Diversity of Fe(2+) entry and oxidation in ferritins.

The essential metal iron presents two major problems for life: it is potentially highly toxic due to its redox activity, and its extremely low solubility in aqueous solution in the presence of O2 can make it hard to acquire and store safely. Ferritins are part of nature's answer to these problems, as they store iron in a safe but accessible form in all types of cells. How they achieve this has been the subject of intense research for several decades. Here, we highlight recent progress in elucidating the routes by which Fe(2+) ions access the catalytic ferroxidase centers, and the mechanisms by which Fe(2+) is oxidized. Emerging from this is a picture of diversity, both in terms of Fe(2+) entry pathways and the roles played by the structurally distinct diiron ferroxidase centers.