Conserved regulatory motifs in bacteria: riboswitches and beyond.

We present a computational approach that identifies regulatory elements conserved across phylogenetically distant organisms. Intergenic regulatory regions were clustered by orthology of the adjacent genes, and an iterative process was applied to search for significant motifs, enabling new elements of the putative regulon to be added in each cycle. With this approach, we identified highly conserved riboswitches and the Gram positive T-box. Interestingly, we identified many other regulatory systems that appear to depend on conserved RNA structures.