Binuclear [2Fe-2S] Clusters in the Escherichia coli SoxR Protein and Role of the Metal Centers in Transcription

Hidalgo, Elena; Jm, Bollinger; Tm, Bradley; Ct, Walsh; Demple, Bruce

doi:10.1074/jbc.270.36.20908

Cited by 192 publications

(178 citation statements)

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“…When activated by the univalent oxidation of the 2Fe-2S clusters of the protein through a not yet explained mechanism (Storz and Imlay, 1999) SoxR induces transcription of soxS, a positive regulator that stimulates transcription of more than 16 other superoxide responsive genes (Wu and Weiss, 1992;Hidalgo et al, 1995). Although this system responds to oxidative stress when cells are exposed to superoxide radical-generating agents, it is not induced by H 2 O 2 (Chan and Tsaneva and Weiss, 1990;Hidalgo et al, 1997).…”

Section: The Soxrsmentioning

confidence: 99%

Several pathways of hydrogen peroxide action that damage the E. coli genome

Asad

Almeida

et al. 2004

Genet. Mol. Biol.

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Hydrogen peroxide is an important reactive oxygen species (ROS) that arises either during the aerobic respiration process or as a by-product of water radiolysis after exposure to ionizing radiation. The reaction of hydrogen peroxide with transition metals imposes on cells an oxidative stress condition that can result in damage to cell components such as proteins, lipids and principally to DNA, leading to mutagenesis and cell death. Escherichia coli cells are able to deal with these adverse events via DNA repair mechanisms, which enable them to recover their genome integrity. These include base excision repair (BER), nucleotide excision repair (NER) and recombinational repair. Other important defense mechanisms present in Escherichia coli are OxyR and SosRS anti-oxidant inducible pathways, which are elicited by cells to avoid the introduction of oxidative lesions by hydrogen peroxide. This review summarizes the phenomena of lethal synergism between UV irradiation (254 nm) and H 2 O 2 , the cross-adaptive response between different classes of genotoxic agents and hydrogen peroxide, and the role of copper ions in the lethal response to H 2 O 2 under low-iron conditions. Key words: hydrogen peroxide, cross-adaptive response, lethal synergism, copper and iron. General AspectsThe appearance of aerobic forms of life was an important step in the evolutionary process, since oxygen consumption leads to the production of ten-fold more energy from glucose than does anaerobic metabolism (Meneghini, 1987). However, this process imposes constraints on cell viability, because of the generation of reactive oxygen species during respiration.The consecutive univalent reduction of molecular oxygen to water produces three active intermediates: superoxide anion (O 2 -• ), hydrogen peroxide (H 2 O 2 ) and hydroxyl radical (OH • ). These intermediates, collectively referred to as reactive oxygen species (ROS) are potent oxidants of lipids, proteins, and nucleic acids (Halliwell and Gutteridge, 1984;Mello-Filho and Meneghini, 1985;Meneghini, 1988). Among the oxidative DNA lesions, one of the major classes of DNA damage leads to modification in purine and pyrimidine bases, together with oligonucleotide strand breaks, DNA-protein cross-links and abasic sites. Increasing evidence suggests that the cumulative damage caused by ROS contributes to numerous degenerative diseases associated with aging, such as atherosclerosis, rheumatoid arthritis and cancer (Ames et al., 1993;Halliwell and Gutteridge, 1999).Living organisms have developed specific mechanisms to prevent the production and effects of ROS. The reduction of O 2 by cytochrome oxidase without yielding ROS, the superoxide dismutase catalysis of O 2 -• into H 2 O 2 through a dismutation reaction, the decomposition of H 2 O 2 by catalase and peroxidases, and the scavenging of ROS by some vitamins comprise part of the set of cellular antioxidant defenses (Halliwell and Gutteridge, 1999). Synthesis of the enzymes that catalyze these reactions is a part of the adaptive response tr...

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Section: The Soxrsmentioning

confidence: 99%

Several pathways of hydrogen peroxide action that damage the E. coli genome

Asad

Almeida

et al. 2004

Genet. Mol. Biol.

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“…Two models have been proposed for the activation of SoxR. The first model states that it is regulated through the reversible disassembly, either partial or complete, of its Fe-S centers, which might be associated with redox reactions (6,7). Like most [2Fe-2S] proteins, the Fe-S clusters of SoxR can be easily stripped from the protein and replaced (8).…”

mentioning

confidence: 99%

“…Like most [2Fe-2S] proteins, the Fe-S clusters of SoxR can be easily stripped from the protein and replaced (8). This disassembly may be facilitated in vitro by thiols (6,7). The apoprotein is inactive although it can still bind to DNA (9), whereas the holoprotein can activate the transcription of soxS (9,10).…”

mentioning

confidence: 99%

“…The apoprotein is inactive although it can still bind to DNA (9), whereas the holoprotein can activate the transcription of soxS (9,10). This model was probably promoted because of early failures to verify the alternative model (6). However, it cannot easily explain why SoxR that was purified from uninduced cells contained intact Fe-S centers, unless one assumes that there is efficient spontaneous reconstitution of the Fe-S centers in cell extracts.…”

mentioning

confidence: 99%

“…SoxR is readily autooxidized, and the protein that is isolated in ambient atmosphere from uninduced cells is transcriptionally active (6,10). Recently, we demonstrated that protein can be reversibly inactivated in vitro by reduction of its Fe-S centers with dithionite under conditions that should not have resulted in dissociation of the Fe-S centers (3).…”

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confidence: 99%

See 2 more Smart Citations

Regulation of the soxRS Oxidative Stress Regulon

Gaudu

Moon

Weiss

1997

Journal of Biological Chemistry

133

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[2 Fe –2 S ] Oxidative‐Stress Sensor Sox R Bound to DNA

Watanabe¹,

Miki²

2004

Handbook of Metalloproteins

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SoxR, a member of the MerR (mercury resistance regulator) family, is a transcriptional activator that contains a [2Fe‐2S] cluster. In entric bacteria, SoxR functions as an oxidative‐stress sensor. However, in other nonentric bacteria, its physiological role appears to be different. SoxR is activated by reversible one‐electron oxidation of the [2Fe‐2S] cluster. In the active state, SoxR and other MerR family proteins activate transcription from unique promoters, which have a long 19 or 20 bp spacer between the −35 and −10 operator elements, by untwisting the promoter DNA. The crystal structures of SoxR and its complex with the target promoter in the oxidized (active) state have been reported. The structure of SoxR monomer consists of a winged helix‐turn helix DNA‐binding domain, a dimerization helix, and a Fe‐S cluster‐binding domain. The SoxR dimer is formed by an antiparallel long coiled coil. The [2Fe‐2S] cluster of SoxR is completely solvent‐exposed and surrounded by an asymmetric environment stabilized by interaction with the other subunit. The asymmetrically charged environment of the [2Fe‐2S] cluster probably causes redox‐dependent conformational changes of SoxR. The structure of the SoxR‐DNA complex provides a structural framework of the transcriptional activation by DNA distortion in the MerR family.

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Binuclear [2Fe-2S] Clusters in the Escherichia coli SoxR Protein and Role of the Metal Centers in Transcription

Abstract: SoxR protein of

Cited by 192 publications

References 37 publications

Several pathways of hydrogen peroxide action that damage the E. coli genome

Several pathways of hydrogen peroxide action that damage the E. coli genome

Regulation of the soxRS Oxidative Stress Regulon

[2 Fe –2 S ] Oxidative‐Stress Sensor Sox R Bound to DNA

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