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| Superoxide destroys the [2Fe-2S](2+) cluster of FNR from Escherichia coli |
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| Author(s): Sutton VR, Stubna A, Patschkowski T, Munck E, Beinert H, Kiley PJ |
| Source: BIOCHEMISTRY Volume: 43 Issue: 3 Pages: 791-798 Published: JAN 27 2004 |
| Times Cited: 24 References: 30 |
| Abstract: The oxygen sensing ability of the transcription factor FNR depends on the presence of a [4Fe-4S](2+) cluster. In the presence Of O-2, 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, O-2, hydrogen peroxide, and superoxide), we found that superoxide, a byproduct of aerobic metabolism, significantly destabilized the [2Fe-2S](2+) cluster. Mossbauer 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. |
| Document Type: Article |
| Language: English |
| Reprint Address: Kiley, PJ (reprint author), Univ Wisconsin, Program Cellular & Mol Biol, 1300 Univ Ave, Madison, WI 53706 USA |
Addresses:
1. Univ Wisconsin, Program Cellular & Mol Biol, Madison, WI 53706 USA
2. Univ Wisconsin, Sch Med, Dept Biomol Chem, Madison, WI 53706 USA
3. Carnegie Mellon Univ, Dept Chem, Pittsburgh, PA 15213 USA
4. Univ Wisconsin, Coll Agr & Life Sci, Dept Biochem, Inst Enzyme Res, Madison, WI 53705 USA |
| Publisher: AMER CHEMICAL SOC, 1155 16TH ST, NW, WASHINGTON, DC 20036 USA |
| Subject Category: Biochemistry & Molecular Biology |
| IDS Number: 766BR |
| ISSN: 0006-2960 |
| DOI: 10.1021/bi0357053 |
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