Figure 1

Distribution of T2SS _α and T2SS _β in non-pathogenic E. coli strains. Phylogeny is from Archer et al. [13], with O157:H7 as an outgroup lacking both T2SS_α and T2SS_β. Loci encoding the two T2SS types (where present) are diagrammed for each strain. Branch lengths are arbitrary. T2SS_αgsp genes are colored yellow, and T2SS_βgsp genes are shown in red.