UNRAVELING THE ROLE OF HELICASES IN TRANSCRIPTION

Proteins with seven conserved ''helicase domains'' play essential role s in all aspects of nucleic acid metabolism. Deriving energy from ATP hydrolysis, helicases alter the structure of DNA, RNA, or DNA:RNA dupl exes, remodeling chromatin and modulating access to the DNA template b y the transcriptional machinery. This review focuses on the diverse fu nctions of these proteins in the process of RNA polymerase II transcri ption in eukaryotes. Known or putative helicases are required for gene ral transcription initiation and for transcription-coupled DNA repair, and may play important roles in elongation, termination, and transcri pt stability. Recent evidence suggests that helicase-domain-containing proteins are also involved in complexes that facilitate the activity of groups of seemingly unrelated genes. BioEssays 20:634-641, 1998. (C ) 1998 John Wiley & Sons, Inc.