  Backtracking of RNA polymerase (RNAP) is an important pausing mechanism
during DNA transcription that is part of the error correction process that
enhances transcription fidelity. We model the backtracking mechanism of RNA
polymerase, which usually happens when the polymerase tries to incorporate a
mismatched nucleotide triphosphate. Previous models have made simplifying
assumptions such as neglecting the trailing polymerase behind the backtracking
polymerase or assuming that the trailing polymerase is stationary. We derive
exact analytic solutions of a stochastic model that includes locally
interacting RNAPs by explicitly showing how a trailing RNAP influences the
probability that an error is corrected or incorporated by the leading
backtracking RNAP. We also provide two related methods for computing the mean
times to error correction or incorporation given an initial local RNAP
configuration.
