Berlin 2015 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 25: Posters: DNA/RNA and related enzymes
BP 25.7: Poster
Dienstag, 17. März 2015, 14:00–16:00, Poster A
Modelling the mechanisms of backtrack and recovery in RNA polymerases I and II — Ana Lisica1,2, Marcus Jahnel1,2, Christoph Engel3, •Edgar Roldan4,5, Patrick Cramer3, and Stephan Grill1,2,4 — 1BIOTEC, Technische Universität Dresden, Tatzberg 47/49, 01307 Dresden, Germany — 2Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrassüe 108, 01307 Dresden, Germany — 3Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany — 4Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Str. 81, 01187 Dresden, Germany — 5GISC - Grupo Interdisciplinar de Sistemas Complejos, Madrid, Spain
Transcription elongation by RNA polymerases is frequently interrupted by pauses. A prominent mechanism of pausing is backtracking, which involves backward movement of the polymerase on the DNA template. To recover from backtracks, polymerases can diffuse or cleave the backtracked RNA. We model the backtrack recovery of Pol I and II as a continuous time random walk between discrete states. We calculate the first-passage time from any position in the backtrack to the elongation competent state and compare it to times required for recovery from a given backtrack depth, as measured with high-resolution dual-trap optical tweezers. The choice of recovery mechanism is here determined by kinetic competition between 1D diffusion and transcript cleavage. Fitting experimental data to our model, we extract diffusion and cleavage rates of both enzymes and characterize the distinct micromehanical features of Pol I and Pol II transcription.