Fig. 4.

Conservation of gene organization in actinomycetes. (A) Conservation of mce operons. Orthologous genes are denoted by the same color. Numbers of operons found in each genome are indicated in parentheses. (B) Comparison of gene organization between the putative siderophore (Upper) and the mycobactin (Lower) biosynthesis gene clusters. Orthologous and nonorthologous genes are denoted by the same color or in gray, respectively. Both clusters contain three nonribosomal peptide synthetases (NRPSs) and two polyketide synthases (PKSs).