Regulation of Gene Expression by Iron

Braun, Volkmar; Schaffer, Sven; Hantke, Klaus; Tröger, Wilfried

doi:10.1007/978-3-642-75969-7_17

Cited by 33 publications

(27 citation statements)

References 30 publications

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“…1). The Furmediated activation of sodB expression was not affected by promoter deletions upstream from position Ϫ39, as shown by the ␤-galactosidase activity resulting from the ⌽(sodB-lacZ) 7 , ⌽(sodB-lacZ) 6 , ⌽(sodB-lacZ) 5 , and ⌽(sodB-lacZ) 4 fusions (data not shown). This suggested that the mechanism of Fur-mediated activation is not of a classical type, with an upstream Ϫ35 bound regulatory protein.…”

Section: Resultsmentioning

confidence: 92%

“…The following thermal cycling program was used: 95°C for 1 min, followed by 25 cycles of 95°C for 1 min, 55°C for 1 min, and 72°C for 1 min and then 72°C for 10 min. Primers sodB 2 5Ј and sodB 2 3Ј, sodB 4 and sodB-BamHI, sodB 5 and sodB-BamHI, and sodB 11 and sodB-BamHI were used to construct ⌽(sodB-lacZ) 2 , ⌽(sodB-lacZ) 4 , ⌽(sodB-lacZ) 5 , and ⌽(sodB-lacZ) 11 , respectively. To generate the sodB 3 fragment, in which the CAATAAGGCTATTGT region (ϩ8 to ϩ22) is replaced with ATCCT, destabilizing the palindromic sequence ( Fig.…”

Section: Methodsmentioning

confidence: 99%

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Fur Positive Regulation of Iron Superoxide Dismutase in Escherichia coli : Functional Analysis of the sodB Promoter

2000

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In Escherichia coli, the expression of sodB, which encodes iron superoxide dismutase, has been suggested to be activated by Fur, the iron-responsive global regulator initially characterized as a transcriptional repressor. We investigated sodB regulation by functional analysis of the sodB promoter using sodB-lac fusions with various truncated and mutated promoters. Several cis-and trans-acting elements involved in sodB regulation have been identified. The ␤-galactosidase activity of sodB-lacZ reporter fusions and RNA analysis showed sevenfold iron-dependent, Fur-mediated activation of expression. A region just downstream from ؊10, including a large palindromic sequence encompassing the ؉1 position followed by a 14-bp AT-rich motif, is the site of Fur positive regulation, and the integrity of both sequences was required for full Fur-mediated activation. The life span of sodB mRNA was three times longer in a fur ؉ strain, indicating that Fur-mediated activation proceeds, at least in part, at the posttranscriptional level. The H-NS and IHF histone-like factors also affected sodB expression. IHF slightly repressed sodB expression independently of Fur regulation. In contrast, H-NS negative regulation operated only in the absence of Fur. Remarkably, psodB behaved like a "pure extended -10" promoter. Deletion of the ؊35 region did not affect expression, whereas expression was totally abolished by a TG-to-CC mutation in the extended ؊10 sequence TGcTACCCT.

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Section: Resultsmentioning

confidence: 92%

Section: Methodsmentioning

confidence: 99%

Fur Positive Regulation of Iron Superoxide Dismutase in Escherichia coli : Functional Analysis of the sodB Promoter

2000

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“…This change in the metal environment could alter the conformation of the protein and, therefore, modify the ability of Fur to bind to DNA. On this purpose, site-directed mutagenesis experiments have shown that a single mutation of residue likely involved in Fe 2ϩ coordination yields an inactive Fur protein (45,46). Mutation especially of His-90, a highly conserved amino acid in Fur sequences, leads to an inactive protein still able to dimerize (45).…”

Section: Discussionmentioning

confidence: 99%

Direct inhibition by nitric oxide of the transcriptional ferric uptake regulation protein via nitrosylation of the iron

D’Autréaux

Touati

Bersch

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

166

165

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“…Several laboratories have begun to define the functional regions of Fur involved in Fe(II) sensing and in binding DNA as a repressor (4,6,(40)(41)(42)50). The results of fusion protein studies combining different domains of Fur and the repressor cI857 indicate that the N terminus of Fur is involved in DNA binding while the C terminus is required for dimerization (50).…”

Section: Discussionmentioning

confidence: 99%

The role of fur in the acid tolerance response of Salmonella typhimurium is physiologically and genetically separable from its role in iron acquisition

1996

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The response of Salmonella typhimurium to low pH includes a low-pH protection system called the acid tolerance response (ATR). The iron-regulatory protein Fur has been implicated in the ATR since fur mutants are acid sensitive and cause altered expression of several acid shock proteins (J. W. Foster, J. Bacteriol. 173:6896-6902, 1991). We have determined that the acid-sensitive phenotype of fur mutations is indeed due to a defect in Fur that can be complemented by a fur ؉ -containing plasmid. However, changes in cellular iron status alone did not trigger the ATR. Cells clearly required exposure to low pH in order to induce acid tolerance. The role of Fur in acid tolerance was found to extend beyond regulating iron acquisition. A mutation in fur converting histidine 90 to an arginine (H90R) eliminated Fur-mediated iron regulation of enterochelin production and deregulated an iroA-lacZ fusion but had no effect on acid tolerance. The H90R iron-blind Fur protein also mediated acid shock induction of several Fur-dependent acid shock proteins and acid control of the hyd locus. In addition, a Fur superrepressor that constitutively repressed iron-regulated genes mediated normal Fur-dependent acid tolerance and pH-controlled gene expression. The results indicate the acid-sensing and iron-sensing mechanisms of Fur are separable by mutation and reinforce the concept of Fur as a major global regulator in the cell.

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Regulation of Gene Expression by Iron

Cited by 33 publications

References 30 publications

Fur Positive Regulation of Iron Superoxide Dismutase in Escherichia coli : Functional Analysis of the sodB Promoter

Fur Positive Regulation of Iron Superoxide Dismutase in Escherichia coli : Functional Analysis of the sodB Promoter

Direct inhibition by nitric oxide of the transcriptional ferric uptake regulation protein via nitrosylation of the iron

The role of fur in the acid tolerance response of Salmonella typhimurium is physiologically and genetically separable from its role in iron acquisition

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