title: Efficient and rapid nucleosome traversal by RNA polymerase II depends on a combination of transcript elongation factors.
abstract: The nucleosome is generally found to be a strong barrier to transcript elongation by RNA polymerase II (pol II) in vitro. The elongation factors TFIIF and TFIIS have been shown to cooperate in maintaining pol II in the catalytically competent state on pure DNA templates. We now show that although TFIIF or TFIIS alone is modestly stimulatory for nucleosome traversal, both factors together increase transcription through nucleosomes in a synergistic manner. We also studied the effect of TFIIF and TFIIS on transcription of nucleosomes containing a Sin mutant histone. The Sin point mutations reduce critical histone-DNA contacts near the center of the nucleosome. Significantly, we found that nucleosomes with a Sin mutant histone are traversed to the same extent and at nearly the same rate as equivalent pure DNA templates if both TFIIS and TFIIF are present. Thus, the nucleosome is not necessarily an insurmountable barrier to transcript elongation by pol II. If unfolding of template DNA from the nucleosome surface is facilitated and the tendency of pol II to retreat from barriers is countered, transcription of nucleosomal templates can be rapid and efficient.
authors.affiliation: Department of Molecular Genetics, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA. lused@ccf.org
authors.forename: Donal S
authors.initials: DS
authors.lastname: Luse
authors.forename: Lisa C
authors.initials: LC
authors.lastname: Spangler
authors.forename: Andrea
authors.initials: A
authors.lastname: Újvári
mesh_terms: D000818:Animals; D006657:Histones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D009707:Nucleosomes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017354:Point Mutation; D012319:RNA Polymerase II / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019473:Transcription Factors, TFII / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D035602:Transcriptional Elongation Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014981:Xenopus
chemical_list: D006657:Histones; D009707:Nucleosomes; D019473:Transcription Factors, TFII; D035602:Transcriptional Elongation Factors; C018648:transcription factor S-II; D012319:RNA Polymerase II; C056604:transcription factor TFIIF