DNA origami and unknotted A-trails in torus graphs.

Autor: Morse, Ada, Adkisson, William, Greene, Jessica, Perry, David, Smith, Brenna, Ellis-Monaghan, Jo, Pangborn, Greta
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Zdroj: Journal of Knot Theory & Its Ramifications; Jun2020, Vol. 29 Issue 07, pN.PAG-N.PAG, 26p
Abstrakt: Motivated by problem of determining the unknotted routes for the scaffolding strand in DNA origami self-assembly, we examine the existence and knottedness of A-trails in graphs embedded on the torus. We show that any A-trail in a checkerboard-colorable torus graph is unknotted and characterizes the existence of A-trails in checkerboard-colorable torus graphs in terms of pairs of quasitrees in associated embeddings. Surface meshes are frequent targets for DNA nanostructure self-assembly, and so we study both triangular and rectangular torus grids. We show that aside from one exceptional family, a triangular torus grid contains an A-trail if and only if it has an odd number of vertices, and that such an A-trail is necessarily unknotted. On the other hand, while every rectangular torus grid contains an unknotted A-trail, we also show that any torus knot can be realized as an A-trail in some rectangular grid. Lastly, we use a gluing operation to construct infinite families of triangular and rectangular grids containing unknotted A-trails on surfaces of arbitrary genus. We also give infinite families of triangular grids containing no unknotted A-trail on surfaces of arbitrary nonzero genus. [ABSTRACT FROM AUTHOR]
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