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| Oxygen sensing by the global regulator, FNR: the role of the iron-sulfur cluster |
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| Author(s): Kiley PJ, Beinert H |
| Source: FEMS MICROBIOLOGY REVIEWS Volume: 22 Issue: 5 Pages: 341-352 Published: DEC 1998 |
| Times Cited: 75 References: 45 |
| Abstract: FNR is a global regulator that controls transcription of genes whose functions facilitate adaptation to growth under O-2 limiting conditions. It has long been appreciated that the activity of FNR must be regulated by O-2 availability, since FNR dependent gene expression is observed in vivo only under anaerobic conditions, while similar levels of this protein are present in both aerobic and anaerobic grown cells. Recent progress in this field has shown that anaerobically purified FNR contains a [4Fe-4S](2+) cluster and that this [4Fe-4S](2+) cluster is sufficiently unstable toward O-2 to make it suitable as an O-2 sensor. The presence of the [4Fe-4S] cluster increases dimerization of FNR which is correlated with an increase in site-specific DNA binding of FNR, a properly expected of transcription factors of the FNR/CRP family. According to Mossbauer spectroscopy on purified FNR and cells containing overexpressed FNR, the [4Fe-4S](2+) cluster of FNR is converted by O-2 to a [2Fe-2S](2+) in high yield. The [2Fe-2S](2+) cluster can be reconverted to the [4Fe-4S](2+) cluster on reduction with dithionite in vitro raising the possibility that the [2Fe-2S](2+) cluster is a biologically inactive intermediate which may be more readily available for reconstitution into the [4Fe-4S](2+) form than the Fe-free apoform. The ability to observe, by Mossbauer spectroscopy, the Fe-S clusters of FNR in cells containing high levels of FNR should be of value in further unraveling how FNR functions in vivo. Attempts to reduce the [4Fe-4S](2+) cluster of FNR with dithionite indicated that the redox potential of the +1/+2 couple is less than or equal to -650 mV and that the [4Fe-4S](+) cluster form is, therefore, not likely to occur in vivo. (C) 1999 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved. |
| Document Type: Review |
| Language: English |
| Reprint Address: Kiley, PJ (reprint author), Univ Wisconsin, Sch Med, Dept Biomol Chem, Med Sci Ctr 574, 1300 Univ Ave, Madison, WI 53706 USA |
Addresses:
1. Univ Wisconsin, Sch Med, Dept Biomol Chem, Med Sci Ctr 574, Madison, WI 53706 USA
2. Univ Wisconsin, Grad Sch, Inst Enzyme Res, Madison, WI 53706 USA
3. Univ Wisconsin, Dept Biochem, Madison, WI 53706 USA |
| Publisher: ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS |
| Subject Category: Microbiology |
| IDS Number: 164WJ |
| ISSN: 0168-6445 |
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| | | | | | | | | Record from Web of Science® | | | | | | | | | |