Figure 1. Model for the assembled T4SS complex in Helicobacter pylori. (A).

The T4SS encoded by the cag pathogenicity island is a multicomponent protein complex spanning the inner and outer membranes and exhibits homology to the VirB/VirD4 T4SS machinery of Agrobacterium and other Gram-negative bacteria. The Helicobacter pylori T4SS assembly and cellular localization of the proteins are shown in a simplified manner and according to current knowledge. Pilus components, core complex proteins, energetic components and other factors are highlighted in the box as indicated. The reported substrates for this T4SS are CagA and possibly peptidoglycan. We have chosen the cag nomenclature to highlight the various factors, see also Table 1. (B) Scanning electron microscopy of H. pylori infection of AGS gastric epithelial cells. Typical T4SS pili are shown, connecting the bacterium with the host cell membrane (arrows).

Scale bar represents 1 μm. For more details see text.

T4SS: Type IV secretion system.

(A) Adapted with permission from [10] © John Wiley and Sons.

(B) Kindly provided by Manfred Rohde (HZI Brausnschweig, Germany) [35] with kind permission from © Nature Publishing. For color figures, please see online at www.futuremedicine.com/doi/full/10.2217/FMB.15.32