Evidence that Arg‐295, Glu‐378, and Glu‐380 are active‐site residues of the ADP‐ribosyltransferase activity of iota toxin

FEBS Letters

Domenighini, Mario¹  Popoff, Michel R²  Perelle, Sylvie² 

[1] Immunobiological Research Institute Siena (IRIS), Via Fiorentina 1, 53100 Sienna, Italy;Unité des Toxines Microbiennes, Institut Pasteur, 28 rue du Dr. Roux, 75724 Paris Cedex 15, France

关键词: Iota toxin;    Clostridium perfringens;    C3 enzyme;    ADP-ribosylating toxin;    C. spiroforme toxin;    C. difficile ADP-ribosyltransferase;   

DOI  :  10.1016/0014-5793(96)01035-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The active site of the enzymatic component (Ia) of the Clostridium perfringens iota toxin has been studied by site-directed mutagenesis. Sequence alignment showed that Ia and C3 enzymes display a segment in their C-terminal part which is homologous to that forming the active domain of pertussis toxin, cholera toxin, and Escherichia coli thermolabile toxins. This structure consists of a β-strand and an α-helix which forms the NAD-binding cavity and which is flanked by two catalytic spatially conserved residues involved in catalysis [Domenighini et al. (1994) Mol. Microbiol. 14, 41–50]. Substitutions (Arg-295-Lys, Glu-378-Ala, Glu-380-Asp, and Glu-380-Ala) induced a drastic decrease in ADP-ribosylation and cytotoxic activities, while substitution of the adjacent Arg (Arg-296-Lys) only partially affected the enzymatic activity and cytotoxicity. These results indicate that Arg-295, Glu-378 and Glu-380 of Ia are involved in the ADP-ribosylation activity which is essential for the morphological changes of cells treated with iota toxin.

【 授权许可】

Unknown