Figure 8.

Distribution of modules of aromatic catabolism mapped on a 16S rRNA tree. In this figure, only presence or absence (not gene order) is indicated. The Phh module (orange) consists of phenylalanine hydroxylase (PhhA), carbinolamine dehydratase (PhhB), and tyrosine aminotransferase (not shown, see Text), and accomplishes the overall conversion of PHE to 4-hydroxyphenylpyruvate. The Hpd module (yellow) is 4-hydroxyphenylpyruvate dioxygenase, which converts 4-hydroxyphenylpyruvate to homogentisate. The Hmg module (blue) catalyzes the 3-step conversion of homogentisate to acetoacetate and fumarate. The distribution of PhhR and TyrR is shown in boxes. In some cases the HmgC member is shaded light blue to indicate that the gene encoding this isomerase could not be found and is probably encoded by an as yet unknown analog. Some long branches are drawn with gaps that represent 25% of the length of the scale bar.