title: Sequence-dependent twist-stretch coupling in DNA.
abstract: Recent single-molecule micromanipulation experiments on DNA subject to small distortion revealed positive coupling between DNA stretching and twisting--for instance, DNA elongates when overtwisted. Here we propose a method to calculate the twist-stretch coupling constant specific to a DNA fragment of a given sequence. The method employs a sequence-dependent dinucleotide force field and is based on constrained minimization of the fragment's deformation energy. Using a force field inferred from atomistic molecular dynamics simulations, we obtain the twist-stretch coupling for random sequence to be 0.30 nm/turn, close to experimental values. An exhaustive calculation for all oligomers of nine basepairs yields values between 0.14 and 0.45 nm/turn, positively correlated with the contents of pyrimidine-purine steps in the sequence. Our method is simple to use and allows one to explore the hypothesis that some sequences may be optimized for twist-stretch coupling.
authors.forename: Timothée
authors.initials: T
authors.lastname: Lionnet
authors.forename: Filip
authors.initials: F
authors.lastname: Lankas
mesh_terms: D001483:Base Sequence; D003198:Computer Simulation; D004247:DNA / Q000737:chemistry*; D008956:Models, Chemical; D009690:Nucleic Acid Conformation
chemical_list: D004247:DNA