RNA Polymerase II C-terminal Heptarepeat Domain Ser-7 Phosphorylation Is Established in a Mediator-dependent Fashion

• Published in: The Journal of biological chemistry Vol. 285; no. 1; pp. 188 - 196
• Main Authors: Boeing, Stefan, Rigault, Caroline, Heidemann, Martin, Eick, Dirk, Meisterernst, Michael
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.01.2010; American Society for Biochemistry and Molecular Biology
• Subjects: Cyclin-Dependent Kinases - metabolism; DNA - metabolism; Gene/Regulation; Gene/Transcription; HeLa Cells; Humans; Jurkat Cells; Mediator Complex - metabolism; Phosphorylation - drug effects; Phosphorylation/Enzymes; Phosphorylation/Kinases/Serine-Threonine; Phosphorylation/Serine/Threonine; Protein Binding - drug effects; Protein Structure, Tertiary; Purines - pharmacology; Repetitive Sequences, Amino Acid; RNA Polymerase II - chemistry; RNA Polymerase II - metabolism; Roscovitine; Serine - metabolism; Templates, Genetic; Transcription; Transcription Factor TFIIH - metabolism; Transcription, Chromatin, and Epigenetics; Transcription, Genetic - drug effects; Transcription/Coactivators; Transcription/RNA Polymerase II; Transcription/Coactivators; Transcription; Phosphorylation/Enzymes; Phosphorylation/Kinases/Serine-Threonine; Transcription/RNA Polymerase II; Phosphorylation/Serine/Threonine; Gene/Transcription; Gene/Regulation
• DOI: 10.1074/jbc.M109.046565
• ISSN: 0021-9258; 1083-351X

The largest subunit of RNA polymerase II (RNAPII) C-terminal heptarepeat domain (CTD) is subject to phosphorylation during initiation and elongation of transcription by RNA polymerase II. Here we study the molecular mechanisms leading to phosphorylation of Ser-7 in the human enzyme. Ser-7 becomes phosphorylated before initiation of transcription at promoter regions. We identify cyclin-dependent kinase 7 (CDK7) as one responsible kinase. Phosphorylation of both Ser-5 and Ser-7 is fully dependent on the cofactor complex Mediator. A subform of Mediator associated with an active RNAPII is critical for preinitiation complex formation and CTD phosphorylation. The Mediator-RNAPII complex independently recruits TFIIB and CDK7 to core promoter regions. CDK7 phosphorylates Ser-7 selectively in the context of an intact preinitiation complex. CDK7 is not the only kinase that can modify Ser-7 of the CTD. ChIP experiments with chemical inhibitors provide evidence that other yet to be identified kinases further phosphorylate Ser-7 in coding regions.