Enhanced rare-earth separation with a metal-sensitive lanmodulin dimer

Joseph A. Mattocks, Jonathan J. Jung, Chi Yun Lin, Ziye Dong, Neela H. Yennawar, Emily R. Featherston, Christina S. Kang-Yun, Timothy A. Hamilton, Dan M. Park, Amie K. Boal, Joseph A. Cotruvo

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Abstract

Technologically critical rare-earth elements are notoriously difficult to separate, owing to their subtle differences in ionic radius and coordination number 1–3. The natural lanthanide-binding protein lanmodulin (LanM) 4,5 is a sustainable alternative to conventional solvent-extraction-based separation 6. Here we characterize a new LanM, from Hansschlegelia quercus (Hans-LanM), with an oligomeric state sensitive to rare-earth ionic radius, the lanthanum(III)-induced dimer being >100-fold tighter than the dysprosium(III)-induced dimer. X-ray crystal structures illustrate how picometre-scale differences in radius between lanthanum(III) and dysprosium(III) are propagated to Hans-LanM’s quaternary structure through a carboxylate shift that rearranges a second-sphere hydrogen-bonding network. Comparison to the prototypal LanM from Methylorubrum extorquens reveals distinct metal coordination strategies, rationalizing Hans-LanM’s greater selectivity within the rare-earth elements. Finally, structure-guided mutagenesis of a key residue at the Hans-LanM dimer interface modulates dimerization in solution and enables single-stage, column-based separation of a neodymium(III)/dysprosium(III) mixture to >98% individual element purities. This work showcases the natural diversity of selective lanthanide recognition motifs, and it reveals rare-earth-sensitive dimerization as a biological principle by which to tune the performance of biomolecule-based separation processes.

Original languageEnglish (US)
Pages (from-to)87-93
Number of pages7
JournalNature
Volume618
Issue number7963
DOIs
StatePublished - Jun 1 2023

All Science Journal Classification (ASJC) codes

  • General

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