Dresden 2020 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 62: Single Molecule Biophysics (joint session BP/CPP)

CPP 62.4: Talk

Wednesday, March 18, 2020, 10:15–10:30, SCH A251

Magnetic tweezers reveal two coexisting and interconverting bacterial RNA polymerase conformations with different open complex stability — •Subhas Chandra Bera¹, Mona Seifert¹, Santeri Maatsola², Eugen Ostrofet¹, Monika Spermann¹, Flavia Stal-Papini¹, Anssi M. Malinen², and David Dulin¹ — ¹Junior Research Group 2, Interdisciplinary Center for Clinical Research, Friedrich Alexander University Erlangen-Nürnberg (FAU), Cauerstr. 3, 91058 Erlangen, Germany — ²Department of Biochemistry, University of Turku, Tykistökatu 6A, 6th floor, 20520 Turku, Finland

To start transcription, the RNA polymerase (RNAP) recognises the promoter, to form the closed complex (CC), and eventually unwinds the DNA to form the open complex (OC), and is then ready for RNA synthesis. OC stability decides the yield of expression in many genes, and is therefore of great importance to regulate expression of a given gene. Using high throughput magnetic tweezers, we investigated OC dynamics. Surprisingly, we observed two OC populations with nearly 10-fold difference in lifetime, where the stability of the OC varies as a function of the nature and the concentration of the anions, as well as the temperature. We further noticed that the RNAP completely dissociates upon return to CC and therefore the two OC populations do not originate from a single interconverting RNAP, but rather from two conformations of RNAP. Our study shows the power of single molecule techniques to resolve two interconverting populations of RNAP that have remained elusive to bulk assays so far.