Generation of Loops in DsDNA
A single molecule study using atomic force microscopy (AFM) and tethered particle motion (TPM) has observed that ISWI can bound naked DNA in absence ATP wrapping DNA around the protein. In presence of ATP, the protein generates DNA loops while simultaneously generating negative supercoils in the template. The first figure in this paper shows three AFM images from where single DNA interacting with ISWI was deposed on mica surfaces. On the center, a single ISWI is bound near the end of a dsDNA template. The right image shows two DNA loops generated by ISWI. These loops contains supercoils. The TPM study instead showed that the duration of loop formed by ISWI was ATP-dependent.
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