Recognition of the Xenopus ribosomal core promoter by the transcription factor xUBF involves multiple HMG box domains and leads to an xUBF interdomain interaction.
AUTOR(ES)
Leblanc, B
RESUMO
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.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=413234Documentos Relacionados
- Variants of the Xenopus laevis ribosomal transcription factor xUBF are developmentally regulated by differential splicing.
- Cooperative binding of the Xenopus RNA polymerase I transcription factor xUBF to repetitive ribosomal gene enhancers.
- The DNA supercoiling architecture induced by the transcription factor xUBF requires three of its five HMG-boxes.
- The RNA polymerase I transcription factor xUBF contains 5 tandemly repeated HMG homology boxes.
- xUBF, an RNA polymerase I transcription factor, binds crossover DNA with low sequence specificity.