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Phosphorylation of UBF at serine 388 is required for interaction with RNA polymerase I and activation of rDNA transcription

2001; National Academy of Sciences; Volume: 98; Issue: 24 Linguagem: Inglês

10.1073/pnas.231071698

1091-6490

Renate Voit, Ingrid Grummt,

Genomics and Chromatin Dynamics

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 G 1 -specific cyclin-dependent kinase (cdk)/cyclin complexes. After G 1 progression 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.