Organization of the toxin gene cluster and surrounding regions in CDC66177. The arrangement of genes in the toxin gene cluster and surrounding regions of strain CDC66177 is compared to that of Alaska E43. The toxin gene cluster of strain CDC66177 is located within the rarA operon similar to the arrangement in strain Alaska E43. Regions I and II (indicated by green font) contain putative insertion sequences and the location of split and intact rarA genes are shown. XbaI restriction sites (indicated by red lines) flanking the larger split rarA gene (indicated by an asterisk) are shown. The nucleotide sequence between alaS and the larger split rarA gene of the indicated strains was used to generate the neighbor-joining tree shown.