Figure 11. IdeR is responsible for maintaining iron homeostasis in Mtb.

When iron is available (left panel) and the cell has satisfied its iron needs, IdeR binds Fe⁺² and is active as repressor of siderophore synthesis, export and import genes and as activator of iron storage genes. IdeR mediated response to iron is required to prevent iron overload and iron mediated toxicity. In the absence of IdeR, (right panel), Mtb has no control over the amount of iron taken-in and has no storage capability. In consequence, free iron increases in the cell, accelerating the Fenton chemistry that produces toxic oxygen radicals which damage all biomolecules, including DNA.