Structure-Function Analysis of Inositol Hexakisphosphate-induced Autoprocessing in Clostridium difficile Toxin A

Journal Article · Fri Sep 25 04:00:00 EDT 2009 · J. Biol. Chem.

DOI:https://doi.org/10.1074/jbc.M109.018929· OSTI ID:1005792

Pruitt, Rory N; Chagot, Benjamin; Cover, Michael; Chazin, Walter J; Spiller, Ben; Lacy, D Borden

The action of Clostridium difficile toxins A and B depends on inactivation of host small G-proteins by glucosylation. Cellular inositol hexakisphosphate (InsP6) induces an autocatalytic cleavage of the toxins, releasing an N-terminal glucosyltransferase domain into the host cell cytosol. We have defined the cysteine protease domain (CPD) responsible for autoprocessing within toxin A (TcdA) and report the 1.6 {angstrom} x-ray crystal structure of the domain bound to InsP6. InsP6 is bound in a highly basic pocket that is separated from an unusual active site by a {beta}-flap structure. Functional studies confirm an intramolecular mechanism of cleavage and highlight specific residues required for InsP6-induced TcdA processing. Analysis of the structural and functional data in the context of sequences from similar and diverse origins highlights a C-terminal extension and a {pi}-cation interaction within the {beta}-flap that appear to be unique among the large clostridial cytotoxins.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: USDOE
• OSTI ID: 1005792
• Journal Information: J. Biol. Chem., Journal Name: J. Biol. Chem. Journal Issue: (33) ; 08, 2009 Vol. 284; ISSN JBCHA3; ISSN 0021-9258
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

36 MATERIALS SCIENCE
ANTIMITOTIC DRUGS
CLEAVAGE
CLOSTRIDIUM
CRYSTAL STRUCTURE
CYSTEINE
FUNCTIONALS
GTP-ASES
INACTIVATION
INOSITOL
PROCESSING
RESIDUES
TOXINS