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Sci Rep. 2016 Nov 29;6:38019. doi: 10.1038/srep38019.

Engineering Genetically-Encoded Mineralization and Magnetism via Directed Evolution.

Author information

1
Wyss Institute for Biologically Inspired Engineering, Harvard University, 3 Blackfan Circle, 5th Floor, Boston, MA 02115, USA.
2
School of Engineering and Applied Sciences, Harvard University, Pierce Hall, 29 Oxford Street, Cambridge, MA 02138, USA.
3
Department of Systems Biology, Harvard Medical School, 200 Longwood Ave, Alpert 536, Boston, MA 02115, USA.
4
Graduate Program in Bioengineering UC Berkeley/UCSF, Department of Bioengineering, 306 Stanley Hall #1762, University of California Berkeley, CA 94720-1762, USA.
5
Harvard College, Harvard University Harvard College, 86 Brattle Street, Cambridge, MA 02138, USA.

Abstract

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.

PMID:
27897245
PMCID:
PMC5126674
DOI:
10.1038/srep38019
[Indexed for MEDLINE]
Free PMC Article

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