**7. Conclusion**

Iron is at the core of cyanobacterial metabolic and regulatory networks, playing a central role in the control of electron delivery and distribution in the photosynthetic and respiratory electron transport chains, the reduction of nitrogenase and central metabolic pathways. The adaptive responses of cyanobacteria to iron limitation affect all those processes, though the iron demand of the cell is subject to a hierarchy in favor of photosynthesis. The high quota of iron in cyanobacteria, its ability to promote oxidative stress and its ubiquity in electron transport pathways require a tight control of iron homeostasis mainly performed by FurA. In order to optimize iron resources, the regulation of FurA activity and expression, as well as the genes composing the FurA regulon are strongly interconnected with other master regulators such as PerR and NtcA.
