The Medicago CDKC;1-CYCLINT;1 kinase complex phosphorylates the carboxy-terminal domain of RNA polymerase II and promotes transcription

Katalin Fülöp, Aladàr Pettkó-Szandtner, Zoltán Magyar, Pál Miskolczi, Éva Kondorosi, Dénes Dudits, Lészló Bakó

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

The Ms;CDKC;1 kinase is structurally similar to those cyclin-dependent kinases (CDKs) that are not involved directly in cell cycle regulation. The presence of a PITAIRE motif in Ms;CDKC;1 suggests that it interacts with cyclins different from known PSTAIRE/PPTALRE kinase regulatory subunits. Here we demonstrate that a Medicago CYCLINT (CYCT) protein is a specific interactor of Ms;CDKC;1 and the interaction between these two proteins gives rise to an active kinase complex that localizes to the nucleus and phosphorylates the carboxy-terminal YSPTSPS heptapeptide repeat domain (CTD) of the largest subunit of RNA polymerase II in vitro. Mutation of Ser to Ala at position 5 within the heptapeptide repeat abolishes substrate phosphorylation by the Ms;CDKC;1 kinase complex. Furthermore, our data show that addition of the Medicago CDKC;1-CYCT;1 heterodimer completely restored the transcriptional activity of a HeLa nuclear extract depleted of endogeneous CDK9 kinase complexes. Together, these results indicate that the Medicago CDKC;1-CYCT;1 complex is a positive regulator of transcription in plants and has a role similar to the CDK9/cyclin T complex of human positive transcription elongation factor P-TEFb.

Original languageEnglish
Pages (from-to)810-820
Number of pages11
JournalPlant Journal
Volume42
Issue number6
DOIs
Publication statusPublished - Jun 1 2005

Keywords

  • CDK-cyclin complex
  • CTD kinase
  • Cell cycle
  • Medicago
  • P-TEFb
  • Transcription

ASJC Scopus subject areas

  • Genetics
  • Plant Science
  • Cell Biology

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