Supercoiling DNA Locates Mismatches

Andrew Dittmore, Sumitabha Brahmachari, Yasuharu Takagi, John F. Marko, Keir C. Neuman

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


We present a method of detecting sequence defects by supercoiling DNA with magnetic tweezers. The method is sensitive to a single mismatched base pair in a DNA sequence of several thousand base pairs. We systematically compare DNA molecules with 0 to 16 adjacent mismatches at 1 M monovalent salt and 3.6 pN force and show that under these conditions, a single plectoneme forms and is stably pinned at the defect. We use these measurements to estimate the energy and degree of end-loop kinking at defects. From this, we calculate the relative probability of plectoneme pinning at the mismatch under physiologically relevant conditions. Based on this estimate, we propose that DNA supercoiling could contribute to mismatch and damage sensing in vivo.

Original languageEnglish (US)
Article number147801
JournalPhysical review letters
Issue number14
StatePublished - Oct 3 2017

ASJC Scopus subject areas

  • General Physics and Astronomy


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