Regensburg 2007 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 9: Regulation and Signaling
BP 9.2: Hauptvortrag
Dienstag, 27. März 2007, 10:00–10:30, H43
Transcription by RNA Polymerase II — •Stephan Grill1,2,3, Eric Galburt3,1, Martin Depken1, and Carlos Bustamante3 — 1Max-Planck-Institut für Physik komplexer Systeme, Dresden — 2Max-Planck-Institut für molekulare Zellbiologie und Genetik, Dresden — 3University of California, Berkeley
RNA polymerase II (RNAP II) is responsible for transcribing all mRNAs in eukaryotic cells in a highly regulated process that serves as a central control point for cellular function. We have investigated the transcription dynamics of single RNAP II molecules against force in the presence and absence of TFIIS, a transcription elongation factor that enables the enzyme to remove copy errors. Using a single-molecule dual-trap optical-tweezers assay, we found that the response of RNAP II to force is entirely determined by enzyme backtracking. We show that backtrack pause durations follow a t−3/2 power law, implying that during backtracking RNAP II performs a random walk in discrete base-pair steps and suggesting that backtracks may account for most of RNAP II pauses. We discuss the implications of our results in light of an optimal balance between speed and accuracy in decoding the genetic information during transcription.