Single-molecule tracking of transcription protein dynamics in living cells: seeing is believing, but what are we seeing?. (April 2021) - Lionnet, Timothée
Graphical abstract: Highlights: Transcription is controlled by large numbers of factors. Mechanistic models require quantitative approaches. Single Molecule Tracking provides direct measurements of k on and k off in the context of the living cell. Transcription Factors in living cells can achieve high occupancy at target sites despite fast turnover (seconds). Clustering of Transcription Factors via low affinity interactions is widespread and contributes to enhanced local activity. Abstract : A universe of transcription factors (TFs), cofactors, as well as chromatin remodeling and modifying enzymes combine or compete on chromatin to control transcription. Measuring quantitatively how these proteins dynamically interact is required in order to formulate models with predictive ability to elucidate transcription control mechanisms. Single molecule tracking (SMT) provides a powerful tool towards this goal: it is a fluorescence microscopy approach that measures the location and mobility of individual TF molecules, as well as their rates of association with and dissociation from chromatin in the physiological context of the living cell. Here we review SMT principles, and discuss key TF properties uncovered by live-cell SMT, such as fast turnover (seconds), and formation of clusters that locally increase activity.