Genomic variability among enteric pathogens: the case of the mutS-rpoS intergenic region

The mutS-rpoS intergenic region of enteric bacteria ranges in size from 88 bp in Yersinia to > 12 000 bp in Salmonella. We interpret this expansion as the result of the horizontal transfer of segments of DNA from diverse origins. Both comparative genomic analysis and selective sequencing of a variety of Escherichia coli pathogens have provided additional evidence for reassortment of segments within this region.