The cloned locus of enterocyte effacement from enterohemorrhagic Escherichia coli O157:H7 is unable to confer the attaching and effacing phenotype upon E-coli K-12

The locus of enterocyte effacement (LEE) pathogenicity island of enterohemorrhagic Escherichia coli (EREC) O157:H7 possesses the same genes in identical order and orientation as the LEE of enteropathogenic E. coli (EPEC) O127:H6 but is unable to form attaching and effacing (A/E) lesions or to secrete Esp proteins when it is cloned in an E. call K-12 background, The A/E phenotype could not be restored by trans complementation with a variety of cloned EPEC LEE fragments, suggesting functional and/or regulatory differences between the LEE pathogenicity islands of EPEC O127:H6 and EHEC O157:H7.