FIG. 3.
(A) Sequence similarities between the binding components of C2 toxin (C2II) and anthrax toxin (PA). Based on sequence homologies to PA, C2II was divided into four domains. Sequence identities and homologies (in parentheses) between C2II and PA are shown below the diagrams. Numbers above the diagrams indicate amino acid residues. Arrows indicate the protease cleavage sites for activation. (B) Generation of C2II fragments and antisera. D1, D3, and D4 of C2II were amplified from pGEX-C2II by PCR. The resulting PCR products were cloned in the pGEX-2T vector, resulting in plasmids pGEX-C2II-D1, pGEX-C2II-D3, and pGEX-C2II-D4, respectively. The respective antisera against the resulting C2II domains were anti-C2II-D1, anti-C2II-D3, and anti-C2II-D4 antisera. Anti-C2II182–196, antiserum against an N-terminal peptide of C2IIa (amino acids 182 to 197); anti-C2II707–721, antiserum against a C-terminal peptide of C2II (amino acids 706 to 721).