Crystal Structure and Function of Actin-Specific ADP Ribosyl Toxin.

Abstract

The family of mono-ADP-ribosyltransferase includes not only bacterial toxins but also mammalian enzymes. Recently, crystal structures of arginine-specific ADP-ribosyltransferase have been revealed, giving a better understanding of type IV toxin. They are VIP2 from Bacillus and Ia from Clostridium perfringens. VIP2 and Ia ADP-ribosylate the Arg177 of actin. They consist of topologically similar N- and C-domains, which have not been expected from the amino acid sequence. C-domain is an enzymatic domain. N-domain interacts with VIP1 and Ib, respectively. C-domain structures were basically the same but the surface charge of N-domain was found significantly different between VIP2 and Ia. Rat ART2.2 and rho-targeted C3 toxin(asparagine-specific)consist of only one domain and the structure is similar to the C-domain of Ia. We summarize the crystal structure and the reaction mechanism of Ia.