Phosphorylation of UBF at Serine 388 is Required for Interaction with RNA Polymerase I and Activation of rDNA Transcription

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 98; no. 24; pp. 13631 - 13636
• Main Authors: Voit, Renate, Grummt, Ingrid
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 20-11-2001; National Acad Sciences; The National Academy of Sciences
• Subjects: 3T3 Cells; Animals; Antibodies; Biochemistry; Biological Sciences; Cell Cycle; Cell Line; Cyclins; Deoxyribonucleic acid; DNA; DNA, Ribosomal; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Enzymes; Mice; NIH 3T3 cells; Phosphatases; Phosphorylation; Pol1 Transcription Initiation Complex Proteins; Ribonucleic acid; Ribosomal DNA; RNA; RNA Polymerase I - metabolism; Serine - genetics; Serine - metabolism; Spodoptera; Transcription Factors - genetics; Transcription Factors - metabolism; Transcriptional Activation; UBF protein
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.231071698

Modulation of the activity of the upstream binding factor (UBF) plays a key role in cell cycle-dependent regulation of rRNA synthesis. Activation of rDNA transcription on serum stimulation requires phosphorylation of UBF at serine 484 by G1-specific cyclin-dependent kinase (cdk)/cyclin complexes. After G1progression UBF is phosphorylated at serine 388 by cdk2/cyclin E and cdk2/cyclin A. Conversion of serine 388 to glycine abolishes UBF activity, whereas substitution by aspartate enhances the transactivating function of UBF. Protein-protein interaction studies reveal that phosphorylation at serine 388 is required for the interaction between RNA polymerase I and UBF. The results suggest that phosphorylation of UBF represents a powerful means of modulating the assembly of the transcription initiation complex in a proliferation- and cell cycle-dependent fashion.