Search

Here, we report the direct visualization of the assembly/disassembly processes of photoresponsive DNA origami nanostructures which can be placed on a lipid bilayer surface. The observation relies on controlled interactions between the bilayer components and cholesterol moieties introduced to the hexagonal origami structures, one of whose outer edges carries Azo-ODNs. The bilayer-placed hexagonal dimer was disassembled into monomer units by UV irradiation, and reversibly assembled again during visible light irradiation. These dynamic processes were directly monitored with high-speed atomic force microscopy. The successful application of our approach should facilitate studies of interactive and functional behaviors of various DNA nanostructures. [ABSTRACT FROM AUTHOR]

Site-specific recombination involves reciprocal exchange between defined DNA sites. The reaction initiates from the formation of a recombinase-DNA synaptic complex, in which two recombination sites arrange in an appropriate configuration. However, there is incomplete information about how the topological state of the substrate influences the synapsis and outcome of the reaction. Here, we show that Cremediated recombination can be regulated by controlling the orientation and topology of the loxP substrate in a DNA frame nanoscaffold. High-speed atomic force microscopy analyses revealed that the loxP-containing substrate strands in the antiparallel orientation can be recombined only through formation of synaptic complexes. By tethering Holliday junction (HJ) intermediates to DNA frames in different connection patterns and using them as a starting substrate, we found that the topological state of the HJ intermediates dictates the outcome of the resolution. Our approach should provide a new platform for structural-functional studies of various DNA targeting enzymes, especially which require formation of synaptic complexes. [ABSTRACT FROM AUTHOR]

A light-driven artificial molecularnanomachine was constructed based on DNA scaffolding. Pyrene-modifiedwalking strands and disulfide bond-connected stator strands, employedas anchorage sites to support walker movement, were assembled intoa 2D DNA tile. Pyrene molecules excited by photoirradiation at 350nm induced cleavage of disulfide bond-connected stator strands, enablingthe DNA walker to migrate from one cleaved stator to the next on theDNA tile. The time-dependent movement of the walker was observed andthe entire walking process of the walker was characterized by distributionof the walker-stator duplex at four anchorage sites on the tile under different irradiation times.Importantly, the light-fuelled mechanical movements on DNA tile werefirst visualized in real time during UV irradiation using high-speedatomic force microscopy (HS-AFM). [ABSTRACT FROM AUTHOR]

Controllable fabrication of DNA origami structures was achieved using cationic comb-type copolymers (CCCs) as locks and polyvinyl sulphonic acid (PVS) as a key. A CCC binds to the phosphate backbone of either M13mp18/staples alone or both together and restricts origami folding, while PVS unlocks the CCC, restoring the formation of origami structures. [ABSTRACT FROM AUTHOR]