For decades, researchers interpreted complex electrical patterns seen when DNA moved through nanopores as signs that the molecule was forming knots. Nanopore experiments, which are widely used to study genetic material, seemed to support this idea.
The comparison was often made to pulling a shoelace through a narrow opening. If the lace becomes tangled, its motion changes in noticeable ways. Scientists believed DNA behaved in the same manner, concluding that irregular signals meant the strand had become knotted as it passed through the pore.
New research now challenges this long-standing view. The study, published in Physical Review X, shows that DNA does not simply become knotted (like the tangled shoelaces) as a result of signal disturbances during nanopore translocation. Instead, many of the structures previously interpreted as knots turn out to be plectonemes. In these configurations, DNA coils around itself in a twisted form, similar to a wound phone cord, rather than forming a true knot.
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