title: A cyclin-dependent protein kinase, CDKC2, colocalizes with and modulates the distribution of spliceosomal components in Arabidopsis.
abstract: Cyclin-dependent kinases (CDKs) play key regulatory roles in diverse cellular functions, including cell-cycle progression, transcription and translation. In plants, CDKs have been classified into several groups, named A through to G, but the functions of most are poorly characterized. CDKCs are known to phosphorylate the C-terminal domain (CTD) of RNA polymerase II (RNAP II), and therefore the CDKC-cyclinT (CycT) complex may have a role similar to the animal CDK9-CycT complex of the positive transcription elongation factor b (P-TEFb). However, we found that the predicted structure of the Arabidopsis CDKC2 protein is more similar to the mammalian cdc2-related kinase, CRK7, than to CDK9. CRK7 is proposed to link transcription with splicing, and CDKC2 contains all the structural features of CRK7 that make the latter distinct from CDK9. Consistent with this, we show that GFP-CDKC2 fusion proteins co-localize with spliceosomal components, that the expression of CDKC2 modifies the location of these components, and that co-localization was dependent on the transcriptional status of the cells and on CDKC2-kinase activity. We propose, therefore, that the Arabidopsis CDKC2 combines the functions of both CRK7 and CDK9, and could also couple splicing with transcription.
authors.affiliation: John Innes Centre, Colney Lane, Norwich NR4 7UH, UK.
authors.forename: Georgios
authors.initials: G
authors.lastname: Kitsios
authors.forename: Konstantinos G
authors.initials: KG
authors.lastname: Alexiou
authors.forename: Max
authors.initials: M
authors.lastname: Bush
authors.forename: Peter
authors.initials: P
authors.lastname: Shaw
authors.forename: John H
authors.initials: JH
authors.lastname: Doonan
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D040081:Protein Array Analysis; D021381:Protein Transport; D017381:Spliceosomes / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C523217:CDKC;2 protein, Arabidopsis; C588277:CRK7 protein, Arabidopsis; D018844:Cyclin-Dependent Kinases