Ferritin Iron Mineralisation: Route of Fe3+ Transfer from the Ferroxidase Centre to the Inner Cavity of Human H-chain ferritin

Bugg, Zinnia, Bradley, Justin M., Hemmings, Andrew M. and Le Brun, Nick E. (2026) Ferritin Iron Mineralisation: Route of Fe3+ Transfer from the Ferroxidase Centre to the Inner Cavity of Human H-chain ferritin. Angewandte Chemie International Edition. ISSN 1433-7851 (In Press)

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Abstract

Ferritin-catalysed Fe2+ oxidation by reaction with O2 occurs at an intra-subunit diiron site known as the ferroxidase centre (FoC). Currently, how Fe3+, the key substrate for iron core nucleation/mineralisation, transfers from the FoC to the inner protein surface/central cavity where the mineral is laid down is unknown. Iron-binding sites that become occupied following exposure of anaerobic, Fe2+-bound human cytosolic H-chain ferritin (HuHF) to O2 were identified by time-resolved X-ray crystallography. In addition to the two FoC iron sites, three further sites were identified, each involving Glu61 as a coordinating residue. Substitution by a non-coordinating residue (variant E61A) eliminated binding at these additional iron sites. Solution kinetic studies of Fe2+ oxidation and iron core mineralisation in wild-type HuHF and its E61A variant showed that rapid Fe2+ oxidation was unaffected by loss of Glu61, ruling out an important role for these sites in either guiding Fe2+ to the FoC, or in the mechanism of FoC-catalysed Fe2+ oxidation. Conversely, the transfer of Fe3+ out of the FoC and core mineralisation were both severely affected in the E61A variant. A mechanism for Fe3+ transfer from the FoC to the inner protein surface is proposed.

Item Type:	Article
Additional Information:	Data availability: All data supporting the conclusions of this study are available within the paper and its Supplementary Information or source data files. Final coordinates and structure factors were deposited in the Protein Data Bank (https://www.rcsb.org) with accession codes 28KA (HuHF anaerobic), 28KC (HuHF 2 min O2), 28LZ (HuHF 20 min O2), 28KB (HuHF 3 hr O2), 28JY (E61A HuHF anaerobic), 28JZ (E61A HuHF 1 hr O2).
Faculty \ School:	Faculty of Science > School of Chemistry, Pharmacy and Pharmacology Faculty of Science > School of Biological Sciences
UEA Research Groups:	Faculty of Science > Research Groups > Pharmacology and Biological Chemistry Faculty of Science > Research Centres > Centre for Molecular and Structural Biochemistry
Depositing User:	LivePure Connector
Date Deposited:	14 May 2026 15:17
Last Modified:	14 May 2026 15:17
URI:	https://ueaeprints.uea.ac.uk/id/eprint/103033
DOI:	issn:1433-7851

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