Kinetics of DNA Melting and Annealing Under Small Tension

Melting double-stranded DNA (dsDNA) is a fundamental part of several biological processes. dsDNA in vivo subject to small tensile forces induced by thermal fluctuations and active Although these general accelerate bond dissociation, recent experimental theoretical studies suggest nontrivial, stabilizing effect force on the duplex (roll-over effect). To investigate ∼pN axial stability, we developed novel single-molecule assay, which utilizes intrinsic bending rigidity exert weak pulling down entropic limit. Combining this assay with FRET, measured kinetics formation dissociation presence tension for many molecules parallel. We observed clear exponential relationship between denaturation rate even low regime, no indication roll-over effect. also compared stabilities RNA-DNA hybrid duplexes found that base sequence dramatically impacts their relative stabilities. Our results reveal stability challenge previously proposed model transition state as pre-ordered single strand.