Phylogenetic distribution of the global regulatory gene csrA among eubacteria.

The gene csrA encodes a unique kind of global regulator, CsrA, which modulates glycolysis, gluconeogenesis, glycogen biosynthesis and glycogen catabolism in Escherichia coli. Southern hybridization and nucleotide sequencing data have revealed apparent csrA homologs within several families of the alpha and gamma subdivisions of the proteobacteria (purple bacteria) and in the Gram-positive bacterium Bacillus subtilis. Thus, the CsrA regulatory system appears widely distributed among eubacteria.