Type IV secretion

Anja Seubert, Rino Rappuoli and Antonello Covacci

September 2004

The type IV secretion systems of Gram-negative bacteria are evolutionarily related to bacterial conjugation systems. Gram-negatives use type IV secretion systems for a variety of biological functions including the exchange of genetic material with other bacteria and the translocation of oncogenic DNA and effector proteins into eukaryotic host cells. The secretion apparatus itself typically comprises a macromolecular complex that spans the bacterial inner and outer membranes and can also span the membrane of eukaryotic host cells. This assembly is typically composed of up to 12 proteins, and recent research has revealed detailed information on the structure and assembly of the secretion apparatus. It is becoming increasingly clear that the type IV-secreted effectors play important roles in the virulence of some Gram-negative pathogens. This poster by Anja Seubert, Rino Rappuoli and Antonello Covacci, which is sponsored by Chiron, summarises our current knowledge of the type IV secreted effectors of selected Gram-negative pathogens and their effects on host cells.