Non-complementary DNA helical structure induced by positive torsional stress

Alexander V. Vologodskii, Xiaoping Yang, Nadrian C. Seeman

Research output: Contribution to journalArticlepeer-review


We have induced a local conformational transition by positive torsional stress in small synthetic circular DNA molecules containing cruciforms with immobile or tetramobile branched junctions. The immobile species correspond to the extruded and intruded extrema of the tetramobile junction. Under normal conditions the sequences of all the branched species prevent them from being re-absorbed into the circle. We have induced positive stress by addition of ethidium to the circle, in a low ionic strength medium. Alterations in gel electrophoretic mobility under increasing concentrations of ethidium suggest that the cruciforms undergo a transition under torsional stress. The product of this transition contains mispaired nucleotides, but interwound backbones. By comparing the electrophoretic mobilities of circles containing these structures with that of a completely complementary circle of the same length, we conclude that the twist in the mispairing region is similiar to that of completely paired species.

Original languageEnglish (US)
Pages (from-to)1503-1508
Number of pages6
JournalNucleic acids research
Issue number6
StatePublished - Mar 15 1998

ASJC Scopus subject areas

  • Genetics


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