Sequence selectivity of c-Myb in vivo. Resolution of a DNA target specificity paradox
| Autor: | K B, Andersson, T, Berge, V, Matre, O S, Gabrielsen |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
Transcriptional Activation
Binding Sites Base Sequence Recombinant Fusion Proteins Molecular Sequence Data Saccharomyces cerevisiae Transfection Cell Line Substrate Specificity DNA-Binding Proteins Proto-Oncogene Proteins c-myb Oligodeoxyribonucleotides Genes Reporter Proto-Oncogene Proteins COS Cells Trans-Activators Animals Humans K562 Cells Luciferases Promoter Regions Genetic |
| Zdroj: | The Journal of biological chemistry. 274(31) |
| ISSN: | 0021-9258 |
| Popis: | We have investigated the basis for the striking difference between the broad DNA sequence selectivity of the c-Myb transcription factor minimal DNA-binding domain R(2)R(3) in vitro and the more restricted preference of a R(2)R(3)VP16 protein for Myb-specific recognition elements (MREs) in a Saccharomyces cerevisiae transactivation system. We show that sequence discrimination in yeast is highly dependent on the expression level of Myb effector protein. Full-length c-Myb and a C-terminally truncated protein (residues 1-360) were also included in the study. All of the tested Myb proteins displayed very similar DNA binding properties in electrophoretic mobility shift assays. Only minor differences between full-length c-Myb and truncated c-Myb(1-360) were observed. In transactivation studies in CV-1 cells, the MRE selectivity was highest at low expression levels of Myb effector proteins. However, the discrimination between MRE variants was rapidly lost with high input levels of effector plasmid. In c-Myb-expressing K-562 cells, the high degree of MRE selectivity was retained, thereby confirming the relevance of the results obtained in the yeast system. These data suggest that the MRE selectivity of c-Myb is an intrinsic property of only the R(2)R(3) domain itself and that the transactivation response of a specific MRE in vivo may be highly dependent on the expression level of the Myb protein in the cell. |
| Databáze: | OpenAIRE |
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