The Medicago CDKC;1-CYCLINT;1 kinase complex phosphorylates the carboxy-terminal domain of RNA polymerase II and promotes transcription.
2005 (English)In: Plant Journal, ISSN 0960-7412, Vol. 42, no 6, 810-20 p.Article in journal (Refereed) Published
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.
Place, publisher, year, edition, pages
2005. Vol. 42, no 6, 810-20 p.
Amino Acid Sequence, Cell Nucleus/metabolism, Cyclin-Dependent Kinases/metabolism, Cyclins/metabolism, Gene Expression Regulation; Plant, Hela Cells, Humans, Medicago/*enzymology, Molecular Sequence Data, Multienzyme Complexes/*metabolism, Plant Proteins/*metabolism, RNA Polymerase II/*metabolism, Sequence Alignment, Sequence Homology; Amino Acid, Transcription; Genetic
IdentifiersURN: urn:nbn:se:umu:diva-15843DOI: doi:10.1111/j.1365-313X.2005.02421.xPubMedID: 15941395OAI: oai:DiVA.org:umu-15843DiVA: diva2:155515