Phylogenetic tree of the CDF family. The Neighbor-Joining phylogenetic tree based on the protein alignment was created with MEGA 3.1. Clusters are represented with different colours with respect to metal specificity: blue is for zinc, green for iron/zinc, violet for manganese and brown for unknown specificity. The three CDF groups are surrounded with coloured boxes with the same colour-code. Bootstrap values are indicated for each cluster. The scale bar indicates an evolutionary distance of 0.1 amino acid substitution per site.