9SOM

Crystal structure of a designed coiled coil with two distinct Terbium sites

Summary for 9SOM

• Entry DOI: 10.2210/pdb9som/pdb
• Descriptor: Designed coiled coil with two distinct Terbium sites, TERBIUM(III) ION (3 entities in total)
• Functional Keywords: coiled coil, metal binding, terbium, de novo, de novo protein
• Biological source: synthetic construct
• Total number of polymer chains: 1
• Total formula weight: 5748.52

Authors

Caulton, S.G.,Peacock, A.F.A.,Lovering, A.L.,Rose, G. (deposition date: 2025-09-15, release date: 2026-06-10)

Primary citation

Slope, L.N.,Shah, A.,Taylor, M.J.,Borghesani, V.,Caulton, S.G.,Brooks, N.J.,Hadley, K.A.,Rose, G.,Hunter, R.I.,Mkami, H.E.L.,Smith, G.M.,Leney, A.C.,Buurma, N.J.,Lovering, A.L.,Lovett, J.E.,Peacock, A.F.A.
Design of a site selective heterochromic bimetallic lanthanide coiled coil with nanometre-scale control.
Chem Sci, 2026

PubMed Abstract: Lanthanide-protein scaffolds hold significant promise for the design of functional biomaterials. Yet the selective incorporation of multiple lanthanide ions with distinct properties into discrete sites at tuneable distances within a single construct remains a key challenge. Here, we report the rational design and structural characterization of the first coiled coil capable of binding two different lanthanide ions at independent, non-equivalent sites with defined intermetallic spacing. By installing orthogonal coordination environments, comprising AsnAsp and Asp-only motifs, at defined positions along the coiled coil axis, we achieve precise, site-specific metal binding across a series of constructs spanning 1 to 5 nm. Site occupancy and intermetallic distances were validated using luminescence, electron paramagnetic resonance (EPR) spectroscopy, mass spectrometry and X-ray crystallography. The latter reveals the first structure of a coiled coil bound to two Tb ions, and the shortest non-bridged metal-metal distance reported to date in such a scaffold (11.9 Å). The chemically distinct coordination sites enable sequential and selective metal loading. Remarkably, this system is capable of binding two different lanthanides, Tb and Yb, at distinct sites, despite their extremely similar coordination chemistries. These results establish a robust and modular platform for constructing nanometre-scale molecular rulers, and highlight new avenues for the rational design of multifunctional metalloproteins.

PubMed: 42164438
DOI: 10.1039/d6sc00813e

Experimental method

X-RAY DIFFRACTION (2.76 Å)