Abstract
The targeting of type III secretion (TTS) proteins at the injectisome is an important process in bacterial virulence. Nevertheless, how the injectisome specifically recognizes TTS substrates among all bacterial proteins is unknown. A TTS peripheral membrane ATPase protein located at the base of the injectisome has been implicated in the targeting process. We have investigated the targeting of the EspA filament protein and its cognate chaperone, CesAB, to the EscN ATPase of the enteropathogenic E. coli (EPEC). We show that EscN selectively engages the EspA-loaded CesAB but not the unliganded CesAB. Structure analysis revealed that the targeting signal is encoded in a disorder-order structural transition in CesAB that is elicited only upon the binding of its physiological substrate, EspA. Abrogation of the interaction between the CesAB-EspA complex and EscN resulted in severe secretion and infection defects. Additionally, we show that the targeting and secretion signals are distinct and that the two processes are likely regulated by different mechanisms.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 709-715 |
| Number of pages | 7 |
| Journal | Cell reports |
| Volume | 3 |
| Issue number | 3 |
| DOIs | |
| State | Published - 2013 |
| Externally published | Yes |
Bibliographical note
Funding Information:This work was supported by the National Institutes of Health (grant AI094623 to C.G.K.), the Operational Programme “Competitiveness and Entrepreneurship” (OPCE II-EPAN II), the National Strategic Reference Framework (NSRF 2007-2013 and 09SYN-11-902 to A.E.), and a Research Excellence Grant from the Greek General Secretariat of Research (1473-Nonaco to A.E.).