Living. with Iron (and Oxygen): Questions and Answers about Iron Homeostasis

摘要

Mechanisms to regulate iron homeostasis are very likely billions of years older than those for oxygen homeostasis since contemporary microbes regulate iron in the absence of oxygen and may model ancient organisms that lived before atmospheric oxygen appeared.1 Moreover, proteins that manage iron and oxidants such as the mini-ferritins in contemporary bacteria, also called Dps (DNA protection during stress) proteins, are expressed in anaerobic archea.2 Mini-ferritins are 12 subunit protein cages from archea and bacteria that contrast with maxi-ferritins, the 24 subunit cages from bacteria, animals and plants, which use iron and dioxygen as substrates, by consuming iron and hydrogen peroxide as substrates to make the mineral inside protein nanocages. Such peroxide-consuming ferritins may be progenitors of modern ferritins and may have contributed to the transition from anaerobic to aerobic life with iron and oxygen.