A flexible peptide linking the periplasmic and cytoplasmic domains of MxiG controls type III secretion signaling and stable sorting platform assembly in <i>Shigella</i>.

ABSTRACT: Shigella flexneri uses its type III secretion system (T3SS) to invade human enterocytes. The T3SS injectisome is controlled by proteins at the tip of an exposed needle that sense host cell contact. Substrate selection and powering of secretion is controlled by a cytoplasmic assembly called the sorting platform (SP). The Shigella SP possesses six pod structures linked to a central ATPase via radial spokes. The SP associates with the injectisome inner membrane ring (IR) via the adaptor protein MxiK. The major IR component is MxiG, whose globular periplasmic domain (MxiG^P) packs with MxiJ in a 24-fold symmetry. MxiG also has a transmembrane helix attached to a small cytoplasmic domain (MxiG^C) via a flexible linker peptide. Change from the IR's 24-fold symme

SUBMITTER: Tachiyama S 

PROVIDER: S-EPMC12358396 | biostudies-literature | 2025

REPOSITORIES: biostudies-literature