These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: The carboxy-terminal C2-like domain of the alpha-toxin from Clostridium perfringens mediates calcium-dependent membrane recognition.
    Author: Guillouard I, Alzari PM, Saliou B, Cole ST.
    Journal: Mol Microbiol; 1997 Dec; 26(5):867-76. PubMed ID: 9426125.
    Abstract:
    The lethal, cytolytic alpha-toxin (phospholipase C) of Clostridium perfringens consists of two distinct modules: the larger N-terminal domain catalyses phospholipid hydrolysis, and its activity is potentiated by a smaller C-terminal domain. Calcium ions are essential for the binding of alpha-toxin to lipid films. Sixteen alpha-toxin variants with single amino acid substitutions in the C-terminal region were obtained using site-directed mutagenesis and T7 expression technology. Five of these variants showed reduced phospholipase C activity and were considerably less active than native alpha-toxin under calcium-limiting conditions. Replacement of Thr-272 by Pro diminished phospholipase C activity, severely affected haemolysis and platelet aggregation and perturbed a surface-exposed conformational epitope. The results of sequence comparisons and molecular modelling indicate that the C-terminal region probably belongs to the growing family of C2 beta-barrel domains, which are often involved in membrane interactions, and that the functionally important substitutions are clustered at one extremity of the domain. The combined findings suggest that the C-terminal region of alpha-toxin mediates interactions with membrane phospholipids in a calcium-dependent manner. Mutations to this domain may account for the natural lack of toxicity of the alpha-toxin homologue, phospholipase C of Clostridium bifermentans.
    [Abstract] [Full Text] [Related] [New Search]