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BP: Fachverband Biologische Physik
BP 22: Single Molecule Biophysics (joint session BP/CPP)
BP 22.1: Vortrag
Mittwoch, 18. März 2020, 09:30–09:45, SCH A251
Magnetic tweezers reveal the mechanism of directional transcription termination in human mitochondria — Eugen Ostrofet1, Flavia Stal Papini1, Britney Johnson2, Jamie Arnold2, Craig Cameron2, and •David Dulin1 — 1Junior Research Group 2, IZKF, FAU Erlangen-Nürnberg, Germany — 2Department of Microbiology and Immunology, The University of North Carolina Chapel Hill, USA
Transcription termination is essential to synthesize functional RNA and to prevent transcription interference with downstream promoters. Therefor, it must be performed efficiently despite the stability of the elongating RNA polymerase (RNAP) on DNA. One approach adopted by eukaryotic cells is directional transcription termination upon collision of RNAP with a termination factor bound to DNA, as for human mitochondria RNAP (mtRNAP) and Pol I. How the termination factor senses the direction of transcribing RNAP remains to be found. We propose that the termination factor senses DNA unwinding, and consequently terminates transcription directionally. To interrogate this hypothesis, we employed a high throughput magnetic tweezers instrument and a hairpin-based force jump assay to mimic DNA unwinding and look into the human mitochondria transcription termination factor 1 (MTERF1). We found that MTERF1 blocks directionally hairpin opening, explaining directional transcription termination. Performing in situ force calibration, we determined accurately the energy landscape of MTERF1 bound to its termination site.