Fig. 4

Conservation of cys regulon proteins. A relationship between the evolution of bacteria and the presence of the cys regulon genes is shown. The list of microorganisms and 16S rRNA sequences used to produce the phylogenetic tree is shown in Additional file 3: Table A3. Termicutes, Chlamydia and Spyrochaetae phyla are not represented because they did not show any evidence of containing orthologs of the cys regulon genes. The microorganisms are represented as a three letters code according to KEGG. All the cys regulon genes are shown as horizontal bars in the table. Colored boxes show the presence of one gene in a determined species. Boxes with an asterisk (*) inside represent fusioned genes. The phylogenetic tree was generated with MEGA version 5 [33] using the Neighbor-Joining Method (1000 bootstrap)