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1: Proc Natl Acad Sci U S A. 2001 Dec 4;98(25):14334-9. Epub 2001 Nov 20.Click here to read Click here to read Links

Differential roles of phosphorylation in the formation of transcriptional active RNA polymerase I.

Fath S, Milkereit P, Peyroche G, Riva M, Carles C, Tschochner H.

Biochemie-Zentrum Heidelberg, Im Neuenheimer Feld 328, D-69120 Heidelberg, Germany.

Regulation of rDNA transcription depends on the formation and dissociation of a functional complex between RNA polymerase I (pol I) and transcription initiation factor Rrn3p. We analyzed whether phosphorylation is involved in this molecular switch. Rrn3p is a phosphoprotein that is predominantly phosphorylated in vivo when it is not bound to pol I. In vitro, Rrn3p is able both to associate with pol I and to enter the transcription cycle in its nonphosphorylated form. By contrast, phosphorylation of pol I is required to form a stable pol I-Rrn3p complex for efficient transcription initiation. Furthermore, association of pol I with Rrn3p correlates with a change in the phosphorylation state of pol I in vivo. We suggest that phosphorylation at specific sites of pol I is a prerequisite for proper transcription initiation and that phosphorylation/dephosphorylation of pol I is one possibility to modulate cellular rDNA transcription activity.

PMID: 11717393 [PubMed - indexed for MEDLINE]

PMCID: PMC64682