Interaction of Helicobacter pylori with host cells: function of secreted and translocated molecules.

Secreted proteins are of general interest from the perspective of bacteria-host interaction. The gastric bacterial pathogen Helicobacter pylori uses a set of secreted and translocated proteins--including outer membrane adhesins, secreted extracellular enzymes and translocated effector proteins--to adapt to its extraordinary habitat, the gastric mucosa. Two major virulence factors of H. pylori are the vacuolating cytotoxin (VacA) and the cag type-IV secretion system and its translocated effector protein, cytotoxin-associated antigen A (CagA). VacA targets not only epithelial cells, but also cells of the immune system and induces immunosuppression. CagA has been shown to interact with a growing set of eucaryotic signaling molecules in phosphorylation-dependent and -independent ways.