BtcA, a class IA type III chaperone, interacts with the BteA N-terminal domain through a globular/non-globular mechanism

Chen Guttman, Geula Davidov, Adi Yahalom, Hadassa Shaked, Sofiya Kolusheva, Ronit Bitton, Shiran Barber-Zucker, Jordan H. Chill, Raz Zarivach

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Bordetella pertussis, the etiological agent of "whooping cough" disease, utilizes the type III secretion system (T3SS) to deliver a 69 kDa cytotoxic effector protein, BteA, directly into the host cells. As with other T3SS effectors, prior to its secretion BteA binds BtcA, a 13.9 kDa protein predicted to act as a T3SS class IA chaperone. While this interaction had been characterized for such effector-chaperone pairs in other pathogens, it has yet to be fully investigated in Bordetella. Here we provide the first biochemical proof that BtcA is indeed a class IA chaperone, responsible for the binding of BteA's N-terminal domain. We bring forth extensive evidence that BtcA binds its substrate effector through a dual-interface binding mechanism comprising of non-globular and bi-globular interactions at a moderate micromolar level binding affinity. We demonstrate that the non-globular interactions involve the first 31 N-terminal residues of BteA287 and their removal leads to destabilization of the effector-chaperone complex and lower binding affinities to BtcA. These findings represent an important first step towards a molecular understanding of BteA secretion and cell entry.

Original languageEnglish
Article numbere81557
JournalPLoS ONE
Volume8
Issue number12
DOIs
StatePublished - 2 Dec 2013

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