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Infection and Immunity, December 2004, p. 6914-6923, Vol. 72, No. 12
0019-9567/04/$08.00+0     DOI: 10.1128/IAI.72.12.6914-6923.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

Fine Mapping of the N-Terminal Cytotoxicity Region of Clostridium perfringens Enterotoxin by Site-Directed Mutagenesis

James G. Smedley III^1,2 and Bruce A. McClane^1,2*

Department of Molecular Genetics and Biochemistry,¹ Molecular Virology and Microbiology Graduate Program, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania²

Received 1 July 2004/ Returned for modification 29 July 2004/ Accepted 13 August 2004

Clostridium perfringens enterotoxin (CPE) has a unique mechanism of action that results in the formation of large, sodium dodecyl sulfate-resistant complexes involving tight junction proteins; those complexes then induce plasma membrane permeability alterations in host intestinal epithelial cells, leading to cell death and epithelial desquamation. Previous deletion and point mutational studies mapped CPE receptor binding activity to the toxin's extreme C terminus. Those earlier analyses also determined that an N-terminal CPE region between residues D45 and G53 is required for large complex formation and cytotoxicity. To more finely map this N-terminal cytotoxicity region, site-directed mutagenesis was performed with recombinant CPE (rCPE). Alanine-scanning mutagenesis produced one rCPE variant, D48A, that failed to form large complexes or induce cytotoxicity, despite having normal ability to bind and form the small complex. Two saturation variants, D48E and D48N, also had a phenotype resembling that of the D48A variant, indicating that both size and charge are important at CPE residue 48. Another alanine substitution rCPE variant, I51A, was highly attenuated for large complex formation and cytotoxicity, but rCPE saturation variants I51L and I51V displayed a normal large complex formation and cytotoxicity phenotype. Collectively, these mutagenesis results identify a core CPE sequence extending from residues G47 to I51 that directly participates in large complex formation and cytotoxicity.

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* Corresponding author. Mailing address: E1240 BSTWR, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261. Phone: (412) 648-9022. Fax: (412) 624-1401. E-mail: bamcc{at}pitt.edu.

Editor: J. T. Barbieri

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Infection and Immunity, December 2004, p. 6914-6923, Vol. 72, No. 12
0019-9567/04/$08.00+0     DOI: 10.1128/IAI.72.12.6914-6923.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

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]  
• Smedley, J. G. III, Uzal, F. A., McClane, B. A. (2007). Identification of a Prepore Large-Complex Stage in the Mechanism of Action of Clostridium perfringens Enterotoxin. Infect. Immun. 75: 2381-2390 [Abstract] [Full Text]