title: Identification of human DNA topoisomerase I as a cofactor for activator-dependent transcription by RNA polymerase II.
abstract: The transcriptional activation of eukaryotic class II genes by sequence-specific regulatory proteins requires cofactors in addition to the general transcription factors. One cofactor (termed PC3) was purified from HeLa cells and identified by sequence analysis and functional assays as human DNA topoisomerase I (EC5.99.1.2). Under identical conditions PC3 mediates both a net activation of transcription by the acidic activator GAL4-AH and repression of basal transcription, thereby leading to a large induction of transcription by the activator. PC3-mediated activation of transcription is dependent on the presence of both the GAL4-AH activation domain and the TATA-binding protein (TBP)-associated-factors (TAFs) in natural transcription factor TFIID, while repression of basal transcription is observed with either TFIID or the derived TBP alone. These results suggest novel functions, apparently through distinct mechanisms, for human DNA topoisomerase I in the regulation of transcription initiation by RNA polymerase II.
authors.affiliation: Laboratory of Biochemistry and Molecular Biology, Rockefeller University, New York, NY 10021.
authors.forename: M
authors.initials: M
authors.lastname: Kretzschmar
authors.forename: M
authors.initials: M
authors.lastname: Meisterernst
authors.forename: R G
authors.initials: RG
authors.lastname: Roeder
mesh_terms: D000595:Amino Acid Sequence; D002467:Cell Nucleus / Q000201:enzymology; D002852:Chromatography, Ion Exchange; D004264:DNA Topoisomerases, Type I / Q000302:isolation & purification* / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D015972:Gene Expression Regulation, Neoplastic; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D008970:Molecular Weight; D012319:RNA Polymerase II / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D035181:TATA-Box Binding Protein; D014157:Transcription Factors / Q000378:metabolism*; D019474:Transcription Factors, TFIII; D014158:Transcription, Genetic
chemical_list: D004268:DNA-Binding Proteins; D011994:Recombinant Proteins; D035181:TATA-Box Binding Protein; D014157:Transcription Factors; D019474:Transcription Factors, TFIII; C053256:transcription factor TFIIID; D012319:RNA Polymerase II; D004264:DNA Topoisomerases, Type I