New structural insights into the bacterial type III secretion system

The virulence-associated type III secretion system (T3SS) enables many Gram-negative bacterial pathogens to translocate proteins into the eukaryotic host cells that they infect. This unique protein transport process is mediated by the type III secretion apparatus (T3SA), a multisubunit membrane-spanning macromolecular assembly comprising >20 different proteins. Recent studies have identified biochemical and structural properties of the core T3SA, in addition to several components constituting this complex, with important implications for both the assembly process and the overall function of the T3SA.