Dual repression by Fe(2+)-Fur and Mn(2+)-MntR of the mntH gene, encoding an NRAMP-like Mn(2+) transporter in Escherichia coli.
The uptake of Mn(2+), a cofactor for several enzymes in Escherichia coli, is mediated by MntH, a proton-dependent metal transporter, which also recognizes Fe(2+) with lower affinity. MntH belongs to the NRAMP family of eukaryotic Fe(2+) and Mn(2+) transporters. In E. coli strains with chromosomal mntH-lacZ fusions, mntH was partially repressed by both Mn(2+) and Fe(2+). Inactivation of fur resulted in the loss of Fe(2+)-dependent repression of mntH transcription, demonstrating that Fe(2+) repression depends on the global iron regulator Fur. However, these fur mutants still showed Mn(2+)-dependent repression of mntH. The Mn(2+)-responsive transcriptional regulator of mntH was identified as the gene product of o155 (renamed MntR). mntR mutants were impaired in Mn(2+) but not Fe(2+) 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.
Patzer
S I
SI
Mikrobiologie/Membranphysiologie, Universität Tübingen, Tübingen, Germany. silke.patzer@mikrobio.uni-tuebingen.de
Hantke
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K
D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D027682:Cation Transport Proteins; D002874:Chromosome Mapping; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D007501:Iron / Q000378:metabolism*; D008345:Manganese / Q000378:metabolism*; D008667:Metalloproteins / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid
D001426:Bacterial Proteins; D002352:Carrier Proteins; D027682:Cation Transport Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D008667:Metalloproteins; C492412:MntH protein, E coli; C433793:MntH protein, bacteria; C499677:MntR protein, E coli; C433792:MntR protein, bacteria; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D012097:Repressor Proteins; C068477:ferric uptake regulating proteins, bacterial; D008345:Manganese; D007501:Iron