Translocations of topologically linked rings from kinetoplast DNA through a solid-state nanopore*

A nanopore sensor measures the ionic current through a solid-state pore over time. DNA molecules translocating through a nanopore results in the displacement of the current, which depends on the size, topology, and conformation of each molecule.  Topologically complex DNA structures such as knots have been observed in nanopores, but topologically linked catenanes have only been studied computationally. Kinteoplasts are complex DNA structures formed from several thousand topologically interlocked circles, found in the mitochondria of trypanosome parasites. The kinetoplast can be broken down into smaller complex shapes through an enzyme reaction, allowing simpler catenanes to be isolated from the network. We use a solid-state nanopore device to observe complex topologies, such as Hopf links, isolated from kinetoplasts from Crithidia fasciculata. Here, we present preliminary observations of the translocation signal and dwell time associated with catenated molecular topologies, and the implications for understanding topological friction in polymers and for determining kinetoplast topology.