The iron uptake mechanisms of enteroinvasive Escherichia coli

Enteroinvasive Escherichia coli strains (EIEC) of different serotypes isola ted from patients with acute diarrhea were examined for the ability to prod uce siderophores and iron-regulated outer membrane proteins (IROMP). For ir on starvation cultures were grown at 37 degreesC in LB supplied with 200 mu M of alpha-alpha 'dypirydil. All strains produced enterobactin and twelve ( 40%) produced aerobactin. The strains showed IROMP varying fr-om 67-82 kDa. Proteins were either induced or stimulated by the iron starvation. Differe nces were observed in the electrophoretic profile among the serotypes, orig inating 5 electrophoretic profiles. All serotypes expressed proteins of 82 kDa (FepA) and 76 kDa (IutA) (except serotype 028ac: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 absence of aerobactin produ ction. Additionally to well characterized proteins (FepA and IutA), we foun d two IROMP of unknown function in some serotypes: a 71 kDa protein was det ected in three profiles and a 67 kDa protein was present in serotype 0152:H -. Moreover, two bands (39 and 43 kDa) which were not iron-regulated bound specifically to human lactoferrin.