Iron-sensing and redox properties of the hemerythrin-like domains of Arabidopsis BRUTUS and BRUTUS-LIKE2 proteins

Pullin, Jacob, Rodríguez-Celma, Jorge, Franceschetti, Marina, Mundy, Julia E. A., Svistunenko, Dimitri A., Bradley, Justin M., Le Brun, Nick E. and Balk, Janneke (2025) Iron-sensing and redox properties of the hemerythrin-like domains of Arabidopsis BRUTUS and BRUTUS-LIKE2 proteins. Nature Communications, 16. ISSN 2041-1723

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Abstract

Iron uptake in plants is negatively regulated by highly conserved hemerythrin (Hr) E3 ubiquitin ligases exemplified by Arabidopsis thaliana BRUTUS (BTS). Physiological studies suggest these are the elusive plant iron sensors, but biochemical evidence is lacking. Here we demonstrate that the N-terminal domains of BTS and BTS-LIKE2 (BTSL2) respectively bind three and two diiron centres within three closely packed Hr-like subdomains. The centres can be reversibly oxidized by O 2 and H 2O 2, resulting in a di-Fe 3+ form that is non-labile. In the reduced state, a proportion of the iron becomes labile, based on accessibility to Fe 2+ chelators and reconstitution experiments, consistent with dynamic iron binding. Impaired iron binding and altered redox properties in the BTS dgl variant correlate with diminished capacity to suppress the downstream signalling cascade. These data provide the biochemical foundation for a mechanistic model of how BTS/Ls function as iron sensors that are unique to the plant kingdom.

Item Type: Article
Additional Information: Data availability statement: The accession codes of Arabidopsis thaliana sequences are: BRUTUS (BTS), AT3G18290; BRUTUS-LIKE2 (BTSL2), AT1G18910. All data supporting the findings of this study are available within the paper and its Supplementary Information. SAXS data have been deposited in the SAS Biological Data Bank (www.sasbdb.org), accession SASDU79. Expression constructs are available upon request from Janneke Balk (janneke.balk@jic.ac.uk). Source data are provided with this paper. Funding information: This work was supported by the Biotechnology and Biological Sciences Research Council, grant awards BB/N001079/1 (to J.R.C, M.F., N.E.L.B. and J.B.); BB/V015095/1 (to J.P., M.F. and J.B.); BB/V014625/1 (to J.M.B. and N.E.L.B.); and BB/R013578/1 for the purchase of an ICP-QQQ-MS instrument (J.B. and N.E.L.B). J.R.C. received additional support from the NextGenerationEU program, award TED2021-130539A-I00; and MCIN/AEI/10.13039/501100011033.
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 > Chemistry of Life Processes
Faculty of Science > Research Centres > Centre for Molecular and Structural Biochemistry
Faculty of Science > Research Groups > Plant Sciences
Faculty of Science > Research Groups > Molecular Microbiology
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Depositing User: LivePure Connector
Date Deposited: 24 Apr 2025 09:32
Last Modified: 04 Jun 2025 11:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/99070
DOI: 10.1038/s41467-025-58853-9

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