Abstract
Dynamic DNA nanodevices are designed to perform structure-encoded motion actuated by a variety of different physicochemical stimuli. In this context, hybrid devices utilizing other components than DNA have the potential to considerably expand the library of functionalities. Here, the reversible reconfiguration of a DNA origami structure using the stimulus sensitivity of elastin-like polypeptides is reported. To this end, a rectangular sheet made using the DNA origami technique is functionalized with these peptides and by applying changes in salt concentration the hydrophilic-hydrophobic phase transition of these peptides actuate the folding of the structure. The on-demand and reversible switching of the rectangle is driven by externally imposed temperature oscillations and appears at specific transition temperatures. Using transmission electron microscopy, it is shown that the structure exhibits distinct conformational states with different occupation probabilities, which are dependent on structure-intrinsic parameters such as the local number and the arrangement of the peptides on the rectangle. It is also shown through ensemble fluorescence resonance energy transfer spectroscopy that the transition temperature and thus the thermodynamics of the rectangle-peptide system depends on the stimuli salt concentration and temperature, as well as on the intrinsic parameters.
Highlights
Due to constraints by the scaffold routing of the DNA origami structure, column 4 had to be shifted by ≈6 nm, which was not observable, in atomic force microscopy (AFM) imaging
As can be which indicates a transition temperature above 55 °C, whereas for [NaCl] ≥ 2 m, Tt was below 10 °C, resulting in a high Förster resonance energy transfer (FRET) signal for all temperatures applied in the experiment
We found that the temperature transition is independent of the rectangle concentration, while Tt can be systemati cally altered through a change in the NaCl concentration, which is shown in Figure 2c for FB with additional 0.5 m NaCl, 1.0 m NaCl, or 1.5 m NaCl
Summary
The underlying mechanical framework used for our peptide actuated nanodevice was provided by a flexible t wistcorrected DNA origami rectangle (90 nm × 60 nm),[10,11] which com prised a central hinge region to promote rotational motion of the two leaves of the structure around the hinge axis (Figure 1a; Figure S9, Supporting Information). In order to determine the binding yield of LDNA–V40 to the binding sites on the hinged rectangles, we used AFM imaging and counted the visible peptides for the configurations ABDE345 (Figure 1d), ABDE1267, and BD345 (Section S2.3, Supporting Information). We first studied reversible opening and closing of ABDE345 and the other ELP-origami constructs in bulk solution using Förster resonance energy transfer (FRET) between the fluo rescent dyes Atto 532 and Atto 647N (Figure 1a; Section S3.1, Supporting Information), which were incorporated into the structure using dye-modified staples. Which indicates a transition temperature above 55 °C, whereas for [NaCl] ≥ 2 m, Tt was below 10 °C, resulting in a high FRET signal for all temperatures applied in the experiment (see Data overview file in the Supporting Information)
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