Ferritin with Atypical Ferroxidase Centers Takes B-Channels as the Pathway for Fe2+ Uptake from Mycoplasma

Here, we present a 1.9 A resolution crystal structure of Mycoplasma Penetrans ferritin, which reveals that its ferroxidase center is located on the inner surface of ferritin but not buried within the four-helix of each subunit. Such a ferroxidase center exhibits a lower iron oxidation activity as compared to the reported ferritin. More importantly, we found that Fe2+ enters into the center via the rarely reported B-channels rather than the normal 3- or 4-fold channels. All these findings may provide the structural bases to explore the new iron oxidation mechanism adopted by this special ferritin, which is beneficial for understanding the relationship between the structure and function of ferritin.

Automated summary

The 1.9 A resolution crystal structure of Mycoplasma Penetrans ferritin reveals that its ferroxidase center is positioned on the inner surface of ferritin rather than buried within each subunit's four-helix. This unique ferritin also shows lower iron oxidation activity and allows Fe2+ to enter via B-channels instead of the usual 3- or 4-fold channels, suggesting a novel iron oxidation mechanism.