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Crystal Structure of Clostridium perfringens Enterotoxin Displays Features of β-Pore-forming Toxins*

By Kengo Kitadokoro, Kousuke Nishimura, Shigeki Kamitani, Aya Fukui-Miyazaki, Hirono Toshima, Hiroyuki Abe, Yoichi Kamata, Yoshiko Sugita-Konishi, Shigeki Yamamoto, Hajime Karatani and Yasuhiko Horiguchi

Abstract

Clostridium perfringens enterotoxin (CPE) is a cause of food poisoning and is considered a pore-forming toxin, which damages target cells by disrupting the selective permeability of the plasma membrane. However, the pore-forming mechanism and the structural characteristics of the pores are not well documented. Here, we present the structure of CPE determined by x-ray crystallography at 2.0 Å. The overall structure of CPE displays an elongated shape, composed of three distinct domains, I, II, and III. Domain I corresponds to the region that was formerly referred to as C-CPE, which is responsible for binding to the specific receptor claudin. Domains II and III comprise a characteristic module, which resembles those of β-pore-forming toxins such as aerolysin, C. perfringens ϵ-toxin, and Laetiporus sulfureus hemolytic pore-forming lectin. The module is mainly made up of β-strands, two of which span its entire length. Domain II and domain III have three short β-strands each, by which they are distinguished. In addition, domain II has an α-helix lying on the β-strands. The sequence of amino acids composing the α-helix and preceding β-strand demonstrates an alternating pattern of hydrophobic residues that is characteristic of transmembrane domains forming β-barrel-made pores. These structural features imply that CPE is a β-pore-forming toxin. We also hypothesize that the transmembrane domain is inserted into the membrane upon the buckling of the two long β-strands spanning the module, a mechanism analogous to that of the cholesterol-dependent cytolysins

Topics: Microbiology
Publisher: American Society for Biochemistry and Molecular Biology
OAI identifier: oai:pubmedcentral.nih.gov:3103334
Provided by: PubMed Central
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