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Bradley, Justin M., Svistunenko, Dimitri A., Pullin, Jacob, Hill, Natalie, Stuart, Rhona K., Palenik, Brian, Wilson, Michael T., Hemmings, Andrew M. 
ORCID: https://orcid.org/0000-0003-3053-3134, Moore, Geoffrey R. and Le Brun, Nick E. ORCID: https://orcid.org/0000-0001-9780-4061
(2019)
Reaction of O2 with a di-iron protein generates a mixed valent Fe2+/Fe3+ center and peroxide.
Proceedings of the National Academy of Sciences of the United States of America (PNAS), 116 (6).
pp. 2058-2067.
ISSN 1091-6490
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Abstract
The gene encoding the cyanobacterial ferritin SynFtn is up-regulated in response to copper stress. Here, we show that, while SynFtn does not interact directly with copper, it is highly unusual in several ways. First, its catalytic diiron ferroxidase center is unlike those of all other characterized prokaryotic ferritins and instead resembles an animal H-chain ferritin center. Second, as demonstrated by kinetic, spectroscopic, and high-resolution X-ray crystallographic data, reaction of O2 with the di-Fe2+ center results in a direct, one-electron oxidation to a mixed-valent Fe2+/Fe3+ form. Iron–O2 chemistry of this type is currently unknown among the growing family of proteins that bind a diiron site within a four α-helical bundle in general and ferritins in particular. The mixed-valent form, which slowly oxidized to the more usual di-Fe3+ form, is an intermediate that is continually generated during mineralization. Peroxide, rather than superoxide, is shown to be the product of O2 reduction, implying that ferroxidase centers function in pairs via long-range electron transfer through the protein resulting in reduction of O2 bound at only one of the centers. We show that electron transfer is mediated by the transient formation of a radical on Tyr40, which lies ∼4 Å from the diiron center. As well as demonstrating an expansion of the iron–O2 chemistry known to occur in nature, these data are also highly relevant to the question of whether all ferritins mineralize iron via a common mechanism, providing unequivocal proof that they do not.
| Item Type: | Article |
|---|---|
| Additional Information: | This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1809913116/-/DCSupplemental. |
| Uncontrolled Keywords: | diiron protein,electron transfer,ferritin,iron,tyrosyl radical,general ,/dk/atira/pure/subjectarea/asjc/1000 |
| Faculty \ School: | Faculty of Science > School of Chemistry (former - to 2024) Faculty of Science > School of Biological Sciences |
| UEA Research Groups: | Faculty of Science > Research Groups > Molecular Microbiology Faculty of Science > Research Centres > Centre for Molecular and Structural Biochemistry Faculty of Science > Research Groups > Plant Sciences Faculty of Science > Research Groups > Chemistry of Life Processes |
| Related URLs: | |
| Depositing User: | LivePure Connector |
| Date Deposited: | 18 Dec 2018 11:30 |
| Last Modified: | 15 Dec 2024 01:20 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/69351 |
| DOI: | 10.1073/pnas.1809913116 |
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