The intersection of metals and structural biology is fascinating and far-reaching.

Biological systems harness and exploit unique properties of metal ions for functions ranging from scaffolding to energy production. Fundamental molecular transformations that are central to global energy and chemical cycles and critical to all domains of life take place at biological metal centers. Organisms have evolved mechanisms to traffic metal ions inside of cells, to scavenge metals from the environment, and for protection against environmental metal toxicity, often remodeling the environment itself. The properties of metals have been fundamental to medical advances from imaging to therapeutics.

CERM/CIRMMP has a long-standing tradition in providing a unique molecular perspective on the mechanisms underlying metal trafficking, metal homeostasis, and the maturation of metalloenzymes. Since 2000, the center has made fundamental contributions to unraveling copper trafficking pathways in human and bacterial cells, structurally characterizing copper-binding proteins and their interactions that mediate copper delivery and insertion into copper enzymes.

More recently, CERM/CIRMMP has turned its focus to iron-sulfur (Fe/S) proteins, molecular structures essential for numerous cellular processes. Specifically, our researchers have used solution NMR to clarify how electrons are transferred from NADPH through FDXR to FDX2 to assemble these clusters. In simple terms, NADPH provides the electrons, FDXR passes them along, and FDX2 delivers them to the molecular machinery that builds the Fe/S clusters. Mutations in any of these proteins can disrupt this critical process leading to severe neurological, hematological and metabolic rare human diseases.

Researchers also investigate IBA57 and its partner ISCA2, two proteins that work together like molecular builders, assembling the larger [4Fe-4S] clusters that cells need to function properly. In addition, they examined CISD3, a protein linked to conditions like cancer, diabetes, and neurodegeneration, and found out how it is affected by nitric oxide. These studies show that solution NMR is a powerful tool for connecting the molecular details of Fe/S cluster formation to human health. 

Overall, these studies show that solution NMR is a powerful tool for connecting the molecular details of Fe/S cluster formation to human health. Understanding these mechanisms at a detailed level is a critical step toward developing new treatments.

In addition to FeS proteins, the heme uptake processes in Gram-negative bacteria and Candida albicans fungi have also been characterised. These studies revealed the binding mode of heme in the corresponding hemoophore proteins and, in the case of Gram-negative bacteria, the interaction site between the hemophore HasA and the external membrane receptor HasR.

With a combination of nuclear magnetic resonance (NMR), X-ray crystallography, electrospray ionisation (ESI) mass spectrometry (MS) and site-directed mutagenesis applied to in human and bullfrog ferritin cages, we tracked the iron(II) pathways to reach the ferroxidase site or nucleation site, and identified the interactions between the protein matrix and iron(III) products.

Another area of research focuses on how metal-based drugs interact with biological systems, using NMR-based metabolomics. Metallodrugs are multitarget compounds, many of which are already in clinical use. Metabolomics can help unravel the main alterations they induce at the cellular level. The work conducted on a small library of gold(I) and gold(III) compounds has highlighted a few mechanisms of action characteristic of clusters of compounds. To enhance the therapeutic effects of the main representatives of each cluster and facilitate their targeted delivery to cancer cells, their conjugation to recombinant human H ferritin cage has been exploited. The resulting ferritin-metallodrug conjugates demonstrated increased intracellular gold accumulation compared to the free drugs, thanks to the internalization mediated by  transferrin receptor 1 while NMR-based metabolomics confirmed that conjugation to ferritin does not affect their intracellular activity.

Selected Publications:

Affinity gradients drive copper to cellular destinations. Banci L, Bertini I, Ciofi-Baffoni S, Kozyreva T, Zovo K, Palumaa P., Nature. 2010 Jun 3;465(7298):645-8 https://doi.org/10.1038/nature09018

Molecular recognition in copper trafficking. Banci L, Bertini I, McGreevy KS, Rosato A.,Nat Prod Rep. 2010 May;27(5):695-710. https://doi.org/10.1039/b906678k

Protein networks in the maturation of human iron-sulfur proteins. Ciofi-Baffoni S, Nasta V, Banci L.,Metallomics. 2018 Jan 24;10(1):49-72. https://doi.org/10.1039/c7mt00269f

N-terminal domains mediate [2Fe-2S] cluster transfer from glutaredoxin-3 to anamorsin. Banci L,Ciofi-Baffoni S, Gajda K, Muzzioli R, Peruzzini R, Winkelmann J., Nat Chem Biol. 2015 Oct;11(10):772-8. https://doi.org/10.1038/nchembio.1892

L. Querci, M. Piccioli, S. Ciofi-Baffoni, L. Banci, Biochim Biophys Acta Mol Cell Res. 2024, 1871,119786. https://doi.org/10.1016/j.bbamcr.2024.119786

D. Grifagni, D. Doni, B. Susini, B.M. Fonseca, R.O. Louro, P. Costantini, S. Ciofi-Baffoni, Protein Science 2024, 33, e5197. https://doi.org/10.1002/pro.5197

B. Bargagna, T. Staderini, S.H. Lang, L. Banci, F. Camponeschi, Int J Mol Sci. 2024, 25, 10466. https://doi.org/10.3390/ijms251910466

D. Grifagni, J.M. Silva, L. Querci, M. Lepoivre, C. Vallières, R.O. Louro, L. Banci, M. Piccioli, M.-P. Golinelli-Cohen, F. Cantini, J Biol Chem. 2024, 300, 105745. https://doi.org/10.1016/j.jbc.2024.105745

Caillet-Saguy C, Delepierre M, Lecroisey A, Bertini I, Piccioli M, Turano P.J Am Chem Soc. 2006 Jan 11;128(1):150-8. doi: 10.1021/ja054902h.

Caillet-Saguy C, Piccioli M, Turano P, Izadi-Pruneyre N, Delepierre M, Bertini I, Lecroisey A.J Am Chem Soc. 2009 Feb 11;131(5):1736-44. doi: 10.1021/ja804783x

Kuznets G, Vigonsky E, Weissman Z, Lalli D, Gildor T, Kauffman SJ, Turano P, Becker J, Lewinson O, Kornitzer D.PLoS Pathog. 2014 Oct 2;10(10):e1004407. doi: 10.1371/journal.ppat.1004407.

Ghini V, Tristán AI, Di Paco G, Massai L, Mannelli M, Gamberi T, Fernández I, Rosato A, Turano P, Messori L.J Proteome Res. 2025 Feb 7;24(2):813-823. doi: 10.1021/acs.jproteome.4c00904.

L. Cosottini et al., Angew. Chem. 2024, 63, e202410791. Unlocking the Power of Human Ferritin: Enhanced Drug Delivery of Aurothiomalate in A2780 Ovarian Cancer Cells https://doi.org/10.1002/anie.202410791

Cosottini L, Giachetti A, Guerri A, Martinez-Castillo A, Geri A, Zineddu S, Abrescia NGA, Messori L, Turano P, Rosato A.Angew Chem Int Ed Engl. 2025 Jul 21;64(30):e202503778. doi: 10.1002/anie.202503778.