Fluorescence-force spectroscopy maps two-dimensional reaction landscape of the holliday junction

Sungchul Hohng, Ruobo Zhou, Michelle K. Nahas, Jin Yu, Klaus Schulten, David M.J. Lilley, Taekjip Ha

Research output: Contribution to journalArticlepeer-review

227 Scopus citations


Despite the recent advances in single-molecule manipulation techniques, purely mechanical approaches cannot detect subtle conformational changes in the biologically important regime of weak forces. We developed a hybrid scheme combining force and fluorescence that allowed us to examine the effect of subpiconewton forces on the nanometer scale motion of the Holliday junction (HJ) at 100-hertz bandwidth. The HJ is an exquisitely sensitive force sensor whose force response is amplified with an increase in its arm lengths, demonstrating a lever-arm effect at the nanometer-length scale. Mechanical interrogation of the HJ in three different directions helped elucidate the structures of the transient species populated during its conformational changes. This method of mapping two-dimensional reaction landscapes at low forces is readily applicable to other nucleic acid systems and their interactions with proteins and enzymes.

Original languageEnglish (US)
Pages (from-to)279-283
Number of pages5
Issue number5848
StatePublished - Oct 12 2007

All Science Journal Classification (ASJC) codes

  • General


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