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- Title
Defining an allosteric circuit in the cysteine protease domain of Clostridium difficile toxins.
- Authors
Shen, Aimee; Lupardus, Patrick J.; Gersch, Malte M.; Puri, Aaron W.; Albrow, Victoria E.; Garcia, K Christopher; Bogyo, Matthew
- Abstract
An internal cysteine protease domain (CPD) autoproteolytically regulates Clostridium difficile glucosylating toxins by releasing a cytotoxic effector domain into target cells. CPD activity is itself allosterically regulated by the eukaryote-specific molecule inositol hexakisphosphate (InsP6). Although allostery controls the function of most proteins, the molecular details underlying this regulatory mechanism are often difficult to characterize. Here we use chemical probes to show that apo-CPD is in dynamic equilibrium between active and inactive states. InsP6 markedly shifts this equilibrium toward an active conformer that is further restrained upon binding a suicide substrate. Structural analyses combined with systematic mutational and disulfide bond engineering studies show that residues within a β-hairpin region functionally couple the InsP6-binding site to the active site. Collectively, our results identify an allosteric circuit that allows bacterial virulence factors to sense and respond to the eukaryotic environment.
- Subjects
ALLOSTERIC regulation; CYSTEINE proteinases; CLOSTRIDIOIDES difficile; TOXINS; EUKARYOTIC cells; GENETIC mutation; BINDING sites; MICROBIAL virulence
- Publication
Nature Structural & Molecular Biology, 2011, Vol 18, Issue 3, p364
- ISSN
1545-9993
- Publication type
Article
- DOI
10.1038/nsmb.1990