We developed a single-molecule method with which one can investigate the kinetics and thermodynamics of spontaneous structural fluctuations of a macromolecular complex at a sub-nm and sub-ms spatiotemporal resolution. The method is based on single-molecule fluorescence resonance energy transfer (smFRET) combined with maximum likelihood estimation (MLE) and fluorescence correlation spectroscopy (FCS). A nucleosome core particle, a protein-DNA complex made of a histone protein core wrapped around by DNA, is a ~11 nm packing unit of DNA in eukaryotes. By using the method, we revealed that the histone core spontaneously and repeatedly docks and undocks in and out of the nucleosome on a sub-ms time scale and a sub-nm length scale. Our study also showed that the frequency of this motion depends on histone lysine acetylation that affects the interaction strength between the histone core and DNA. Based on these results, we propose a mechanism of lysine acetylation modulating the kinetic and thermodynamic stabilities of the histone-DNA complex, thereby contributing to gene activation. This study illustrates that the method provides an efficient and robust means to probe small and fast structural dynamics of a macromolecular complex at a sub-nm and sub-ms spatiotemporal resolution.

Single-molecule fluorescence spectroscopy to probe structural dynamics of a macromolecular complex at a sub-nm and sub-ms resolution

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.