PMID:14730984
| Citation |
Sutton, VR, Stubna, A, Patschkowski, T, Münck, E, Beinert, H and Kiley, PJ (2004) Superoxide destroys the [2Fe-2S]2+ cluster of FNR from Escherichia coli. Biochemistry 43:791-8 |
|---|---|
| Abstract |
The oxygen sensing ability of the transcription factor FNR depends on the presence of a [4Fe-4S]2+ cluster. In the presence of O2, conversion of the [4Fe-4S]2+ cluster to a [2Fe-2S]2+ cluster inactivates FNR, but the fate of the [2Fe-2S]2+ cluster in cells grown under aerobic conditions is unknown. The present study shows that the predominant form of FNR in aerobic cells is apo-FNR (cluster-less FNR) indicating that the [2Fe-2S]2+ cluster, like the [4Fe-4S]2+ cluster, is not stable under these conditions. By quantifying the amount of [2Fe-2S]2+ cluster in 2Fe-FNR in vitro in the presence of various reductants and oxidants (GSH, DTT, cysteine, O2, hydrogen peroxide, and superoxide), we found that superoxide, a byproduct of aerobic metabolism, significantly destabilized the [2Fe-2S]2+ cluster. Mössbauer spectroscopy was used to monitor the effects of superoxide on 2Fe-FNR in vivo; under cellular conditions that favored superoxide production, we observed the disappearance of the signal representative of the [2Fe-2S]2+ cluster. We conclude that the [2Fe-2S]2+ cluster of FNR is labile to superoxide both in vitro and in vivo. This lability may explain the absence of the [2Fe-2S]2+ cluster form of FNR under aerobic growth conditions. |
| Links |
PubMed Online version:10.1021/bi0357053 |
| Keywords |
Aerobiosis; Escherichia coli/growth & development; Escherichia coli/metabolism; Escherichia coli Proteins/chemistry; Escherichia coli Proteins/isolation & purification; Escherichia coli Proteins/metabolism; Iron/metabolism; Iron-Sulfur Proteins/chemistry; Iron-Sulfur Proteins/isolation & purification; Iron-Sulfur Proteins/metabolism; Multienzyme Complexes/chemistry; Multienzyme Complexes/isolation & purification; Multienzyme Complexes/metabolism; Oxidation-Reduction; Oxygen/metabolism; Solutions; Spectroscopy, Mossbauer; Succinate Dehydrogenase/chemistry; Succinate Dehydrogenase/isolation & purification; Succinate Dehydrogenase/metabolism; Sulfur/metabolism; Superoxides/chemistry; Transcription Factors/chemistry; Transcription Factors/isolation & purification; Transcription Factors/metabolism |
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