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Journal of Bacteriology, August 2001, p. 4806-4813, Vol. 183, No. 16
Mikrobiologie/Membranphysiologie,
Universität Tübingen, Tübingen, Germany
Received 19 March 2001/Accepted 30 May 2001
The uptake of Mn2+, a cofactor for several enzymes in
Escherichia coli, is mediated by MntH, a proton-dependent
metal transporter, which also recognizes Fe2+ with lower
affinity. MntH belongs to the NRAMP family of eukaryotic Fe2+ and Mn2+ transporters. In E. coli strains with chromosomal mntH-lacZ fusions, mntH was partially repressed by both Mn2+ and
Fe2+. Inactivation of fur resulted in the loss
of Fe2+-dependent repression of mntH
transcription, demonstrating that Fe2+ repression depends
on the global iron regulator Fur. However, these fur
mutants still showed Mn2+-dependent repression of
mntH. The Mn2+-responsive transcriptional
regulator of mntH was identified as the gene product of
o155 (renamed MntR). mntR mutants were impaired in Mn2+ but not Fe2+ repression of
mntH transcription. Binding of purified MntR to the
mntH operator was manganese dependent. The binding region was localized by DNase I footprinting analysis and covers a nearly perfect palindrome. The Fur binding site, localized within 22 nucleotides of the mntH operator by in vivo operator
titration assays, resembles the Fur-box consensus sequence.
0021-9193/01/$04.00+0 DOI: 10.1128/JB.183.16.4806-4813.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Dual Repression by Fe2+-Fur and
Mn2+-MntR of the mntH Gene, Encoding an
NRAMP-Like Mn2+ Transporter in Escherichia
coli
*
Corresponding author. Mailing address:
Mikrobiologie/Membranphysiologie, Universität Tübingen, Auf
der Morgenstelle 28, 72076 Tübingen, Germany. Phone:
49-7071-2974646. Fax: 49-7071-295843. E-mail:
silke.patzer{at}mikrobio.uni-tuebingen.de.
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