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Sensitive yet rapid methods for detection of rare earth elements (REEs), including lanthanides (Lns), would facilitate mining and recycling of these elements. Here we report a highly selective, ge-netically encoded fluorescent sensor for Lns, LaMP1, based on the recently characterized protein, lanmodulin. LaMP1 displays a 7-fold ratiometric response to all Ln(III)s, with apparent Kds of 10-50 pM, but only weak response to other common divalent and trivalent metal ions. We use LaMP1 to demonstrate for the first time that a Ln-utilizing bacterium, Methylobacterium extorquens, selectively transports early Lns [La(III)-Nd(III)] into its cytosol, a surprising ob-servation as the only Ln-proteins identified to date are periplasmic. Finally, we apply LaMP1 to suggest the existence of a Ln(III) uptake system utilizing a secreted metal chelator, akin to siderophore-mediated Fe(III) acquisition. LaMP1 not only sheds light on Ln biology but also may be a useful technology for detecting and quantifying REEs in environmental and industrial samples.
PMID: 30726674 [PubMed - as supplied by publisher]