Fig. 5. Phylogenetic analysis of the editing domain of AlaRS. (A) Maximum parsimony tree derived from the alignment of the editing domains of AlaRS (corresponding to G535–S686 of E.coli AlaRS), rooted with AlaXp (Schimmel and Ribas De Pouplana, 2000). The numbers in branch nodes correspond to bootstrap frequencies after 1000 bootstrap cycles in parsimony and distance trees. The root of the tree was derived from the position of the AlaXp clade (shown as a red branch). The overall geometry obtained with the editing domain sequences is identical to that obtained for the active site domain alone (Chihade et al., 2000), indicating that the editing domain has evolved with the active site of the protein from the inception of modern AlaRSs. (B) Distribution of the editing domain throughout the tree of life in ThrRS (red squares) and AlaRS (blue circles).