Upstream binding factor stabilizes Rib 1, the TATA-binding-protein-containing Xenopus laevis RNA polymerase I transcription factor, by multiple protein interactions in a DNA-independent manner.
Initiation of RNA polymerase I transcription in Xenopus laevis requires Rib 1 and upstream binding factor (UBF). UBF and Rib 1 combine to form a stable transcription complex on the Xenopus ribosomal gene promoter. Here we show that Rib 1 comprises TATA-binding protein (TBP) and TBP-associated factor components. Thus, Rib 1 is the Xenopus equivalent of mammalian SL 1. In contrast to SL 1, Rib 1 is an unstable complex that readily dissociates into TBP and associated components. We identify a novel function for UBF in stabilizing Rib 1 by multiple protein interactions. This stabilization occurs in solution in a DNA-independent manner. These results may partially explain the difference in UBF requirement between Xenopus and mammalian systems.
Bodeker
M
M
Biomedical Research Centre, University of Dundee, Ninewells Hospital and Medical School, Scotland.
Cairns
C
C
McStay
B
B
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D001665:Binding Sites; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D008322:Mammals; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology; D035463:Pol1 Transcription Initiation Complex Proteins; D011485:Protein Binding; D014176:Protein Biosynthesis; D012318:RNA Polymerase I / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D016385:TATA Box; D035181:TATA-Box Binding Protein; D014157:Transcription Factors / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D014158:Transcription, Genetic; D029867:Xenopus Proteins; D014982:Xenopus laevis
D000906:Antibodies; D004268:DNA-Binding Proteins; D010446:Peptide Fragments; D035463:Pol1 Transcription Initiation Complex Proteins; D011994:Recombinant Proteins; C092979:Rib1 protein, Xenopus; D035181:TATA-Box Binding Protein; D014157:Transcription Factors; D029867:Xenopus Proteins; C063660:transcription initiation factor TIF-IB; D004247:DNA; D012318:RNA Polymerase I