Mechanism of transcription initiation and promoter escape by RNA polymerase II

Recently, key advances in biochemical and structural studies of RNA polymer ase II (pol II) and the basal transcriptional machinery have shed considera ble light on the basic mechanisms underlying the initiation stage of eukary otic mRNA synthesis. The development of methods for obtaining crystal struc tures of pot II and its complexes has revolutionized transcriptional studie s and holds promise that aspects of initiation will soon be understood at a tomic resolution; crosslinking studies have revealed intriguing features of the topology of the pot II initiation complex and provided working models for dynamic steps of initiation; and mechanistic studies have identified pr omoter escape as a critical step during initiation and brought to light nov el roles for the general initiation factors TFIIE, TFIIF, and TFIIH in this process.