PRBB-CRG Sessions Arnaud Krebs

07/06/202412:00MARIE CURIEPRBB-CRG SessionsArnaud KrebsEuropean Molecular Biology Laboratory (EMBL)"Cooperativity and antagonisms in transcription regulation"Host: Renee BeekmanAbstract:Transcription factors (TFs) bind at cis-regulatory elements (CREs) such as enhancers and promoters to activate transcription. In higher eukaryotes, chromatin presents a physical barrier that needs to be overcomed by TFs to access their DNA recognition motifs and activate transcription. Cooperativity is assumed to be a key mechanism for TFs to outcompete nucleosomes. Yet, the contribution of individual TFs to chromatin accessibility at CREs, and how their functions are assembled is currently not understood.
Current bulk assays used to map TF occupancy average binding events arising from millions of individual cells, not informing on the potential cooperativity and the antagonisms that organize their binding at CRE. To move beyond this boundary, we developed Single Molecule Footprinting (SMF) to quantify the binding of TFs at mouse regulatory regions. The method allows to simultaneously measure the occurrence of multiple TFs, nucleosomes and DNA methylation on individual molecules genome-wide.
I will illustrate how we leveraged this new layer of information to understand mechanisms of TF cooperativity and dissect the basic assembly rules used by TFs to open chromatin at CREs. I will discuss our recent efforts to use natural genetic variation and high-throughput genome engineering to define the quantitative contribution of individual TFs to open chromatin and explain how their function are combined to form active CREs.