title: Fluorescence-force spectroscopy maps two-dimensional reaction landscape of the holliday junction.
abstract: 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.
authors.affiliation: Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA. tjha@uiuc.edgu
authors.forename: Sungchul
authors.initials: S
authors.lastname: Hohng
authors.forename: Ruobo
authors.initials: R
authors.lastname: Zhou
authors.forename: Michelle K
authors.initials: MK
authors.lastname: Nahas
authors.forename: Jin
authors.initials: J
authors.lastname: Yu
authors.forename: Klaus
authors.initials: K
authors.lastname: Schulten
authors.forename: David M J
authors.initials: DM
authors.lastname: Lilley
authors.forename: Taekjip
authors.initials: T
authors.lastname: Ha
mesh_terms: D010582:Bacteriophage lambda; D055592:Biophysical Phenomena; D001703:Biophysics; D045566:DNA, Cruciform / Q000737:chemistry*; D004279:DNA, Viral / Q000737:chemistry; D031541:Fluorescence Resonance Energy Transfer; D009690:Nucleic Acid Conformation; D052898:Optical Tweezers
chemical_list: D045566:DNA, Cruciform; D004279:DNA, Viral