TY - JOUR
T1 - Direct observation of DNA knots using a solid-state nanopore
AU - Plesa, Calin
AU - Verschueren, Daniel
AU - Pud, Sergii
AU - Van Der Torre, Jaco
AU - Ruitenberg, Justus W.
AU - Witteveen, Menno J.
AU - Jonsson, Magnus P.
AU - Grosberg, Alexander Y.
AU - Rabin, Yitzhak
AU - Dekker, Cees
N1 - Publisher Copyright:
© 2016 Macmillan Publishers Limited, part of Springer Nature.
PY - 2016/12/1
Y1 - 2016/12/1
N2 - Long DNA molecules can self-entangle into knots. Experimental techniques for observing such DNA knots (primarily gel electrophoresis) are limited to bulk methods and circular molecules below 10 kilobase pairs in length. Here, we show that solid-state nanopores can be used to directly observe individual knots in both linear and circular single DNA molecules of arbitrary length. The DNA knots are observed as short spikes in the nanopore current traces of the traversing DNA molecules and their detection is dependent on a sufficiently high measurement resolution, which can be achieved using high-concentration LiCl buffers. We study the percentage of molecules with knots for DNA molecules of up to 166 kilobase pairs in length and find that the knotting occurrence rises with the length of the DNA molecule, consistent with a constant knotting probability per unit length. Our experimental data compare favourably with previous simulation-based predictions for long polymers. From the translocation time of the knot through the nanopore, we estimate that the majority of the DNA knots are tight, with remarkably small sizes below 100nm. In the case of linear molecules, we also observe that knots are able to slide out on application of high driving forces (voltage).
AB - Long DNA molecules can self-entangle into knots. Experimental techniques for observing such DNA knots (primarily gel electrophoresis) are limited to bulk methods and circular molecules below 10 kilobase pairs in length. Here, we show that solid-state nanopores can be used to directly observe individual knots in both linear and circular single DNA molecules of arbitrary length. The DNA knots are observed as short spikes in the nanopore current traces of the traversing DNA molecules and their detection is dependent on a sufficiently high measurement resolution, which can be achieved using high-concentration LiCl buffers. We study the percentage of molecules with knots for DNA molecules of up to 166 kilobase pairs in length and find that the knotting occurrence rises with the length of the DNA molecule, consistent with a constant knotting probability per unit length. Our experimental data compare favourably with previous simulation-based predictions for long polymers. From the translocation time of the knot through the nanopore, we estimate that the majority of the DNA knots are tight, with remarkably small sizes below 100nm. In the case of linear molecules, we also observe that knots are able to slide out on application of high driving forces (voltage).
UR - http://www.scopus.com/inward/record.url?scp=84982182589&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84982182589&partnerID=8YFLogxK
U2 - 10.1038/nnano.2016.153
DO - 10.1038/nnano.2016.153
M3 - Article
AN - SCOPUS:84982182589
SN - 1748-3387
VL - 11
SP - 1093
EP - 1097
JO - Nature Nanotechnology
JF - Nature Nanotechnology
IS - 12
ER -