Recent advances in single molecule studies of nucleosomes

► DNA unzipping reveals the detailed histone-DNA interactions within a nucleosome. ► A novel nucleosome disassembly intermediate is observed using smFRET. ► Distinct PTMs in a nucleosome separately regulate unwrapping rates and disassembly. ► Chromatin higher order structures are identified for various linker DNA lengths. ► Pol II may transcribe through the nucleosome using a Brownian ratchet mechanism. As the fundamental packing units of DNA in eukaryotes, nucleosomes play a central role in governing DNA accessibility in a variety of cellular processes. Our understanding of the mechanisms underlying this complex regulation has been aided by unique structural and dynamic perspectives offered by single molecule techniques. Recent years have witnessed remarkable advances achieved using these techniques, including the generation of a detailed histone–DNA energy landscape, elucidation of nucleosome disassembly processes, and real-time monitoring of molecular motors interacting with nucleosomes. These and other highlights of single molecule nucleosome studies will be discussed in this review.