The role of Fe–S proteins in sensing and regulation in bacteria

Fe–S clusters are key to the sensing and transcription functions of three transcription factors, FNR, IscR and SoxR. All three proteins were discovered in Escherichia coli but experimental data and bioinformatic predictions suggest that homologs of these proteins exist in other bacterial species, highlighting the widespread nature of Fe–S-dependent regulatory networks. In addition, the nearly ubiquitous citric acid cycle enzyme, aconitase, plays a role in translational regulation in E. coli and Bacillus subtilis when it loses its Fe–S cluster. Although these regulatory proteins have the common feature of containing an Fe–S cluster, they differ in the physiological signals that they respond to. Therefore, these regulatory factors provide insights into the chemical versatility of Fe–S clusters.