Mechanism of transcription initiation and promoter escape by RNA polymerase II.

Recently, key advances in biochemical and structural studies of RNA polymerase II (pol II) and the basal transcriptional machinery have shed considerable light on the basic mechanisms underlying the initiation stage of eukaryotic mRNA synthesis. The development of methods for obtaining crystal structures of pol II and its complexes has revolutionized transcriptional studies and holds promise that aspects of initiation will soon be understood at atomic resolution; crosslinking studies have revealed intriguing features of the topology of the pol II initiation complex and provided working models for dynamic steps of initiation; and mechanistic studies have identified promoter escape as a critical step during initiation and brought to light novel roles for the general initiation factors TFIIE, TFIIF, and TFIIH in this process.