Conserved gene clusters in Streptomyces and Frankia . Four biosynthetic gene clusters were found to be well conserved in Frankia and three in Streptomyces. (A) The conservation of gene content was used to find putative gene cluster boundaries. The first and last conserved gene numbers are shown, along with the cluster name from our analysis. The standard six gene window extending from a pHMM hit are shown, with the exception of FRAAL_16 (Frankia alni ACN14a cluster 16) where additional genes are shown downstream of the original cluster due to continuing gene cluster content similarity. SCO_17 (“Streptomyces coelicolor” A3(2) cluster 17) occurs in a large, well conserved region, so no cluster boundaries were determined. (B) shows the sequence logo of all putative lanthipeptide precursors in Frankia clusters similar to FRAAL_9. (C) and (D) The occurrence of the well conserved gene clusters in Frankia and Streptomyces are shown on subtrees of the ribosomal protein phylogeny from Figure 1, along with the closest outgroup taxa. FRAAL_16 was found in all strains shown in (C) and is therefore not shown. Open circles show the start of branches lacking the relevant gene cluster. Open squares show the start of branches containing clusters with the same basic machinery but large scale changes compared to the other genomes. These branches are also shown with dashed lines. The number of lanthipeptide clusters similar to FRAAL_9 present in each Frankia genome is shown in red above the terminal branch on the tree.