Phylogenetic tree derived from members of peptidase family A1. The tree was generated for all peptidase unit sequences of family A1 holotypes, plus those from the sequences of the bacteria listed in Table 1. The tree is unrooted, but the sequence of plasmepsin-5, which is very divergent, was chosen as the outgroup. Homologues from bacteria are highlighted with a blue background. Branches that were present in 90% of the bootstrap trees are shown in red. Key: [see Additional file 1].