Abstract
Experiments were designed to study the effect of iron on the expression of CFA/I fimbriae by enterotoxigenic E. coli (ETEC). Addition of 0.05 mM ferrous sulfate to growth media decreased CFA/I antigen and fimbrial production by the CFA/I-positive ETEC strain H-10407 as measured by quantitative ELISA and hemagglutination assay. The repressive effect was reversed by the addition of the iron chelators, sodium citrate or dipyridyl. With a CFA/I subunit gene promoter- lacZ fusion, it was found that the activity of the subunit gene promoter was significantly higher in the presence of iron chelators than in medium containing iron in the fur + strain DHB24. This difference was not observed in the fur mutant strain SBC24, suggesting that the global E. coli metalloregulatory protein Fur ( f erric u ptake r egulation) is involved in the repression. The repressor may bind to the promoter of the CFA/I subunit gene since several potential Fur-binding sites were identified in the promoter area.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
