Sequence-Dependent Kinetic Model for Transcription Elongation by RNA Polymerase

Michelle Wang
Cornell University

Lu Bai, Alla Shundrovsky, and Michelle D. Wang*



Cornell University, Department of Physics, Ithaca, NY 14853, USA



We present a kinetic model for the sequence-dependent motions of RNA polymerase (RNAP) during transcription elongation. For each NTP incorporation, RNAP has a net forward translocation of one base pair along the DNA template. However, this process may involve the exploration of backtracked and forward-tracked translocation modes. In our model, the kinetic rates for the reaction pathway, calculated based on the stabilities of transcription elongation complex (TEC), necessarily lead to sequence-dependent NTP incorporation rates. Simulated RNAP elongation kinetics is in good agreement with data from transcription gels and single-molecule studies. The model provides a kinetic explanation for well-known backtracked pauses at transcript positions with unstable TECs. It also predicts a new type of pause caused by an energetically unfavorable transition from pre- to post-translocation modes.


Back to Workshop IV: Molecular Machines