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Structure and function of C-terminal catalytic region of Pasteurella multocida toxin

  • Kengo Kitadokoro1Email author,
  • Shigeki Kamitani2,
  • Aya Fukui2,
  • Hiromi Toshima2,
  • Masami Miyake2 and
  • Yasuhiko Horiguchi2
BMC Proceedings20082(Suppl 1):P32

Published: 23 September 2008


DisulfideDisulfide BondVirulence FactorPapainClostridium Difficile

Pasteurella multocida toxin (PMT) is one of the virulence factors responsible for pathogenesis in some Pasteurellosis. We determined the crystal structure of the C-terminal region of PMT (C-PMT), which carries an intracellularly active moiety. The overall structure of C-PMT displays a Trojan horse structure, composed of three domains arranged in feet, body and head subunits with each linker loops, which were designated C1, C2, and C3 domains from the N- to C-terminus, respectively.

The C1 domain showing marked similarity in steric structure to the N-terminal domain of Clostridium difficile toxin B, was found to lead the toxin molecule to the plasma membrane. We found in the C3 domain the Cys-His-Asp catalytic triad that is organized only when the Cys is released from a disulfide bond. The steric alignment of the triad corresponded well to that of papain or other enzymes carrying the Cys-His-Asp triad. Our results indicate that PMT is an enzyme toxin carrying the cysteine protease-like catalytic triad dependent on the redox state, and functions oncytoplasmic face of the plasma membrane of target cells.

Authors’ Affiliations

Kyoto Institute of Technology, Matsugasakigosyokaidou-cho, Sakyo-ku, Kyoto, Japan
Research Institute for Microbial Diseases, Osaka University, Suita, Japan


© Kitadokoro et al; licensee BioMed Central Ltd. 2008

This article is published under license to BioMed Central Ltd.