The Discovery of RNA Polymerase

In all organisms, genes coding for proteins are transcribed by the multisubunit complex, DNA-dependent RNA polymerase. In prokaryotes, this is accomplished by the core RNA polymerase linked to a number of sigma factors that specify its binding to different promoter elements. In eukaryotes, this process is more complex because of the presence of three distinct RNA polymerases, each responsible for the transcription of a different class of RNA. During the past few years, structural and biochemical studies have provided enormous insight into how these macromolecular machines interact with DNA and carry out many of the detailed steps in the initiation and elongation of RNA chains (1, 2).