Mechanism of [4Fe-4S](Cys)4 cluster nitrosylation is conserved among NO-responsive regulators

Jason C Crack, Melanie R Stapleton, Jeffrey Green, Andrew J Thomson, Nick E Le Brun

Research output: Contribution to journalArticlepeer-review

53 Citations (Scopus)


The Fumarate nitrate reduction (FNR) regulator from Escherichia coli controls expression of >300 genes in response to O2 through reaction with its [4Fe-4S] cluster cofactor. FNR is the master switch for the transition between anaerobic and aerobic respiration. In response to physiological concentrations of nitric oxide (NO), FNR also regulates genes, including the nitrate reductase (nar) operon, a major source of endogenous cellular NO, and hmp, which encodes an NO-detoxifying enzyme. Here we show that the [4Fe-4S] cluster of FNR reacts rapidly in a multiphasic reaction with eight NO molecules. Oxidation of cluster sulfide ions (S(2-)) to sulfane (S(0)) occurs, some of which remains associated with the protein as Cys persulfide. The nitrosylation products are similar to a pair of dinuclear dinitrosyl iron complexes, [Fe(I)2(NO)4(Cys)2](0), known as Roussin's red ester. A similar reactivity with NO was reported for the Wbl family of [4Fe-4S]-containing proteins found only in actinomycetes, such as Streptomyces and Mycobacteria. These results show that NO reacts via a common mechanism with [4Fe-4S] clusters in phylogenetically unrelated regulatory proteins that, although coordinated by four Cys residues, have different cluster environments. The reactivity of E. coli FNR toward NO, in addition to its sensitivity toward O2, is part of a hierarchal network that monitors, and responds to, NO, both endogenously generated and exogenously derived.
Original languageEnglish
Pages (from-to)11492-502
Number of pages11
JournalThe Journal of Biological Chemistry
Issue number16
Publication statusPublished - 19 Apr 2013


  • Aerobiosis
  • Anaerobiosis
  • Escherichia coli
  • Escherichia coli Proteins
  • Iron
  • Iron-Sulfur Proteins
  • Mycobacterium
  • Nitric Oxide
  • Operon
  • Oxygen
  • Streptomyces
  • Sulfides

Cite this