DNA, at a stretch

UV light can affect the properties of DNA detrimentally, unraveling the ability of the double helix to replicate and to interact with the transcriptional machinery for making proteins. One phenomenon that has not been studied in detail until now is the changes in elasticity of DNA under UV light. Piotr Marszalek and his colleagues at Duke University have now stretched DNA to its limits. They used a scanning probe microscope to do the stretching and their single-molecule force spectroscopic measurements show how crosslinks formed in DNA by UV irradiation alter the molecule's elasticity directly. Even small changes in elasticity can severely affect DNA's elasticity and so hinder its normal functions. "These are the first measurements that establish a relationship between DNA nanomechanics and damage," explains Marszalek. He adds that the research paves the way for using stretch-release force spectroscopy measurements in DNA diagnostics.