Figure 6.

Structure of Moco and clustering of COG2154 genes with Moco biosynthesis genes in bacterial genomes. A, The structures of Moco and its precursor molybdopterin compared to that of a typical tetrahydropterin. The tetrahydropterin ring structure is colored blue. The form of Moco shown occurs in xanthine dehydrogenase and aldehyde oxidase. B, Clustering of COG2154 genes with up to four genes of Moco biosynthesis (moaA, moaC, moaD, and a moaD-moaE fusion). Matching colors correspond to orthologous genes; gray arrows are unrelated genes. Note that the genomes of Mycobacterium bovis and Mycobacterium tuberculosis each have two clusters and that the genes flanking the COG2154-moaC pair in Nitrococcus mobilis and Alkalilimnicola ehrlichei are different, so that only the pair is conserved.