title: The rice cyclin-dependent kinase-activating kinase R2 regulates S-phase progression.
abstract: Cyclin-dependent kinases (CDKs) are the central components of eukaryotic cell cycle regulation. Phosphorylation of CDKs at a conserved threonine residue is required for their full activity and is mediated by a CDK-activating kinase (CAK). The CAK R2 from rice belongs to those CAKs that phosphorylate not only CDKs but also the C-terminal domain (CTD) of RNA polymerase II. We showed that R2 is a nuclear protein with increased expression and increased CTD kinase activity in S-phase. Increasing R2 abundance through a transgenic approach accelerated S-phase progression and overall growth rate in suspension cells. In planta, the CTD kinase activity of R2 was induced by a growth-promoting signal. R2 regulation, therefore, may constitute a plant-specific adaptive mechanism that is used to adjust the rate of cell proliferation in response to a changing environment.
authors.affiliation: Institut für Allgemeine Botanik, Universität Hamburg, Ohnhorststrasse 18, 22609 Hamburg, Germany.
authors.forename: Tanja
authors.initials: T
authors.lastname: Fabian-Marwedel
authors.forename: Masaaki
authors.initials: M
authors.lastname: Umeda
authors.forename: Margret
authors.initials: M
authors.lastname: Sauter
mesh_terms: D000222:Adaptation, Physiological; D016203:CDC2 Protein Kinase / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics; D002478:Cells, Cultured; D018844:Cyclin-Dependent Kinases / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D009687:Nuclear Proteins / Q000235:genetics; D012275:Oryza / Q000201:enzymology / Q000235:genetics*; D030821:Plants, Genetically Modified; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D018749:RNA, Plant / Q000032:analysis; D016196:S Phase / Q000235:genetics* / Q000502:physiology; D013045:Species Specificity; D000095043:Cyclin-Dependent Kinase-Activating Kinase
chemical_list: D018797:Cell Cycle Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; D017346:Protein Serine-Threonine Kinases; D016203:CDC2 Protein Kinase; D018844:Cyclin-Dependent Kinases; D000095043:Cyclin-Dependent Kinase-Activating Kinase