RT Journal Article SR Electronic T1 Engineering Genetically-Encoded Mineralization and Magnetism via Directed Evolution JF bioRxiv FD Cold Spring Harbor Laboratory SP 085233 DO 10.1101/085233 A1 Xueliang Liu A1 Paola A. Lopez A1 Tobias W. Giessen A1 Michael Giles A1 Jeffrey C. Way A1 Pamela A. Silver YR 2016 UL http://biorxiv.org/content/early/2016/11/02/085233.abstract AB Genetically encoding the synthesis of functional nanomaterials such as magnetic nanoparticles enables sensitive and non-invasive biological sensing and control. Via directed evolution of the natural iron-sequestering ferritin protein, we discovered key mutations that lead to significantly enhanced cellular magnetism, resulting in increased physical attraction of ferritin-expressing cells to magnets and increased contrast for cellular magnetic resonance imaging (MRI). The magnetic mutants further demonstrate increased iron biomineralization measured by a novel fluorescent genetic sensor for intracellular free iron. In addition, we engineered Escherichia coli cells with multiple genomic knockouts to increase cellular accumulation of various metals. Lastly to explore further protein candidates for biomagnetism, we characterized members of the DUF892 family using the iron sensor and magnetic columns, confirming their intracellular iron sequestration that results in increased cellular magnetization.