Single-molecule studies of chromatin fibers: a personal report

With the advent of single-molecule techniques, macromolecular science has reached new horizons. Nowadays, we can observe, touch, stretch and twist biological macromolecules or their complexes, one-at-a time, in attempts to better understand their mechanical properties and to gain insights into their behavior in the living cell. Chromatin structure and function has been the focus of our research interests for many years. In the past decade, we have added some of the newly emerged single-molecule approaches to the more traditional biochemical and biophysical methods that we have been using throughout the years. This paper briefly summaries our studies on individual chromatin fibers using the atomic force microscope (AFM), optical tweezers, and magnetic tweezers. We believe that our results so far have contributed significantly to our understanding of chromatin, but we also hope that this is only the beginning, and that more exciting times lie ahead.