Figure 1.

Reconstruction of ancestral polar amino acid PBPs. Midpoint-rooted maximum likelihood phylogeny of the amino acid-binding protein family used for reconstruction of ancestral sequences. Branches are drawn to scale and labeled with bootstrap values from 100 replicates. Sequences are identified by their GI number from the NCBI database, and are labeled with their putative binding specificity on the basis of functional annotation and homology to proteins of known function. The scale bar represents 0.4 substitutions per site. Three clades of closely related proteins are compressed for clarity.