Inositol hexakisphosphate-dependent processing of Clostridium sordellii lethal toxin and Clostridium novyi alpha-toxin.

Abstract

Clostridium sordellii lethal toxin and Clostridium novyi α-toxin, which are virulence factors involved in the toxic shock and gas gangrene syndromes, are members of the family of clostridial glucosylating toxins. The toxins inactivate Rho/Ras proteins by glucosylation or attachment of GlcNAc (α-toxin). Here, we studied the activation of the autoproteolytic processing of the toxins by inositol hexakisphosphate (InsP(6)) and compared it with the processing of Clostridium difficile toxin B. In the presence of low concentrations of InsP(6) (<1 μM), toxin fragments consisting of the N-terminal glucosyltransferase (or GlcNAc-transferase) domains and the cysteine protease domains (CPDs) of C. sordellii lethal toxin, C. novyi α-toxin, and C. difficile toxin B were autocatalytically processed. The cleavage sites of lethal toxin (Leu-543) and α-toxin (Leu-548) and the catalytic cysteine residues (Cys-698 of lethal toxin and Cys-707 of α-toxin) were identified. Affinity of the CPDs for binding InsP(6) was determined by isothermal titration calorimetry. In contrast to full-length toxin B and α-toxin, autocatalytic cleavage and InsP(6) binding of full-length lethal toxin depended on low pH (pH 5) conditions. The data indicate that C. sordellii lethal toxin and C. novyi α-toxin are InsP(6)-dependently processed. However, full-length lethal toxin, but not its short toxin fragments consisting of the glucosyltransferase domain and the CPD, requires a pH-sensitive conformational change to allow binding of InsP(6) and subsequent processing of the toxin.

• Authors: Gregor Guttenberg, Panagiotis Papatheodorou, Selda Genisyuerek, Wei Lü, Thomas Jank, Oliver Einsle, Klaus Aktories
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 286 Issue 17 Pg. 14779-86 (Apr 29 2011) ISSN: 1083-351X [Electronic] United States
• PMID: 21385871 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Bacterial Proteins
• Bacterial Toxins
• Peptide Fragments
• toxB protein, Clostridium difficile
• Phytic Acid

Topics

• Bacterial Proteins
• Bacterial Toxins (chemistry, metabolism)
• Clostridium (chemistry)
• Clostridium sordellii (chemistry)
• Hydrogen-Ion Concentration
• Peptide Fragments (pharmacology)
• Phytic Acid (metabolism)
• Protein Binding
• Protein Conformation