schematic representation of T3, T4 and T6SS showing their relation to flagellum, conjugative DNA transfer and phage structures, and their common targets in the host cell. Bacteria (in green) are shown hosting the secretion system and related machineries: flagella for T3SS, conjugative DNA transfer complexes for T4SS, and phage tails for T6SS. Their bacterial targets are also shown: recipient bacteria for DNA transfer (T4SS), or bacteria killed (dotted lines) by T6SS-injected toxins. The three secretion systems can translocate effectors to the human cell, shown to the right, together with the most common subverted cellular functions.