Jeff Gelles

To transcribe DNA, RNA polymerase (RNAP) rapidly moves along the DNA template, powered by free energy liberated by nucleotide polymerization and RNA folding reactions. This chemical-to-mechanical energy conversion by RNAPs is analogous to that of myosins, kinesins, dyneins, and the bacterial flagellar motors. However, RNAPs are more mechanically complex than the other molecular motors reviewed in this issue in that they perform a variety of different types of movements along DNA during transcription. RNAPs are also more chemically complex than other motors because they function as the primary targets for the regulation of gene expression. This review describes our current understanding of RNAP mechanical processes, focusing on recent studies that have observed directly the movement of single RNAP molecules along DNA. These studies already have yielded insights into the mechanics and mechanisms of RNAP movement; their further development and application promises to help resolve fundamental questions about how RNAP translocates along DNA and to help elucidate mechanisms of transcription regulation.