title: Functional cooperativity between transcription factors UBF1 and SL1 mediates human ribosomal RNA synthesis.
abstract: The human ribosomal RNA promoter contains two distinct control elements (UCE and core) both of which are recognized by the sequence-specific DNA binding protein UBF1, which has now been purified to apparent homogeneity. The purified factor activates RNA polymerase I (RNA pol I) transcription through direct interactions with either control element. A second RNA pol I transcription factor, designated SL1, participates in the promoter recognition process and is required to reconstitute transcription in vitro. Although SL1 alone has no sequence-specific DNA binding activity, deoxyribonuclease I footprinting experiments reveal that a cooperative interaction between UBF1 and SL1 leads to the formation of a new protein-DNA complex at the UCE and core elements. In vitro transcription experiments indicate that formation of the UBF1-SL1 complex is vital for transcriptional activation by UBF1. Thus, protein-protein interactions between UBF1 and SL1 are required for targeting of SL1 to cis-control sequences of the promoter.
authors.affiliation: Howard Hughes Medical Institute, Department of Biochemistry, University of California, Berkeley 94720.
authors.forename: S P
authors.initials: SP
authors.lastname: Bell
authors.forename: R M
authors.initials: RM
authors.lastname: Learned
authors.forename: H M
authors.initials: HM
authors.lastname: Jantzen
authors.forename: R
authors.initials: R
authors.lastname: Tjian
mesh_terms: D001483:Base Sequence; D002846:Chromatography, Affinity; D004247:DNA / Q000378:metabolism; D004275:DNA, Ribosomal / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism*; D003850:Deoxyribonuclease I / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D011401:Promoter Regions, Genetic; D012318:RNA Polymerase I / Q000378:metabolism; D012335:RNA, Ribosomal / Q000096:biosynthesis*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D004275:DNA, Ribosomal; D004268:DNA-Binding Proteins; D012335:RNA, Ribosomal; D014157:Transcription Factors; D004247:DNA; D012318:RNA Polymerase I; D003850:Deoxyribonuclease I