The iron uptake mechanisms of enteroinvasive "Escherichia coli"

ABSTRACT

Enteroinvasive "Escherichia coli" strains (EIEC) of different serotypes isolated from patients with acute diarrhea were examined for the ability to produce siderophores and iron-regulated outer membrane proteins (IROMP). For iron starvation cultures were grown at 37ºC in LB supplied with 200(micro)M of (alpha)-(alpha)'dypirydil. All strains produced enterobactin and twelve (40(per cent)) produced aerobactin. The strains showed IROMP varying from 67-82 kDa. Proteins were either induced or stimulated by the iron starvation. Differences were observed in the electrophoretic profile among the serotypes, originating 5 electrophoretic profiles. All serotypes expressed proteins of 82kDa (FepA) and 76 kDa (IutA) (except serotype O28ac:H(-) that did not produce the 76 kDa protein). Several strains (O29:H(-), O144:H(-), 0152:H(-), and O167:H(-)) expressed IutA in the outer membrane, in the abscence of aerobactin production. Additionally to well characterized proteins (FepA and IutA), we found two IROMP of unknown function in some serotypes: a 71 kDa protein was detected in three profiles and a 67 kDa protein was present in serotype O152:H(-). Moreover, two bands (39 and 43 kDa) which were not iron-regulated bound specifically to human lactoferrin