title: Promoter escape by RNA polymerase II. Formation of an escape-competent transcriptional intermediate is a prerequisite for exit of polymerase from the promoter.
abstract: Shortly after initiating promoter-specific transcription in vitro, mammalian RNA polymerase II becomes highly susceptible to arrest in a promoter-proximal region 9-13 base pairs downstream of the transcriptional start site (Dvir, A., Conaway, R. C., and Conaway, J. W. (1996) J. Biol. Chem. 271, 23352-23356). Arrest by polymerase in this region is suppressed by TFIIH in an ATP-dependent reaction (Dvir, A., Conaway, R. C., and Conaway, J. W. (1997) Proc. Natl. Acad. Sci. U. S. A. 94, 9006-9010). In this report, we present evidence that, in addition to TFIIH and an ATP cofactor, efficient transcription by RNA polymerase II through this promoter-proximal region requires formation of an "escape-competent" transcriptional intermediate. Formation of this intermediate requires template DNA 40-50 base pairs downstream of the transcriptional start site. This requirement for downstream DNA is transient, since template DNA downstream of +40 is dispensable for assembly of the preinitiation complex, for initiation and synthesis of the first 10-12 phosphodiester bonds of nascent transcripts and for further extension of transcripts longer than approximately 14 nucleotides. Thus, promoter escape requires that the RNA polymerase II transcription complex undergoes a critical structural transition, likely driven by interaction of one or more components of the transcriptional machinery with template DNA 40-50 base pairs downstream of the transcriptional start site.
authors.affiliation: Department of Biological Sciences, Oakland University, Rochester, Michigan 48309-4401, USA.
authors.forename: A
authors.initials: A
authors.lastname: Dvir
authors.forename: S
authors.initials: S
authors.lastname: Tan
authors.forename: J W
authors.initials: JW
authors.lastname: Conaway
authors.forename: R C
authors.initials: RC
authors.lastname: Conaway
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000378:metabolism; D004926:Escherichia coli; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012319:RNA Polymerase II / Q000378:metabolism*; D051381:Rats; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D035381:TATA-Binding Protein Associated Factors; D013698:Templates, Genetic; D035362:Transcription Factor TFIID; D051758:Transcription Factor TFIIH; D014157:Transcription Factors / Q000378:metabolism; D019473:Transcription Factors, TFII; D014158:Transcription, Genetic
chemical_list: D029701:Saccharomyces cerevisiae Proteins; C490039:TAF6 protein, S cerevisiae; D035381:TATA-Binding Protein Associated Factors; D035362:Transcription Factor TFIID; D014157:Transcription Factors; D019473:Transcription Factors, TFII; D051758:Transcription Factor TFIIH; D000255:Adenosine Triphosphate; D004247:DNA; D012319:RNA Polymerase II