Interaction of Th(IV), Pu(IV) and Fe(III) with ferritin protein: how similar?

• Published in: Journal of synchrotron radiation Vol. 29; no. 1; pp. 45 - 52
• Main Authors: Zurita, Cyril, Tsushima, Satoru, Solari, Pier Lorenzo, Jeanson, Aurélie, Creff, Gaëlle, Den Auwer, Christophe
• Format: Journal Article
• Language: English
• Published: 5 Abbey Square, Chester, Cheshire CH1 2HU, England International Union of Crystallography 01.01.2022; John Wiley & Sons, Inc
• Subjects: Actinide Physics and Chemistry; Actinides; Actinoid Series Elements - metabolism; Animals; Ferric Compounds; Ferric hydroxide; Ferritin; Ferritins; Horses; Iron; nuclear toxicology; Oxidation; Plutonium; Plutonium - metabolism; Proteins; Questions; Spleen; Thorium; Thorium - metabolism; Toxicology; Valence; X‐ray absorption spectroscopy; ferritin; X-ray absorption spectroscopy; plutonium; nuclear toxicology
• ISSN: 1600-5775; 0909-0495; 1600-5775
• DOI: 10.1107/S1600577521012340

Ferritin is the main protein of Fe storage in eukaryote and prokaryote cells. It is a large multifunctional, multi‐subunit protein consisting of heavy H and light L subunits. In the field of nuclear toxicology, it has been suggested that some actinide elements, such as thorium and plutonium at oxidation state +IV, have a comparable `biochemistry' to iron at oxidation state +III owing to their very high tendency for hydrolysis and somewhat comparable ionic radii. Therefore, the possible mechanisms of interaction of such actinide elements with the Fe storage protein is a fundamental question of bio‐actinidic chemistry. We recently described the complexation of Pu(IV) and Th(IV) with horse spleen ferritin (composed mainly of L subunits). In this article, we bring another viewpoint to this question by further combining modeling with our previous EXAFS data for Pu(IV) and Th(IV). As a result, the interaction between the L subunits and both actinides appears to be non‐specific but driven only by the density of the presence of Asp and Glu residues on the protein shell. The formation of an oxyhydroxide Th or Pu core has not been observed under the experimental conditions here, nor the interaction of Th or Pu with the ferric oxyhydroxide core. The mechanisms of interaction of thorium and plutonium with Fe storage horse spleen ferritin protein (L subunit) have been described by combining modeling with EXAFS data. The interaction between the L subunits and both actinides appears to be driven by the density of the presence of Asp and Glu residues on the protein shell.