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Preparation of Quality Inositol Pyrophosphates
Published on: September 3, 2011
Structure-function analysis of inositol hexakisphosphate-induced autoprocessing in Clostridium difficile toxin A
Rory N Pruitt1, Benjamin Chagot2, Michael Cover1
1Departments of Microbiology and Immunology, Nashville, Tennessee 37232.
The Journal of Biological Chemistry
|June 26, 2009
Summary
Clostridium difficile toxins are inactivated by cellular inositol hexakisphosphate (InsP6). This study reveals the cysteine protease domain
Area of Science:
- * Molecular biology
- * Structural biology
- * Biochemistry
Background:
- * Clostridium difficile toxins A and B disrupt host cell function by inactivating small G-proteins via glucosylation.
- * Cellular inositol hexakisphosphate (InsP6) triggers autocatalytic cleavage of these toxins, releasing the glucosyltransferase domain into the host cell.
Purpose of the Study:
- * To define the cysteine protease domain (CPD) responsible for autoprocessing in Toxin A (TcdA).
- * To elucidate the structural basis of InsP6-mediated TcdA cleavage through X-ray crystallography.
- * To identify key residues and structural features involved in TcdA processing.
Main Methods:
- * X-ray crystallography to determine the 1.6 Å structure of the TcdA CPD bound to InsP6.
- * Functional assays to investigate the mechanism of TcdA autoprocessing.
- * Sequence analysis of TcdA and related clostridial toxins.
Main Results:
- * The 1.6 Å crystal structure of the TcdA CPD bound to InsP6 was determined.
- * InsP6 binds to a basic pocket, separated from the active site by a beta-flap.
- * Functional studies confirmed an intramolecular cleavage mechanism and identified critical residues for InsP6-induced processing.
- * Unique structural features, including a C-terminal extension and a pi-cation interaction in the beta-flap, were identified.
Conclusions:
- * The structure and functional data provide a detailed understanding of InsP6-mediated TcdA autoprocessing.
- * The identified unique structural elements may contribute to the specific activity of TcdA among clostridial toxins.
- * This research offers insights into the mechanism of toxin activation and potential therapeutic targets.
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