Phys.org October 28, 2024
Elucidating details of biology’s selective uptake and trafficking of rare earth elements, particularly the lanthanides, has the potential to inspire sustainable biomolecular separations of these essential metals for many modern technologies. Researchers at The Pennsylvania State University biochemically and structurally characterized Methylobacterium (Methylorubrum) extorquens LanD from a bacterial gene cluster for lanthanide uptake. The protein provided only four ligands at its surface-exposed lanthanide-binding site, allowing for metal-centered protein dimerization that favored the largest lanthanide, LaIII. Selective dimerization enriched high-value PrIII and NdIII relative to low-value LaIII and CeIII in an all-aqueous process, achieved higher separation factors than lanmodulins and comparable or better separation factors than common industrial extractants. However, the monomer preferred NdIII and SmIII, which were disfavored lanthanides for cellular utilization. Structure-guided mutagenesis of a metal-ligand and an outer-sphere residue weakens metal binding to the LanD monomer. They showed that LanD interacts with lanmodulin (LanM). According to the researchers, their work showed how relatively weak chelators could achieve high selectivity, and form the basis for the design of protein dimers for separation of adjacent lanthanide pairs and other metal ions… read more. TECHNICAL ARTICLE