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Infect. Immun. doi:10.1128/IAI.01737-06
Copyright (c) 2007, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Identification of a Pre-Pore Large Complex Stage in the Mechanism of Action of Clostridium perfringens Enterotoxin

Department of Molecular Genetics and Biochemistry; Molecular Virology and Microbiology Graduate Program; California Animal Health and Food Safety Laboratory, University of California, Davis

^* To whom correspondence should be addressed. Email: bamcc{at}pitt.edu.

	Abstract

Clostridium perfringens enterotoxin (CPE) is the etiological agent of the 3^rd most common food-borne illness in the U.S.A. The enteropathogenic effects of CPE result from formation of large CPE-containing complexes in eukaryotic cell membranes. Formation of these 155 and 200 kDa complexes coincides with plasma membrane permeability changes in eukaryotic cells, causing a Ca²⁺ influx that drives cell death pathways. CPE contains a stretch of amino acids (residues 81-106) that alternates markedly in side chain polarity (a pattern shared by the transmembrane domains of the -barrel pore-forming toxin family). The goal of this study, therefore, was to investigate whether this CPE region is involved in pore formation. Complete deletion of the CPE 81-106 region produced a CPE variant that was non-cytotoxic for Caco-2 cells and was unable to form CPE pores. However, this variant maintained the ability to form the 155 kDa large complex. This large complex appears to be a pre-pore present on the plasma membrane surface since it showed greater susceptibility to proteases, increased complex instability, and a higher degree of dissociation from membranes when compared to the large complex formed by rCPE. When a D48A mutation was engineered into this pre-pore forming CPE variant, the resultant variant was unable to form any pre-pore 155 kDa large complex. Collectively these findings reveal a new step in CPE action, whereby receptor binding is followed by formation of a pre-pore large complex which then inserts into membranes to form a pore.

This article has been cited by other articles:

• Smedley, J. G. III, Saputo, J., Parker, J. C., Fernandez-Miyakawa, M. E., Robertson, S. L., McClane, B. A., Uzal, F. A. (2008). Noncytotoxic Clostridium perfringens Enterotoxin (CPE) Variants Localize CPE Intestinal Binding and Demonstrate a Relationship between CPE-Induced Cytotoxicity and Enterotoxicity. Infect. Immun. 76: 3793-3800 [Abstract] [Full Text]