Regulation of type III secretion systems.

Type III secretion systems are utilised by numerous Gram-negative bacteria to efficiently interact with a host. Appropriate expression of type III genes is achieved through the integration of several regulatory pathways that ultimately co-ordinate the activity of a central transcriptional activator usually belonging to the AraC family. The complex regulatory cascades allow this virulence strategy to be utilised by different bacteria even if they occupy diverse niches that define a unique set of environmental cues. Simulating the appropriate combination of signals in vitro to allow a meaningful interpretation of the type III assembly and secretion regulatory cascade remains a common goal for researchers. Pieces of the puzzle slowly emerge to provide insightful views into the complex regulatory networks that allow bacteria to assemble and utilise type III secretion to efficiently colonise a host.