RNA polymerase I, bending the rules?

Abstract

Transcription initiation is one of the key regulatory steps in expressing the genetic information encoded in the DNA . Mechanisms of RNA Pol II transcription have been extensively studied, whereas the structural basis of RNA Pol I and III transcription is still poorly defined. Three recent studies discussed here give a first glimpse into the molecular mechanisms underlying the process of RNA Pol I transcriptional initiation and reveal unexpected structural differences compared to the previously described homologous Pol II structures.