Dresden 2020 – scientific programme

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BP: Fachverband Biologische Physik

BP 12: Active Matter II (joint session BP/CPP/DY)

BP 12.11: Talk

Tuesday, March 17, 2020, 12:45–13:00, HÜL 386

The step-wise induction of transcription drives morphological changes in aggregates of RNA polymerase II — Agnieszka Pancholi¹, Roshan Prizak¹, Tim Klingberg², Weichun Zhang¹, Amra Noa¹, Gerd Ulrich Nienhaus^1,3, Vasily Zaburdaev², and •Lennart Hilbert¹ — ¹Karlsruhe Institute of Technology — ²Friedrich-Alexander University Erlangen-Nuremberg — ³University of Illinois at Urbana-Champaign

In eukaryotic cells, a main control point of transcription is the transient pausing of engaged RNA polymerase II (Pol II) just before transcript elongation. Paused Pol II forms transient polymeric aggregates that exhibit diverse morphologies. Here, we use super-resolution microscopy in embryonic zebrafish cells to show how entry into and exit from Pol II pausing determines these aggregate morphologies. Instant structured illumination microscopy (iSIM) in live embryos revealed that aggregates initially are morphology complex, round up as they grow, and unfold again when actual transcript elongation begins. Using transcription inhibitors, we confirm that Pol II pausing indeed drives aggregate rounding. Further resolving aggregates by STimulated Emission Double Depletion (STEDD) microscopy, we found a granular fine-structure that suggests clustering aggregation rather than liquid-liquid compartmentalization. We currently develop a theoretical model to explain what underlying macro-molecular interactions could result in the observed morphologies.