Figure 1.

Phylogenetic relationship between the enzymatic and binding components of clostridial binary toxins. Evolutionary history of clostridial binary toxins was inferred using the Neighbor-Joining method (Saitou and Nei, 1987). The optimal tree with sum of branch length = 1.11845902. The percentage of replicate trees in which the associated taxa clustered together in the bootstrap test (500 replicates) are shown next to the branches (Felsenstein, 1985). The tree is drawn to scale, with branch lengths in the same units as those of the evolutionary distances used to infer the phylogenetic tree. The evolutionary distances were computed using the Poisson correction method (Zuckerkandl and Pauling, 1965) and are in units of the number of amino acid substitutions per site. All positions containing gaps and missing data were eliminated from the dataset (complete deletion option). There were a total of 710 and 405 positions for the B and A component sequences, respectively, in the final dataset. Phylogenetic analyses were conducted in MEGA4 (Tamura et al., 2007).