RNA Polymerase Backtracking in Gene Regulation and Genome Instability

RNA polymerase is a ratchet machine that oscillates between productive and backtracked states at numerous DNA positions. Since its first description 15 years ago, backtracking—the reversible sliding of RNA polymerase along DNA and RNA—has been implicated in many critical processes in bacteria and eukaryotes, including the control of transcription elongation, pausing, termination, fidelity, and genome instability.