Hierarchical protein targeting and secretion is controlled by an affinity switch in the type III secretion system of enteropathogenic <i>Escherichia coli</i>.

ABSTRACT: Type III secretion (T3S), a protein export pathway common to Gram-negative pathogens, comprises a trans-envelope syringe, the injectisome, with a cytoplasm-facing translocase channel. Exported substrates are chaperone-delivered to the translocase, EscV in enteropathogenic Escherichia coli, and cross it in strict hierarchical manner, for example, first "translocators", then "effectors". We dissected T3S substrate targeting and hierarchical switching by reconstituting them in vitro using inverted inner membrane vesicles. EscV recruits and conformationally activates the tightly membrane-associated pseudo-effector SepL and its chaperone SepD. This renders SepL a high-affinity receptor for translocator/chaperone pairs, recognizing specific chaperone signals. In a second, SepD-coup

SUBMITTER: Portaliou AG 

PROVIDER: S-EPMC5709732 | biostudies-literature | 2017 Dec

REPOSITORIES: biostudies-literature