Phylogenomic analysis of COG2154 proteins and AAH homologs in plants and microorganisms. A, Distribution of canonical and noncanonical COG2154 proteins and AAH homologs. COG2154 sequences taken as canonical contain the motif [DE]-x(3)-H-H-P-x(5)-[YW]-x(9)-H-x(8)-D. Major groups of plants and microorganisms are represented by single genera. For plant groups, the genus is typical of all members of the group. For microorganism groups, the genus has a distribution pattern that is common in the group but not necessarily universal. Gene clustering in prokaryotes is symbolized by connecting lines. The major groups of proteobacteria (α, β, γ) are indicated. Asterisks denote organisms whose COG2154 proteins were tested for PCD activity in this study. Schizosaccharo., Schizosaccharomyces. B, Clustering of bacterial genes encoding COG2154 and AAH with each other and with genes of the homogentisate pathway of Tyr degradation. Matching colors correspond to orthologous genes; gray arrows are unrelated genes. The steps in the homogentisate pathway and the corresponding genes are shown on the right.