Rid family genes cluster on bacterial chromosomes with pyrimidine and arginine metabolism genes, particularly those related to carbamoyl phosphate. (A) The layout is the same as in Figure 3. (B) The metabolic pathways of pyrimidine and arginine synthesis (black arrows) and breakdown (light blue arrows) are shown. Dark blue bars under each enzyme indicate the relative proportion of genomes (in the set of 981 genomes analyzed) in which each gene of pyrimidine or arginine metabolism is clustered on the chromosome with a Rid family gene. The longest bar (ACT in the pyrimidine pathway) corresponds to 58 instances of clustering.