A protein engineered to bind uranyl selectively and with femtomolar affinity

• Published in: Nature chemistry 2014-03, Vol.6 (3), p.236-241
• Main Authors: Zhou, Lu, Bosscher, Mike, Zhang, Changsheng, Özçubukçu, Salih, Zhang, Liang, Zhang, Wen, Li, Charles J., Liu, Jianzhao, Jensen, Mark P., Lai, Luhua, He, Chuan
• Format: Article
• Language: English
• Subjects: 119/118; 639/638/45/49/1141; 639/638/541/911; Algorithms; Analytical Chemistry; Binding Sites; Biochemistry; Biotechnology; Chemistry; Chemistry/Food Science; Design; Inorganic Chemistry; Ligands; Metal concentrations; Metal ions; Metal Nanoparticles - chemistry; Metals; Models, Molecular; Organic Chemistry; Physical Chemistry; Protein Engineering; Proteins; Proteins - chemistry; Proteins - metabolism; Remediation; Seawater; Uranium; Uranium - chemistry
• ISSN: 1755-4330; 1755-4349
• DOI: 10.1038/nchem.1856

Uranyl (UO 2 2+ ), the predominant aerobic form of uranium, is present in the ocean at a concentration of ~3.2 parts per 10 9 (13.7 nM); however, the successful enrichment of uranyl from this vast resource has been limited by the high concentrations of metal ions of similar size and charge, which makes it difficult to design a binding motif that is selective for uranyl. Here we report the design and rational development of a uranyl-binding protein using a computational screening process in the initial search for potential uranyl-binding sites. The engineered protein is thermally stable and offers very high affinity and selectivity for uranyl with a K d of 7.4 femtomolar (fM) and >10,000-fold selectivity over other metal ions. We also demonstrated that the uranyl-binding protein can repeatedly sequester 30–60% of the uranyl in synthetic sea water. The chemical strategy employed here may be applied to engineer other selective metal-binding proteins for biotechnology and remediation applications. The extraction of uranium from seawater is limited by the high concentrations of carbonate and competing metal ions. Now, a highly selective uranyl-binding protein with femtomolar affinity has been developed. This protein can extract up to 60% uranium from synthetic seawater when immobilized on bacterial cell surfaces or amylose resin.