Nonequilibrium Synthesis and Assembly of Hybrid Inorganic-Protein Nanostructures Using an Engineered DNA Binding Protein

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• 作者：Haixia Dai ; Woo-Seok Choe ; Corrine K. Thai ; Mehmet Sarikaya ; Beth A. Traxler ; Franç ; ois Baneyx ; and Daniel T. Schwartz
• 刊名：Journal of the American Chemical Society
• 出版年：2005
• 出版时间：November 9, 2005
• 年：2005
• 卷：127
• 期：44
• 页码：15637 - 15643
• 全文大小：346K
• 年卷期：v.127,no.44(November 9, 2005)
• ISSN：1520-5126

文摘

We show that a protein with no intrinsic inorganic synthesis activity can be endowed with theability to control the formation of inorganic nanostructures under thermodynamically unfavorable (nonequilibrium) conditions, reproducing a key feature of biological hard-tissue growth and assembly. Thenonequilibrium synthesis of Cu₂O nanoparticles is accomplished using an engineered derivative of theDNA-binding protein TraI in a room-temperature precursor electrolyte. The functional TraI derivative(TraIi1753::CN225) is engineered to possess a cysteine-constrained 12-residue Cu₂O binding sequence,designated CN225, that is inserted into a permissive site in TraI. When TraIi1753::CN225 is included inthe precursor electrolyte, stable Cu₂O nanoparticles form, even though the concentrations of [Cu⁺] and[OH^-] are at 5% of the solubility product (K_sp,Cu2O). Negative control experiments verify that Cu₂O formationis controlled by inclusion of the CN225 binding sequence. Transmission electron microscopy and electrondiffraction reveal a core-shell structure for the nonequilibrium nanoparticles: a 2 nm Cu₂O core issurrounded by an adsorbed protein shell. Quantitative protein adsorption studies show that the unexpectedstability of Cu₂O is imparted by the nanomolar surface binding affinity of TraIi1753::CN225 for Cu₂O (K_d =1.2 × 10^-8 M), which provides favorable interfacial energetics (-45 kJ/mol) for the core-shell configuration.The protein shell retains the DNA-binding traits of TraI, as evidenced by the spontaneous organization ofnanoparticles onto circular double-stranded DNA.