Extreme Bendability of DNA Less than 100 Base Pairs Long Revealed by Single-Molecule Cyclization

摘要: The classical view of DNA posits that must be stiff below the persistence length [<150 base pairs (bp)], but recent studies addressing this have yielded contradictory results. We developed a fluorescence-based, protein-free assay for studying cyclization single molecules in real time. samples equilibrium population sharply bent, transient species is entirely suppressed single-molecule mechanical measurements and biologically more relevant than annealed sampled traditional ligase-based assay. looping rate has weak dependence between 67 106 bp cannot described by worm-like chain model. Many important protein-DNA interactions involve bending 100 likely use intrinsic bendability DNA.