title: Mössbauer spectroscopy as a tool for the study of activation/inactivation of the transcription regulator FNR in whole cells of Escherichia coli.
abstract: The global regulator FNR (for fumarate nitrate reduction) controls the transcription of >100 genes whose products facilitate adaptation of Escherichia coli to growth under O2-limiting conditions. Previous Mössbauer studies have shown that anaerobically purified FNR contains a [4Fe-4S]2+ cluster that, on exposure to oxygen, is converted into a [2Fe-2S]2+ cluster, a process that decreases DNA binding by FNR. Using 57Fe Mössbauer spectroscopy of E. coli cells containing overexpressed FNR, we show here that the same cluster conversion also occurs in vivo on exposure to O2. Furthermore, the data show that a significant amount of the [4Fe-4S]2+ cluster is regenerated when the cells are shifted back to an anaerobic environment. The present study also demonstrates that 57Fe Mössbauer 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.
authors.affiliation: Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA.
authors.forename: C V
authors.initials: CV
authors.lastname: Popescu
authors.forename: D M
authors.initials: DM
authors.lastname: Bates
authors.forename: H
authors.initials: H
authors.lastname: Beinert
authors.forename: E
authors.initials: E
authors.lastname: Münck
authors.forename: P J
authors.initials: PJ
authors.lastname: Kiley
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D004926:Escherichia coli / Q000737:chemistry / Q000378:metabolism*; D029968:Escherichia coli Proteins; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000378:metabolism*; D015204:Spectroscopy, Mossbauer; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C060704:FNR protein, E coli; D007506:Iron-Sulfur Proteins; D014157:Transcription Factors