Figure 6: The bacterial ExoY-like nucleotidyl cyclase toxin subfamily.

(a) Phylogenetic tree. The amino-acid sequences of Pseudomonas aeruginosa ExoY and various ExoY-related effector domains/toxins found in several emerging Gram-negative bacterial pathogens were aligned as shown in Supplementary Fig. 8 and clustered on phylogram branches on the basis of the similarity of their amino-acid sequences using the Phylogeny.fr platform⁶¹. Calmodulin-activated edema factor and Cya Adenylate Cyclase Domains (ACD) were used as an outgroup more distantly related to ExoY-like nucleotidyl cyclase toxins to root the phylogeny. NCBI accessions of bacterial protein sequences are given in Supplementary Table 2. Pairwise sequence similarities (%) with P. aeruginosa ExoY or V. nigripulchritudo ExoY-like (VnExoY-L) are given in green and blue, respectively (see Supplementary Table 2 for more details). Similarity values without parenthesis indicate the ExoY-like sequences that are the most significantly related to actin-activated ExoY or VnExoY-L nucleotidyl cyclases. (b) Activation of VnExoY-L catalysed synthesis of cAMP by actin (MA-L). Reactions containing 10 ng VnExoY-L (3.7 nM) and actin at indicated concentrations were started by the addition of 2 mM ATP and incubated for 30 min at 30 °C. The background activity without actin was about 1 nmol of cAMP min⁻¹ mg⁻¹. Error bars correspond to s.d. of two experimental replicates.