Phylogenetic tree of CcoN from Pseudomonas species. Amino acid sequences were aligned using ClustalW. Tree topology and evolutionary distance estimations were done by the neighbor-joining method. The numbers indicated at the nodes are bootstrap values calculated from 1,000 replicates. The CcoN1-, CcoN2-, CcoN3-, and CcoN4-like sequences are indicated by blue, yellow, red, and green fan-shaped boxes, respectively. Several CcoN sequences from Rhodobacter, Shewanella, Pseudoalteromonas, and Vibrio species were used as outgroups.