Moessbauer spectroscopy as a tool for the study of activation/inactivation of the transcription regulator FNR in whole cells of Escherichia coli

The global regulator FNR (for fumarate nitrate reduction) controls the transcription of >100 genes whose products facilitate adaptation of Escherichia coli to growth under O sub(2)-limiting conditions. Previous Moessbauer studies have shown that anaerobically purified FNR contains a [4Fe-4S] supe...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1998-11, Vol.95 (23), p.13431-13435
Main Authors: Popescu, C V, Bates, D M, Beinert, H, Muenck, E, Kiley, P J
Format: Article
Language:English
Subjects:
Escherichia coli
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Summary:The global regulator FNR (for fumarate nitrate reduction) controls the transcription of >100 genes whose products facilitate adaptation of Escherichia coli to growth under O sub(2)-limiting conditions. Previous Moessbauer studies have shown that anaerobically purified FNR contains a [4Fe-4S] super(2+) cluster that, on exposure to oxygen, is converted into a [2Fe-2S] super(2+) cluster, a process that decreases DNA binding by FNR. Using super(57)Fe Moessbauer spectroscopy of E. coli cells containing overexpressed FNR, we show here that the same cluster conversion also occurs in vivo on exposure to O sub(2). Furthermore, the data show that a significant amount of the [4Fe- 4S] super(2+) cluster is regenerated when the cells are shifted back to an anaerobic environment. The present study also demonstrates that super( 57)Fe Moessbauer spectroscopy can be employed to study the in vivo behavior of (overexpressed) proteins. The use of this technique to study other iron-containing cell components is discussed.
ISSN:0027-8424