Chemistry

Holding U Tight

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Science  27 Feb 2009:
Vol. 323, Issue 5918, pp. 1148
DOI: 10.1126/science.323.5918.1148a

Sensitive and selective detection of uranium is a prerequisite for both effective bioremediation and the treatment of radiation poisoning. Wegner et al. show that such detection may be possible with a reengineered metal protein that binds to DNA only in the presence of uranyl cations (UO2 2+), the most stable form of uranium in oxygen- and water-containing environments. The authors use the E. coli nickel-responsive repressor protein, which binds nickel (Ni2+) in a square-planar geometry. By changing just two amino acids, they shift this binding environment to one in which the uranium center binds to six ligands in the equatorial plane (as supported by x-ray absorption spectroscopy); one of the two oxygens of the uranyl cation is poised to be held in place through coordination to a third mutated amino acid. Whereas the wild-type nickel-binding protein binds to other metal cations commonly found in the environment, such as copper (Cu2+) and zinc (Zn2+), the mutated protein is selective for uranyl. — JFU

Angew. Chem. Int. Ed. 48, 10.1002/anie.200805262 (2009).

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