Transcription factor NsrR from Bacillus subtilis senses nitric oxide with a 4Fe-4S cluster

Erik T. Yukl, Mohamed A. Elbaz, Michiko M. Nakano, Pierre Moènne-Loccoz

Research output: Contribution to journalArticle

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Abstract

In Bacillus subtilis, NsrR is required for the upregulation of ResDE-dependent genes in the presence of nitric oxide (NO). NsrR was shown to bind to the promoters of these genes and inhibit their transcription in vitro. NO relieves this inhibition by an unknown mechanism. Here, we use spectroscopic techniques (UV-vis, resonance Raman, and EPR) to show that anaerobically isolated NsrR from B. subtilis contains a [4Fe-4S]2+ cluster, which reacts with NO to form dinitrosyl iron complexes. This method of NO sensing is analogous to that of the FNR protein of Escherichia coli. The Fe-S cluster of NsrR is also reactive toward other exogenous ligands such as cyanide, dithiothreitol, and O2. These results, together with the fact that there are only three cysteine residues in NsrR, suggest that the 4Fe-4S cluster contains a noncysteinyl labile ligand to one of the iron atoms, leading to high reactivity. Size exclusion chromatography and cross-linking experiments show that NsrR adopts a dimeric structure in its [4Fe-4S]2+ holo form as well as in the apo form. These findings provide a first stepping stone to investigate the mechanism of NO sensing in NsrR.

Original languageEnglish (US)
Pages (from-to)13084-13092
Number of pages9
JournalBiochemistry
Volume47
Issue number49
DOIs
StatePublished - Dec 9 2008

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ASJC Scopus subject areas

  • Biochemistry

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