A diatom ferritin optimized for iron oxidation but not iron storage

Stephanie Pfaffen, Justin Bradley, Raz Abdulqadir, Marlo R. Firme, Geoff Moore, Nick Le Brun, Michael Murphy

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Ferritin from the marine pennate diatom Pseudo-nitzschia multiseries (PmFTN) plays a key role in sustaining growth in iron-limited ocean environments. The di-iron catalytic ferroxidase center of PmFTN (sites A and B) has a nearby third iron site (site C) in an arrangement typically observed in prokaryotic ferritins. Here we demonstrate that Glu44, a site C ligand, and Glu130, a residue that bridges iron bound at sites B and C, limit the rate of post-oxidation reorganization of iron coordination and the rate at which Fe3+ exits the ferroxidase center for storage within the mineral core. The latter, in particular, severely limits the overall rate of iron mineralization. Thus, the diatom ferritin is optimized for initial Fe2+ oxidation but not for mineralization, pointing to a role for this protein in buffering iron availability and facilitating iron-sparing rather than only long-term iron storage.
Original languageEnglish
Pages (from-to)28416-28427
JournalThe Journal of Biological Chemistry
Volume290
Early online date22 Sep 2015
DOIs
Publication statusPublished - 20 Nov 2015

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