Single Molecule Studies of DNA-Histone Interactions

Mechanically-induced unfolding of protein-compacted-DNA molecules is a powerful tool for studying protein-DNA interactions at the single-molecule level. We perform single molecule experiments using horizontal magnetic tweezers on histones complexed with tethered DNA under tension. Native or hyperacetylated histones purified from cultured cells were used. Our experiments allowed us to characterize the step-length distribution for nucleosomes reconstituted from native histones allowing for a comparison to data from hyperacetylated histones. Here we present preliminary data characterizing the mechanical properties of DNA molecules bound to native and post-translationally modified histones.