The Escherichia coli zupT (formerly ygiE) gene encodes a cytoplasmic membrane protein (ZupT) related to members of the eukaryotic ZIP family of divalent metal ion transporters. Previously, ZupT was shown to be responsible for uptake of zinc. In this study, we show that ZupT is a divalent metal cation transporter of broad substrate specificity. An E. coli strain with a disruption in all known iron uptake systems could grow in the presence of chelators only if zupT was expressed. Heterologous

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... ession of Arabidopsis thaliana ZIP1 could also alleviate iron deficiency in this E. coli strain, as could expression of indigenous mntH or feoABC. Transport studies with intact cells showed that ZupT facilitates uptake of 55 Fe 2؉ similarly to uptake of MntH or Feo. Other divalent cations were also taken up by ZupT, as shown using 57 Co 2؉ . Expression of zupT rendered E. coli cells hypersensitive to Co 2؉ and sensitive to Mn 2؉ . ZupT did not appear to be metal regulated: expression of a ⌽(zupT-lacZ) operon fusion indicated that zupT is expressed constitutively at a low level.