Lanmodulin (LanM) is the first natural lanthanide-selective chelator to be characterized, a protein with picomolar affinity for all rare earth elements. LanM contains three functional carboxylate-rich metal coordination motifs known as EF hands, motifs that instead bind calcium in most other proteins. Additionally, LanM displays a cooperative and highly lanthanide-selective conformational change from a largely disordered state to an ordered one upon lanthanide binding. By incorporating sensitizers site-specifically into each EF hand, we probe thermodynamic, kinetic, and structural aspects of LanM’s selective lanthanide recognition using terbium luminescence, the first application of this method to a native lanthanide-binding biomolecule. Finally, we show that LanM’s combination of high affinity and selectivity enables specific detection of terbium at low levels in complex mixtures, outperforming synthetic luminescence-based sensors.

Using sensitized terbium luminescence to probe lanmodulin’s mechanism of lanthanide selectivity

ACS Fall 2021

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