Hierarchical effector protein transport by the Salmonella Typhimurium SPI-1 type III secretion system.

Background: Type III secretion systems (TTSS) are employed by numerous pathogenic and symbiotic bacteria to inject a cocktail of different "effector proteins" into host cells. These effectors subvert host cell signaling to establish symbiosis or disease.

Methodology/principal Findings: We have studied the injection of SipA and SptP, two effector proteins of the invasion-associated Salmonella type III secretion system (TTSS-1).