Polyketide synthases and histidine kinases of D. purpureum. (a) The phylogram of putative polyketide synthases was constructed from the ketoacyl synthase and acyltransferase domains of each predicted protein. Red numbers indicate D. discoideum genes and blue numbers indicate D. purpureum genes, with the corresponding genomic loci given in Table S6 in Additional file 1. Orthologous genes are circled in grey; the steely (stlA, stlB) and the putative fatty acid synthase (fas) genes are indicated. (b) Unrooted phylogram of the putative histidine kinases and the AcrA protein of D. discoideum and D. purpureum (denoted with 'Dp' before the gene names). Bootstrap values at each node are given for 1,000 iterations of tree building. The red numbers indicate the percent amino acid sequence identity between each pair of predicted proteins. Note the striking one-to-one correspondence between each gene in the two species.