The iron sensor IdeR in complex with DNA

This is a crystal structure of the iron-sensing transcription factor IdeR from *Saccharopolyspora erythraea* activated by iron and bound to its DNA recognition sequence. The main function of IdeR is to repress the expression of iron uptake genes when the intracellular iron levels are sufficient, so that the iron concentration does not reach toxic levels. When the intracellular iron levels are low, metal-free IdeR is inactive, and iron uptake genes are expressed. Once the iron concentration is sufficiently high so that iron ions occupy the metal-binding sites in IdeR, the regulator is activated and able to bind to its recognition sequence in the promoter regions of its target genes. In most cases IdeR binding blocks transcription of the regulated genes, but it can also activate some genes, e.g. iron storage genes. You can find this structure on the PDB here: https://www.rcsb.org/structure/7B20 And it is described in this publication: https://doi.org/10.1093/nar/gkab711