Multi-subunit RNA polymerases (RNAP) are ornate molecular machines that translocate on a DNA template as they generate a complementary RNA chain. RNAPs are highly conserved in evolution among eukarya, eubacteria, archaea, and some viruses. As such, multi-subunit RNAPs appear to be an irreplaceable advance in the evolution of complex life on earth. Because of their stepwise movement on DNA, RNAPs are considered to be molecular motors, and because RNAPs catalyze a templated polymerization reaction, they are central to biological information flow. The history of RNAP discovery and investigation of its mechanism and regulation appear as complex as RNAP itself. The central role of templated RNA synthesis in biological information flow was predicted by Jacob and Monod, and the enzymatic activity promoting formation of RNA polymers was reported in eubacteria and eukaryotes at that time by several groups. However, the DNA-dependent RNA polymerase proved elusive until 1960, when it was independently identified in bacteria by Hurwitz and Stevens and in plants by the Bonner group.
M. Kireeva, M. Kashlev, Z. Burton Chem. Rev., 2013, 113 (11), pp 8325–8330