title: Recognition of the Xenopus ribosomal core promoter by the transcription factor xUBF involves multiple HMG box domains and leads to an xUBF interdomain interaction.
abstract: The interaction of the ribosomal transcription factor xUBF with the RNA polymerase I core promoter of Xenopus laevis has been studied both at the DNA and protein levels. It is shown that a single xUBF-DNA complex forms over the 40S initiation site (+1) and involves at least the DNA sequences between -20 and +60 bp. DNA sequences upstream of +10 and downstream of +18 are each sufficient to direct complex formation independently. HMG box 1 of xUBF independently recognizes the sequences -20 to -1 and +1 to +22 and the addition of the N-terminal dimerization domain to HMG box 1 stabilizes its interaction with these sequences approximately 10-fold. HMG boxes 2/3 interact with the DNA downstream of +22 and can independently position xUBF across the initiation site. The C-terminal segment of xUBF, HMG boxes 4, 5 or the acidic domain, directly or indirectly interact with HMG box 1, making the core promoter sequences between -11 and -15 hypersensitive to DNase. This interaction also requires the DNA sequences between +17 and +32, i.e. the HMG box 2/3 binding site. The data suggest extensive folding of the core promoter within the xUBF complex.
authors.affiliation: Centre de Recherche en Cancérologie, Université Laval, Hôtel-Dieu de Québec, Canada.
authors.forename: B
authors.initials: B
authors.lastname: Leblanc
authors.forename: C
authors.initials: C
authors.lastname: Read
authors.forename: T
authors.initials: T
authors.lastname: Moss
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D004247:DNA / Q000378:metabolism; D006609:High Mobility Group Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012318:RNA Polymerase I / Q000235:genetics*; D012269:Ribosomal Proteins / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism*; D029867:Xenopus Proteins; D014982:Xenopus laevis
chemical_list: D006609:High Mobility Group Proteins; D012269:Ribosomal Proteins; D014157:Transcription Factors; C062332:UBFT protein, Xenopus; D029867:Xenopus Proteins; D004247:DNA; D012318:RNA Polymerase I